Multi-criteria Land Evaluation for Rice Production using GIS and Analytic Hierarchy Process in Kilombero Valley, Tanzania

Abstract

A GIS-based multi-criteria land evaluation (MCE) was performed in Kilombero Valley, Tanzania to avail decision makers and farmers with evidence based decision support tool for improved and sustainable rice production. Kilombero valley has been identified by the government and investors for rice production intensification. Five most important criteria for rice production in the area were identified through literature search and discussion with local agronomists and lead farmers. The identified criteria were 1) soil properties, 2) surface water resources, 3) accessibility, 4) distance to markets, and 5) topography. Surveys, on-screen digitizations, reclassifications and overlays in GIS software were used to create spatial layers of the identified criteria. Analytic hierarchy process (AHP) method was used to score the criteria using local extension staff and lead farmers as domain experts on a scale of 0.0 – 1.0. Surface water resource scored the highest weight (0.462) followed by soil chemical properties (0.234). Other criteria and their weight in paranthesis are soil physical properties (0.19), topography (0.052), accessibility (0.036), and distance to market (0.025). The MCE results showed that about 8% of the study area was classified as having low suitability for rice production while only 2% was highly suitable. The majority of the area (about 89%) was classified as having medium suitability for rice production. Since the suitability decision was dominated by the surface water resource criterion, the rice suitability in the study area can be greatly improved by improving the water resources management.

Keywords: AHP, Kilombero Valley, multicriteria land evaluation, lowland rice, suitability analysis.