The overall goal of this project (funding by DFG) is to quantitatively characterize the water storage dynamics of large lakes and wetlands around the globe by combining satellite information on water level height and open water extent with global-scale hydrological modelling.
Large lakes and wetlands are very important components of the global water cycle, affecting evapotranspiration, runoff and precipitation. Flow and storage dynamics of large lakes and wetlands have a strong influence on downstream river flows, and thus water availability and flood risk. Lakes and wetlands form the habitat of a large number of species, while lakes also provide water, food and a platform for transportation to humans. Many lakes and wetlands are strongly impacted by human activities, including water abstraction. Therefore, a better understanding and an improved modelling of flow and storage dynamics of large lakes and wetlands is required.
Today, the assessment of lake and wetland systems and of the river basins in which they are located are strongly limited by the availability of time series of in-situ observations of discharge, water table and open water area. The aim of this project is to develop a methodology to overcome this limitation.
DGFI contributes to this project by retrieving higher-accuracy time series of water table elevation of the selected large lakes and wetlands from satellite altimetry, using improved retracking and various satellite missions. Furthermore, time series of surface water area and water storage of the water bodies shall be retrieved. To understand the dynamics of the water balance, the consistent time series of water elevation, area and storage will be combined with hydrological modelling of the global hydrological model WaterGAP done by the project partners with enhanced multi-objective calibration (responsible: GFZ) and an improved model structure and validation (responsible: Goethe University Frankfurt ). The final consolidated consistent time series will be made publicly available.
The project covers first of all the time period 1993-2011 with available satellite data and focuses on six study areas in Africa, America, Asia, and Europe, encompassing three large lakes with small variations in surface water extent, and three large seasonal wetlands:
- Lake Tanganyika
- Lake Turkana
- Lake Constance
- Tonle Sap and surrounding floodplains
- Sudd Swamps