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標題: 集水區邊界自動劃定之評估與改善
Assessment & Improvement of Automatic Watershed Boundary Delineation
作者: Hung, Wen-Chieh
關鍵字: 數值地形模型;DTM;集水區;Watershed
出版社: 水土保持學類
The watershed delineation is the basis of hydrology routing
andflood control engineering. In order to reduce the
disadvantage of delineating watershed by manual option and save
the time of dataprocessing, the DTM of Liyutan watershed and
Chungkongshi watershedwere used in this research to investigate
the problem that may cause inwatershed automatic delineating
with image processing softwareEASI/PACE. The results of
watersheds which were delineated by (1)automatic delineation
approach via computer, (2) by manual operationwith the
topographic map and by field check with GPS were
comparedaccordingly to discuss their accuracy. Four space
processing methodswere utilized to modify the watershed boundary
delineation with computer. In addition, the different resolution
of DTM which weremodified with resampling were used to process
the watershed automaticdelineation. These were to investigate
the effect that caused by the inaccuracy of the automatic
delineation. The results was summarized as following:1.Even
though there were some restrictions in using DTM to acquire the
boundary of automatic delineated watershed,with some help of
manual judgment we might increase its accuracy.2.The area error
percent of automatic delineated watershed was far less than the
perimeter,circularity ratio and compactness error percent.3.The
error percent of perimeter,circularity ratio and compactness of
automatic delineated watershed increase with respect to the
circularity ratio and compactness ratio. The major reason was
the difference of data format between raster and vector.4.In
order to decrease the error of perimeter,circularity ratio and
compactness of delineated watersheds, both commands-CLEAN and
GENERALIZE of Arc/Info,attributed the most significant effect in
converting raster format to vector format.5.Although it might
reduce the area error percent by means of resampling with
higher resolution of DTM data and delineating watershed
boundary automatically,it might also increase the error
percent of perimeter,circularity ratio and compactness
simultaneously. So one should weigh its advantage and
disadvantage when he wants to delineate the watershed boundary

材料進行自動劃定集水區邊界雖有其限制,然若輔以一 些人為之判釋,
遠小於周長、圓比值、 密集度等之誤差率。3.集水區自動劃定所得的周
長、圓比值興密集度等之誤差率,由於 網格式與向量式資料間格式的差
異,會隨著集水區圓比值與密集 度的增加而增加。4.對於改善自動劃定
所得集水區周長、圓比值與密集度等之誤差 率,以Arc/Info之指令
Clean 及Generalize的處理最具顯著效 果。5.以再取樣方式提高DTM的
解析度再進行集水區自動劃定,雖可減 少自動劃定集水區的面積誤差率
,但相對地卻會增加周長、圓比 值與密集度等的誤差率,宜斟酌為之。
Appears in Collections:水土保持學系

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