Topographic Wetness Index Computed Using Multiple Flow Direction Algorithm and Local Maximum Downslope Gradient

摘要：

Topographic wetness index (TWI) can quantify the control of local topography on hydrological processes and indicate the spatial distribution of soil moisture and surface saturation. The formulation is TWI=ln(α/tanβ), where α is the upslope contributing area per unit contour length and β is the local gradient. Many of the existing flow-direction algorithms for computing a use global partition exponent to allocate the flow among downslope neighboring cells, which lead to unrealistic partitioning of flow. For approximatingβ, the downslope gradient can reflect impacts of local terrain on local drainage better than slope gradient at the point. This paper examines how TWI is impacted by computing α with a new multiple-flow-direction algorithm and approximating β with local maximum downslope gradient. The new multiple-flow-direction algorithm is adaptive to local terrain conditions by altering the flow partition exponent based on local maximum downslope gradient. The proposed approach for computing TWI was applied to a small catchment (about 60 km2) with low relief in the Nenjiang watershed in Northeastern China. The results show that the distribution of TWI by the proposed approach is more adaptive to terrain conditions than widely-used algorithm for TWI.

关键词： Gridded DEM topographic wetness index multiple flow direction algorithm maximum downslope gradient

作者: Chengzhi Qin A-xing Zhu Lin Yang Baolin Li Tao Pei

作者单位: State Key Laboratory of Resources and Environment Information System, Chinese Academy of Science, Be State Key Laboratory of Resources and Environment Information System, Chinese Academy of Science, Be

会议类型: 国际会议

会议名称: 北京国际地理信息系统学术讨论会第七届会议（7th International Workshop Geographical Information System

会议地点: 北京

会议语种:英文

页码: 87-91

在线出版日期: 2007-09-14（万方平台首次上网日期，不代表论文的发表时间）