Technical Reports

  • WATCH Technical Report Number 20: Hydrological drought characteristics of the Nedožery sub catchment, Upper Nitra, Slovakia, based on HBV modelling A River Basin Hydrological Model (RBHM) using HBV has been developed for the Nedožery catchment, Upper Nitra (Slovakia), which is a a focal area in the WATCH Test Basin Upper-Nitra (Slovakia). The hydrological regime of the Nedožery catchment is affected by snow, in particular in the headwaters. It is a fast-responding catchment (crystalline rocks). The model has been tested against time series of observed river flow, groundwater levels and snow. Trend analysis on the model input data showed downward trends in the observed discharge and upward trends in the observed precipitation and the annual number of snow days, which resulted in an over- (1974-1990) and underestimation (1991-2006) of the observed discharge. Time series of observations and outcome from the models were used to identify different drought types (meteorological drought, hydrological drought). Hydrological droughts (both winter and summer) in Nedožery catchment develop due to above average temperatures combined with below average precipitation. In winter this leads to a below average snow cover (resulting in lower spring discharges) and the occurrence of above average evapotranspiration. In winter, hydrological drought can also be caused by below average temperature, because water is stored on the surface as snow for a longer period. Such a winter drought does not continue into summer, because it ends by above average snowmelt in spring. HBV’s results were compared with outcome from the lumped, conceptual hydrological model BILAN and the distributed, physically-based hydrological model FRIER to test the impact of model structure on drought assessment. The BILAN model gives a lower number of droughts which are longer as compared with HBV. Recession curves simulated with BILAN are long and response on precipitation events during the recession is almost invisible. FRIER output shows more, but shorter droughts which indicates FRIER reacts faster to precipitation than HBV and BILAN. The RBHM and the outcome will be used in the WATCH project: (1) to develop a generic method for drought propagation, (2) to test the usefulness of large-scale forcing data (WATCH Forcing Dataset), and (3) to test the ability of large-scale land surface models (LSHMs) and global hydrological models (GHMs) to capture droughts.
    Jacob Oosterwijk, Anne F. van Loon, Andrej Machlica, Oliver Horvát, Henny A.J. van Lanen & Miriam Fendeková, December 28, 2009

  • WATCH Technical Report Number 19: Drought analysis for the Upper-Metuje and Upper-Sázava catchments (Czech Republic) using the hydrological model HBV River Basin Hydrological Models (RBHMs) using HBV have been developed for the Upper-Metuje and the Upper-Sázava catchments, which are focal areas in the WATCH Test Basin Upper-Elbe (Czech Republic). Both catchments have been selected for their contrasting hydrogeology, i.e. the Upper-Metuje catchment is a more slowly-responding catchment (sandstones), whereas the Upper-Sázava catchment is fast-responding catchment (crystalline rocks). The models have been tested against time series of observed river flow and groundwater levels. Time series of observations and outcome from the models have been used to identify different drought types (meteorological drought, hydrological drought). The RBHM for the Upper-Metuje catchment performs rather well. In the period 1982-2006 about 100 streamflow droughts were identified. This is slightly less than the number of droughts in the precipitation, but significantly more than the number of droughts in groundwater. The RBHM for the Upper-Sázava catchment performs less, because of monitoring of water abstractions and sewage water releases at a too low temporal resolution. The RBHMs and the outcome will be used in the WATCH project: (1) to develop a generic method for drought propagation, (2) to test the usefulness of large-scale forcing data (WATCH Forcing Dataset), and (3) to test the ability of large-scale land surface models (LSHMs) and global hydrological models (GHMs) to capture droughts.
    Oldrich Rakovec, Anne F. van Loon, Stanislav Horacek, Ladislav Kasparek, Henny A.J. van Lanen & Oldrich Novicky, September 16, 2009

  • WATCH Technical Report Number 18: Preliminary water quality module: state of development and plan for linkage to the overall modelling framework In this study preliminary estimates of recent trends in water quality in Europe especially in the Danube river basin are presented, including parameters like BOD, TC, TDS and water temperature. The specific aim of this paper was to provide background information on the new WorldQual model to be capable of operating on global scale. It provides insight in getting national loadings for the above mentioned indicators covering both, point and diffuse sources. These data sets have been put together to drive a grid based water quality model with a view to estimate the impacts on water quality of socio-economic and policy driven changes. In general modelling results show a promising step forward in building the first model of surface water quality to be capable in operating on the global scale. The data set presented in this study and the resulting outputs from the WorldQual model will form a baseline against which the impact of future scenarios can then be measured.
    Frank Voß, Anja Voß, Ilona Bärlund, Joseph Alcamo (CESR), March 11, 2009

  • WATCH Technical Report Number 17: Preliminary spatially explicit estimates of past and present domestic water use In this study preliminary estimates of past and present domestic water use are presented. The specific aim of this paper is to provide background information on the new global database of spatially explicit numbers of domestic water use. It provides an indicative picture of water use in the domestic sector across all continents.
    Frank Voß, Martina Flörke, Joseph Alcamo (Universität-Kassel, CESR - Center for Environmental Systems Research), February 18, 2009

  • WATCH Technical Report Number 16: Process that impact runoff generation in Northern Latitudes This technical report lays out the fundamental processes that affect the river flows in the Northern Latitudes and how they are represented in both hydrological and meteorological models. The question that it aims to answer is: to what processes are the river in the northern latitudes sensitive and how can we represent these processes in our large scale models?
    Eleanor Blyth, Centre for Ecology and Hydrology, February 13, 2009

  • WATCH Technical Report Number 15: Methodology for atmospheric analysis and feedback correction The overall objective of this report is to define the analysis needed to quantify the atmospheric corrections required for offline hydrological modelling. The theory of atmospheric feedback is summarised, including a review of previous studies. It is clear that there are two feedbacks that are key to water resources: feedback on the precipitation and on the evaporative demand. The precipitation feedback will often require a large scale three-dimensional model to study it. Previous model runs can be used to define where and how nudges to the precipitation fields will be needed. A one-dimensional model can be used if the precipitation is convective. The evaporative demand feedback may be quantified using a one-dimensional analytical model of the atmosphere. It is proposed that such a model will be built for use with the water resource models.
    Eleanor Blyth, Centre for Ecology and Hydrology, February 13, 2009

  • WATCH Technical Report Number 14: Methodology for evaluating the uncertainty of means and extremes from climate Land surface and hydrological models can be forced with either observed or climate model data. Climate model data is used when there are limited or no observations available, such as in a data sparse region or in studies of future climate. The forcing data these models required can vary from as little as daily precipitation and air temperature to sub-hourly rainfall, snowfall, air temperature, humidity and wind speed, downward shortwave and longwave radiation and surface pressure. Climate models inevitably produce imperfect forcing data, both in terms or its mean and extreme values. These errors will clearly impact on the hydrological cycle simulated by the land surface and hydrological models. This report describes the analysis of climate model errors both in terms of the mean and extremes.
    Nicola Gedney, UK Met Office, February 03, 2009

  • WATCH Technical Report Number 13: Intercomparison of methods for trend detection in hydrological extremes derived from gridded data Technical Report No. 13 of the WATCH Project reviews and compares methods for detection of change in extremes derived from gridded data. Univariate and multivariate approaches are considered. Methodological aspects of trend detection of gridded hydrological or climatical data are examined. Among issues tackled are significance estimation, trend index, resampling, and cluster-based analysis.
    Maciej Radziejewski and Zbigniew W. Kundzewicz (Research Centre for Agricultural and Forest Environment, Polish Academy of Sciences, Poznań, Poland), February 02, 2009

  • WATCH Technical Report Number 12: Description of the WATCH Modelling Framework One aim of WATCH is to study the vulnerability of water resources for the 20th and 21st century. To do this WATCH will develop a modelling framework which connects the climate, hydrological and water resources assessment models in a consistent way. Until recently, research on climate models and hydrological models was mostly separate. To study global water resources, global hydrologic models (GHMs) have been developed and; land surface hydrological models (LSM) have been developed and improved. Both GHMs and LSMs will be incorporated in the modelling framework and both driven by a common input dataset at the same spatial scale. Briefly, the modelling framework will be used to ensure common input date are used, for model intercomparisons, to facilitate model improvements and to study the global water cycle of the 20th and 21st century. This work leads towards an assessment of the vulnerability of future global water resources.
    Fulco Ludwig (WUR) Frank Voss (CESR), January 26, 2009

  • WATCH Technical Report Number 11: Indices for different types of droughts and floods at different scales Indices are provided that characterizes hydrological extremes (drought and floods). Clearly, no single drought or flood characteristic is suitable to assess and describe hydrological extremes for any type of analyses in any region. At site indices (e.g. gauging stations, observation wells) and areal indices are described both for drought and floods. The current document is an open document that will be completed over the lifetime of the WATCH project, including all recent experiences.
    Henny A.J. van Lanen, Zbigniew W. Kundzewicz, Lena M. Tallaksen, Hege Hisdal, Miriam Fendeková & Christel Prudhomme, January 26, 2009

  • WATCH Technical Report Number 10: Preliminary Water Assessment Reports of the test basins of the WATCH Project Most of the analyses within the WATCH project focus on the global and continental scale. To test what the value of these global result is at the local level, a series of test basins is used within the project. The Catchment-level case studies are used to allow for a first-order translation (downscaling) of the WB6 type of water resource vulnerability assessments to scales which are actively managed. These catchments can also serve as a test bed for dissemination activities and facilitate an evaluation of the practical impact of WB6 findings. This report presents the initial plans of the case studies, how they link to rest of the WATCH project and on which water resources they will focus. This report will function as the basis for further discussions on how to improve the integration of the case studies within the project and to develop a more general protocol for each of the case studies.
    Fulco Ludwig, Miguel Candel, Jesús Carrera, Miriam Fendekova, Ingjerd Haddeland, Stanislav Horacek, Jorge Jódar, Aristeidis Koutroulis Vicente Navarro, Ioannis Tsanis, January 22, 2009

  • WATCH Technical Report Number 9: Estimation of Land Surface Temperature using AVHRR sensors on the NOAA satellite The theoretical basis for the land surface temperature (LST) and land surface emissivity (LSE) retrieval from the Advanced Very High Resolution Radiometer (AVHRR) is given, using split-window techniques. The algorithms proposed use calibrated reflectances and brightness temperatures from the AVHRR channels 1, 2, 4, 5 as well as NDVI images to produce a global LST. The algorithms can be used globally as they have been simulated from a worldwide emissivity and brightness temperature data base. The cloud tests applied to the LST data are also provided. This document describes the mathematical basis for the algorithms, the ancillary data-sets required and the validation strategy.
    J. A. Sobrino, Y. Julien, V. Hidalgo, J.C. Jimenez, G. Soria, C. Mattar, B. Franch, R. Oltra, J. Cuenca, December 10, 2008


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