STELAR-S2S

catchment modelling

The channel morphodynamic model we are using in this research requires estimates (time series) of flow discharge and suspended sediment load at the upstream boundary of the study reach (at Kratie). Although flow discharges have been measured at Kratie since 1924, sporadic suspended sediment monitoring has only been undertaken since 1995. We are therefore using the VMod basin hydrological hydrological and sediment delivery model (Koponen et al., 2010; Lauri et al., 2012) to estimate these critically important water and sediment fluxes. As implemented for the Mekong, VMod employs a 5×5km grid, with topographic and soil type data in each cell being extracted from SRTM DEM and FAO soil type data sets, respectively. Vegetation is based on the GLC2000 land cover data supplemented by other satellite and historical imagery. VMod is forced with precipitation data from NOAA’s CLIMVIS dataset. However, suitable climate data within the Mekong Basin do not exist prior to 1981, so for the earlier period - and to investigate the impacts of future changes in climate on Mekong River sediment dynamics - we are using precipitation and temperature data obtained by downscaling the outputs from an ensemble of GCMs.

VMod computes a local water balance in each of its grid cells, before routing local runoff downstream

references

Koponen, J., H. Lauri, N. Veijalainen, and J. Sarkkula (2010), HBV and IWRM Watershed Modelling User Guide, MRC Information and Knowledge Management Programme, Available online

Lauri, H. (2009), VMod 5km Grid Hydrological Modeling Report (EIA Ltd.), Aalto University, Finland