Water availability is defined as the capacity of a water source to sustain additional water demand after considering current water uses and water conditions (IPIECA 2014). Water availability studies are often conducted to assess existing water sources and determine whether these resources can support future economic growth. One of the main factors currently affecting water availability is climate change, in particular precipitation and temperature. Changes in climate can have profound impacts on the hydrological cycle which in turn affects the amount of available water. In addition to reducing available water resources, climate change also influences the way water is used. Studies have shown that an increase in temperature and a decrease in precipitation leads to an increase in evapotranspiration (Abtew and Melesse 2013). This increases the demand for irrigation water since the crops will need to remain cool and avoid heat stress.