Global warming increases the frequency of river floods in Europe

EURO-CORDEX, a new generation of downscaled climate projections, has become available for climate change impact studies in Europe. New opportunities arise in the investigation of potential effects of a warmer world on meteorological and hydrological extremes at regional scales. In this work, an ensemble of EURO-CORDEX RCP 8.5 scenarios is used to drive a distributed hydrological model and assess the projected changes in flood hazard in Europe through the current century. Changes in magnitude and frequency of extreme streamflow events are investigated by statistical distribution fitting and peak over threshold analysis. A consistent method is proposed to evaluate the agreement of ensemble projections. Results indicate that the change in frequency of discharge extremes is likely to have a larger impact on the overall flood hazard as compared to the change in their magnitude. On average in Europe, flood peaks with return period above 100 years are projected to double in frequency within a time range of three decades.JRC.H.7-Climate Risk Managemen

GloFAS – global ensemble streamflow forecasting and flood early warning

Anticipation and preparedness for large-scale flood events have a key role in mitigating their impact and optimizing the strategic planning of water resources. Although several developed countries have well-established systems for river monitoring and flood early warning, figures of population affected every year by floods in developing countries are unsettling. This paper presents the Global Flood Awareness System, which has been set up to provide an overview on upcoming floods in large world river basins. The Global Flood Awareness System is based on distributed hydrological simulation of numerical ensemble weather predictions with global coverage. Streamflow forecasts are compared statistically to climatological simulations to detect probabilistic exceedance of warning thresholds. In this article, the system setup is described, together with an evaluation of its performance over a two-year test period and a qualitative analysis of a case study for the Pakistan flood, in summer 2010. It is shown that hazardous events in large river basins can be skilfully detected with a forecast horizon of up to 1 month. In addition, results suggest that an accurate simulation of initial model conditions and an improved parameterization of the hydrological model are key components to reproduce accurately the streamflow variability in the many different runoff regimes of the Earth.JRC.H.7-Climate Risk Managemen

Current water resources in Europe and Africa - Matching water supply and water demand

Ensuring good quality water in sufficient quantities for all legitimate uses is a major policy aim of the European Commission, and the main aim of the Blueprint to Safeguard Europe's Water, which will be launched in 2012. The Blueprint is the EU policy response to emerging challenges in the field of water. It is within this policy framework that JRC carries out research on hydrological simulation modelling, aiming to provide scientific assessments of general available water resources and floods, droughts and water scarcity. The main aim of the work is to assess current and future water availability versus current and future water demands from different economic sectors. Before future challenges can be addressed, a thorough analysis of current water resources is needed. The scope of this study is an analysis of current water resources in Europe and Africa, and matching water supply and water demand from various sectors. Several attempts already have been made to assess European, African and global water resources. Recently, Haddeland et al. (2011) produced a multimodel estimate of the global terrestrial water balance at 0.5o spatial resolution. This has been achieved within the Global Water Availability Assessment (GWAVA), developed in the context of the EU-funded WATCH project (https://gateway.ceh.ac.uk ). Within another EU-funded project GLOWASIS (Global Water Scarcity Information System), Utrecht University and Deltares develop a global water scarcity map also at 0.5o spatial resolution, to be finished Dec 2012 (http://glowasis.eu ). First results are published in Van Beek et al (2011). JRC is partner in this project to benchmark the global product with the higher resolution European and African assessments. A further study was conducted by Hoekstra and Mekonnen (2011), assessing global water scarcity for the world’s major river basins. Other available information on global water resources are available from: • FAO, Aquastat portal http://www.fao.org/nr/water/aquastat/globalmaps/index.stm • UNEP: http://maps.grida.no/go/graphic/freshwater-availability-groundwater-and-river-flow • Cleaningwater: http://cleaningwater.se/whats-new/geographical-distribution • IWMI Institute: http://www.iwmi.cgiar.org/WAtlas/Default.aspx • World Resources Institute: http://earthtrends.wri.org/maps_spatial/maps_detail_static.php?map_select=265&theme=4 • Monde diplomatique: http://www.monde-diplomatique.fr/cartes/disponibiliteeau • GRID-Arendal (Africa): http://www.grida.no/publications/vg/africa/ • EEA (Europe): http://www.eea.europa.eu/data-and-maps/figures/annual-water-availability-per-capita-by-country-2001 In general however, the analysis done in the products described above is done at national scales, at relatively coarse spatial resolution (0.5o), and using water demand data from the year 2000 or before, because more recent data are not yet available. The scope of the study presented here, is to carry out an higher spatial resolution analysis for Europe (5 km ~ 0.05o) and Africa (0.1o), using a daily timescale for modelling, and using for Europe new JRC analysis of water uses for irrigation, livestock, industry and energy, and domestic purposes. The analysis is carried out using the JRC LISFLOOD hydrological simulation model, supported by several other available models (EPIC, LUMP).JRC.H-Institute for Environment and Sustainability (Ispra

Spatially-resolved Assessment of Land and Water Use Scenarios for Shale Gas Development: Poland and Germany

The analysis presented in this report focuses specifically on two issues of potential concern with respect to shale gas development in EU member states using hydraulic fracturing technologies: pressure on freshwater resources, and land use competition. Potential alternative technologies, such as “dry fracking”, are not considered, because they are still at the research and development stage. We reviewed available literature in order to identify important variables that may influence the land and water requirements associated with shale gas development. We further derived a range of representative values spanning worst-, average- and best-case scenarios for each variable. We then coupled specific technology scenarios (incorporating these variables) regarding water and land use requirements for shale gas development from 2013-2028 with spatially-resolved water and land availability/demand modeling tools (i.e. using the European Land Use Modelling Platform (LUMP)). Scenario analyses (intended to represent worst-, average- and best-case assumptions) were subsequently implemented that incorporate a subset of the identified variables for shale gas development in the Lower Paleozoic Baltic-Podlasie-Lublin basin in Poland and for Germany as a whole from 2013-2028. In addition, we undertook a screening-level risk assessment of potential human and ecosystem health impacts attributable to accidental or operational release of chemicals used in hydraulic fracturing of shale formations, as well as the average gaseous emissions (per active well) associated with shale gas development activities that might be anticipated within a shale play. Finally, we developed a qualitative discussion of necessary considerations to support future air quality impact assessments for shale gas development activities.JRC.H.8-Sustainability Assessmen

Assimilation of MODIS snow cover area data in a distributed hydrological model

Snow is an important component of the water cycle, and its estimation in hydrological models is of great significance concerning the simulation and forecasting of flood events due to snow-melt. The assimilation of Snow Cover Area (SCA) in physical distributed hydrological models is a possible source of improvement of snowmelt-related floods. In this study, the assimilation in the LISFLOOD model of the MODIS sensor SCA has been evaluated, in order to improve the streamflow simulations of the model. This work is realized with the final scope of improving the European Flood Awareness System (EFAS) pan-European flood forecasts in the future. For this purpose daily 500 m resolution MODIS satellite SCA data have been used. Tests were performed in the Morava basin, a tributary of the Danube, for three years. The particle filter method has been chosen for assimilating the MODIS SCA data with different frequencies. Synthetic experiments were first performed to validate the assimilation schemes, before assimilating MODIS SCA data. Results of the synthetic experiments could improve modelled SCA and discharges in all cases. The assimilation of MODIS SCA data with the particle filter shows a net improvement of SCA. The Nash of resulting discharge is consequently increased in many cases.JRC.H.7-Climate Risk Managemen

LISVAP Evaporation Pre-Processor for the LISFLOOD Water Balance and Flood Simulation Model

The LISVAP revised User Manual documents the LISVAP application. LISVAP is a pre-processor for the LISFLOOD water balance and flood simulation model that calculates estimates of potential evaporation and evapotranspiration for three separate reference surfaces, all based on the Penman-Monteith equation. The results are reported as raster grids that can be readily used as input to LISFLOOD. The first part of this document describes the characteristics of the LISVAP application in detail, focusing on process descriptions and the governing equations. The second part covers all practical LISVAP issues, such as installing the application, setting up the necessary input data and running it.JRC.H.1-Water Resource

Assessing the role of uncertain precipitation estimates on the robustness of hydrological model parameters under highly variable climate conditions

1. Study region Four headwaters in Southern Africa. 2. Study focus The streamflow regimes in Southern Africa are amongst the most variable in the world. The corresponding differences in streamflow bias and variability allowed us to analyze the behavior and robustness of the LISFLOOD hydrological model parameters. A differential split-sample test is used for calibration using seven satellite-based rainfall estimates, in order to assess the robustness of model parameters. Robust model parameters are of high importance when they have to be transferred both in time and space. For calibration, the modified Kling-Gupta statistic was used, which allowed us to differentiate the contribution of the correlation, bias and variability between the simulated and observed streamflow. 3. New hydrological insights Results indicate large discrepancies in terms of the linear correlation (r), bias (β) and variability (γ) between the observed and simulated streamflows when using different precipitation estimates as model input. The best model performance was obtained with products which ingest gauge data for bias correction. However, catchment behavior was difficult to be captured using a single parameter set and to obtain a single robust parameter set for each catchment, which indicate that transposing model parameters should be carried out with caution. Model parameters depend on the precipitation characteristics of the calibration period and should therefore only be used in target periods with similar precipitation characteristics (wet/dry).JRC.D.2-Water and Marine Resource

Hochwasservorhersage in Afrika: Kann die Methode des Europäischen Hochwasser-Frühwarnsystems auf Afrikanische Einzugsgebiete Übertragen Werden?

Das Europäische Hochwasser-Frühwarnsystem (EFAS) erstellt Hochwasserwarnungen für mittel- und großskalige Einzugsgebiete mit einer Vorwarnzeit bis zu 10 Tagen. Diese basieren auf probabilistischen meteorologischen Vorhersagen und der persistenten Überschreitung von kritischen Schwellenwerten. Die Vorhersagemethode wurde über verschiedene Klimazonen in den mittleren Breiten Europas ausführlich anhand von verschiedenen Hochwasserereignissen getestet. In diesem Beitrag wird die Übertragbarkeit von EFAS auf äquatoriale afrikanische Einzugsgebiete am Beispiel des Juba-Shabelle Gebietes, unter der Verwendung verschiedener meteorologischer Eingangsdaten, getestet. Die Ergebnisse zeigen, dass das Hochwassersignal in über 85 % der Fälle erfolgreich, mit einer hohen Genauigkeit bezüglich der Eintrittszeit und der Stärke des Hochwassers, ermittelt werden konnte.JRC.DDG.H.7-Land management and natural hazard

Das Europäische Hochwasser-Frühwarnsystem (EFAS)

Das Europäische Hochwasser-Frühwarnsystem (EFAS) wird von der Gemeinsamen Forschungsstelle der Europäischen Kommission seit 2003 in Zusammenarbeit mit den Nationalen hydrologischen Diensten entwickelt. Die Ziele sind, zum einen den Nationalen Wasserbehörden zusätzliche Frühwarninformationen für das ganze Einzugsgebiet zukommen zu lassen, zum anderen die internationale Zusammenarbeit beim Katastrophenmanagement in Europa generell zu verbessern. Seit 2005 wird der EFAS Prototyp getestet. Zweimal täglich stellt er probabilistische hydrologische Vorhersagen für nationale Vorhersagezentren mit einem Vorlauf von 3 bis 10 Tagen bereit. Dieser Artikel gibt einen Überblick über die Methodik von EFAS und das zugrundeliegende Niederschlags-Abfluss Modell LISFLOOD. Mit einer Fallstudie werden EFAS Ergebnisse illustriert. The European Flood Alert System (EFAS) was launched in 2003 by the European Commission Joint Research Centre, in close collaboration with the national hydrological and meteorological services. It aims to increasing preparedness for floods in trans-national European river basins by providing local water authorities with early warning information. Since 2005 the EFAS prototype has been running pre-operationally for all of Europe. It is now providing 3 to 10 day probabilistic hydrological forecasts for national hydrological services twice-a-day. This article gives an overview of EFAS and the rainfall-runoff model LISFLOOD. A case study illustrates the EFAS results.JRC.DDG.H.7-Land management and natural hazard

A dynamic runoff co-efficient to improve flash flood early warning in Europe: evaluation on the 2013 Central European floods in Germany

Flash floods are listed among the deadliest and costliest weather-driven hazard worldwide. Yet, only few systems to predict flash floods run operationally in Europe. Recently, the European Precipitation Index based on Climatology (EPIC) was developed and then set up for daily flash flood early warning for an area covering most of the continent. EPIC is a purely rainfall-driven indicator based on the prediction of statistical threshold exceedance of the upstream precipitation to provide early warning up to 5 days in advance. Its main assumption is that flash floods are directly and solely related to extreme accumulations of upstream precipitation. It does not take into account any geo-factors such as slope, land use, or processes like initial soil moisture, which can have a significant impact on the triggering of such events. This study proposes an enhanced version of EPIC through a dynamic and distributed runoff coefficient which depends on the initial soil moisture. This coefficient, namely the European Runoff Index based on Climatology (ERIC), is used to weigh each contribution of the upstream precipitation proportionally to the initial soil moisture. The evaluation based on one year of daily runs proved that ERIC reaches a threat score of 0.5 if it forecasts a probability larger than 35 % of exceeding the 20 year return period of upstream runoff. This result is 0.16 higher than for EPIC. A case study of the flash flooding affecting central Europe in June 2013 demonstrated the ability of ERIC to successfully detect and locate the affected areas.JRC.H.7-Climate Risk Managemen