Web-based GIS-Hydrologic Modeling for Siting Water Harvesting Reservoirs

Abstract

Rainwater harvesting has been practiced at various scales in dry land and semiarid areas as a means to channel and store scarce rainfall for later on- farm or domestic use. The locations for water collecting structures are determined by a multitude of factors, often less than intuitive and involving compromise of interests. The Analytical Hierarchy Process (AHP) provides a systematic approach in conducting multi-criteria analysis and decision making. It allows for the comparison of alternatives based on the quantification of mostly qualitative characteristics of a given watershed/region. In this research, a Web-based GIS-hydrologic modeling system was designed to implement a spatial AHP process for selecting the most suitable and practical location for building water harvesting reservoirs. An on-line GIS digitizing tool helps user locate potential watershed, extract spatial data related to hydrologic characteristics as input for hydrologic model, which in turn produces needed runoff estimates from sub watersheds, together with land use and land cover data and experts opinions to produce a single Reservoir Suitability Index (RSI). Ranking of RSI allows for quick determination of suitable locations. The methodology was tested on a remote marginal watershed in Northeastern Lebanon. Major features and potential application of the Web-based tool are presented.