River Ona Discharge Modeling using GIS and Logarithmic Transformation Model

Abstract

Climate unpredictability and change in climatic parameters have direct influence on environment and human existence. A negative change in the climate, always have its corresponding dysfunctional impacts on man and the ecosystem globally or locally leading to flooding, poor agricultural yields, famine, and even death at some stages.Goal and objectives:Knowledge and information on the climatic variation parameters in an environment is very vital for environmental study assessment and proper planning. Therefore, evaluating the effect of weather variability on discharge of Ona River in Ibadan cannot be under-estimated.Methodology:A methodology to evaluate river discharge exclusively from remotely sensed data was developed. Water surface width and maximum channel width measured from satellite images of Ona River was coupled with channel slope data obtained from topographic maps created using Shuttle Radar Topography Mission (SRTM) were used to estimate the discharge. Landsat images were acquired for the years 1990, 2000 and 2015, which were used to determine anthropogenic activities. SRTM and Quick bird were used to model environmental changes and effects on the discharge of Ona River. The weather change effects on water discharge from Ona River in Ibadan was examined in three phases; site observation and data collection which was done in 2015 to get weather and discharge data of Ona River for each month, model simulation of temperature to determine discharge was done using regression model analysis.Results:The rainfall distribution is being revealed to have strong effect on the discharge rate (R2 = 0.77) and that of temperature on discharge rate of Ona River (R2 = 0.80). In 2015, the influence of rainfall on discharge rate was stronger (R2 = 0.85) while the discharge was 2.88m3/s. The monthly temperature-discharge gives a negative relationship (R2=0.55). There is strong negative relationship between vegetation and rainfall, -0.7. It has been projected that in 2028, the discharge rate will be reduced to 2.17 m3/s. There is evidence of dynamic responses of rivers to precipitation rate, which implied a significant response between rainfall and discharge and the negative effect of anthropogenic activities on rivers. This result can be used to predict the discharge of rivers given weather and environmental factors