ALBERT

Description: Since the development of the coastal areas near present-day Houston, Texas, USA, subsidence has been a significant public policy concern. Subsidence in this area is caused by the extraction of groundwater from the Coastal Lowlands aquifer system, locally referred to as the Gulf Coast Aquifer. Concerns associated with subsidence in the Houston area include coastal inundation from storm surge, inland flooding, and critical infrastructure damage. The Houston area receives about 126 cm of precipitation each year, making flooding a critical issue in the region. The Houston area is the 4th largest city in the United States with a population of about 6.89 million (2017) and has a total water demand of about 4 Mm3 per day (2017). In the 1950s the City of Houston began the development of several reservoirs to provide water for the rapidly growing city. In 1975, following decades of subsidence totaling over 3 m, the Harris-Galveston Subsidence District (District) began regulating the use of groundwater and shifting the primary water supply for the region from groundwater to treated surface water to cease on-going and prevent future subsidence. Leveraging the alternative resources developed by the City of Houston in the 1950s, the District's regulatory framework focuses on spatial prioritization and the systematic conversion to alternative source waters. The District's regulatory plan includes three planning areas. Currently, the regional water authorities and the City of Houston are developing nearly five billion dollars (USD) in infrastructure to produce and deliver an additional 1.2 Mm3 per day of treated surface water to Houston and the surrounding communities. Resource development, public engagement, and political foresight have resulted in a reasonable approach to shift source waters and implement a plan to dramatically reduce and stop subsidence in the region. Figure 2 presents subsidence rates (2017) by regulatory area. Results show that the implementation of the regulatory program has substantially slowed subsidence in Areas 1 and 2, where full conversion has taken place. Planning the future water needs of the Houston area resulted in a robust and effective collaboration between the regulated community and the District. Analysis of historical source water use, aquifer response, and subsidence in the Houston area shows that the reasonable management of groundwater use in the Houston region is vital for the long-term prevention of subsidence and increases the resilience of the entire region.

Description: The goal of an interdisciplinary team of scientists at the Climate Service Center Germany (GERICS) was to make the findings of the special report IPCC SR1.5 more accessible to the citizens of Hamburg. Therefore, a flyer was created that is understandable to non-climate scientists, visually attractive and generates interest. It contains up-to-date climate information, readily understandable texts and several graphical visualisations. The team has been working intensively on analysing and processing further the consequences of a 1.5 ∘C global warming for the Hamburg metropolitan region. While the team's natural scientists elaborated the impacts on specific climate indices, other team members focused on the visualisation and communication of the results.

Description: In the Houston, Texas region, groundwater use is regulated by the Harris-Galveston Subsidence District (District) because of historical regional subsidence from groundwater development. The District regulates groundwater production in the Coastal Lowlands Aquifer System (CLAS) to mitigate subsidence through the implementation of District Groundwater Regulatory Plan. The District has successfully reduced groundwater pumping as a percent of demand regionally while controlling subsidence through the implementation of alternative water supplies. Aquifer Storage and Recovery (ASR) is an alternative water supply strategy that provides a means to store water underground and increase water supply more cost effectively than traditional storage expansion strategies. Groundwater users in the District are interested in the many potential benefits of ASR as a water supply strategy. Little is known about the potential effects on compaction and land surface subsidence resulting from ASR operations. Recognizing this, the District funded research on the potential subsidence risk associated with ASR. Two hypothetical, though representative, ASR projects were developed and analysed: (1) an industrial ASR project meant to provide water supply during a drought of record (DOR), and (2) a municipal ASR project designed to provide an annual municipal summer peaking water supply. Simulations of groundwater hydraulics and subsidence were performed at three potential locations within the CLAS to provide insight into variability associated with location and aquifer depth. Theoretical simulations confirmed the potential for subsidence associated with the application of ASR in the CLAS, although operating an ASR for summer peaking needs has less potential risk of subsidence than the DOR scenario in the scenarios simulated. The study simulations provide insight into how an ASR project may be designed and operated to minimize compaction and potential subsidence. Based on this study, ASR operated to address summer peaking showed the greatest potential to reduce additional compaction verses sourcing all water from groundwater. This theoretical study provides a basis for future research on subsidence associated with ASR and provides a framework for consideration for the regulation of ASR within the District.

Description: Significant undeveloped brackish groundwater resources exist within the Coastal Lowlands Aquifer System (Gulf Coast Aquifer System) near Houston, Texas, USA. As the development of these frontier resources is imminent, an improved understanding of the impact development may have on the availability of the resource and land subsidence is needed. In this region, land subsidence is caused by the depressurization of the aquifer and compaction of the many clay lenses in the subsurface. The Gulf Coast Aquifer System in the study area includes three primary water bearing units (from shallow to deep): the Chicot (Pleistocene and Pliocene) and Evangeline (Pliocene and Miocene) aquifers, and the Jasper aquifer (Miocene). Although there has been much research and data supporting the causal relation between water-level decline and subsidence in the areas of fresh groundwater development, little data exists to inform on the potential subsidence impacts upon deeper brackish groundwater development. Data were compiled, and multiple hydrologic parameters were utilized to improve the understanding of the brackish resources within the study area. Geophysical logs were compiled and analysed to refine the aquifer stratigraphy, determine the binary classification of sand and clay, and estimate the groundwater salinity. These data were used to develop a MODFLOW groundwater flow model to estimate the risk of compaction and land subsidence upon the development of brackish zones within the Jasper aquifer. Compiled data detailing the total clay thickness, clay bed thickness, and clay bed location were input into the model along with a hypothetical stress to predict compaction within the Jasper aquifer across the study area while incorporating the observed heterogeneity in clay properties. Using the results from the model simulations and two other risk performance measures (depth of burial and surface flood risk), the total subsidence normalized risk score was estimated. The results of this study confirm the potential for compaction in the Jasper aquifer and for land subsidence to occur upon development. Areas with the highest risk are located in the up-dip, inland areas, near where the aquifer becomes fresh and is currently used for municipal supply. The results will inform water managers and planners in the Houston area on the future availability of brackish groundwater resources.

Description: Within the context of the predicted and observed increase in droughts and floods with climate change, large summer floods are likely to become more frequent. These extreme events can alter typical biogeochemical patterns in coastal systems. The extreme Elbe River flood in June 2013 not only caused major damages in several European countries but also generated large-scale biogeochemical changes in the Elbe estuary and the adjacent German Bight. The high-frequency monitoring network within the Coastal Observing System for Northern and Arctic Seas (COSYNA) captured the flood influence on the German Bight. Data from a FerryBox station in the Elbe estuary (Cuxhaven) and from a FerryBox platform aboard the M/V Funny Girl ferry (traveling between Büsum and Helgoland) documented the salinity changes in the German Bight, which persisted for about 2 months after the peak discharge. The Elbe flood generated a large influx of nutrients and dissolved and particulate organic carbon on the coast. These conditions subsequently led to the onset of a phytoplankton bloom, observed by dissolved oxygen supersaturation, and higher than usual pH in surface coastal waters. The prolonged stratification also led to widespread bottom water dissolved oxygen depletion, unusual for the southeastern German Bight in the summer.

Description: The Coastal Observing System for Northern and Arctic Seas (COSYNA) was established in order to better understand the complex interdisciplinary processes of northern seas and the Arctic coasts in a changing environment. Particular focus is given to the German Bight in the North Sea as a prime example of a heavily used coastal area, and Svalbard as an example of an Arctic coast that is under strong pressure due to global change.The COSYNA automated observing and modelling system is designed to monitor real-time conditions and provide short-term forecasts, data, and data products to help assess the impact of anthropogenically induced change. Observations are carried out by combining satellite and radar remote sensing with various in situ platforms. Novel sensors, instruments, and algorithms are developed to further improve the understanding of the interdisciplinary interactions between physics, biogeochemistry, and the ecology of coastal seas. New modelling and data assimilation techniques are used to integrate observations and models in a quasi-operational system providing descriptions and forecasts of key hydrographic variables. Data and data products are publicly available free of charge and in real time. They are used by multiple interest groups in science, agencies, politics, industry, and the public.

Description: The Icelandic Meteorological Office (IMO) conducted meteorological buoy measurements in the central Iceland Sea in the time period 2007–2009, specifically in the Northern Dreki Area on the southern segment of the Jan Mayen Ridge. Due to difficulties in deployment and operations in-situ measurements in this region are sparse. Here the buoy, deployment and measurements are described with the aim of giving a future user of the data set as comprehensive information as possible. The data set has been quality checked, suspect data removed and the data set made publicly available from Pangaea Data Publisher (doi:10.1594/PANGAEA.876206).

Description: The Icelandic Meteorological Office (IMO) conducted meteorological buoy measurements in the central Iceland Sea in the time period 2007–2009, specifically in the northern Dreki area on the southern segment of the Jan Mayen Ridge. Due to difficulties in deployment and operations, in situ measurements in this region are sparse. Here the buoy, deployment and measurements are described with the aim of giving a future user of the data set information that is as comprehensive as possible. The data set has been quality-checked, suspect data removed and the data set made publicly available from PANGAEA Data Publisher (https://doi.org/10.1594/PANGAEA.876206).

Description: The adaptation of some benthic foraminiferal species to low oxygen conditions provides the prospect of using the chemical composition of their tests as proxies for bottom water oxygenation. Manganese may be particularly suitable as such a geochemical proxy, because this redox element is soluble in reduced form (Mn2+), and hence can be incorporated into benthic foraminiferal tests under low oxygen conditions. Therefore, intra- and inter-test differences in foraminiferal Mn / Ca ratios may hold important information about short term variability in pore water Mn2+ concentrations and sediment redox conditions. Here, we studied Mn / Ca inter- and intra-test variability of living individuals of the shallow infaunal foraminifer Ammonia tepida sampled in Lake Grevelingen (The Netherlands) in three different months of 2012. The deeper parts of this lake are characterised by seasonal hypoxia/anoxia with associated shifts in microbial activity and sediment geochemistry, leading to seasonal Mn2+ accumulation in the pore water. Earlier laboratory experiments with similar seawater Mn2+ concentrations as encountered in the pore waters of Lake Grevelingen suggest that intrinsic intra-test variability in A. tepida (11–25 % RSD) is responsible for a considerable portion of the observed variability in Mn / Ca. Our results show that the seasonally highly dynamic environmental conditions in the study area lead to a strongly increased Mn / Ca intra- and inter-test variability (average of 45 % RSD). Within single specimens, both increasing and decreasing trends in Mn / Ca ratios with size are observed. Our results suggest that the variability of successive single chamber Mn / Ca ratios reflects the temporal variability of pore water Mn2+. Additionally, active or passive migration of the foraminifera in the surface sediment may explain part of the observed Mn / Ca variability.

Description: In December 2015, 195 countries agreed in Paris to hold the increase in global mean surface temperature (GMT) well below 2.0 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C. Since large financial flows will be needed to keep GMTs below these targets, it is important to know how GMT has progressed since pre-industrial times, taking short-term and long-term (decadal) natural variability into account. However, the Paris Agreement is not conclusive as for methods to calculate it. Should trend progression be deduced from GCM simulations or from instrumental records by (statistical) trend methods? Which trend model should be chosen and what is pre-industrial? Does trend progression depend on the specific GMT dataset chosen? To find answers to these questions we performed an uncertainty and sensitivity analysis where datasets and model choices have been varied. For all cases we evaluated trend progression since pre-industrial, along with uncertainty information. To do so, we analysed four trend approaches and applied these to the five leading GMT products. As a parallel path, we calculated GMT progression from an ensemble of 106 GCM simulations, corrected for natural variability. We find GMT progression to be largely independent of various trend model approaches. However, GMT progression is significantly influenced by the choice of GMT datasets. Both sources of uncertainty are dominated by natural variability. Mean progression derived from GCM-based GMTs appears to lie within the range of the trend-dataset combinations. A difference between both approaches lies in the width of uncertainty bands: bands for GCMs are much wider. Results appear to be robust as for specific choices for pre-industrial. Our Paris policy recommendation would be to choose a spline or IRW trend model and estimate it on the average of the five leading GMT datasets, where 1880 is taken as base year. Given this choice trend progression for 2016 accounts for 1.01 ± 0.13 °C (2-σ).