GIS-Based prediction and comparative Analysis of Potential Evaporation using Selected Methods at Omi Kampe Watershed, Nigeria

Abstract

The study predicted potential evapo-transpiration (PET) of Omi Kampe watershed upstream in Kogi State, Nigeria using Soil and Water Assessment Tool (SWAT) based on Priestley Taylor, Penman Monteith and Hargreaves methods. The model input data used were Digital Elevation Model, Soil map, Land use map and 30-year temporal weather data (January 1987- December 2016) for the simulation of the hydrological processes. The results showed that Penman Monteith and Hargreaves methods exhibited high correlation in the predicted values of PET while Priestley Taylor results for PET are least correlated with the other two methods and suspected to have under predicted PET values. On the other hand, all the three methods predicted the actual evapo-transpiration of the watershed with insignificant result variations. Outcome of this research could serve as a guide to water professionals and other stakeholders in selecting appropriate methods for evaluation of PET in the study area and sub region in Nigeria.