Delineating wetland areas from the cut-and-fill method using a Digital Elevation Model (DEM)

Abstract

ABSTRACT Satellite imagery has been widely used to delineate, map and monitor different wetland types. However, the influence of clouds and spectral confusion between wetlands and other land cover types has a negative effect on classification accuracies across nearly all methods. Most wetlands are topographic lowlands surrounded by uplands, and this study explores the possibilities of delineating wetlands from Digital Elevation Models (DEMs) using the cut-and-fill method. The objectives were: (1) to examine the possible use of the cut-and-fill method, which is commonly used in construction, to delineate different types of large floodplain wetlands, and (2) to compare the accuracy of the cut-and-fill method with wetness indices commonly used for delineating wetlands from satellite images. Comparison between the cut-and-fill method, the Normalised Difference Water Index (NDWI) and the Modified Normalised Water Difference Index (MNDWI) showed that the cut-and-fill method was superior in terms of overall accuracy and kappa statistics while the NDWI was the poorest of the three methods. The study concluded that the cut-and-fill method can be useful in delineating wetland areas, especially for wetlands in confined valley settings and where cloud-free images are not available.