tailieunhanh - GIS for Water Resources and Watershed Management - Chapter 3

Khi phát triển một mô hình lượng mưa, dòng chảy phân phối sử dụng Mô hình độ cao kỹ thuật số, nó là quan trọng cần xem xét các phương pháp với một phân bố không gian của đại diện nào IS độ cao, vì bề mặt của một phương thức đại diện xác định cấu trúc của một mô hình lượng mưa, dòng chảy phân phối. Ba phương pháp chính để Cơ cấu một mạng lưới các dữ liệu độ cao là các mạng lưới vuông, đường viền các mạng, và các mạng lưới không đều triangulated (Moore và. | CHAPTER 3 Development of a Basin Geomorphic Information System Using a TIN-DEM Data Structure Yasuto Tachikawa Michiharu Shiiba and Takuma Takasao INTRODUCTION When developing a distributed rainfall-runoff model using Digital Elevation Models it is important to consider the method with which a spatial distribution of elevations is represented because the method of a surface representation determines the structure of a distributed rainfall-runoff model. Three principal methods for structuring a network of elevation data are square-grid networks contour-based networks and triangulated irregular networks Moore et al. 1991 . Using contour-based networks a watershed basin can be subdivided into irregular polygons bounded by contour lines and adjacent to their orthogonals flow trajectories that define the boundaries of drainage areas O Loughlin 1986 Moore et al. 1988 . Moore and Foster 1990 modified these methods and provided a structure for modeling overland flow TAPES. For dynamic hydrologic modeling contour-based methods have a great advantage in considering the directions of water flow but they need heavy data storage and much computation time. Square-grid networks are the most common form of DEMs used for topographic analysis of a river basin O Callaghan and Mark 1984 Band 1986 Hutchinson 1989 Tarboton et al. 1989 Takasao and Takara 1989 Takara and Takasao 1991 and rainfall runoff modeling Lu et al. 1989 Wyss et al. 1990 Quinn et al. 1991 . Grid-based DEMs have advantages for their ease of computational implementation efficiency and availability of topographic databases. However when considering the directions of water flow these methods are not appropriate for hydrological applications because those trajectories represent only crudely the movements of water from one grid to one of the eight neighboring grids. A more applicable approach for hydrological modeling is the Triangulated Irregular Networks TINs . Palacios and Curvas 1986 1991 made it possible to delineate