Assessing Irrigation Potential under Drought Scenarios In The Lwampanga Sub-Catchment Of Nakasongola District.

Abstract

The Lwampanga Sub- County in Nakasongola District is frequently affected by drought, resulting in reduced agricultural productivity and increased vulnerability of communities that depend on rainfed agriculture. Although irrigation has been identified as key adaptation strategy, limited information on the spatial distribution of land suitable for irrigation development under varying drought conditions. This study investigated irrigation potential under normal, moderate drought, and severe drought scenarios in the Lwampanga Sub- County using Geographic Information systems (GIS), Remote sensing, and multi-Criteria Decision Analysis (MCDA). Spatial datasets, including Digital elevation Model (DEM) of 30m resolution, soil properties, land-use/land-cover, road networks, and water resources, were processed and integrated within a GIS environment. The analytical Hierarchy Process (AHP) was used to assign weights to irrigation suitability factors which included distance from water resources 42%, slope 18%, elevation 13%, land-use/land cover 13%, drainage 5%, soil depth 4%, soil type 3%, distance from the road 2% as per calculations from pairwise matrix and weighted overlay analysis was performed to generate suitability maps. Drought scenarios of normal, moderate, severe were developed by progressively reducing available surface water resources by considering all rivers, streams and other water bodies available for irrigation, excluding seasonal streams and wetlands for moderate and considering only major water bodies like permanent rivers lakes for severe drought. The results showed that water availability, slope, soil characteristics, and land-use/ land-cover strongly influenced irrigation suitability. Under normal conditions, the sub-catchment contained areas classified as 67.68ha (0.7%) highly suitable 5886ha (61%) moderately suitable, and 3688ha (38.3%) marginally suitable for irrigation development. Irrigation potential declined as drought severity increased due to reduced available water resources as seen with increase of land from 67.68ha highly suitable during normal conditions to 190.84ha located near perennial water resources and characterized by favorable soil and topographic conditions remained suitable, even water under severe drought conditions