tailieunhanh - GIS for Water Resources and Watershed Management - Chapter 17

Công nghệ tiến bộ trong tham số tự động bề mặt đất từ độ cao Mô hình kỹ thuật số Địa hình đóng vai trò quan trọng trong năm và phân phối nước và năng lượng dòng chảy bề mặt đất tự nhiên Trong thời hạn. Ví dụ cổ điển bao gồm dòng chảy bề mặt, bốc hơi, xâm nhập, và trao đổi nhiệt là quá trình thủy văn nào đó diễn ra tại giao diện mặt đất-không khí. Việc đánh giá định lượng của quá trình phụ thuộc vào cấu hình địa hình của bề mặt đất, nào là một. | CHAPTER 17 Technological Advances in Automated Land Surface Parameterization from Digital Elevation Models Jurgen Garbrecht Lawrence W. Martz and Patrick J. Starks INTRODUCTION Topography plays an important role in the distribution and flux of water and energy within natural land surfaces. Classical examples include surface runoff evaporation infiltration and heat exchange which are hydrologic processes that take place at the ground-atmosphere interface. The quantitative assessment of the processes depend on the topographic configuration of the land surface which is one of several controlling boundary conditions. Many topographic parameters can be computed directly from a Digital Elevation Model DEM Band 1986 Jenson and Domingue 1988 Mark 1988 Martz and Garbrecht 1992 1993 Moore et al. 1991 Tarboton et al. 1991 Wolock and McCabe 1995 . This automated extraction of topographic parameters from DEMs is recognized as a viable alternative to traditional surveys and manual evaluation of topographic maps particularly as the quality and coverages of DEM data increase. Manual evaluation of topography is general tedious time-consuming error-prone and often subjective Richards 1981 . This chapter presents four advances in computerized methods to extract topographic parameters from DEMs. The first two advances address the treatment of depressions and flat surfaces in the DEM. Most existing methods for handling depressions and flat areas in DEM processing for drainage analysis are based on some common and fundamental assumptions about the nature of these features. These assumptions are largely implicit to the methods and are usually not recognized explicitly. These are 1 that closed depressions and flat areas are spurious features that arise from data errors and limitations of DEM resolution 2 that flow directions across flat areas are determined solely by adjacent cells of lower elevation and 3 that closed depressions are caused exclusively by the underestimation of DEM .