An approach to computing topographic wetness index based on maximum downslope gradient
An approach to computing topographic wetness index based on maximum downslope gradient
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基于最大下坡梯度的地形湿度指数计算方法
DOI：
10.1007/s11119-009-9152-y
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发表时间：
2011-02
影响因子：
6.2
通讯作者：
ZHOU Cheng-Hu
中科院分区：
文献类型：
--
作者：
QIN Cheng-Zhi;ZHU A-Xing;PEI Tao;LI Bao-Lin;SCHOLTEN Thomas;BEHRENS Thorsten;ZHOU Cheng-Hu
地形湿度指数（TWI）作为精准农业中广泛使用的重要地形属性，旨在量化局部地形对水文过程的影响，并用于模拟土壤湿度和地表饱和度的空间分布。该指数的公式为 TWI = ln(a/tanβ)，其中单位等高线长度的上坡贡献面积（或特定流域面积，SCA），tanβ 是用于估计水力梯度的局部坡度梯度。 Botha和tanβ的计算需要反映当地地形对当地排水的影响。现有的许多流向计算算法都使用全局参数，导致流向划分不切实际。β通常用像素周围的斜率梯度来近似。事实上，像素的下坡梯度是β更好的近似。本文研究了适应当地地形的多流路由算法和最大下坡梯度 asβ 的使用对 TWI 的影响。自适应多流路由算法通过基于局部最大下坡梯度改变流划分参数来划分流。所提出的计算 TWI 的方法使用四种类型的人工地形进行定量评估，这些人工地形分别构建为具有一系列分辨率（1、5、10、20 和 30 m）的 DEM。结果表明，使用该方法计算的 TWI 的误差通常低于广泛使用的方法计算的 TWI 的误差。新方法应用于中国东北嫩江流域的低地势农业流域（约 60 平方公里）。应用结果表明，该方法的TWI分布更好地反映了当地的地形条件。
As an important topographic attribute widely-used in precision agriculture, topographic wetness index (TWI) is designed to quantify the effect of local topography on hydrological processes and for modeling the spatial distribution of soil moisture and surface saturation. This index is formulated as TWI = ln(a/tanβ), whereais the upslope contributing area per unit contour length (or Specific Catchment Area, SCA) and tanβis the local slope gradient for estimating a hydraulic gradient. The computation of bothaand tanβneed to reflect impacts of local terrain on local drainage. Many of the existing flow direction algorithms for computingause global parameters, which lead to unrealistic partitioning of flow.βis often approximated by slope gradient around the pixel. In fact, the downslope gradient of the pixel is a better approximation ofβ. This paper examines how TWI is impacted by a multiple flow routing algorithm adaptive to local terrain and the employment of maximum downslope gradient asβ. The adaptive multiple flow routing algorithm partitions flow by altering the flow partition parameter based on local maximum downslope gradient. The proposed approach for computing TWI is quantitatively evaluated using four types of artificial terrains constructed as DEMs with a series of resolutions (1, 5, 10, 20, and 30 m), respectively. The result shows that the error of TWI computed using the proposed approach is generally lower than that of TWI by the widely used approach. The new approach was applied to a low-relief agricultural catchment (about 60 km2) in the Nenjiang watershed, Northeastern China. The results of this application show that the distribution of TWI by the proposed approach reflects local terrain conditions better.
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影响因子：
5.4
作者：
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通讯作者：
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影响因子：
5.4
作者：
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影响因子：
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作者：
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影响因子：
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