基于梯田信息的地形湿度指数表达研究

目的]研究基于梯田DEM的地形湿度指数,为深化黄土高原地区土壤水分的研究提供依据。方法]以黄土高原地区梯田为研究对象,选择5mDEM、基于真实田坎方法构建的1m梯田DEM和基于激光点云数据构建的高精度1 m DEM数据分别对研究样区的地形湿度指数进行表达并作对比分析。结果]3种不同梯田DEM数据对地形湿度指数的表达有显著差异。(1)5m DEM数据仅能表现出地形湿度指数的宏观分布特征,不具备梯田地形特征信息;(2)基于真实田坎方法构建的1m梯田DEM能较准确细致地实现对梯田样区地形湿度指数的表达,梯田田面和田坎特征分布明显。但与高精度1 m DEM相比,在单个田面和田坎内部地形湿度指数定量表达有所偏差。结论]基于真实田坎方法构建出的梯田DEM可以更加准确地表达出梯田区域的地形湿度指数分布特征,但与真实地形相比,在田面和田坎内部的表达上仍然有所偏差,其构建方法需要进一步改进。

A Study of Topographic Wetness Index Based on Terraces DEM

Objective] We aim to study topographic wetness index (TWI) based on terraces digital elevation model (DEM), in order to provide basis for the study of soil water content and runoff capacity.Methods] Using 5 m resolution DEM, 1 m resolution DEM data generated with terrace information (T-DEM) based on the real field method and 1 m resolution DEM data generated from the laser point cloud data (H-DEM), we analyzed and compared the differences among three TWIs in the terrace fields of the Loess Plateau.Results] First, the result of 5 m resolution DEM data could show the macroscopic distribution, but it was too coarse to show the terrain feature of terrace. Second, although the 1 m resolution T-DEM data could accurately show the terrain humidity of terraced field and obviously reflect the characteristics of terrace surface and ridge feature, it showed larger deviation compared to H-DEM in the single terrace surface and the ridge.Conclusion] T-DEM can show the distribution characteristics of the TWI in terraced fields more accurately, but it has larger deviation in terrace surface and ridge in comparison to real terrace. T-DEM''s generating method need to be improved in future study.