Technical Reports

  • WATCH Technical Report Number 56 - Executive summary of the completed WATCH project The WATCH (Water and Global Change) project is a European Union funded project to improve our understanding of the terrestrial water cycle. It has brought together scientists from 25 European research Institutions (as well as others from America and Japan) from many disciplines - hydrology, climate, water resources, remote sensing etc) to achieve this common goal. This document provides a summary of the objectives, results and achievements of this project spanning the full of the project (2007-2011).
    WATCH Secretary, December 05, 2011

  • WATCH Technical Report Number 55: Water for utilities: Climate change impacts on water quality and water availability for utilities in Europe This report provides an assessment of the consequences of changing water availability for production of drinking water, the manufacturing industry and power production in Europe, due to climate change and socio-economic developments. The report is based upon projections of demographic and socio-economic trends and climate change impacts, according to the SRES A2 and B1 scenario’s also used by IPCC. Chapter 2 deals with water quality impacts of climate change in a European context, focusing solely on chloride and water temperature. Chapter 3 deals with water demand of domestic and industrial water use (manufacturing and power production), water availability and water stress on a European scale, as projected for the time horizons 2050 and 2100.
    J.J.G. Zwolsman, M. van Vliet, M. Bonte, N. Gorski, M. Flörke, S. Eisner & F. Ludwig, September 15, 2011

  • WATCH Technical Report Number 54: Methodology for the assessment of uncertainty in hydrological extremes This technical report addresses to assess how the uncertainty of climate models, GCMs as well as RCMs, is propagated on to hydrological models including the effect of downscaling required for the latter. This report presents a methodology to evaluate the uncertainty propagation. The method is general and can be applied to any hydrologic model, regardless of its complexity, in terms of both, the accounted processes and also the spatial discretization of the model (i.e. lumped or distributed models). The results are presented in terms of meteorological and hydrological droughts. We find that the BC forcing overestimates the most extreme drought events (greater deficit) of both, the aquifer storage and the ground water recharge. The DS forcing underestimates the most extreme drought events (greater deficit) of both, the precipitation deficit and the ground water recharge.
    Jorge Jódar Bermúdez, Gonzalo Sapriza Azuri, Jesús Carrera Ramírez (IDAEA-CSIC), August 30, 2011

  • WATCH Technical Report Number 53: Flood studies at the river basin scale: case study of the Thames at Kingston (UK) The Thames catchment in Southern England was used as a test basin for modelling and testing of high flow extremes and floods. The river basin hydrological model used was CLASSIC (Crooks and Naden, 2007), which is applied on a grid-square framework. CLASSIC was run using local data (observed rainfall and MORECS potential evaporation) and Watch Forcing Data (WFD) for 1961 to 2001 and the impacts on simulated flow of using different sets of input data were assessed. Analyses of discharge data for the Thames from three global hydrological models were compared with those from the River Basin Hydrology Models.
    S.M. Crooks, August 18, 2011

  • WATCH Technical Report Number 52: Seasonal forecast model experiments with WATCH soil moisture data Seasonal forecasting is an active area of research, with the potential for large economic and social benefits from the development of improved forecasts. There is considerable scope for better forecasts through improved simulation of physical mechanisms that offer predictability on monthly or longer timescales. One such source of predictability is soil moisture, which affects surface climate - for example, wetter soil can lead to lower surface air temperature and increased precipitation in certain circumstances. Here, the impact of two alternative soil moisture datasets on the Met Office seasonal forecasting system GloSea4 is investigated.
    David Fereday, August 05, 2011

  • WATCH Technical Report Number 51: Global-Scale Detection and Attribution Results Regarding the Hydrological Cycle The research picture for global-scale detection and attribution of changes in the hydrological cycle has moved on since the design of the WATCH project, and we have adapted our work accordingly. A recent study showed some evidence of a detectable signal of human influence on global precipitation, but the evidence was clearly rather weak, and the study acknowledged concerns about the long-term stability of the observation-based datasets used and the quality of the CMIP-3 (third Coupled Model Intercomparison Project) generation climate models as tools for simulating precipitation signals. A particular problem with the latter is the simulation of precipitation features in the wrong location, which we have attempted to address using a novel approach that adapts techniques from neuro-imaging. This shows considerable promise and we hope to make an important contribution to the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report with CMIP-5 models when they become available. A simple thermodynamic framework was investigated for assessing the change in regional flood risk under global surface warming attributable to anthropogenic greenhouse emissions. We present results for flood risk in England and Wales during the record-wet autumn of 2000.
    Pardeep Pall, Jara Imbers, William Ingram, & Myles Allen, August 01, 2011

  • WATCH Technical Report Number 50: International Summer School on: Water Resources and The Water Cycle in a Changing World The WATCH project has the ambitious aim of assessing, for the first time, the impact of climate change on the water cycle at a global level and regional level. As a means to transfer this knowledge to researchers a summer school for postgraduates and early career scientists was organises. A particular effort was made to include participants from developing countries who may not normally have access to such events. The summer school was designed to be a combination of presentations on the results from the different work blocks of WATCH, as well as including more collaborative training modules where participants would learn the novel approaches undertaken by WATCH researchers. In essence this summer school was a summary of the key areas of WATCH work and its major results were presented.
    Warnaars. T. A., August 03, 2011

  • WATCH Technical Report Number 49: Projected changes in future runoff variability - a multi model analysis using the A2 emission scenario The effect of the IPCC A2 emission scenario on the future variability of global runoff is analyzed as a change in variability may impact the generation of extreme hydrological events. Runoff variability was characterized using the coefficient of variation (i.e. the standard deviation divided by the mean) derived from monthly runoff, the mean annual cycle of runoff, and monthly runoff anomalies. Model uncertainty is assessed using a multi model ensemble of eight large-scale hydrological models the majority being forced with three different global circulation models. Changes in runoff variability are assessed by comparing the 30 year control period (1971 - 2000) to the 2071 – 2100 time interval. The A2 emission scenario triggers significant changes in the future runoff variability, which is predicted to decrease at northern latitudes, and increase at mid latitudes (northern and southern hemisphere). The decreasing runoff variability in the northernmost regions is likely to be related to the diminishing importance of snow on runoff regimes in a warming climate. The increasing runoff variability at the mid latitudes suggest that increasing evaporation rates in a warming climate can be related to an increase in runoff variability.
    Gudmundsson, L., Tallaksen, L.M. & Stahl, K., August 03, 2011

  • WATCH Technical Report Number 48: Space-time characteristics of large-scale droughts in Europe derived from streamflow observations and WATCH multi-model simulations This report presents a detailed analysis of major historical droughts in Europe in the last part of the 20th century using novel methods for drought characterization that account for spatial extent and severity. The analyses were based on observed streamflow as well as runoff simulated by the WATCH multi-model ensemble comprising nine large-scale models. The ensemble median of the models was found to perform better than the ensemble mean when comparing two benchmark indices against observed streamflow for nine different anomaly levels. Based on the ensemble median and the 20% threshold from the empirical distribution (non-exceedance frequency), two extended drought periods (40% or more of the grid cells in drought) were identified, namely the autumn 1975 to late summer 1976, and spring and summer of 1990. A detailed spatial and temporal analysis revealed major differences in the drought development of the two events (build-up, consolidation and recovery phase), and in the models’ ability to reproduce their behaviour. The occurrence of larger and longer drought events agreed largely among models, however, the spatial coverage and variability within the drought affected area varied considerably. In the last part of the report a comparison of various methods for deriving Severity-Area-Frequency (SAF) curves for different return periods is made, suggesting that the drought clustering method performs better than methods that do not account for spatial continuity.
    Tallaksen, L., Stahl, K. & Wong, G., September 02, 2011

  • WATCH Technical Report Number 47: Climate change and irrigation: feedbacks and impacts This report summarises work done in WATCH's Work Block 3 on the effects of human activities on climate and the water balance and, vice versa, on climate impacts upon human water withdrawal. It includes three (preliminary) studies concerned with 1) impacts of potential future irrigation on regional climate (in southern Asia); 2) impacts of 21st century climate change on irrigation requirements globally; and 3) effects of dams on global river discharge.
    Dieter Gerten, Stefan Hagemann, Hester Biemans, Fahad Saeed, Markus Konzmann, July 31, 2011

  • WATCH Technical Report Number 46: Development of Spatially detailed global estimates of 20th and 21st Century sectoral water requirements This Technical Report analyses the past, current and future demand of water for the agricultural, domestic, and industrial sectors. Spatially detailed scenarios of population and economic activity from WP2.1 and climate data sets from WP1 and WP3 are used to calculate scenarios of future water use for human and economic activities that investigate the impact of demographic and economic changes, new water-saving technologies, competition for water from other sectors, and climate change. Spatial downscaling of past (from statistical data) and projected water-related activities provide locations and estimates of water use, moreover, hot spots of water abstractions become visible. Based on information from WB3, the main uncertainties, risks and related vulnerabilities of the water requirements for human and economic activities are assessed. Spatially explicit information is given for past, present and future water withdrawals and consumption for all sectors in form of gridded data sets which were made available to WATCH partners.
    Martina Flörke and Stephanie Eisner, July 27, 2011

  • WATCH Technical Report Number 45: Projected hydrological changes in the 21st century and related uncertainties obtained from a multi-model ensemble 21st century climate change is likely to have a significant impact on the hydrological cycle and thus has the potential to impose additional water stress in several regions. Thus, this study focuses on the assessment of the implications of climate change for global hydrological regimes and related water resources states for the 21st century. Different climate and hydrological models show quite different projected changes with a large variation of uncertainty within the climate - hydrology modelling chain. Therefore, multiple climate and hydrological models were used within the European project "Water and Global Change" (WATCH) to assess the hydrological response to climate change and to project the future state of global and large scale water resources. Climate model data were taken from projections of three coupled atmosphere-ocean General Circulation Models (GCMs) (ECHAM5/MPIOM, CNRM-CM3, LMDZ-4) following the A2 and B1 emission scenarios. Due to the systematic errors of climate models, their output has been corrected with a statistical bias correction method and then the output was used directly to force global hydrological models (GHMs) (MPI-HM, LPJmL, WaterGAP, VIC, MacPDM, H08, GWAVA, JULES) to calculate the corresponding changes in hydrological fluxes. The analyses focus on the changes in the hydrological characteristics for twelve large, continental river basins without taking into account direct anthropogenic influences in the hydrological simulations. The hydrological cycle was evaluated and multiple-model based projections were analysed for the terrestrial components of the hydrological cycle focusing on the time period of 2071-2100. Global maps are constructed to identify regions where the water cycle and associated water resources are significantly impacted by climate change, and which regions are vulnerable to these changes in terms of e.g. water availability. The uncertainties due to the choice of GCM and GHM are also assessed.
    Chen, C., Hagemann, S., Clark, D., Folwell, S., Gosling, S., Haddeland, I., Hanasaki, N., Heinke, J., Ludwig, F., Voβ, F. and Wiltshire, A, August 25, 2011


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