The impact of Hillslope Length parameter on SWAT streamflow prediction in the Upper Danube

A main challenge for eco-hydrological modeling at large scale concerns the identification of the best input data in order to assess hydrological processes and water quality efficiently. Model spatial input data are the primary sources of the uncertainty in hydrological modeling (Zhang et al., 2014). The impact of topographic data and the quality of spatial prediction is well documented (e.g. Chaplot, 2005, Zhang et al., 2014). In the SWAT model (Soil and Water Assessment Tool, Arnold et al., 1998), the topographic attributes of the sub-basins are all derived from Digital Elevation Models, DEM, (Chaubey et al., 2005; Jha et al., 2004). DEM resolution affects the watershed delineation, stream network and sub-basins classification (Cotter et al. 2003; Chaubey, 2005). A courser DEM resulted in decreased representation of watershed area, decreased slope, increased Hillslope Length, decreased streamflow, sediment, NO3-N and TP load predictions (Lin et al., 2010). However, Robison et al. (1995) and Jha et al. (2004) pointed out that after a certain threshold in the number of sub-basins was reached, few changes in streamflow outputs were observed. Among the topographic parameters, the sub-basin Hillslope Length parameter plays an important role in predicting runoff, lateral flow, and sediment yield through the peak runoff. Over the last 20 years several algorithms have been developed based on the geographic information system (GIS) technology for the Hillslope Length estimations. Recently, Zhang et al. (2012) proposed a GIS toolbox to estimate Hillslope Length based on flow accumulation. The objective of this study was to analyse the impact of DEM resolution (25 or 100 m) and Hillslope Length estimations on SWAT model streamflow output

MALAGO Anna;  VIGIAK Olga;  BOURAOUI Faycal;  FRANCHINI Marco; 

2014-12-03

XXVI Conference of the Danubian Countries -Conference 2014

JRC90345

www.danubeconference.org,    https://publications.jrc.ec.europa.eu/repository/handle/JRC90345,