SPAC system water movement model based on GIS and spatial database

The spatial variation of water in crop field soil-plant-atmosphere-continuum(SPAC) is often significant. One-dimension model could not describe the spatial distribution and movement of water accuracy. This study presents a regional SPAC water movement tool based on spatial database and ComGIS. It integrates hydrological process function that is suitable for north-China plain. This tool can be loaded in ArcMap(ESRITM) as a tool-box. The model combines spatial analyses, spatial database management and simulation of hydrological process. The results of SPAC water movement simulation can be outputted two-dimension or three-dimension. It is consisted by several submodules, also can be used for estimating evapotranspiration(ET). The validation of the model shows that the grid number absolute error bellowing 0.05 is 95.61% in regional soil moisture simulation. In wheat ET simulation the absolute error and average relative error are 0.15mm and 3.1%, respectively. In summer corn ET simulation the absolute error and average relative error are 0.13mm and 5%, respectively.