ALBERT

Description: The daily rainfall-runoff relationship in an experimental watershed was modeled using a statistical method and an artificial neural network method. The estimations were examined and a performance evaluation was done. It was seen that the ANN method, FFBP (Feed Forward Back Propagation), provided closer flow estimations reproducing the shape of the observed hydrograph more realistic. The superiority of FFBP was reflected in the performance evaluation criteria. The extreme flows, i.e., high and low flows, were relatively better approximated by FFBP indicating its promise as a useful tool for hydrologic studies such as flood modeling. The Rational Method was also used, as a conventional tool, to predict the maximum discharge for selected return periods. It was found to be realistic for the forested watershed under consideration when the C coefficient was taken as 0.20 for the 10-year period.

Description: A procedure for optimal design of District Metered Areas (DMAs) within a water distribution network based on a multilevel balancing and refinement algorithm to partition the network and determine the optimal meter positions, coupled with a pressure driven hydraulic simulator to quantify the hydraulic performance of the districtualized system, is presented. Unlike other procedures based on graph partitioning techniques proposed in the scientific literature, the two main issues involved in the design of the DMAs, namely a) how to partition the nodes into the required number of districts, and b) which pipes linking districts to leave open, and fitted with an assigned number of flow meters, and which to close, are simultaneously resolved. The application of this procedure to a real case shows that this approach provides design solutions well adapted to different numbers of measuring points, yielding superior performance indicator values to similar procedures reported in the literature and used here for comparative purposes.

Description: Sustainable groundwater management requires approaches to assess the influence of climate and management actions on the evolution of groundwater systems. Traditional approaches that apply continuity to assess groundwater sustainability fail to capture the spatial variability of aquifer responses. To address this gap, our study evaluates groundwater elevation data from the Coachella Valley, California, within a groundwater sustainability framework given the adoption of integrative management strategies in the valley. Our study details an innovative approach employing traditional statistical methods to improve understanding of aquifer responses. In this analysis, we evaluate trends at individual groundwater observation wells and regional groundwater behaviors using field significance. Regional elevation trends identified no significant trends during periods of intense groundwater replenishment, active since 1973, despite spatial variability in individual well trends. Our results illustrate the spatially limited effects of groundwater replenishment occur against a setting of long-term groundwater depletion, raising concerns over the definition of sustainable groundwater management in aquifer systems employing integrative management strategies.

Description: Extreme rainfall events are among the natural hazards with catastrophic impacts on human society. Trend analysis is important to understand the effects of climate change and variability on extreme rainfalls. In this study, extreme rainfall (i.e., annual maximums) trends were investigated in Victoria (Australia) using data from 23 stations for storm durations of 10 and 30 min, and 1, 3, 6, 12, 24 and 48 h. The Mann-Kendal and Spearman’s Rho tests were employed for detection of temporal trends. Moreover, the spatial variability of extreme rainfall trends was investigated through interpolation of Theil-Sen’s estimator over Victoria. In general, increasing extreme rainfall trends were detected for short storm durations (i.e., 10 and 30 min, and 1 and 3 h), whereas decreasing extreme rainfall trends were found for long storm durations (i.e., 6, 12, 24 and 48 h). Increasing trends for short storm durations were mostly statistically significant, while decreasing trends for long storm durations were statistically insignificant. Trend analysis with respect to the four regions (i.e., Western, Northern, Central and Gippsland) in Victoria showed that increasing trends were present in general in the Northern and east Central Region, whereas decreasing trends were detected in the Western and west Gippsland Regions.

Description: To make full use of water captured by reservoirs in flood seasons, methods such as forecast-based reservoir flood control (i.e., reservoir operation during flood periods based on precipitation or inflow forecasts) have been developed in China in the past few decades. The success of forecast-based reservoir flood control depends heavily on the precision of the precipitation or inflow forecasts. This study analyzes the sources of uncertainty and quantifies it in the process of reservoir flood control based on forecasts. First, flood inflow series is regarded as a random process with the forecasted flood inflows as its expectation process; the flood inflow error series, which is the difference between the observed inflow process and the forecasted inflow process, is obtained according to the statistical characteristics of the flood forecasts. Second, reservoir flood routing simulations are carried out using the Monte Carlo method with the flood inflow error series as an input to obtain output water level and discharge series. Finally, the frequency distributions of the maximum water level (MWL) reached during the passage of floods are used to evaluate the uncertainties and the corresponding risks associated with forecast-based flood control. These uncertainties and risks are what the operators of the reservoirs care about the most.

Description: This paper introduces a reservoir design optimization model adapted to incorporate performance norms so that the active storage capacity can be determined assuming that failures may occur during the reservoir operation. The model is able to find the optimal reservoir capacity admitting either a predefined minimum number of failure periods or a maximum failure magnitude, or both. It is formulated as a mixed integer linear program that properly manages reservoir spills and includes evaporation losses. The procedure performs effectively for an example problem and Monte Carlo simulations and shows that lower accepted reliabilities and higher accepted vulnerabilities require less active storage.

Description: Increased groundwater accessibility resulting from the expansion of deep and shallow tube wells helped Bangladesh attain near self-sufficiency in rice, with national output increasing over 15 million tons in the last two decades. However, problems associated with the excessive exploitation of groundwater notably declining water tables, deteriorating water quality, increasing energy costs and carbon emissions are threatening the sustainability of Bangladesh’s groundwater irrigated economy. The forefront challenge, therefore, is to shift the focus from development to management of this precious resource. To ease out pressure on groundwater resources, attention must be diverted to further develop surface water resources. In addition to increasing supplies, water demand also need to be curtailed by increasing water use efficiency through the adoption of water conserving practices such as reduced tillage, raised bed planting, and the right choices of crops. Decreasing water availability both in terms of quantity and quality suggest that the unchecked expansion of dry season boro rice cultivation may not be a long-term option for Bangladesh. Therefore less thirsty wheat and maize crops may be promoted as feasible alternatives to boro . In addition to technical solutions, strong linkage between different institutions will be needed to evaluation strategic options and effective implementation of national policies for the management of groundwater resources.

Description: Since 2001, a rising water table occurred in the eastern part of the city of Naples (Italy), leading to flooding of the foundations of many buildings and of the underground infrastructures (garages, subway tracks, etc.). This resulted from the reduction in the exploitation of water for industrial use and drinking water in the central part of the groundwater body of the eastern plain of Naples: the groundwater withdrawal decreased from up to 3 m 3 /s in 1990 to a few hundred litres per second in 1998. The variation of piezometric levels led to flooding of foundations of many buildings and of underground infrastructures, this is a big amount of water lost by the aquifer system and that should be evaluated. In order to assess aquifer hydraulic features and the groundwater quantitative status, a 3D hydrostratigraphic model reconstruction was developed to support the groundwater flow modeling and the evaluation of the groundwater balance. The 3D hydrostratigraphic model reconstructed the subsoil of the study area: layers of tuff and lenses of peat, which play an important hydrogeologic role as aquitard and aquiclude, are faithfully defined. Indeed, the model allows the depiction of the horizontal extension and of the thickness of each hydrofacies, even if strongly heteropic. The groundwater flow model was defined using the 3D hydrostratigraphic model in the construction of the geometry and assignment of hydrodynamic parameters. The calibration and sensitivity analysis prove the goodness of the assigned hydraulic conductivity values. The model, together with a detailed computation of the paved areas with reduced infiltration, evaluated the recharge in 0.101 m 3 /s. The model calibration assessed an evapotranspiration rate lower than the prefixed value, probably due to the absence of vegetation that restricts the phenomenon almost exclusively to evaporation. Moreover, the calibration of the model confirmed: − the assumed groundwater flow towards the sea in 0.313 m 3 /s; − the hypothesized amount of the subsurface inflow from upstream in 0.504 m 3 /s. A considerable amount of water lost by the aquifer system, about 0.315 m 3 /s, could be used by Municipality for different public uses.

Description: Structural and operational management methods are used to meet water demands in watersheds around the world. Most river systems are affected by reservoirs, dams, or other engineering structures, and decisions regarding their construction and operation are made in advance of knowing what water demands will be. Numerical models are used to predict future water needs and evaluate the effectiveness of water management strategies. It is important to consider a variety of management methods and future environmental conditions to ensure future demands can be met. In this work, a coupled surface water operations and hydrologic model of the Lower Republican River Basin in portions of Nebraska and Kansas, USA is used to evaluate the ability of several water management strategies, including structural and operational, to meet future demands of a water-stressed agricultural basin under a variety of future climate scenarios. Simulations indicate recent administrative and operational changes to the distribution of water between Nebraska and Kansas have significantly decreased water shortages for irrigation districts in Kansas and will continue to do so. Simulations also indicate that structural alternative of reservoir expansion is most effective at minimizing shortages to demands under a repeat of historical climate conditions. However, an operational alternative of increasing water supplies for Kansas' exclusive use, such as those historically purchased under the Warren Act (US Code 43 Section 523–524), is most effective at minimizing shortages to demands under a hotter and drier climate, demonstrating how optimal water management strategies can vary significantly depending upon climate scenario.

Description: In this article we propose a new method - the Most Probable Precipitation Method (MPPM) - for estimating the precipitation at regional scale. Comparisons with the Thiessen polygons methods (TPM), inverse distance weighting interpolation (IDW) and ordinary kriging (OK) on annual, monthly, seasonal and annual maximum monthly precipitation are provided. In all cases MPPM performs better than IDW and OK, and in most of them, better than TPM.