GWSC-VMR, a GIS supported conceptual distributed hydrological model for cold and arid regions

Our research focuses on the study of the particular hydrological process in cold and arid regions. Our aims are to develop a Geographical Information System (GIS) supported conceptual model that could be applied to simulate a drainage basin's hydrological process in cold and arid regions and to verify it through a case study. We built a model named the Vertically-Mixed Runoff Model with Grid-based Water Storage Capacity (GWSC-VMR for short). GWSC-VMR includes two parts, i.e. the spatial distributed model of water storage capacity and the vertically-mixed runoff module. First, drainage basin land cover map and typical vegetation rooting depth were acquired by interpreting remote sensing images or accessing land cover database. Second, through the processing of DEM data, we decided water flow direction, catchment area, basin boundary, and the slope of grided basin. Third, we determined the spatial distribution of water storage capacity based on the vegetation rooting depth. Because vegetation root system is a complicated system which is affected by the depth of active soil layer, and the depth of active soil layer is related to the slope, we put forward a series of concepts—upper critical slope gradient, lower critical slope gradient and critical soil layer depth to describe the grid tension water storage capacity and the grid free water storage capacity. Lastly, we integrated the vertically-mixed runoff mechanism and the spatial distribution of drainage basin water storage capacity to develop the GWSC-VMR, which could be applied to simulate drainage basin hydrologic processes, such as snow melt, canopy interception, evapotranspiration, and flow concentration.