Development of a Sugarcane Crop Water Use Based Water Budgeting Calibration Tool for Catchment Water Management. Case Study: Zimbabwe’s South-Eastern Lowveld

Abstract

Zimbabwe’s Lowveld sugarcane farmers depends on at least 70 % irrigation for their crop production. Small scale sugarcane farmers (Out-growers) in the area are lacking technical capacities and finances to hire consultants to do their water budgeting predictions. They end up withdrawing unallocated water for their irrigation. This is posing a challenge to the supplier who ends up failing to supply water to deserving consumers. Conflict emerges among water users as they compete for the limited water resource. Many water budgeting tools have been developed over the past years with different goals and approaches being used in the development of these tools. Many of these tools focus on irrigation water management and mainly depend on current weather data as input parameters for their operations. Those that are more into water budget predictions, are either locality based and only consider the pumping capacities and pumping duration as their bases for budgeting and they do not take into account the Crop Water Use (CWU)/ ET crop. Due to the short comings of the existing tools, it was of paramount importance to develop a sugarcane CWU water budgeting tool for Catchment Water Management (CWM). Meteorological data from local weather stations and Satellite data for the past 14 years from 2003 to 2017 and 30 years from 1987 to 2017 respectively for the Lowveld area, incorporated with some formulas was used in determining CWU database in the calibration tool. Through evaluation, the development of this tool resulted in 100 % time saving, 60 % improved water management strategies and 30 % efficient and effective utilization of water resources.