tailieunhanh - GIS for Water Resources and Watershed Management - Chapter 2

Đánh giá hiệu suất của Phân đoạn đầu nguồn tự động từ Mô hình độ cao kỹ thuật số Đầu nguồn phân khúc và định nghĩa kênh IS mạng thường yêu cầu trong mô hình thủy văn phân phối. Bản đồ phân khúc tay từ IS là một công việc tẻ nhạt, tốn thời gian, và chủ quan, đặc biệt đối với lưu vực sông lớn. Việc khai thác tự động của phân đoạn đầu nguồn và mạng lưới kênh, tài sản subwatershed từ dữ liệu raster độ cao đại diện tại cách thuận tiện và nhanh chóng để tham số. | CHAPTER 2 Assessing the Performance of Automated Watershed Segmentation from Digital Elevation Models By Jurgen Garbrecht and Lawrence W. Martz INTRODUCTION Watershed segmentation and channel network definition is often required in distributed hydrologic modeling. Manual segmentation from maps is a tedious time-consuming and subjective task particularly for large watersheds. The automated watershed segmentation and extraction of channel network and subwatershed properties from raster elevation data represents a convenient and rapid way to parameterize a watershed. The increasing availability of DEM coverage for many areas of the United States makes this automated watershed segmentation and characterization a promising approach for a wide range of hydrologic investigations. However assessment of the generated watershed data beyond the usual visual inspection is required to develop confidence in the automated approach. Early research on automated landscape analysis focused on algorithm development and treatment of unique situations such as depressions flat areas or the connectivity of the network. DEM processing models which identify upward concave areas Pueker and Douglas 1975 Jenson 1985 Band 1986 often produce discontinuous network segments that must subsequently be connected O Callaghan and Mark 1984 and may require additional adjustments to produce a reasonable pattern Douglas 1986 . Other models rely on flow routing concepts. In this approach the steepest downslope direction defines the flow paths Jenson and Domingue 1988 Martz and de Jong 1988 Morris and Heerdegen 1988 . For either approach problems arise in low relief terrain when the vertical resolution of the DEM is insufficient to identify either upward concave areas or a downslope flow direction. Little work has been done to extend DEM processing methods to low relief terrain such as found in the central plains of the . This chapter investigates the performance of automated watershed segmentation .