Modeling Using Dryness Index to Predict Evapotranspiration in a Sub-Saharan Environment

Abstract

There is a growing concern especially in Africa, about the consequences of climate change for food systems and food security. There is also concern that meeting the rising demand for food is leading to environmental degradation thereby exacerbating factors in part responsible for climate change, and further undermining the food systems upon which food security is based. Based on crop-climate studies from the viewpoint of modeling and predictability, this paper presents a new dryness index (DI), the ratio of rainfall over reference evapotranspiration (ET), for Ilorin (8.48o N) in the transition zone between humid and semi-arid climatic belts in Nigeria. The ET values were computed using the Blanney-Criddle and Hargreaves equations using the maximum and minimum temperatures as input. The number of days with DI more than unity was better represented by the Hargreaves equation at the study site. The daily rainfall analysis showed signs of a possible climate change. The implication of this in developing a sustainable crop plan for Nigeria and in crop-climate studies towards boosting the food production system in a changing climate is emphasized.

Keywords: evapotranspiration; sustainable; food; Nigeria; water; agriculture