Distributed Hydrodynamic Model of the Rich and Coarse Sediment Area of the Yellow River Basin

According to the basic theories of erosion dynamics, hydrology, and sediment mechanics and using the geographical information system-short for GIS as research platform, this research studies develop the distributed soil loss model and support system of the rich and coarse sediment area of the Yellow River basin based on physical model test about the mechanism of erosion and sediment yield of the Loess hill slope-gully system. In this paper, the interrelation between erosion and sediment yield of the hill slope-gully system under the effects of vegetation is revealed. The sediment yield in the basin is dominated by hill slope or gully slope, which is related to the vegetation coverage. When the vegetation cover ratios is more than 80%, the sediment yield of gully slope is the main factor, vice versa, hill slope. The conception of “equivalent roughness” was put forward in order to quantitative characterize the regulatory effect of engineering measures—such as terraced fields, check dams and small reservoirs—to the flow and sediment. The sediment transport ratio estimation formula of small watershed with flow and sediment transport mechanism is constructed. The distributed hydrodynamic model for soil erosion based on GIS is established, which includes vegetation interception, evapotranspiration, calculation of excess-infiltration, confluence, raindrop erosion, runoff erosion, gully slope erosion, the interrelation between erosion and sediment yield of the hill slope-gully system, sediment-transporting of gully slope, sediment delivery ratio, and other simulation modules. Also, the support system based on ArcGIS is developed, includes the basic data organization, interpolation, and discretization of spatiotemporal data, correlation spatial analysis based on watershed topographic data, basic hydrological analysis, model operation, data management, and querying. With the ArcObjects for basic operations and spatial analysis, this model provides the appropriate interface to each function of ArcGIS8.x and its further component-based system, which mainly uses the ArcGIS Personal Geodatabase data model for data storage and management. Through all-round communication with ArcGIS, all of the functions can be implemented by this interface, such as data management required by the data model, analysis calculation, and display. Using the development tools provided by ArcGIS to realize all the functions of ArcGIS, also, the interface of the system and the database are unified in ArcGIS system, close coupling can be achieved between the GIS and the soil loss model, runoff-convergence model, and sediment transport model.