Rainwater Harvesting for Irrigation in the Wake of Climate Change: A Model-based Design

Abstract

Water is a fundamental element in the attainment of food security and socio economic development any country. Spatiotemporal variation in rainfall and lack of scientific research in water resource utilization and management greatly affect conventional agricultural production. Rainfall is very important for the economic growth and development of any nation; hence there is dire need to study the monthly and annual trends. Rainfall in Botswana is highly variable characterized by frequent droughts and flash floods. In addition to that understanding the rainfall variability in a catchment is essential in policy formulation regarding for integrated water management and monitoring. Consistent water shortage of water call for the need to study the hydrological processes in order to plan for the limited resource. Descriptive statistical techniques like time series analysis, mean and standard deviation were employed to depict the temporal distribution of rainfall over the area. The main

objective of this study is to model rainwater harvesting for irrigation taking into account spatio- temporal variations of rainfall, its influences on streamflows, basin yield and their relationships with

climate change. The results of rainfall analysis reveals that Francistown catchment has high rainfall variability as indicated by regression analysis R2, Skewness, and Kurtosis coefficients of respectively. There is a shift in the rainy season onset and cessation coupled with recurrent droughts and floods. These are clear indicators of that climate is changing. The rainfall distribution is also highly variable with space and time which confirms that the catchment is situated in a semi-arid climate. Findings of these model and rainfall analysis are useful planning for activities such as irrigable farming, agricultural processing industries which strongly relies on year-to-year climatic variations.