Assessment of Precipitation and Temperature Variability on Land Suitability for Surface Irrigation in Kilosa District, Morogoro, Tanzania

Abstract

Africa is susceptible to the impacts of climate change due to its high dependence on rain-fed agriculture. Many African countries, including Tanzania, are experiencing variations in rainfall patterns and increased frequency of droughts and floods, which significantly affect agricultural productivity. This study focused on assessing the impacts of precipitation and temperature variability on land suitability in relation to surface irrigation in Kilosa district, Tanzania, utilising a multidisciplinary approach integrating remote sensing, geographical information systems (GIS), and multiple-criteria decision-making (MCDA) methods. The study evaluated various factors, including precipitation, temperature, soil texture, soil depth, drainage, slope, altitude, distance from water source (river proximity) and land use/land cover to determine land suitability classes. The land suitability was analyzed by considering the baseline period (1981-2005) and climate scenarios. Precipitation and temperature data for the baseline period were downloaded from CHIRPS and ERA5 Ag datasets, while the future climate scenarios (2011-2035) were projected using statistical downscaling methods based on Representative Concentration Pathways (RCPs). Proximity to water sources was a crucial criterion in assessing land suitability for surface irrigation in the study area. The river proximity was analyzed and categorized into four groups using QGIS. By incorporating the factors, the land suitability for surface irrigation was analyzed for both baseline periods and climatic scenarios. The suitability analysis employed the Analytical Hierarchy Process (AHP) to assign weights to the contributing factors. The three key principles, which are decomposition, comparative judgment, and synthesis of priorities, were used to guide the method. Results indicated that approximately 796,024.48(53.36%) hectares of the study area were recommended for surface irrigation within a baseline period, while for the projected period under RCPs, the recommended areas were reduced significantly. The study underscored the importance of considering climate factors, specifically precipitation and temperature, in irrigation land planning and emphasized the need for adaptive management strategies to ensure sustainable surface irrigation practices.