| The impact of resolution on the accuracy of hydrologic data derived from DEMs |
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| 作者姓名： | TANG Guo-an HUI Yang-he Josef Strobl LIU Wang-qing |
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| 作者单位： | 1. Department of Geography，Northwest University，Xin 710069，China; 2. Department of Geography，Salzburg University，A-5020，Austria |
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| 基金项目： | National Natural Science Foundation of China No. 49971065，Open Research Fund Program of LIESMARS，No. WKL 99-0302，High-visiting Scholar Fund of the Key Laboratory of Continental Dynamics，Ministry of Education，China |
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| 摘 要： | 1 Introduction Automated extraction of drainage features from DEMs is an effective alternative to the tedious manual mapping from topographic maps. The derived hydrologic characteristics include stream-channel networks, delineation of catchment boundaries, catchment area, catchment length, stream-channel long profiles and stream order etc. Other important characteristics of river catchments, such as the stream-channel density, stream-channel bifurcation ratios, stream-channel order, number…
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| 收稿时间： | 20 June 2001 |
| 修稿时间： | 30 July 2001 |
The impact of resolution on the accuracy of hydrologic data derived from DEMs |
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| TANG Guo-an,HUI Yang-he,Josef Strobl,LIU Wang-qing.The impact of resolution on the accuracy of hydrologic data derived from DEMs[J].Journal of Geographical Sciences,2001,11(4):393-401. |
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| Authors: | Tang Guo-an PhD Hui Yang-he Josef Strobl Liu Wang-qing |
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| Institution: | 1. Department of Geography, Northwest University,
2. Department of Geography, Salzburg University, |
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| Abstract: | Hydrologic data derived from digital elevation models (DEM) has been regarded as an effective method in the spatial analysis
of geographical information systems (GIS). However, both DEM resolution and terrain complexity has impacts on the accuracy
of hydrologie derivatives. In this study, a multi-resolution and multi-relief comparative approach was used as a major methodology
to investigate the accuracy of hydrologie data derived from DEMs. The experiment reveals that DEM terrain representation error
affects the accuracy of DEM hydrological derivatives (drainage networks and watershed etc.). Coarser DEM resolutions can usually
cause worse results. However, uncertain result commonly exists in this calculation. The derivative errors can be found closely
related with DEM vertical resolution and terrain roughness. DEM vertical resolution can be found closely related with the
accuracy of DEM hydrological derivatives, especially in the smooth plain area. If the mean slope is less than 4 degrees, the
derived hydrologie data are usually unreliable. This result may be helpful in estimating the accuracy of the hydrologie derivatives
and determining the DEM resolution that is appropriate to the accuracy requirement of a particular user. By applying a threshold
value to subset the cells of a higher accumulation flow, a stream network of a specific network density can be extracted.
Some very important geomorphologie characteristics, e.g., shallow and deep gullies, can be separately extracted by means of
adjusting the threshold value. However, such a flow accumulationbased processing method can not correctly derive those streams
that pass through the working area because it is hard to accumulate enough flow direction values to express the stream channels
at the stream’s entrance area. Consequently, errors will definitely occur at the stream’s entrance area. In addition, erroneous
derivatives can also be found in deriving some particular rivers, e.g., perched (hanging up) rivers, anastomosing rivers and
braided rivers. Therefore, more work should be done to develop and perfect the algorithms. |
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| Keywords: | DEM resolution stream network accuracy |
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