基于GeoProcessing方法的岷江上游流域数字水系建模

DIGITAL DRAINAGE NETWORK MODEL OF THE UPPER MINJIANG RIVER BASIN BASED ON GEOPROCESSING

GeoProcessing不仅提供空间数据分析的简单功能,而且支持建立非常复杂的地理处理模型来完成定制的地理处理任务和执行批处理操作。通过GeoProcessing地理处理新方法建立流域数字水系模型,是流域水文构成模拟计算、流域水土流失分析等的重要基础。为水文过程模拟分析提供有力支持。以岷江上游流域为研究区,首先使用GeoProcessing建模方法生成岷江上游流域30 m×30 m DEM并对其进行洼地的确定、填充和平地的抬升等预处理,采用D8法计算水流方向和汇流面积,在此基础上实现流域分水岭、河网水系和子流域等参数提取,并建立岷江上游流域数字水系模型。通过模型计算,较精确地确定了岷江上游的流域边界,其提取结果与传统的手工数字化成果吻合程度高,且细节部分更加突出;与传统的分步式操作相比,提高了水系河网提取的阈值试验条件设置次数,可批量处理,自动化程度高,人为干扰小,结果更加可信。当取汇水累计量≥600栅格单元(面积约为0.05km2)且综合长度≤500 m的水系时得到的结果与手工数字化地形图水系吻合较好。

Geoprocessing not only provides the simple function for spatial data analysis, but also supports establishing very complicated geographical processing models to lightly complete aforehand geographical processing tasks and realize batch processing. Using the new method of geographical processing to build watershed digital drainage network model is going to be the important basis of basin hydrological structure simulation calculation, soil erosion analysis and so on, and it can provides beneficial support for hydrological process simulation calculation. The upper Minjiang River Basin is chosen for the study area. After being pre-processed that depressions are identified and filled and flat areas are lifted, the 30 m × 30 m DEM of upper Minjiang River Basin is build based on the method of geoprocessing modeling. On basis of the DEM,the flow direction and catchment area are determined by using the D8 algorithms. According to these works, the drainage watershed,stream networks and the division of sub-basins are extracted automatically,and finally the digital drainage of watershed model of upper Minjiang River Basin is build. Based on the model calculation,the boundary of upper Minjiang River Basin is extracted exactly. This watershed boundary is not only basically consistent with the factual drainage network, but with better details. There are many advantages compared with the traditional operation of fractional steps, by using the geoprocessing model, many conditions can be added to the threshold setting to realize batch processing and higher automaticity. More important, It is less of artificial disturbance. All of these factors decide the more credible result. The experiment proved that if the catchment＇s cumulative amount ≥600 cells （the are is about 0.05km^2） and the total length of network ≤500m,the result of extraction for the upper Minjiang River Basin boundary is going to be in excellent agreement with the manual digitization topographic map.