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プロジェクト情報(概要) / Project information (abstract)

基本情報 / Basic Information

研究題目
Research Title
A method to trace flow paths from DEMs using distance transform
A method to trace flow paths from DEMs using distance transform
状態
Status
完了
Completed projects
研究番号
Research Number
174
研究代表者
PI
小口 高 / 東京大学空間情報科学研究センター
Oguchi Takashi / -
受入CSIS教員
CSIS reception staff
小口 高 / -
Takashi OGUCHI / -
研究内容
Abstract
Driving by gravity, surface flow paths are formed following the downhill paths of least resistance toward streams or coasts. Previous studies have shown that the use of deriving flow paths from DEMs plays a key role in many hydrological analysis and applications, such as the extraction of hydrological characteristics, hydrological modeling, landslide monitoring, soil erosion prediction, and sediment or pollutant transport. The conventional method to trace surface flow paths from a scanned topographic map is based on an eight-flow direction matrix (D8). However, there are three limitations largely resulting from the only use of elevation information to calculate flow directions: (1) the result of flow directions is highly sensitive to DEM errors; (2) it is difficult to determine the flow directions in flat areas where the cells do not contain enough morphological information to determine the local flow direction; (3) the flows of water will be directed into the depressions where the cells are completely surrounded by other cells at a higher elevation, which can prevent simulated water flow from draining into outlets. Although some functions have been implemented to address these problems through a DEM post-creation modification technique like stream and depression filling, these problems still are the hard tasks. In this study, we will propose a new method for tracing flow paths by adopting two strategies: (1) rather than using neither grid DEMs nor vector contours, this method uses a raster contour map as input for taking the advantages of both simple raster structure and contours; (2) considering a further reason for the problems of the grid-based methods would be attributed to the use of elevation values to calculate flow directions, the new method concentrates on a new algorithm to calculate flow direction, particularly by using the distance transform of a raster contour image. The new method will be tested on some river watersheds in Japan.
研究期間
Research Period
2007-12-20 - 2008-03-31

研究者 / Researchers

申請中の研究者は表示されません。
Pending researchers are not shown.

小口 高 東京大学空間情報科学研究センター
Oguchi Takashi
呉艶蘭 東京大学大学院理学系研究科地球惑星科学 研究生
Go Tsuya Ran

利用データセット / Datasets used

申請中のデータセットは表示されません。
Pending datasets are not shown.

北海道地図 GISMAP 25000V データセット
Hokkaido-Chizu GISMAP 25000V
北海道地図 GISMAP for Terrain データセット 2005年提供版
Hokkaido-Chizu GISMAP for Terrain 2005
数値地図2500 データセット
数値地図50mメッシュ標高 データセット
数値地図250mメッシュ標高 データセット
数値地図2500 (空間データ基盤) 世界測地系版 データセット
数値地図25000 (地図画像) データセット
数値地図25000(行政界・海岸線)(世界測地系・地理情報標準版)2006年版
数値地図25000(土地条件)(世界測地系・地理情報標準版)データセット

研究成果 / Publications

研究成果は存在しません。
No Publication.

報告書 / Annual reports

報告書は存在しません。
No annual report.