GIS MODELING OF RIPARIAN ZONES UTILIZING DIGITAL ELEVATION MODELS AND FLOOD HEIGHT DATA: AN INTELLIGENT APPROACH

摘要

Riparian ecotones are unique, diverse networks of vegetation and soils in close proximity to freshwater streams, rivers and lakes. These ecotones are linked to the watercourse network via flooding and intercepting upland runoff. Vegetation communities along stream banks often delineate riparian boundaries. However, geology, soil chemistry, and hydrologic changes need to be considered as well. Previous approaches to riparian boundary delineation utilized fixed width buffers, but this methodology has proven to be inadequate as there are two factors that all riparian ecotones are dependent on: the watercourse and its associated floodplain. Using a fixed width riparian buffer only takes the watercourse into consideration. Past research has determined the 50-year floodplain is the optimal hydrologic descriptor of a riparian ecotone. By hydrologically defining a riparian ecotone to occur at the 50-year flood height and incorporating digital elevation data, the spatial modeling capabilities of GIS are utilized to map riparian zones accurately and efficiently. The objective of this study is to develop a GIS based model to delineate a variable-width riparian boundary that characterizes a stream's ecotone. This approach offers advantages over other previously used methods of riparian ecotone mapping by better characterizing the watercourse and its associated floodplain. The riparian zones delineated using 10 and 30 meter DEMs, along with stream course information from the National Hydrological Data were found to be statistically significant (p < 0.001). This approach to delineating riparian areas is easily implemented and customized within ArcMap.