ALBERT

Description: Multiple domain evaluation of watershed hydrology models Karthik Kumarasamy and Patrick Belmont Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-121,2017 Manuscript under review for HESS (discussion: open, 0 comments) Watershed scale models simulating hydrology and water quality have advanced rapidly in sophistication. Given the importance of these models to support decision-making for a wide range of environmental issues, the hydrology community is compelled to improve the metrics used to evaluate model performance. We introduce a suite of new tools and metrics for model evaluation. We propose general guidelines for selecting parameters that should be included for matching predicted flow with measured flow.

Description: Moment-based Metrics for Global Sensitivity Analysis of Hydrological Systems Aronne Dell'Oca, Monica Riva, and Alberto Guadagnini Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-90,2017 Manuscript under review for HESS (discussion: open, 0 comments) We propose new metrics to assist global sensitivity analysis of Earth systems. Our approach allows assessing the impact of model parameters on the first four statistical moments of a target model output, allowing to ascertain which parameters can affect some moments of the model output pdf while being uninfluential to others. Our approach is fully compatible with analysis in the context of model complexity reduction, design of experiment, uncertainty quantification and risk assessment.

Description: Seasonal forecasting of hydrological drought in the Limpopo Basin: a comparison of statistical methods Mathias Seibert, Bruno Merz, and Heiko Apel Hydrol. Earth Syst. Sci., 21, 1611-1629, doi:10.5194/hess-21-1611-2017, 2017 Seasonal early warning is vital for drought management in arid regions like the Limpopo Basin in southern Africa. This study shows that skilled seasonal forecasts can be achieved with statistical methods built upon driving factors for drought occurrence. These are the hydrological factors for current streamflow and meteorological drivers represented by anomalies in sea surface temperatures of the surrounding oceans, which combine to form unique combinations in the drought forecast models.

Description: A sprinkling experiment to quantify celerity-velocity differences at the hillslope scale Willem J. van Verseveld, Holly R. Barnard, Chris B. Graham, Jeffrey J. McDonnell, J. Renée Brooks, and Markus Weiler Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-125,2017 Manuscript under review for HESS (discussion: open, 0 comments) How stream water responds immediately to a rainfall or snow event while the average time it takes water to travel through the hillslope can be years or decades, is poorly understood. We assessed this difference by combining a 24 day sprinkler experiment (a tracer was applied at the start) with a process based hydrologic model. Immobile soil water, deep groundwater contribution and soil depth variability explained this difference at our hillslope site.

Description: Analysis of streamflow response to land use land cover changes using satellite data and hydrological modelling: case study of Dinder and Rahad tributaries of the Blue Nile (Ethiopia/Sudan) Khalid Hassaballah, Yasir Mohamed, Stefan Uhlenbrook, and Khalid Biro Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-128,2017 Manuscript under review for HESS (discussion: open, 0 comments) The Dinder and Rahad experienced significant hydrological changes during recent years. This is claimed to be due to land use land cover changes (LULCC). Specific studies on LULCC in the Dinder and Rahad basins are still missing. This paper aims to understand the LULCC in the Dinder and Rahad and its implications on streamflow using satellite data and hydrological modelling. We expect that this study will be of high importance for decision making related to water resources planning and management.

Description: A conceptual prediction model of seasonal drought processes using atmospheric and oceanic Standardized Anomalies: application in four recent severe drought events in China Zhenchen Liu, Guihua Lu, Hai He, Zhiyong Wu, and Jian He Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-136,2017 Manuscript under review for HESS (discussion: open, 0 comments) Process prediction of seasonal drought is the goal of our study. We developed a drought prediction model based on atmospheric/oceanic anomalies. It is essentially the synchronous statistical relationship between atmospheric/oceanic anomalies and precipitation anomalies, forced by seasonal climate forecast models. It can predict seasonal drought development very well, despite its weakness in drought severity.

Description: A national-scale seasonal hydrological forecast system: development and evaluation over Britain Victoria A. Bell, Helen N. Davies, Alison L. Kay, Anca Brookshaw, and Adam A. Scaife Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-154,2017 Manuscript under review for HESS (discussion: open, 0 comments) The research presented here provides the first evaluation of the skill of a seasonal hydrological forecast for the UK. The forecast scheme combines rainfall forecasts from the Met Office GloSea5 forecast system with a national-scale hydrological model to provide estimates of river flows 1 to 3 months ahead. The skill in the combined model is assessed for different seasons and regions of Britain, and the analysis indicates that Autumn/Winter flows can be forecast with reasonable confidence.

Description: High-magnitude flooding across Britain since AD 1750 Neil Macdonald and Heather Sangster Hydrol. Earth Syst. Sci., 21, 1631-1650, doi:10.5194/hess-21-1631-2017, 2017 We use historical records to extend current understanding of flood risk, examining past spatial and temporal variability and ask are the perceived high-magnitude flood events witnessed in recent years really unprecedented? We identify that there are statistically significant relationships between the British flood index and climatic drivers, whereby the largest floods often transcend single catchments affecting regions and that the current flood-rich period is not unprecedented.

Description: Heterogeneity measures in hydrological frequency analysis: review and new developments Ana I. Requena, Fateh Chebana, and Taha B. M. J. Ouarda Hydrol. Earth Syst. Sci., 21, 1651-1668, doi:10.5194/hess-21-1651-2017, 2017 The notion of a measure to quantify the degree of heterogeneity of a region from which information is required to estimate the magnitude of events at ungauged sites is introduced. These heterogeneity measures are needed to compare regions, evaluate the impact of particular sites, and rank the performance of delineating methods. A framework to define and assess their desirable properties is proposed. Several heterogeneity measures are presented and/or developed to be assessed, giving guidelines.

Description: Long-term projections of global water use for electricity generation under the Shared Socioeconomic Pathways and climate mitigation scenarios Nozomi Ando, Sayaka Yoshikawa, Shinichiro Fujimori, and Shinjiro Kanae Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-27,2017 Manuscript under review for HESS (discussion: open, 0 comments) Electricity generation may become a key factor that accelerates water scarcity. In this study, we estimated the future global water use for electricity generation from 2005 to 2100 in 17 global sub-regions. Consequently, We indicated that the socioeconomic changes had a larger impact on water withdrawal and consumption for electricity generation, compared with the climate mitigation changes represented by the climate mitigation scenarios.

Description: Recent changes in terrestrial water storage in the Upper Nile Basin: an evaluation of commonly used gridded GRACE products Mohammad Shamsudduha, Richard G. Taylor, Darren Jones, Laurent Longuevergne, Michael Owor, and Callist Tindimugaya Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-146,2017 Manuscript under review for HESS (discussion: open, 0 comments) This study tests the ability of five commonly used GRACE satellite datasets to measure a large and accurately observed reduction in water storage of 75 km 3 that occurred in the Lake Victoria Basin of East Africa from 2004 to 2006. Substantial differences among the datasets to represent the amplitude of this change in the total terrestrial water storage are revealed. Resolving changes in groundwater storage specifically from GRACE data is hindered by uncertainty in simulated soil moisture data.

Description: The Future of Earth Observation in Hydrology Matthew F. McCabe, Matthew Rodell, Douglas E. Alsdorf, Diego G. Miralles, Remko Uijlenhoet, Wolfgang Wagner, Arko Lucieer, Rasmus Houborg, Niko E. C. Verhoest, Trenton E. Franz, Jiancheng Shi, Huilin Gao, and Eric F. Wood Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-54,2017 Manuscript under review for HESS (discussion: open, 0 comments) We examine the opportunities and challenges that technological advances in Earth observation will present to the hydrological community. From advanced space-based sensors, to unmanned aerial vehicles and ground-based distributed networks, these emergent systems are set to revolutionise our understanding and interpretation of hydrological and related processes.

Description: Soil Moisture Estimation Based on Probabilistic Inversion over Heterogeneous Vegetated Fields Using Airborne PLMR Brightness Temperature Chunfeng Ma, Xin Li, and Shuguo Wang Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-34,2017 Manuscript under review for HESS (discussion: open, 0 comments) We present a SM estimation based on the combination of Bayesian probabilistic inversion with airborne L‐band radiometer observations. The work has obtained a desirable SM estimation and uncertainty quantification, which may offer an insight into the future SM inversion based on passive microwave remote sensing.

Description: The challenge of forecasting impacts of flash floods: test of a simplified hydraulic approach and validation based on insurance claim data Guillaume Le Bihan, Olivier Payrastre, Eric Gaume, David Moncoulon, and Frederic Pons Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-344,2017 Manuscript under review for HESS (discussion: open, 0 comments) This paper illustrates how an integrated flash flood monitoring (or forecasting) system may be designed to directly provide information on possibly flooded areas and associated impacts on a very detailed river network and over large territories. The approach is extensively tested in the regions of Alès and Draguignan, located in south-eastern France. Validation results are presented in terms of accuracy of the estimated flood extents and related impacts (based on insurance claim data).

Description: Water–food–energy nexus with changing agricultural scenarios in India during recent decades Beas Barik, Subimal Ghosh, A. Saheer Sahana, Amey Pathak, and Muddu Sekhar Hydrol. Earth Syst. Sci., 21, 3041-3060, https://doi.org/10.5194/hess-21-3041-2017, 2017 The article summarises changing patterns of the water-food-energy nexus in India during recent decades. The work first analyses satellite data of water storage with a validation using the observed well data. Northern India shows a declining trend of water storage and western-central India shows an increasing trend of the same. Major droughts result in a drop in water storage which is not recovered due to uncontrolled ground water irrigation for agricultural activities even in good monsoon years.

Description: Water footprint of crop production for different crop structures in the Hebei southern plain, North China Yingmin Chu, Yanjun Shen, and Zaijian Yuan Hydrol. Earth Syst. Sci., 21, 3061-3069, https://doi.org/10.5194/hess-21-3061-2017, 2017 In this study, we analyzed the water footprint (WF) of crop production and found winter wheat, summer maize and vegetables were the top water-consuming crops in the Hebei southern plain (HSP). The total WF, WFblue, WFgreen and WFgrey for 13 years (2000–2012) of crop production were 604.8, 288.5, 141.3 and 175.0 km 3 , respectively, with an annual downtrend from 2000 to 2012. Finally, we evaluated a reasonable farming structure by analyzing scenarios of the main crops' WF.

Description: An adaptive two-stage analog/regression model for probabilistic prediction of local precipitation in France Jérémy Chardon, Benoit Hingray, and Anne-Catherine Favre Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-62,2017 Manuscript under review for HESS (discussion: open, 0 comments) We present a hybrid Statistical Downscaling Model for the probabilistic prediction of local precipitation, where the downscaling statistical link is estimated from atmospheric circulation analogs of the current prediction day. The model allows for a day-to-day adaptive and tailored downscaling. It can reveal specific predictors for peculiar and non-frequent weather configurations. This approach noticeably improves the skill of the prediction for both precipitation occurrence and quantity.

Description: Remapping annual precipitation in mountainous areas based on vegetation patterns: a case study in the Nu River basin Xing Zhou, Guang-Heng Ni, Chen Shen, and Ting Sun Hydrol. Earth Syst. Sci., 21, 999-1015, doi:10.5194/hess-21-999-2017, 2017 We develop a fusion framework to improve precipitation estimation by jointly utilizing the gauge precipitation and vegetation index and then applying them to mountainous areas of the Nu River basin. The results demonstrate the reliability of the framework in reproducing the high-resolution precipitation regime and capturing its high spatial variability in the Nu River basin. The framework can significantly reduce the errors in precipitation estimates as compared with the IDW and TRMM methods.

Description: Comparison of performance of tile drainage routines in SWAT 2009 and 2012 in an extensively tile-drained watershed in the Midwest Tian Guo, Margaret Gitau, Venkatesh Merwade, Jeffrey Arnold, Raghavan Srinivasan, Michael Hirschi, and Bernard Engel Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-52,2017 Manuscript under review for HESS (discussion: open, 0 comments) The new tile drainage routine in SWAT model provided more realistic and accurate simulation of tile drainage, and the new curve number retention parameter adjustment factor improved surface runoff simulation, and is suitable for surface runoff simulation in mildly-sloped watersheds. This study can provide guidance for selection of tile drainage routines for tile drainage simulation, and can allow accurate simulation of hydrologic systems at both field and watershed scales.

Description: Marginal cost curves for water footprint reduction in irrigated agriculture: guiding a cost-effective reduction of crop water consumption to a benchmark or permit level Abebe D. Chukalla, Maarten S. Krol, and Arjen Y. Hoekstra Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-63,2017 Manuscript under review for HESS (discussion: open, 0 comments) In the current study, we have developed a method to obtain marginal cost curves (MCCs) for WF reduction in crop production. The method is innovative by employing a model that combines soil water balance accounting and a crop growth model and assessing costs and WF reduction for all combinations of irrigation techniques, irrigation strategies and mulching practices. While this approach has been used in the field of constructing MCCs for carbon footprint reduction, this has never been done before.

Description: Identification of runoff formation with two dyes in a mid-latitude mountain headwater Lukáš Vlček, Philipp Schneider, and Kristýna Falátková Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-77,2017 Manuscript under review for HESS (discussion: open, 0 comments) The role of mountain headwater area in hydrological cycle was investigated at two opposite hillslopes covered by mineral and organic soils. Similarities and differences in percolation and preferential flowpaths between the hillslopes were identified by sprinkling experiments with Brilliant Blue and Fluorescein. The dye solutions infiltrated into the soil and continued either as lateral subsurface pipeflow (organic soil), or percolated vertically towards the bedrock (mineral soil).

Description: Geostatistical upscaling of rain gauge data to support uncertainty analysis of lumped urban hydrological models Manoranjan Muthusamy, Alma Schellart, Simon Tait, and Gerard B. M. Heuvelink Hydrol. Earth Syst. Sci., 21, 1077-1091, doi:10.5194/hess-21-1077-2017, 2017 In this study we develop a method to estimate the spatially averaged rainfall intensity together with associated level of uncertainty using geostatistical upscaling. Rainfall data collected from a cluster of eight paired rain gauges in a small urban catchment are used in this study. Results show that the prediction uncertainty comes mainly from two sources: spatial variability of rainfall and measurement error. Results from this study can be used for uncertainty analyses of hydrologic modelling.

Description: A case study of field-scale maize irrigation patterns in western Nebraska: implications for water managers and recommendations for hyper-resolution land surface modeling Justin Gibson, Trenton E. Franz, Tiejun Wang, John Gates, Patricio Grassini, Haishun Yang, and Dean Eisenhauer Hydrol. Earth Syst. Sci., 21, 1051-1062, doi:10.5194/hess-21-1051-2017, 2017 The human use of water for irrigation is often ignored in models and operational forecasts. We describe four plausible and relatively simple irrigation routines that can be coupled to the next generation of models. The routines are tested against a unique irrigation dataset from western Nebraska. The most aggressive water-saving irrigation routine indicates a potential irrigation savings of 120 mm yr −1 and yield losses of less than 3 % against the crop model benchmark and historical averages.

Description: On the consistency of scale among experiments, theory, and simulation James E. McClure, Amanda L. Dye, Cass T. Miller, and William G. Gray Hydrol. Earth Syst. Sci., 21, 1063-1076, doi:10.5194/hess-21-1063-2017, 2017 A complicating factor in describing the flow of two immiscible fluids in a porous medium is ensuring that experiments, theory, and simulation are all formulated at the same length scale. We have quantitatively analyzed the internal structure of a two-fluid system including the distribution of phases and the location of interfaces between phases. The data we have obtained allow for a clearer definition of capillary pressure at the averaged scale as a state function that describes the system.

Description: Rapid surface-water volume estimations in beaver ponds Daniel J. Karran, Cherie J. Westbrook, Joseph M. Wheaton, Carol A. Johnston, and Angela Bedard-Haughn Hydrol. Earth Syst. Sci., 21, 1039-1050, doi:10.5194/hess-21-1039-2017, 2017 Beaver ponds are found in many landscapes and their transient nature makes it difficult to account for the surface water they store using traditional methods. We found that reliable estimates of surface water storage in beaver ponds can be made with simple measurements of pond depth and surface area. This makes it possible for hydrologists and environmental managers to include beaver ponds in models and land use planning decisions without the need for resource intensive topographic surveys.

Description: Modeling nitrate from land-surface to wells' perforations under agricultural land: success, failure, and future scenarios in a Mediterranean case study Yehuda Levy, Roi H. Shapira, Benny Chefetz, and Daniel Kurtzman Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-55,2017 Manuscript under review for HESS (discussion: open, 0 comments) Nitrate-nitrogen is a groundwater contaminant worldwide, that originates commonly from agricultural fertilization. In this work, we built a computer model which follows the fate of nitrogen from land surface to deep (~ 100 m) and distant (~ km) groundwater wells. The model succeeded estimating total groundwater nitrate, yet failed to point-estimate contaminated wells, extra assumptions fixed it. This enabled prediction of future groundwater-nitrate which revealed the need to reduce fertilization.

Description: Stable isotopes reveal evaporation dynamics at the soil-plant-atmosphere interface of the critical zone Matthias Sprenger, Doerthe Tetzlaff, and Chris Soulsby Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-87,2017 Manuscript under review for HESS (discussion: open, 0 comments) We sampled the isotopic composition in the top 20 cm at four different sites in the Scottish Highlands in 5 cm intervals over one year. The relationship between the soil water isotopic fractionation and evapotranspiration showed a hysteresis pattern due to a lag response to on- and offset of the evaporative losses. The isotope data revealed that vegetation had a significant influence on the soil evaporation with evaporation being double from soils beneath Scots pine compared to heather.

Description: Systematic shifts in Budyko relationships caused by groundwater storage changes Laura E. Condon and Reed M. Maxwell Hydrol. Earth Syst. Sci., 21, 1117-1135, doi:10.5194/hess-21-1117-2017, 2017 We evaluate the impact of groundwater–surface water exchanges on the fraction of precipitation that leaves a watershed as either surface runoff or evapotranspiration. Results show that groundwater storage can systematically influence watershed behavior at the land surface. This is an important finding because most studies of tradeoffs between runoff and evapotranspiration assume that watersheds are in a steady-state condition where there are no net exchanges between the surface and subsurface.

Description: Impact of model structure on flow simulation and hydrological realism: from lumped to semi-distributed approach Federico Garavaglia, Matthieu Le Lay, Fréderic Gottardi, Rémy Garçon, Joël Gailhard, Emmanuel Paquet, and Thibault Mathevet Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-82,2017 Manuscript under review for HESS (discussion: open, 0 comments) Model intercomparison experiments are widely used to investigate and improve hydrological model performances. However, a study based only on runoff simulation is not sufficient to discriminate different model structures. Hence, there is a need to improve hydrological models for specific signatures of streamflow (e.g. low and high flow) and multivariable predictions (e.g. soil moisture, snow and groundwater). This study assesses the impact of model structure on flow simulation and hydrological realism using three versions of an hydrological model called MORDOR: the historical lumped structure and a revisited formulation inflected for lumped and semi-distributed structures. In particular, the main goal of this paper is to investigate the relative impact of model equations and spatial discretization on flow simulation, snowpack representation and evapotranspiration estimate. The models comparison is based on an extensive dataset composed of 50 catchments located in French mountainous regions. The evaluation framework is founded on a multi-criteria split sample strategy. All models were calibrated using an automatic optimization method based on an efficient genetic algorithm. The evaluation framework is enriched by the assessment of snow and evapotranspiration modeling against in-situ and satellite data. The results showed that the new model formulations perform significantly better than the initial one in terms of the various streamflow signatures, snow and evapotranspiration predictions. The semi-distributed approach provides better calibration-validation performances for snow cover area, snow water equivalent and runoff simulation especially for nival catchments.

Description: Developing a representative snow-monitoring network in a forested mountain watershed Kelly E. Gleason, Anne W. Nolin, and Travis R. Roth Hydrol. Earth Syst. Sci., 21, 1137-1147, doi:10.5194/hess-21-1137-2017, 2017 We present a coupled modeling approach used to objectively identify representative snow-monitoring locations in a forested watershed in the western Oregon Cascades mountain range. The resultant Forest Elevational Snow Transect (ForEST) represents combinations of forested and open land cover types at low, mid-, and high elevations.

Description: Improved SWAT vegetation growth module for tropical ecosystem Tadesse Alemayehu, Ann van Griensven, and Willy Bauwens Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-104,2017 Manuscript under review for HESS (discussion: open, 0 comments) The Soil and Water Assessment Tool (SWAT) is a globally applied river basin eco-hydrological simulator in a wide spectrum of studies, ranging from land use change and climate change impacts studies to research for the development of best water management practices. However, SWAT has limitations in simulating the seasonal growth cycles for trees and perennial vegetation in tropics, where the major plant growth controlling factor is the rainfall (via soil moisture) rather than temperature. Our goal is to improve the vegetation growth module of the SWAT model for simulating the vegetation parameters such as the leaf area index (LAI) for tropics. Therefore, we present a modified SWAT version for the tropics (SWAT-T) that uses of a simple but robust soil moisture index (SMI) – a quotient of the rainfall (P) and reference evapotranspiration (PET) – to initiate a new growing season after a defined dry season. Our results for the Mara Basin (Kenya/Tanzania) show that the SWAT-T simulated LAI corresponds well with the Moderate Resolution Imaging Spectroradiometer (MODIS) LAI for evergreen forest, savanna grassland and shrubs, indicating that the SMI is a reliable proxy to dynamically initiate a new growing cycle. The water balance components (evapotranspiration and flow) simulated by the SWAT-T exhibit a good agreement with remote sensing-based evapotranspiration (RS-ET) and observed flow. The SWAT-T simulator with the proposed improved vegetation growth module for tropical ecosystem could be a robust tool for several applications including land use and climate change impact studies.

Description: Landscape-scale water balance monitoring with an iGrav superconducting gravimeter in a field enclosure Andreas Güntner, Marvin Reich, Michal Mikolaj, Benjamin Creutzfeldt, Stephan Schroeder, and Hartmut Wziontek Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-103,2017 Manuscript under review for HESS (discussion: open, 0 comments) Monitoring water storage changes beyond the point scale is a challenge. Here we show that an integrative and non-invasive way is by observing variations of gravity that are induced by water mass changes. A high-precision superconducting gravimeter is successfully operated in the field and allows for direct and continuous monitoring of the water balance and of its components, such as actual evapotranspiration.

Description: Slope–Velocity–Equilibrium and evolution of surface roughness on a stony hillslope Mark A. Nearing, Viktor O. Polyakov, Mary H. Nichols, Mariano Hernandez, Li Li, Ying Zhao, and Gerardo Armendariz Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-83,2017 Manuscript under review for HESS (discussion: open, 0 comments) This study presents novel scientific understanding about the way that hillslope surfaces forms when exposed to rainfall erosion, and the way those surface interact with and influence runoff velocities during rain events. The data show that hillslope surfaces form such that flow velocities are independent of slope gradient, and only dependent on flow rates alone. This result represents a shift in thinking about surface water runoff.

Description: Stream flow simulation and verification in ungauged zones by coupling hydrological and hydrodynamic models: a case study of the Poyang Lake ungauged zone Ling Zhang, Jianzhong Lu, Xiaoling Chen, Sabine Sauvage, and José-Miguel Sanchez Perez Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-64,2017 Manuscript under review for HESS (discussion: open, 0 comments) To solve the problem of estimating and verifying stream flows without direct observation data; we extend existing techniques for estimating stream flows in ungauged zones, coupling a hydrological model with a hydrodynamic model, using the Poyang Lake basin as a test case. We simulated stream flows in the land covered area of the ungauged zone by building a SWAT model for the entire catchment area covering gauged stations and the land covered area; then estimated stream flows in the water covered area of the ungauged zone using the simplified water balance equation. To verify the results, we built two scenarios (original and adjusted scenarios) using the Delft3D model. In this study, the original scenario did not take stream flows in the ungauged zone into consideration, unlike the adjusted scenario that accounts for the ungauged zones. Experimental results show there was a narrower discrepancy between the stream flows observed at the outlet of the lake and the simulated stream flows in adjusted scenario. Using our technique, we estimated that the ungauged zone of Poyang Lake produces stream flows of approximately 180 billion m 3 ; representing about 11.4 % of the total inflow from the entire watershed. We also analysed the impact of the stream flows in ungauged zone on the water balance between inflow and outflow of the lake. These results, incorporating the estimated stream flow in ungauged zone, significantly improved the water balance as indicated by R 2 with higher value and percent bias with lower value, as compared to the results when the stream flows in the ungauged zone were not taken into account, R 2 with lower value and percent bias with higher value. The method can be extended to other lake, river, or ocean basins where observation data is unavailable.

Description: Unrepresented model errors – effect on estimated soil hydraulic material properties Stefan Jaumann and Kurt Roth Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-109,2017 Manuscript under review for HESS (discussion: open, 0 comments) We investigate the quantitative effect of neglected sensor position, small-scale heterogeneity, and lateral flow on soil hydraulic material properties. Therefore, we analyze a fluctuating water table experiment in a 2D architecture (ASSESS) with increasingly complex studies based on Time Domain Reflectometry and hydraulic potential data. We found that 1D studies may yield biased parameters and that estimating sensor positions as well as small-scale heterogeneity improves the model significantly.

Description: Extending flood forecasting lead time in a large watershed by coupling WRF QPF with a distributed hydrological model Ji Li, Yangbo Chen, Huanyu Wang, Jianming Qin, Jie Li, and Sen Chiao Hydrol. Earth Syst. Sci., 21, 1279-1294, doi:10.5194/hess-21-1279-2017, 2017 Quantitative precipitation forecast produced by the WRF model has a similar pattern to that estimated by rain gauges in a southern China large watershed, hydrological model parameters should be optimized with QPF produced by WRF, and simulating floods by coupling the WRF QPF with a distributed hydrological model provides a good reference for large watershed flood warning and could benefit the flood management communities due to its longer lead time.

Description: Peatland bog pedogenesis is reflected in unsaturated hydraulic properties Tobias K. D. Weber, Sascha C. Iden, and Wolfgang Durner Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-297,2017 Manuscript under review for HESS (discussion: open, 0 comments) In ombrotrophic peatlands, the moisture content of the acrotelm (vadoze zone) controls oxygen diffusion rates, redox state, and the turnover of organic matter. Thus, variably saturated flow processes determine whether peatlands act as sinks or sources of atmospheric carbon, and modelling these processes is crucial to assess effects of changed environmental conditions on the future development of these ecosystems. We show that the Richards equation can be used to accurately describe the moisture dynamics under evaporative conditions in variably saturated peat soil, encompassing the transition from the topmost living moss layer to the decomposed peat as part of the vadose zone. Soil hydraulic properties (SHP) were identified by inverse simulation of evaporation experiments on samples from the entire acrotelm. To obtain consistent descriptions of the observations, the traditional van Genuchten–Mualem model was extended to account for non-capillary water storage and flow. We found that the SHP of the uppermost moss layer reflect a pore-size distribution (PSD) that combines three distinct pore systems of the Sphagnum moss. For deeper samples, acrotelm pedogenesis changes the shape of the SHPs due to the collapse of inter-plant pores and an infill with smaller particles. This leads to gradually more homogeneous and bi-modal PSDs with increasing depth, which in turn can serve as a proxy for increasing state of pedogenesis in peatlands. From this, we derive a nomenclature and size classification for the pore spaces of Sphagnum mosses and define inter-, intra-, and inner-plant pore spaces, with effective pore diameters of 〉 300 μm, 300–30 μm and 30–10 μm, respectively.

Description: Calibrating electromagnetic induction conductivities with time-domain reflectometry measurements Giovanna Dragonetti, Alessandro Comegna, Ali Ajeel, Gian Piero Deidda, Nicola Lamaddalena, Giuseppe Rodriguez, Giulio Vignoli, and Antonio Coppola Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-288,2017 Manuscript under review for HESS (discussion: open, 0 comments) The paper aims to infer the bulk electrical conductivity distribution in the root zone from EMI readings. TDR measurements were used as ground-truth data to evaluate the goodness of the estimations by EMI inversion. The approach is based on the mean and standard deviation of the EMI and TDR series. It looks for the physical reasons for the differences between EMI- and TDR-based electrical conductivity and provides a correction of the bias based on the statistical sources of the discrepancies.

Description: Examining the impacts of precipitation isotope input ( δ 18 O ppt ) on distributed, tracer-aided hydrological modelling Carly J. Delavau, Tricia Stadnyk, and Tegan Holmes Hydrol. Earth Syst. Sci., 21, 2595-2614, https://doi.org/10.5194/hess-21-2595-2017, 2017 Hydrological models have large amounts of uncertainty in streamflow predictions. Using extra data (e.g. isotope tracers) helps evaluate whether the model is getting the right answers for the right reasons. In a Canadian basin, three types of isotope in precipitation input are used to drive a tracer-aided model and assess the resulting model uncertainty. This study shows how a tracer-aided model can be used at the larger scale, and that the model can be of value in such regions.

Description: Sustaining the Ogallala Aquifer: From the Wells to People, A Holistic CNH Model Joseph A. Aistrup, Tom Bulatewicz, Laszlo J. Kulcsar, Jeffrey M. Peterson, Stephen M. Welch, and David R. Steward Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-300,2017 Manuscript under review for HESS (discussion: open, 0 comments) A system level theoretical approach is developed utilizing OpenMI methods to study the collective impacts of groundwater depletion in one of the world's most important regions for agricultural production (congressional district with the highest historical cash value in the USA). Water policy is analyzed to forecast groundwater depletion across changes in human activity and climate, and the economic and societal impacts are provided towards informing public policy and management.

Description: Patterns and comparisons of human-induced changes on river flood impacts in cities Stephanie Clark, Ashish Sharma, and Scott A. Sisson Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-162,2017 Manuscript under review for HESS (discussion: open, 0 comments) This study investigates global patterns relating urban river flood impacts to socioeconomic development and changing hydrologic conditions are established, and comparisons are provided between 98 individual cities. This paper condenses and communicates large amounts of information to accelerate the understanding of relationships between local urban conditions and global processes, and to potentially motivate knowledge transfer between decision makers facing similar circumstances.

Description: Scaling properties reveal regulation of river flows in the Amazon through a forest reservoir Juan F. Salazar, Juan Camilo Villegas, Angela M. Rendón, Estiven Rodríguez, Isabel Hoyos, Daniel Mercado-Bettín, and Germán Poveda Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-278,2017 Manuscript under review for HESS (discussion: open, 0 comments) River flow regimes are being altered by global change. Understanding the mechanisms behind such alterations is crucial for hydrological prediction. We introduce a novel interpretation of river flow metrics (scaling), that allows to classify any river basin as regulated or unregulated, and to identify a critical threshold between these states. We propose the forest reservoir concept to explain how forest loss can force the Amazonian river basins from regulated to unregulated states.

Description: On the Relationship Between Flood and Contributing Area Christopher Spence and Samson Girma Mengistu Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-252,2017 Manuscript under review for HESS (discussion: open, 0 comments) This research summarizes the application of a hydrological model to determine the relationships between streamflow and the area that contributes water to it. The model performed well. Results show that the frequency of streamflow events and with which areas contribute are not necessarily the same. There are implications from this research for determining the sources of water and nutrients available downstream in lakes vulnerable to eutrophication.

Description: Quantification of surface water volume changes in the Mackenzie Delta using satellite multi-mission data Cassandra Normandin, Frédéric Frappart, Bertrand Lubac, Simon Bélanger, Vincent Marieu, Fabien Blarel, Arthur Robinet, and Léa Guiastrennec-Faugas Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-170,2017 Manuscript under review for HESS (discussion: open, 0 comments) Quantification of surface water storage in extensive floodplains and their dynamics are crucial for a better understanding of global hydrological and biogeochemical cycles. In this study, we present estimates of both surface water extent and storage combining multi-missions remotely-sensed observations and their temporal evolution over more than 15 years in the Mackenzie Delta. The Mackenzie Delta is located in the North West of Canada and is the second largest delta in the Arctic Ocean. The delta is frozen from October to May and the recurrent ice break up provokes an increase of the river's flows. Thus, this phenomenon causes intensive floods along the delta every year with dramatic environmental impacts. In this study, the dynamics of surface water extent and volume analyzed from 2000 to 2015 by combining multi-satellite information from MODIS multispectral images at 500 m spatial resolution and river stages derived from ERS-2 (1995–2003), ENVISAT (2002–2010) and SARAL (since 2013) altimetry data. The surface water extent (permanent water and flooded area) peaked in June with an area of 9,600 km 2 (±200 km 2 ) on average, representing approximately 70 % of the delta's total surface. Altimetry-based water levels exhibit annual amplitudes ranging from 4 m in the downstream part to more than 10 m in the upstream part of the Mackenzie Delta. A high overall correlation between the satellite-derived and in situ water heights (R〉0.84) is found for the three altimetry missions. Finally, using altimetry-based water levels and MODIS-derived surface water extents, maps of interpolated water heights over the surface water extents are produced. Results indicate a high variability of the water height magnitude that can reach 10 meters compared to the lowest water height in the upstream part of the delta during the flood peak in June. Furthermore, the total surface water volume is estimated and shows an annual variation of approximately 8.5 km 3 during the whole study period, with a maximum of 14.4 km 3 observed in 2006. The good agreement between the total surface water volume retrievals and in situ river discharges (R=0.66) allows validating this innovative multi-mission approach and highlights the high potential to study the surface water extent dynamics.

Description: Hydrology of inland tropical lowlands: the Kapuas and Mahakam wetlands Hidayat Hidayat, Adriaan J. Teuling, Bart Vermeulen, Muh Taufik, Karl Kastner, Tjitske J. Geertsema, Dinja C. C. Bol, Dirk H. Hoekman, Gadis Sri Haryani, Henny A. J. Van Lanen, Robert M. Delinom, Roel Dijksma, Gusti Z. Anshari, Nining S. Ningsih, Remko Uijlenhoet, and Antonius J. F. Hoitink Hydrol. Earth Syst. Sci., 21, 2579-2594, https://doi.org/10.5194/hess-21-2579-2017, 2017 Hydrological prediction is crucial but in tropical lowland it is difficult, considering data scarcity and river system complexity. This study offers a view of the hydrology of two tropical lowlands in Indonesia. Both lowlands exhibit the important role of upstream wetlands in regulating the flow downstream. We expect that this work facilitates a better prediction of fire-prone conditions in these regions.

Description: Development of a hydrological ensemble prediction system and a visualization approach for improved interpretation during typhoon events Sheng-Chi Yang, Tsun-Hua Yang, Ya-Chi Chang, Cheng-Hsin Chen, Mei-Ying Lin, Jui-Yi Ho, and Kwan-Tun Lee Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-264,2017 Manuscript under review for HESS (discussion: open, 0 comments) This study proposes a system to produce assessments of surface runoff and the associated flooding and it also presents an modified visualization methodology to interpret the forecast results for operational purposes. The system and methodology have been applied in a watershed in Taiwan. The proposed system and the modified visualization approach have demonstrated their potential for both decreasing the uncertainty of numerical rainfall forecasts and improving the performance of flood forecasts.

Description: A large set of potential past, present and future hydro-meteorological time series for the UK Benoit P. Guillod, Richard G. Jones, Simon J. Dadson, Gemma Coxon, Gianbattista Bussi, James Freer, Alison L. Kay, Neil R. Massey, Sarah N. Sparrow, David C. H. Wallom, Myles R. Allen, and Jim W. Hall Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-246,2017 Manuscript under review for HESS (discussion: open, 0 comments) Assessing the potential impacts of extreme events such as drought and flood requires large datasets of such events, especially when looking at the most severe and rare events. Using a state-of-the-art climate modelling infrastructure that is simulating large numbers of weather time series on volunteers' computers, we generate such a large dataset for the United Kingdom. The dataset covers the recent past (1900–2006) as well as two future time periods (2030s and 2080s).

Description: Reviving the “Ganges Water Machine”: where and how much? Lal Muthuwatta, Upali A. Amarasinghe, Aditya Sood, and Lagudu Surinaidu Hydrol. Earth Syst. Sci., 21, 2545-2557, https://doi.org/10.5194/hess-21-2545-2017, 2017 Agricultural production in the Ganges River basin is affected by the water shortage in the dry months, while the excess water during the rainy season causes floods in the downstream. Annual total surface runoff generated in the basin is about 298 ± 99 Bm3, and runoff in the monsoon months contributes up to 80 % of this total runoff. Comparison of sub-basin-wise surface runoff with the estimated unmet water demand indicated that capturing only a portion of the wet-season runoff would be sufficient.

Description: Assessment of extreme flood events in a changing climate for a long-term planning of socio-economic infrastructure in the Russian Arctic Elena Shevnina, Ekaterina Kourzeneva, Viktor Kovalenko, and Timo Vihma Hydrol. Earth Syst. Sci., 21, 2559-2578, https://doi.org/10.5194/hess-21-2559-2017, 2017 This paper presents the probabilistic approach to evaluate design floods in a changing climate, adapted in this case to the northern territories. For the Russian Arctic, the regions are delineated, where it is suggested to correct engineering hydrological calculations to account for climate change. An example of the calculation of a maximal discharge of 1 % exceedance probability for the Nadym River at Nadym is provided.

Description: Role of forcing uncertainty and background model error characterization in snow data assimilation Sujay V. Kumar, Jiarui Dong, Christa D. Peters-Lidard, David Mocko, and Breogán Gómez Hydrol. Earth Syst. Sci., 21, 2637-2647, https://doi.org/10.5194/hess-21-2637-2017, 2017 Data assimilation deals with the blending of model forecasts and observations based on their relative errors. This paper addresses the importance of accurately representing the errors in the model forecasts for skillful data assimilation performance.

Description: Estimating extreme river discharges in Europe through a Bayesian network Dominik Paprotny and Oswaldo Morales-Nápoles Hydrol. Earth Syst. Sci., 21, 2615-2636, https://doi.org/10.5194/hess-21-2615-2017, 2017 Large-scale hydrological modelling of flood hazards requires adequate extreme discharge data. In practise, models based on physics are applied alongside those utilizing only statistical analysis. The former require enormous computational power, while the latter are mostly limited in accuracy and spatial coverage. In this paper we introduce an alternate, statistical approach based on Bayesian networks (BNs), a graphical model for dependent random variables. We use a non-parametric BN to describe the joint distribution of extreme discharges in European rivers and variables representing the geographical characteristics of their catchments. Annual maxima of daily discharges from more than 1800 river gauges (stations with catchment areas ranging from 1.4 to 807 000 km 2 ) were collected, together with information on terrain, land use and local climate. The (conditional) correlations between the variables are modelled through copulas, with the dependency structure defined in the network. The results show that using this method, mean annual maxima and return periods of discharges could be estimated with an accuracy similar to existing studies using physical models for Europe and better than a comparable global statistical model. Performance of the model varies slightly between regions of Europe, but is consistent between different time periods, and remains the same in a split-sample validation. Though discharge prediction under climate change is not the main scope of this paper, the BN was applied to a large domain covering all sizes of rivers in the continent both for present and future climate, as an example. Results show substantial variation in the influence of climate change on river discharges. The model can be used to provide quick estimates of extreme discharges at any location for the purpose of obtaining input information for hydraulic modelling.

Description: Hydrological characterization of cave drip waters in a porous limestone: Golgotha Cave, Western Australia Kashif Mahmud, Gregoire Mariethoz, Andy Baker, and Pauline C. Treble Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-127,2017 Manuscript under review for HESS (discussion: open, 0 comments) This study explores the relationship between drip water and rainfall in a SW Australian karst, where both intra- and inter-annual hydrological variations are strongly controlled by seasonal variations in recharge. The hydrological behaviour of cave drips is examined at daily resolution with respect to mean discharge and the flow variation. We demonstrate that the analysis of the time series produced by cave drip loggers generates useful hydrogeological information that can be applied generally.

Description: Hydrogeological effects of dredging navigable canals through lagoon shallows. A case study in Venice Pietro Teatini, Giovanni Isotton, Stefano Nardean, Massimiliano Ferronato, Annamaria Mazzia, Cristina Da Lio, Luca Zaggia, Debora Bellafiore, Massimo Zecchin, Luca Baradello, Francisco Cellone, Fabiana Corami, Andrea Gambaro, Giovanni Libralato, Elisa Morabito, Annamaria Volpi Ghirardini, Riccardo Broglia, Stefano Zaghi, and Luigi Tosi Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-317,2017 Manuscript under review for HESS (discussion: open, 0 comments) We investigate the effects of digging a navigable canal on the hydrogeological system underlying a coastal lagoon. The research has been promoted by the Water Venice Authority who is investigating different possibilities to avoide the passage of large cruise ships through the historic centre of Venice, Italy. Numerical simulations supported by a proper hydrogeological characterization show that the exchange of water and contaminants from the subsurface and surface systems will be significanced.

Description: SWAT-CUP for Calibration of Spatially Distributed Hydrological Processes and Ecosystem Services in a Vietnamese River Basin Using Remote Sensing Lan T. Ha, Wim G. M. Bastiaanssen, Ann van Griensven, Albert I. J. M. van Dijk, and Gabriel B. Senay Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-251,2017 Manuscript under review for HESS (discussion: open, 0 comments) The paper shows a new approach in calibrating hydrological model using remote sensing data from open access sources. The innovation is that the parameters of the soil-vegetation processes were optimized that will make SWAT a useful tool for optimizing water conservation, agricultural outputs, and ecosystem services such as reduced soil erosion, better water quality standards, carbon sequestration, micro-climate cooling and appraising scenarios of green growth.

Description: Ross scheme, Newton–Raphson iterative methods and time-stepping strategies for solving the mixed form of Richards' equation Fadji Hassane Maina and Philippe Ackerer Hydrol. Earth Syst. Sci., 21, 2667-2683, https://doi.org/10.5194/hess-21-2667-2017, 2017 In many fields like climate change, hydrology and agronomy, water movement in unsaturated soils is usually simulated using the Richards equation. However, this equation requires lot of computational effort to be solved due to its highly nonlinear behavior, which hampers its use in simulations. In this paper, we analyze and developed some numerical strategies and we evaluate their reliability and efficiency.

Description: Does Nonstationarity in Rainfall Requires Nonstationary Intensity-Duration-Frequency Curves? Poulomi Ganguli and Paulin Coulibaly Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-325,2017 Manuscript under review for HESS (discussion: open, 0 comments) Using statistical models, we test whether nonstationary versus stationary models show any significant differences in design storm estimates at different durations across Southern Ontario. We find that signatures of nonstationarity in rainfall extremes do not necessarily imply the use of nonstationary IDFs for design considerations. An update an order of 2 ~ 30 % is required in current design standards based on return periods to mitigate the risk of storm-induced urban flooding.

Description: Spatial Extent of Future Changes in the Hydrologic Cycle Components in Ganga Basin using Ranked CORDEX RCMs Jatin Anand, Manjula Devak, Ashwini Kumar Gosain, Rakesh Khosa, and Chandrika Thulaseedharan Dhanya Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-189,2017 Manuscript under review for HESS (discussion: open, 0 comments) Impact assessment of future climate change on hydrologic response is essential while carrying out management and adaptation strategies in a changing climate. We adopted a multi-criteria ranking approach to select few suitable climate models from the CORDEX community, to reduce the huge uncertainty in the future projections. We deployed a hydrologic model to simulate the hydrology of Ganga basin and quantified the future dramatic changes in different hydrological sub-system and its mass-transfer.

Description: Minimum forest cover for sustainable water flow regulation in a watershed under rapid expansion of oil palm and rubber plantations Suria Tarigan, Kerstin Wiegand, and Sunarti Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-116,2017 Manuscript under review for HESS (discussion: open, 0 comments) In respect of the rapid expansion of the oil palm plantation and its negative impact on water flow regulation, the government in Indonesia is questioning the minimum proportion of the forest cover and the maximum area of the oil palm in a watershed for acceptable water flow regulation of the watershed. This paper will be the first publication to answer this very crucial question and to help spatial planner to manage scientifically based land cover in a watershed.

Description: A coupled human-natural system to assess the operational value of weather and climate services for irrigated agriculture Yu Li, Matteo Giuliani, and Andrea Castelletti Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-304,2017 Manuscript under review for HESS (discussion: open, 0 comments) The paper contributes a comparative analysis of the operational value of different forecast products for the agricultural sector. The underlying idea is that accuracy per se might not be the most effective indicator of the goodness of a forecast but the behaviour of the farmers using the forecast should somehow also be taken into consideration and, correspondingly, the benefit generated by the forecast. This paper explores and validates this idea with a model based analysis.

Description: Evaluating climate change impacts on streamflow variability based on a multisite multivariate GCM downscaling method Zhi Li and Jiming Jin Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-295,2017 Manuscript under review for HESS (discussion: open, 0 comments) We developed an efficient multisite and multivariate GCM downscaling method and generated climate change scenarios for SWAT to evaluate the streamflow variability within a watershed in China. The application of the ensemble techniques enables us to better quantify the model uncertainties. The peak values of precipitation and streamflow have a tendency to shift from the summer to spring season over the next 30 years. The number of extreme flooding and drought events will increase.

Description: Development of a monthly to seasonal forecast framework tailored to inland waterway transport in Central Europe Dennis Meißner, Bastian Klein, and Monica Ionita Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-293,2017 Manuscript under review for HESS (discussion: open, 1 comment) Inland waterway transport is a commercial sector relying on hydrological forecasts on different time-scales. This manuscript describes the set-up of a monthly to seasonal forecasting system for the German waterways. Multiple approaches are tested, compared and combined. Despite the predictive limitations on longer lead-times, this study reveals the existence of a valuable predictability at monthly up to seasonal time-scales. Forecast quality depends on forecast location, lead-time and season.

Description: Technical Note: Combining Quantile Forecasts and Predictive Distributions of Stream-flows Konrad Bogner, Katharina Liechti, and Massimiliano Zappa Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-291,2017 Manuscript under review for HESS (discussion: open, 0 comments) The enhanced availability of many different weather prediction systems nowadays makes it very difficult for flood and water resources managers to choose the most reliable and accurate forecast. In order to circumvent this problem of choice different approaches for combining this information have been applied at the Sihl river (CH) and the results have been verified. The outcome of this study highlights the importance of forecast combination in order to improve the quality of forecast systems.

Description: Exploration of virtual catchments approach for runoff predictions of ungauged catchments Jun Zhang, Dawei Han, Yang Song, and Qiang Dai Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-289,2017 Manuscript under review for HESS (discussion: open, 0 comments) We explore unit hydrograph (UH) affected by geomorphology that could be used in ungauged catchments. Virtual catchments approach (VCA) is used instead of gauged catchments in runoff modelling. Catchment shape is newly introduced and the agreement of the results with the hydrological principles verifies the reliability of VCA. With the robust VCA, a large amount of catchments can be created with desirable features to explore a more comprehensive equation that can be used in ungauged catchments.

Description: Experimental determination of the flood wave transformation and the sediment resuspension in a small regulated stream in an agricultural catchment David Zumr, Tomáš Dostál, Jan Devátý, Petr Valenta, Pavel Rosenforf, Alexander Eder, and Peter Strauss Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-266,2017 Manuscript under review for HESS (discussion: open, 0 comments) Intensively cultivated landscape is the main non-point source of the eroded sediment. The soil particles, carrying bounded nutrients and pollutants, cause both environmental and economic problems downstream. We did several flooding experiments in a typical rural drainage channel to show, how the eroded sediment behaves in the headwater streams during spring and summer. We conclude that the channel behaves as a sediment trap during summer. In spring the sediment moves quickly.

Description: Data-based mechanistic model of catchment phosphorus load improves predictions of storm transfers and annual loads in surface waters Mary C. Ockenden, Wlodek Tych, Keith J. Beven, Adrian L. Collins, Robert Evans, Peter D. Falloon, Kirsty J. Forber, Kevin M. Hiscock, Michael J. Hollaway, Ron Kahana, Kit J. A. Macleod, Martha L. Villamizar, Catherine Wearing, Paul J. A. Withers, Jian G. Zhou, Sean Burke, Richard J. Cooper, Jim E. Freer, and Philip M. Haygarth Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-314,2017 Manuscript under review for HESS (discussion: open, 0 comments) This paper describes simple models of phosphorus load which are identified for three catchments in the UK. The models use new hourly observations of phosphorus load, which capture the dynamics of phosphorus transfer in small catchments that are often missed by models with a longer timestep. Unlike more complex, process-based models, very few parameters are required, leading to low parameter uncertainty. Interpretation of the dominant phosphorus transfer modes is made based solely on the data.

Description: Microwave implementation of two-source energy balance approach for estimating evapotranspiration Thomas R. Holmes, Christopher Hain, Wade T. Crow, Martha C. Anderson, and William P. Kustas Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-301,2017 Manuscript under review for HESS (discussion: open, 0 comments) In an effort to apply cloud tolerant microwave data to satellite based monitoring of evapotranspiration (ET), this study reports on an experiment where microwave-based land surface temperature is used as the key diagnostic input to a two-source energy balance method for the estimation of ET. Comparisons of this microwave ET with the conventional thermal infrared estimates show widespread agreement in spatial and temporal patterns from seasonal to inter-annual time scales over Africa and Europe.

Description: A dimensionless approach for the runoff peak assessment: effects of the rainfall event structure Ilaria Gnecco, Anna Palla, and Paolo La Barbera Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-267,2017 Manuscript under review for HESS (discussion: open, 0 comments) The paper proposes a dimensionless analytical framework to predict the hydrologic response of a given catchment thus assessing the impact of the rainfall event structure on the runoff peak. A set of analytical expressions are derived for constant-intensity hyetograph to assess the highest runoff peak for a given rainfall event structure irrespective of the specific catchment. The approach has been applied to a real catchment for rainfall events characterized by different internal structure.

Description: Precipitation Pattern in the Western Himalayas revealed by Four Datasets Hong Li, Jan Erik Haugen, and Chongyu Xu Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-296,2017 Manuscript under review for HESS (discussion: open, 0 comments) Precipitation is a key on the water system and glacier fate in the great Himalayas Region. We examine four datasets of available types in Western Himalayas and they show very large differences. The differences much depend on the data source are particularly large in monsoon seasons and high elevation areas. All the datasets show a trend to wetter summer and drier winter based and this trend reveals a tendency towards a high flow seasonality and an unfavorable condition for glaciers.

Description: How can expert knowledge increase the realism of conceptual hydrological models? A case study in the Swiss Pre-Alps Manuel Antonetti and Massimiliano Zappa Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-322,2017 Manuscript under review for HESS (discussion: open, 0 comments) We developed 60 modelling chain combinations based on either experimentalist’s (bottom-up) or modellers’ (top-down) thinking and forced them with data of increasing accuracy. Results showed that the differences in performance arising from the forcing data were due to compensation effects. We also found that modellers’ and experimentalists’ concept of "model realism" differs, and the level of detail a model should have to reproduce the processes expected must be agreed in advance.

Description: Dead Sea evaporation by eddy covariance measurements versus aerodynamic, energy budget, Priestley–Taylor, and Penman estimates Jutta Metzger, Manuela Nied, Ulrich Corsmeier, Jörg Kleffmann, and Christoph Kottmeier Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-187,2017 Manuscript under review for HESS (discussion: open, 0 comments) This paper is motivated by the need for more precise evaporation rates from the Dead Sea water surface and methods to estimate and forecast the evaporation. This study provides an applicable method to investigate the diurnal and intra-annual variability of evaporation using an onshore eddy covariance system. Furthermore, it shows that the aerodynamic method provides best evaporation results when using shoreline data and is at the same time a cost-efficient method.

Description: A multi-sensor data-driven methodology for all-sky passive microwave inundation retrieval Zeinab Takbiri, Ardeshir M. Ebtehaj, and Efi Foufoula-Georgiou Hydrol. Earth Syst. Sci., 21, 2685-2700, https://doi.org/10.5194/hess-21-2685-2017, 2017 We present a multi-sensor retrieval algorithm for flood extent mapping at high spatial and temporal resolution. While visible bands provide flood mapping at fine spatial resolution, their capability is very limited in a cloudy sky. Passive microwaves can penetrate through clouds but cannot detect small-scale flooded surfaces due to their coarse resolution. The proposed method takes advantage of these two observations to retrieve sub-pixel flooded surfaces in all-sky conditions.

Description: Multivariate statistical modelling of compound events via pair-copula constructions: analysis of floods in Ravenna (Italy) Emanuele Bevacqua, Douglas Maraun, Ingrid Hobæk Haff, Martin Widmann, and Mathieu Vrac Hydrol. Earth Syst. Sci., 21, 2701-2723, https://doi.org/10.5194/hess-21-2701-2017, 2017 We develop a conceptual model to quantify the risk of compound events (CEs), i.e. extreme impacts to society which are driven by statistically dependent climatic variables. Based on this model we study compound floods, i.e. joint storm surge and high river level, in Ravenna (Italy). The model includes meteorological predictors which (1) provide insight into the physical processes underlying CEs, as well as into the temporal variability, and (2) allow us to statistically downscale CEs.

Description: Land surface model performance using cosmic-ray and point-scale soil moisture measurements for calibration Joost Iwema, Rafael Rosolem, Mostaquimur Rahman, Eleanor Blyth, and Thorsten Wagener Hydrol. Earth Syst. Sci., 21, 2843-2861, https://doi.org/10.5194/hess-21-2843-2017, 2017 We investigated whether the simulation of water flux from the land surface to the atmosphere (using the Joint UK Land Environment Simulator model) could be improved by replacing traditional soil moisture sensor data with data from the more novel Cosmic-Ray Neutron soil moisture sensor. Despite observed differences between the two types of soil moisture measurement data, we found no substantial differences in improvement in water flux estimation, based on multiple calibration experiments.

Description: Hydrological threats to riparian wetlands of international importance – a global quantitative and qualitative analysis Christof Schneider, Martina Flörke, Lucia De Stefano, and Jacob D. Petersen-Perlman Hydrol. Earth Syst. Sci., 21, 2799-2815, https://doi.org/10.5194/hess-21-2799-2017, 2017 Riparian wetlands are disappearing worldwide due to altered river flow regimes. The WaterGAP3 modeling framework is used to compare modified to natural flow regimes at 93 Ramsar sites. Results indicate that water resource management seriously impairs inundation patterns at 29 % of the sites. New dam initiatives are likely to affect especially wetlands located in South America, Asia, and the Balkan Peninsula. Hotspots for climate change impacts could be eastern Europe and South America.

Description: Saturated hydraulic conductivity model computed from bimodal water retention curves for a range of New Zealand soils Joseph Alexander Paul Pollacco, Trevor Webb, Stephen McNeill, Wei Hu, Sam Carrick, Allan Hewitt, and Linda Lilburne Hydrol. Earth Syst. Sci., 21, 2725-2737, https://doi.org/10.5194/hess-21-2725-2017, 2017 Descriptions of soil hydraulic properties, such as soil moisture release curve, θ ( h ), and saturated hydraulic conductivities, K s , are a prerequisite for hydrological models. Because it is usually more difficult to describe K s than θ ( h ) from pedotransfer functions, we developed a physical unimodal model to compute K s solely from hydraulic parameters derived from the Kosugi θ ( h ). We further adaptations to this model to adapt it to dual-porosity structural soils.

Description: A non-stationary stochastic ensemble generator for radar rainfall fields based on the short-space Fourier transform Daniele Nerini, Nikola Besic, Ioannis Sideris, Urs Germann, and Loris Foresti Hydrol. Earth Syst. Sci., 21, 2777-2797, https://doi.org/10.5194/hess-21-2777-2017, 2017 Stochastic generators are effective tools for the quantification of uncertainty in a number of applications with weather radar data, including quantitative precipitation estimation and very short-term forecasting. However, most of the current stochastic rainfall field generators cannot handle spatial non-stationarity. We propose an approach based on the short-space Fourier transform, which aims to reproduce the local spatial structure of the observed rainfall fields.

Description: Unravelling abiotic and biotic controls on the seasonal water balance using data-driven dimensionless diagnostics Simon Paul Seibert, Conrad Jackisch, Uwe Ehret, Laurent Pfister, and Erwin Zehe Hydrol. Earth Syst. Sci., 21, 2817-2841, https://doi.org/10.5194/hess-21-2817-2017, 2017 Runoff production mechanisms and their corresponding physiographic controls continue to pose major research challenges in catchment hydrology. We propose innovative data-driven diagnostic signatures for overcoming the prevailing status quo in inter-comparison studies. Specifically, we present dimensionless double mass curves which allow us to infer information on runoff generation at the seasonal and annual timescales. The method is based on commonly available data.

Description: Understanding hydrologic variability across Europe through catchment classification Anna Kuentz, Berit Arheimer, Yeshewatesfa Hundecha, and Thorsten Wagener Hydrol. Earth Syst. Sci., 21, 2863-2879, https://doi.org/10.5194/hess-21-2863-2017, 2017 Our study aims to explore and understand the physical controls on spatial patterns of pan-European flow signatures by taking advantage of large open datasets. Using tools like correlation analysis, stepwise regressions and different types of catchment classifications, we explore the relationships between catchment descriptors and flow signatures across 35 215 catchments which cover a wide range of pan-European physiographic and anthropogenic characteristics.

Description: Global evaluation of runoff from 10 state-of-the-art hydrological models Hylke E. Beck, Albert I. J. M. van Dijk, Ad de Roo, Emanuel Dutra, Gabriel Fink, Rene Orth, and Jaap Schellekens Hydrol. Earth Syst. Sci., 21, 2881-2903, https://doi.org/10.5194/hess-21-2881-2017, 2017 Runoff measurements for 966 catchments around the globe were used to assess the quality of the daily runoff estimates of 10 hydrological models run as part of tier-1 of the eartH2Observe project. We found pronounced inter-model performance differences, underscoring the importance of hydrological model uncertainty.

Description: Testing and Development of Transfer Functions for Weighing Precipitation Gauges in WMO-SPICE John Kochendorfer, Rodica Nitu, Mareile Wolff, Eva Mekis, Roy Rasmussen, Bruce Baker, Michael E. Earle, Audrey Reverdin, Kai Wong, Craig D. Smith, Daqing Yang, Yves-Alain Roulet, Tilden Meyers, Samuel Buisan, Ketil Isaksen, Ragnar Brækkan, Scott Landolt, and Al Jachcik Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-228,2017 Manuscript under review for HESS (discussion: open, 0 comments) Due to the effects of wind, precipitation gauges typically underestimate the amount of precipitation that occurs as snow. Measurements recorded during a World Meteorological Organization intercomparison of precipitation gauges were used to evaluate and improve the adjustments that are available to address this issue. Adjustments for specific types of precipitation gauges and wind shields that have never been evaluated before were tested and recommended.

Description: A global hydrological simulation to specify the sources of water used by humans Naota Hanasaki, Sayaka Yoshikawa, Yadu Pokhrel, and Shinjiro Kanae Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-280,2017 Manuscript under review for HESS (discussion: open, 0 comments) Six new schemes were added to the H08 global hydrological model (GHM) to better represent water abstraction of humanity with the closure of water balance at each grid cell at daily interval. By incorporating these six schemes, H08 has become one of the most detailed GHMs for attributing the water sources available to humanity. Among the six schemes, local reservoirs, aqueduct water transfer, and seawater desalination were incorporated into GHMs for the first time, to the best of our knowledge.

Description: Hydrogeological controls on spatial patterns of groundwater discharge in peatlands Danielle K. Hare, David F. Boutt, William P. Clement, Christine E. Hatch, Glorianna Davenport, and Alex Hackman Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-282,2017 Manuscript under review for HESS (discussion: open, 0 comments) This research examines what processes drive the location and strength of groundwater springs within a peatland environment. Using temperature and geophysical methods, we demonstrate that the relationship between regional groundwater flow gradients and the basin shape below the peatland surface control where groundwater springs occur. Understanding this relationship will support effective restoration efforts, as groundwater spring locations are important to overall peatland function and ecology.

Description: Detecting seasonal and long-term vertical displacement in the North China Plain using GRACE and GPS Linsong Wang, Chao Chen, Jinsong Du, and Tongqing Wang Hydrol. Earth Syst. Sci., 21, 2905-2922, https://doi.org/10.5194/hess-21-2905-2017, 2017 The North China Plain (NCP), as the interest region in this study, is one of the most uniformly and extensively altered areas due to overexploitation of groundwater by humans. Here, we use GRACE and GPS to study the seasonal and long-term mass change and its resulting vertical displacement. We also removed the vertical rates, which are induced by terrestrial water storage (TWS) from GPS-derived data to obtain the corrected vertical velocities caused by tectonic movement and human activities.

Description: Performance of METRIC in estimating hourly and daily evapotranspiration fluxes over an irrigated field in Saudi Arabia Rangaswamy Madugundu, Khalid A. Al-Gaadi, ElKamil Tola, Abdalhaleem A. Hassaballa, and Virupakshagouda C. Patil Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-206,2017 Manuscript under review for HESS (discussion: open, 0 comments) This paper is carried out to investigate the performance of METRIC model in the estimation of ET over alfalfa field against Eddy Covariance system measurements under hyper-arid conditions. Because of the fact that such studies are limited in the Middle-East region, where arid irrigated agricultural fields are surrounded by deserts, this paper should be of interest to readers in the areas of agriculture (in general), water management, remote sensing and precision agriculture.

Description: A Nonparametric Statistical Technique for Combining Global Precipitation Datasets: Development and Hydrological Evaluation over the Iberian Peninsula Md Abul Ehsan Bhuiyan, Efthymios I. Nikolopoulos, Emmanouil N. Anagnostou, Pere Quintana-Seguí, and Anaïs Barella-Ortiz Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-268,2017 Manuscript under review for HESS (discussion: open, 0 comments) This study investigates the use of a nonparametric model for combining multiple global precipitation datasets and characterizing estimation uncertainty. Inputs to the model included three satellite precipitation products, an atmospheric reanalysis precipitation datasets, satellite-derived near-surface daily soil moisture data and terrain elevation. We evaluated the technique based on a high-resolution reference precipitation data and further used generated ensembles to force a hydrologic model.

Description: Scaled distribution mapping: a bias correction method that preserves raw climate model projected changes Matthew B. Switanek, Peter A. Troch, Christopher L. Castro, Armin Leuprecht, Hsin-I Chang, Rajarshi Mukherjee, and Eleonora M. C. Demaria Hydrol. Earth Syst. Sci., 21, 2649-2666, https://doi.org/10.5194/hess-21-2649-2017, 2017 The commonly used bias correction method called quantile mapping assumes a constant function of error correction values between modeled and observed distributions. Our article finds that this function cannot be assumed to be constant. We propose a new bias correction method, called scaled distribution mapping, that does not rely on this assumption. Furthermore, the proposed method more explicitly accounts for the frequency of rain days and the likelihood of individual events.

Description: Water levels of the Mekong River Basin based on CryoSat-2 SAR data classification Eva Boergens, Karina Nielsen, Ole B. Andersen, Denise Dettmering, and Florian Seitz Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-217,2017 Manuscript under review for HESS (discussion: open, 0 comments) The water levels of the Mekong River are observed with the SAR altimeter measurements of CryoSat-2. Even small rivers in the river system with a width of 50 m can be observed due to the higher resolution of the SAR measurements. To identify the rivers regardless of a land-water-mask we employ an unsupervised classification on features derived from the SAR measurements. The river water levels are validated and compared to gauge and Envisat data which shows the good performance of the SAR data.

Description: On the use of GRACE intersatellite tracking data for improved estimation of soil moisture and groundwater in Australia Natthachet Tangdamrongsub, Shin-Chan Han, and Mark Decker Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-318,2017 Manuscript under review for HESS (discussion: open, 0 comments) An accurate estimation of soil moisture and groundwater is essential for monitoring the availability of water supply in domestic and agricultural sectors. In order to improve the water storage estimates, previous studies assimilated terrestrial water storage variation (∆TWS) derived from Gravity Recovery and Climate Experiment (GRACE) into land surface models. However, the GRACE-derived δTWS was generally computed from the high level products (e.g., land grid). The gridded data products are subjected to several drawbacks such as signal attenuation and/or distortion caused by ad hoc posteriori filters, and a lack of error covariance information. The consequence is undesired alteration of δTWS data and its statistical property. To exploit the GRACE information rigorously and negate these limitations, this study uses the fundamental GRACE satellite tracking Level 1B (L1B) data, not the post-processed ∆TWS grid data. The approach combines the GRACE's least-squares normal equation (full error variance-covariance information) of L1B data with the results from the Community Atmosphere Land Exchange (CABLE) model to improve soil moisture and groundwater estimates. This study demonstrates, for the first time, an importance of using the raw GRACE data. The GRACE-combine (GC) approach is developed for optimal least-squares combination maximizing the strength of the model and observations while suppressing the weaknesses. The approach is applied to estimate the soil moisture and groundwater over 10 Australian river basins and the results are validated against the satellite soil moisture observation and the in-situ groundwater data. We demonstrate the GC approach delivers evident improvement of water storage estimates, consistently from all basins, yielding better agreement at seasonal and inter-annual time scales. Significant improvement is found in groundwater storage while marginal improvement is observed in surface soil moisture estimates likely due to limitation of GRACE's temporal and spatial resolution.

Description: A bootstrap method to estimate the influence of rainfall spatial uncertainty in hydrological simulations Ang Zhang, Haiyun Shi, Tiejian Li, and Xudong Fu Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-273,2017 Manuscript under review for HESS (discussion: open, 0 comments) Rainfall stations with a certain number and spatial distribution supply sampling records of rainfall processes in a river basin. Uncertainty may be introduced when the station records are spatially interpolated for the purpose of hydrological simulations. This study adopts a bootstrap method to quantitatively estimate the uncertainty of areal rainfall estimates and its effects on hydrological simulations. The observed rainfall records are first analysed using clustering and correlation methods, and possible average basin rainfall amounts are calculated with a bootstrap method using various combinations of rainfall station subsets. Then, the uncertainty of simulated runoff, which is propagated through a hydrological model from the spatial uncertainty of rainfall estimates, is analysed with the bootstrapped rainfall inputs. By comparing the uncertainties of rainfall and runoff, the responses of the hydrological simulation to the spatial uncertainty of rainfall are discussed. Analyses are performed for three rainfall events in the upstream of the Qingjian River basin, a sub-basin of the Yellow River. Using the Digital Yellow River Integrated Model, the results show that the uncertainty of rainfall estimates derived from rainfall station network has a direct influence on simulated runoff processes. This quantified relationship between rainfall input and simulation performance can provide useful information on managing rainfall station density in river basins. The proposed method could be a guide to quantify an approximate range of simulated error caused by the spatial uncertainty of rainfall input.

Description: A simple global Budyko model to partition evaporation into interception and transpiration Ameneh Mianabadi, Miriam Coenders-Gerrits, Pooya Shirazi, Bijan Ghahraman, and Amin Alizadeh Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-306,2017 Manuscript under review for HESS (discussion: open, 0 comments) Estimating evaporation at the global scale remains challenging, while it is utmost importance for food security, hydrological modelling, and flood or drought forecasting. In this paper we present a simple analytical model that can estimate evaporation (both transpiration and interception evaporation) just based on remotely sensed data sources. Despite its simplicity it is able to model evaporation well in comparison to complex land surface models.

Description: Evaluation and Comparison among Multiple Forcing Data Sets for Precipitation and Shortwave Radiation over Mainland China Fan Yang, Hui Lu, Kun Yang, Wei Wang, Chengwei Li, Menglei Han, and Yishan Li Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-321,2017 Manuscript under review for HESS (discussion: open, 0 comments) In this manuscript, we show that precipitation estimates of CMFD and GLDAS are more credible and CMFD outperforms CLDAS and GLDAS in shortwave radiation estimation over mainland China. The main target of this research is to identify the advantages and also the weakness of these data sets over mainland China, which could benefit researchers for forcing data selection and uncertainty quantification and also could provide clues for data producers to further improve their data sets.

Description: Regional-scale brine migration along vertical pathways due to CO 2 injection – Part 1: The participatory modeling approach Dirk Scheer, Wilfried Konrad, Holger Class, Alexander Kissinger, Stefan Knopf, and Vera Noack Hydrol. Earth Syst. Sci., 21, 2739-2750, https://doi.org/10.5194/hess-21-2739-2017, 2017 Stakeholder participation in numerical modeling of brine migration due to injection of CO 2 into deep saline aquifers is tested in this work. Part 1 reports the process of participatory modeling in the development of a numerical model and Part 2 discusses essential technical findings obtained through this model, showing that notable increases in salt concentrations are confined to regions where they were already high a priori and where barrier layers are discontinuous.

Description: Reconstruction of droughts in India using multiple land surface models (1951–2015) Vimal Mishra, Reepal Shah, Syed Azhar, Harsh Shah, Parth Modi, and Rohini Kumar Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-302,2017 Manuscript under review for HESS (discussion: open, 0 comments) India has witnessed some of the most severe droughts in the current decade and severity, frequency, and areal extent of droughts have been increasing. As a large population of India is dependent on agriculture, soil moisture droughts adversely affect agriculture and groundwater resources. Due to lack of observations, soil moisture is generally simulated using land surface hydrological models (LSMs), however, these LSMs have uncertainty due to model parameterization. Here we reconstruct agricultural drought events during the period of 1951–2015 based on simulated soil moisture from three LSMs, the Variable Infiltration Capacity (VIC), the Noah, and the Community Land Model (CLM). We find a higher uncertainty in soil moisture droughts over a large part of India during the major crop growing season (Rabi season, November to February: NDJF) than that of the monsoon season (June to September: JJAS). Moreover, uncertainty in drought estimates is higher for severe and localized droughts. Higher uncertainty in the soil moisture droughts is largely due to the difference in model parameterizations; resulting in different persistence of soil moisture simulated by the three LSMs. Our study highlights the importance of accounting for the LSMs uncertainty and consideration of multimodel ensemble for the real-time monitoring and prediction of drought over India.

Description: Regional-scale brine migration along vertical pathways due to CO 2 injection – Part 2: A simulated case study in the North German Basin Alexander Kissinger, Vera Noack, Stefan Knopf, Wilfried Konrad, Dirk Scheer, and Holger Class Hydrol. Earth Syst. Sci., 21, 2751-2775, https://doi.org/10.5194/hess-21-2751-2017, 2017 Stakeholder participation in numerical modeling of brine migration due to injection of CO 2 into deep saline aquifers is tested in this work. Part 1 reports the process of participatory modeling on the development of a numerical model and Part 2 discusses essential technical findings obtained through this model showing that notable increases in salt concentrations are confined to regions where they were already high a priori and where barrier layers are discontinuous.

Description: Ensemble reconstruction of spatio-temporal extreme low-flow events in France since 1871 Laurie Caillouet, Jean-Philippe Vidal, Eric Sauquet, Alexandre Devers, and Benjamin Graff Hydrol. Earth Syst. Sci., 21, 2923-2951, https://doi.org/10.5194/hess-21-2923-2017, 2017 The historical depth of streamflow observations in France is extended through daily hydrometeorogical reconstructions from 1871 onwards over a large set of near-natural catchments. Innovative approaches are proposed to identify and intercompare extreme low-flow events from these reconstructions, both in time and across France in a homogeneous way over more than 140 years. Analyses bring forward recent well-known events like 1976 and 1989–1990 but also much older ones like 1878 and 1893.

Description: Global change in flood and drought intensities under climate change in the 21 st century Behzad Asadieh and Nir Y. Krakauer Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-253,2017 Manuscript under review for HESS (discussion: open, 0 comments) Multi-model analysis of global daily streamflow extremes for the 20th and 21st centuries under two warming scenarios is performed. About 37 % and 43 % of global land areas are exposed to increases in flood and drought intensities. Nearly 10 % of global land areas, holding around 30 % of world’s population, will face increases in both flood and drought risks. Significant increase in streamflow of the regions near and above the Arctic Circle, and decrease in subtropical arid areas, is projected.

Description: Climate and basin drivers of seasonal river water temperature dynamics Cédric L. R. Laizé, Cristian Bruna Meredith, Michael J. Dunbar, and David M. Hannah Hydrol. Earth Syst. Sci., 21, 3231-3247, https://doi.org/10.5194/hess-21-3231-2017, 2017 Stream temperature controls many river processes, making it vital to know how climate affects it. Climate and stream temperatures at 35 British sites and associated basin properties were used to model climate–water temperature associations and to assess how they are influenced by basins. Associations vary with season and water temperature range. Basin permeability, size, and elevation have the main influence; smaller upland or impermeable basins are the most sensitive to climate.

Description: Increase in urban flood risk resulting from climate change – The role of storm temporal patterns Suresh Hettiarachchi, Conrad Wasko, and Ashish Sharma Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-352,2017 Manuscript under review for HESS (discussion: open, 0 comments) The study examines the impact of higher temperatures expected in a future climate on how rainfall varies with time during severe storm events. The results show that these impacts increase future flood risk in urban environments and current design guidelines need to be adjusted so that effective adaptation measures can be implemented.

Description: Assessing glacier melt contribution to streamflow at Universidad Glacier, central Andes of Chile Claudio Bravo, Thomas Loriaux, Andrés Rivera, and Ben W. Brock Hydrol. Earth Syst. Sci., 21, 3249-3266, https://doi.org/10.5194/hess-21-3249-2017, 2017 We present an analysis of meteorological conditions and melt for Universidad Glacier in central Chile. This glacier is characterized by high melt rates over the ablation season, representing a mean contribution of between 10 and 13 % of the total runoff observed in the upper Tinguiririca Basin during the November 2009 to March 2010 period. Few studies have quantified the glacier melt contribution to river runoff in Chile, and this work represents a new precedent for the Andes.

Description: Retrospective forecasts of the upcoming winter season snow accumulation in the Inn headwaters (European Alps) Kristian Förster, Florian Hanzer, Elena Stoll, Adam A. Scaife, Craig MacLachlan, Johannes Schöber, Matthias Huttenlau, Stefan Achleitner, and Ulrich Strasser Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2017-370,2017 Manuscript under review for HESS (discussion: open, 0 comments) This article presents predictability analyses of snow accumulation for the upcoming winter season. The results achieved using two coupled atmosphere–ocean general circulation models and a water balance model show that the tendency of snow water equivalent anomalies (i.e. the sign of anomalies) is correctly predicted in up to 11 of 13 years. The results suggest that some seasonal predictions may be capable of predicting tendencies of hydrological model storages in parts of Europe.