Rainfall Trend, Changes And Their Socio-Economic And Ecological Impacts On The Sumampa Catchment For The 1980-2019 Period

Abstract

The study investigatedtrend and variability of rainfall in the Sumampa catchment by assessing daily, monthly, annual and decadal changes from 1980 to 2009. Monthly, seasonal and annual data were computed from the daily data series and graphically and statistically analysed to detect trend, changes and variability. The mean daily rainfall for the dry, minor and major seasons increased respectively by 63.9%, 17.57% and 11.84% in the 2000-2009 decade. The mean daily and decadal rainfalls respectively increased by 11.07% and 6.24% in 2000-2009.56.33% and32.44% of rainfall were respectively recorded in the major and minor cropping seasons. The Augmented Dickey-Fuller Test (ADF test) shows statistical evidence of stationary series (p = 0.01); the ARIMA model and the Holt-Winters method forecasted maximum amount of rainfall in the month of June and the minimum in January with no general trend of increase or decrease over the ten year period.