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Het IMPREX Horizon-2020-onderzoeksprogramma is gericht op het verbeteren van verwachtingen van meteorologische en hydrologische extremen en hun impact. Voor betere beheersing van droogterisico’s is er behoefte aan voldoende betrouwbare langetermijnverwachtingen van droogte (Honingh e.a., 2020). Daarom is onderzocht of meteorologische seizoensverwachtingen gebruikt kunnen worden om grondwaterstanden een aantal maanden vooruit te voorspellen. Veranderingen in grondwaterstanden volgen relatief traag na veranderingen in neerslag. Hierdoor wordt verondersteld dat grondwaterstandsverwachtingen verder vooruit in de tijd gebruikt kunnen worden dan meteorologische verwachtingen alleen.

In Nederland ligt vrijwel elke winter gedurende enige tijd sneeuw. De hoeveelheid is meestal beperkt, maar niet altijd; in sommige gevallen kan het neerslag-afvoerproces aanzienlijk beïnvloed worden doordat (een deel van) de neerslag niet direct beschikbaar is voor infiltratie of afstroming. Toch wordt sneeuw in Nederlands waterbeheer maar zelden beschouwd in modellering. We laten zien dat sneeuw-gerelateerde processen relatief eenvoudig mee te nemen zijn door de neerslag van tevoren te pre-processen. Hiertoe vergelijken we een aantal modellen, zowel voor het splitsen van neerslag in regen en sneeuwval, als voor het smelten van het sneeuwdek, en toetsen deze aan metingen van het KNMI. Hieruit blijkt dat eenvoudige modellen in Nederland het best voldoen: sneeuw in Nederlandse omstandigheden is zo heterogeen en metingen zijn zo schaars dat complexe modellen moeilijk te kalibreren zijn. Met eenvoudige modellen worden zowel de timing van sneeuwgebeurtenissen als de dikte van het sneeuwdek goed gesimuleerd. We toetsen het effect van sneeuw op het afvoerverloop van twee sub-stroomgebieden van de Berkel. Dit effect is doorgaans klein, behalve bij dikke sneeuwpakketten zoals in de winter van 2010/2011.In die gevallen verbetert de modelprestatie aanmerkelijk. Op de beschreven manier kan sneeuw dus relatief eenvoudig meegenomen worden in zowel langjarige modelsimulaties als in een operationele context: zo is één van de hier beschreven modellen geïmplementeerd in een operationeel Delft-FEWS systeem bij waterschap Rijn en IJssel.

Deze watersysteemrapportage van de Randmeren Oost geeft een beeld over het nabije verleden (2008-2018) en de huidige toestand (2018-2019) van het watersysteem Randmeren Oost waarbij wordt nagegaan in hoeverre wordt voldaan aan de functies uit het Beheer en ontwikkelplan voor de rijkswateren 2016-2021 (BPRW). Het rapport toont de ontwikkelingen op het gebied van areaalgegevens, waterkwantiteit, waterkwaliteit, ecologie, waterbodem, emissies en functies.

Mass changes of the Greenland ice sheet may be estimated by the Input Output Method (IOM), satellite gravimetry, or via surface elevation change rates (dh/dt). While the first two methods have been shown to agree well in reconstructing ice-sheet wide mass changes over the approximately the last decade (since 2003 for gravimetry), there are few long records from satellite altimetry and none that provide a time evolving trend that can be readily compared with the other methods. Here, we interpolate radar and laser altimetry data between 1995 and 2014 in both space and time to reconstruct the evolving volume changes. We use a novel interpolation approach that incorporates prior information related to ice dynamics. A firn densification model forced by the output of a regional climate model is used to convert volume to mass. We find that mass changes are dominated by SMB until about 2001, when mass loss rapidly accelerates. The onset of this acceleration is somewhat later, and less gradual, compared to the IOM. Our time averaged mass changes agree well with recently published estimates based on gravimetry, IOM, laser altimetry, and with radar altimetry when merged with airborne data over outlet glaciers. We demonstrate, that with appropriate treatment, satellite radar altimetry can provide reliable estimates of mass trends for the Greenland ice sheet. We also examine the impact of the extreme melt event in 2012 on the volume and, consequent, mass change for that year and compare with GRACE to assess how well our methodology accounts for this anomaly. Our time series could, potentially, be extended back to 1992 with the aid of ERS-1 data but the early part of this mission had varying orbit repeat cycles, which adds complexity to the analysis. The Cryosat-2 data used, since 2010 provides robust results, which can be extended for the length of the mission and supplemented with Sentinel 3 data after its launch.

Changes in both global and regional mean sea level, and changes in the magnitude of extreme flood heights, are the result of a combination of several distinct contributions most, but not all, of which are associated with climate change. These contributions include effects in the solid earth, gravity field, changes in ocean mass due to ice-loss from ice sheets and glaciers, thermal expansion, alterations in ocean circulation driven by climate change and changing freshwater fluxes, and the intensity of surge tides. Due to the diverse range of models required to simulate these systems, the contributions to sea-level change have usually been discussed in isolation rather than as a fully-coupled system. Focusing on the coastline of Northwest Europe, we consider all these processes and their relative impact on 21st century regional mean sea levels and extreme flood height. As far as possible our projections of change are derived from process-based models forced by the A1B emissions scenario to provide a self-consistent comparison of the contributions. We address uncertainty by considering both a mid-range and an illustrative high-end combination of the different components. For our mid-range ice-loss scenario we find that thermal expansion of seawater is the dominant contributor to change in sea level by 2100. However, the projected contribution to extreme sea level, due to changes in storminess alone, is significant and in places is comparable to the global mean contribution of thermal expansion. For example, under the A1B emissions scenario, by 2100, change in storminess contributes around 15 cm to the increase in projected height of the 50 yr storm surge on the west coast of the Jutland Peninsula, compared with a contribution of around 22 cm due to thermal expansion. An illustrative combination of our high-end projections suggests increases in the 50 yr return level of 86 cm at Sheerness, 95 cm at Roscoff, 106 cm at Esbjerg, and 67 cm at Bergen. The notable regional di

In order to increase the understanding of the changing climate, the European Space Agency has launched the Climate Change Initiative (ESA CCI), a program which joins scientists and space agencies into 13 projects either affecting or affected by the concurrent changes. 5 This work is part of the Ice Sheets CCI and four parameters are to be determined for the Greenland Ice Sheet (GrIS), each resulting in a dataset made available to the public: Surface Elevation Changes (SEC), surface velocities, grounding line locations, and calving front locations. All CCI projects have completed a so-called Round Robin exercise in which the scientific community was asked to provide their 10 best estimate of the sought parameters as well as a feedback sheet describing their work. By inter-comparing and validating the results, obtained from research institutions world-wide, it is possible to develop the most optimal method for determining each parameter. This work describes the SEC Round Robin and the subsequent conclusions leading to the creation of a method for determining GrIS SEC values. The participants 15 used either Envisat radar or ICESat laser altimetry over Jakobshavn Isbræ drainage basin, and the submissions led to inter-comparisons of radar vs. altimetry as well as cross-over vs. repeat-track analyses. Due to the high accuracy of the former and the high spatial resolution of the latter, a method, which combines the two techniques will provide the most accurate SEC estimates. The data supporting the final GrIS analysis 20 stem from the radar altimeters on-board Envisat, ERS-1 and ERS-2. The accuracy of laser data exceeds that of radar altimetry; the Round Robin analysis has, however, proven the latter equally capable of dealing with surface topography thereby making such data applicable in SEC analyses extending all the way from the interior ice sheet to margin regions. This shows good potential for a future inclusion of ESA CryoSat-2 25 and Sentinel-3 radar data in the ana, Geoscience and Remote Sensing, Civil Engineering and Geosciences

We present a new bed elevation dataset for Greenland derived from a combination of multiple airborne ice thickness surveys undertaken between the 1970s and 2012. Around 420 000 line kilometres of airborne data were used, with roughly 70 % of this having been collected since the year 2000, when the last comprehensive compilation was un- dertaken. The airborne data were combined with satellite- derived elevations for non-glaciated terrain to produce a con- sistent bed digital elevation model (DEM) over the entire is- land including across the glaciated–ice free boundary. The DEM was extended to the continental margin with the aid of bathymetric data, primarily from a compilation for the Arc- tic. Ice thickness was determined where an ice shelf exists from a combination of surface elevation and radar soundings. The across-track spacing between flight lines warranted in- terpolation at 1 km postings for significant sectors of the ice sheet. Grids of ice surface elevation, error estimates for the DEM, ice thickness and data sampling density were also pro- duced alongside a mask of land/ocean/grounded ice/floating ice. Errors in bed elevation range from a minimum of ±10 m to about ±300 m, as a function of distance from an obser- vation and local topographic variability. A comparison with the compilation published in 2001 highlights the improve- ment in resolution afforded by the new datasets, particularly along the ice sheet margin, where ice velocity is highest and changes in ice dynamics most marked. We estimate that the volume of ice included in our land-ice mask would raise mean sea level by 7.36 m, excluding any solid earth effects that would take place during ice sheet decay.

In order to increase the understanding of the changing climate, the European Space Agency has launched the Climate Change Initiative (ESA CCI), a program which joins scientists and space agencies into 13 projects either affecting or affected by the concurrent changes. This work is part of the Ice Sheets CCI and four parameters are to be determined for the Greenland Ice Sheet (GrIS), each resulting in a dataset made available to the public: Surface Elevation Changes (SEC), surface velocities, grounding line locations, and calving front locations. All CCI projects have completed a so-called Round Robin exercise in which the scientific community was asked to provide their best estimate of the sought parameters as well as a feedback sheet describing their work. By inter-comparing and validating the results, obtained from research institutions world-wide, it is possible to develop the most optimal method for determining each parameter. This work describes the SEC Round Robin and the subsequent conclusions leading to the creation of a method for determining GrIS SEC values. The participants used either Envisat radar or ICESat laser altimetry over Jakobshavn Isbræ drainage basin, and the submissions led to inter-comparisons of radar vs. altimetry as well as cross-over vs. repeat-track analyses. Due to the high accuracy of the former and the high spatial resolution of the latter, a method, which combines the two techniques will provide the most accurate SEC estimates. The data supporting the final GrIS analysis stem from the radar altimeters on-board Envisat, ERS-1 and ERS-2. The accuracy of laser data exceeds that of radar altimetry; the Round Robin analysis has, however, proven the latter equally capable of dealing with surface topography thereby making such data applicable in SEC analyses extending all the way from the interior ice sheet to margin regions. This shows good potential for a~future inclusion of ESA CryoSat-2 and Sentinel-3 radar data in the analysis, and thu

The National Airborne Field Experiment's (NAFE) were a series of intensive experiments recently conducted in different parts of Australia. These hydrologic-focused experiments have been designed to answer a range of questions which can only be resolved through carefully planned and executed field experiments in well instrumented basins together with intensive ground and airborne measurements of the appropriate type and spatial/temporal resolution. While the data collected have a specific focus on soil moisture, they are applicable to a wide range of hydrologic activities. The NAFE'05 experiment was undertaken in the Goulburn River catchment (New South Wales, Australia) during November 2005, with the objective of providing high resolution data for process level understanding of soil moisture retrieval, scaling and data assimilation. The NAFE'06 experiment was undertaken in the Murrumbidgee catchment (NSW, Australia) during November 2006, with the objective of providing data for SMOS (Soil Moisture and Ocean Salinity; a dedicated soil moisture satellite to be launched in 2008) like soil moisture retrieval, downscaling and data assimilation. To meet these objectives, the Polarimetric L-band Multibeam Radiometer (PLMR), a thermal imager, full-wave transform lidar, tri-spectral scanner and digital camera were flown onboard a small aircraft, together with coincident ground data collection on soil moisture, rock coverage and temperature, surface roughness, land surface skin and soil temperature, vegetation dew amount and vegetation water content. Each campaign was 3 to 4 weeks in duration and encountered favourable meteorological conditions, meaning that data was collected across a range of soil moisture conditions. Moreover, data was collected across diverse landcover and landuse settings in two different climatic regimes. The data described in this paper are available on the World Wide Web at www.nafe.unimelb.edu.au.

Climate change has the potential to influence global mean sea level through a number of processes including (but not limited to) thermal expansion of the oceans and enhanced land ice melt. In addition to their contribution to global mean sea level change, these two processes (among others) lead to local departures from the global mean sea level change, through a number of mechanisms including the effect on spatial variations in the change of water density and transport, usually termed dynamic sea level changes. In this study, we focus on the component of dynamic sea level change that might be given by additional freshwater inflow to the ocean under scenarios of 21st-century land-based ice melt. We present regional patterns of dynamic sea level change given by a global-coupled atmosphere–ocean climate model forced by spatially and temporally varying projected ice-melt fluxes from three sources: the Antarctic ice sheet, the Greenland Ice Sheet and small glaciers and ice caps. The largest ice melt flux we consider is equivalent to almost 0.7m of global mean sea level rise over the 21st century. The temporal evolution of the dynamic sea level changes, in the presence of considerable variations in the ice melt flux, is also analysed. We find that the dynamic sea level change associated with the ice melt is small, with the largest changes occurring in the North Atlantic amounting to 3 cm above the global mean rise. Furthermore, the dynamic sea level change associated with the ice melt is similar regardless of whether the simulated ice fluxes are applied to a simulation with fixed CO2 or under a business-as-usual greenhouse gas warming scenario of increasing CO2.

Climate change has the potential to influence global mean sea level through a number of processes including (but not limited to) thermal expansion of the oceans and enhanced land ice melt. In addition to their contribution to global mean sea level change, these two processes (among others) lead to local departures from the global mean sea level change, through a number of mechanisms including the effect on spatial variations in the change of water density and transport, usually termed dynamic sea level changes. In this study, we focus on the component of dynamic sea level change that might be given by additional freshwater inflow to the ocean under scenarios of 21st-century land-based ice melt. We present regional patterns of dynamic sea level change given by a global-coupled atmosphere–ocean climate model forced by spatially and temporally varying projected ice-melt fluxes from three sources: the Antarctic ice sheet, the Greenland Ice Sheet and small glaciers and ice caps. The largest ice melt flux we consider is equivalent to almost 0.7m of global mean sea level rise over the 21st century. The temporal evolution of the dynamic sea level changes, in the presence of considerable variations in the ice melt flux, is also analysed. We find that the dynamic sea level change associated with the ice melt is small, with the largest changes occurring in the North Atlantic amounting to 3 cm above the global mean rise. Furthermore, the dynamic sea level change associated with the ice melt is similar regardless of whether the simulated ice fluxes are applied to a simulation with fixed CO2 or under a business-as-usual greenhouse gas warming scenario of increasing CO2.