Chang Chia-Ling, Lo Shang-Lien, Yu Shaw-L
Graduate Institute of Environmental Engineering, Taiwan University, No. 71, Chou-Shan Road, Taipei 106, Chinese Taiwan.
Environ Monit Assess. 2006 Oct;121(1-3):289-301. doi: 10.1007/s10661-005-9123-3. Epub 2006 Jun 1.
The uncertainty of modeling input will increase the simulation error, and this situation always happens in a model without user-friendly interface. WinVAST model, developed by the University of Virginia in 2003, treats an entire multi-catchment by a tree-view structure. Its extra computer programs can connect geographic information system (GIS). Model users can prepare all the necessary information in ArcGIS. Extracting information from GIS interface can not only decrease the inconvenience of data input, but also lower the uncertainty due to data preparation. The Daiyuku Creek and Qupoliao Creek in the Fei-tsui reservoir watershed in Northern Taiwan provided the setting for the case study reported herein. The required information, including slope, stream length, subbasin area, soil type and land-use condition, for WinVAST model should be prepared in a Microsoft Access database, which is the project file of WinVAST with extension mdb. In ArcGIS interface, when the soil layer, land-use layer, and Digital Elevation Model (DEM) map are prepared, all the watershed information can be created as well. This study compared the simulation results from automatically generated input and manual input. The results show that the relative simulation error resulting from the rough process of data input can be around 30% in runoff simulation, and even reach 70% in non-point source pollution (NPSP) simulation. It could conclude that GIS technology is significant for predicting watershed responses by WinVAST model, because it can efficiently reduce the uncertainty induced by input errors.
建模输入的不确定性会增加模拟误差，这种情况在没有用户友好界面的模型中经常发生。弗吉尼亚大学于2003年开发的WinVAST模型通过树形视图结构处理整个多集水区。其额外的计算机程序可以连接地理信息系统（GIS）。模型用户可以在ArcGIS中准备所有必要信息。从GIS界面提取信息不仅可以减少数据输入的不便，还可以降低数据准备带来的不确定性。台湾北部翡翠水库集水区的大峪溪和曲婆寮溪为本文报道的案例研究提供了背景。WinVAST模型所需的信息，包括坡度、溪流长度、子流域面积、土壤类型和土地利用状况，应在Microsoft Access数据库中准备，该数据库是扩展名为mdb的WinVAST项目文件。在ArcGIS界面中，当准备好土壤层、土地利用层和数字高程模型（DEM）地图时，所有集水区信息也可以创建。本研究比较了自动生成输入和手动输入的模拟结果。结果表明，在径流模拟中，数据输入粗略过程导致的相对模拟误差可能在30%左右，在非点源污染（NPSP）模拟中甚至达到70%。可以得出结论，GIS技术对于用WinVAST模型预测集水区响应具有重要意义，因为它可以有效降低输入误差引起的不确定性。
