Integration Of Digital Basin And Digital Hydrological Model

Digital hydrological model is developed on the platform of digital basin derived from raster-based digital elevation data. The software system is developed which could automatically delineate watershed divides, generate the river network and subcatchments, and establish the topological river network structure. It can be coupled with the modified Xin'anjiang model by object-oriented method.The depressions which are frequently present in DEMs may represent the actual topography, but are often the result of errors. Creating a depression-free surface is commonly required prior to deriving flow direction, flow accumulation, flow network, and watershed boundary maps. After comparing the performance of the usual algorithms used to remove depressions from DEMs, a simple method is introduced which is originally applied in the study of soil erosion process. The algorithm is easy to understand and to implement, requiring only a few tens of code lines. It is much faster than usual algorithms. On the basis of the algorithm, D8 (eight flow direction matrix) method and Garbrecht's coding system, a software is designed and developed to generate digital basin and to establish the topological river network structure. Moreover, control points, such as hydrological stations and reservoirs, are allowed to be added to the process of generating digital basin, so as to be easily coupled with hydrological model..Researches were made on several key techniques of visualizing hydrological system, viz. how to code digital drainage networks and digital basin and how to select the suitable data structure to match digital hydrological model. The system was developed by OpenGL graph library(Version 1.2) and Visual C++(Version 6.0). The system could provide the platform, on which it is easy to calibrate model parameters, visualize the spatial distributions and time series of hydrological elements, such as precipitation, evaporation, discharge, and state variable. Finally, a case study was implemented on the Baohe Catchment, the tributary of the Hanjiang River in Shanxi Province.