ISSN 2360-7955
Abstract
Accepted 27th May, 2020.
The aim of this paper was to study the rainfall trend and investigate the implications of anthropogenic activities and rainfall for flooding at Lakota. 18 years annual rainfall data and 32 years hydrological (discharge and river stage) data of the study area were collected from Nigerian Meteorological Agency (NIMET) and National Inland Water Ways (NIWA) respectively. Other data used include pre-disaster and during disaster moderate resolution (MODIS) satellite image of 2012 flood within the study area, GPS coordinates of buildings within the areas ravaged by flood and data collected using questionnaires. Software used is ArcGIS10.1 and Microsoft Excel 2011 version. Proximity analysis in GISs environment was used to investigate the level of agreement of development to regulation standard while statistical parameters and least square regression analysis were respectively, used for investigation of 2012 rainfall intensity and rainfall trend analysis. Equation which approximates the linear relationship between rainfall amounts (the dependent variable (Y)) and the year (the independent variable (X) was developed using time series rainfall data. With the equation we were able to predict rainfall intensity from 2013 to 2025 and determined range of acceptable rainfall at 95% confidence limit. Furthermore, the technique was used to ascertain the contributions of rainfall to flooding in the study area. Result shows that 2012 flood rainfall intensity was higher than long term average and this contributed to increase in water level beyond average along the river Niger course resulting to higher water discharge within the study area. There is also an increasing trend in rainfall as could be seen from the linear trend in figurg4. The model of the linear trend is; Y = 9.032x – 16807, meaning that the area is getting wetter at the rate of 9.032mm. With this increase, there is enough water for the ground water storage and river flow which will increase flooding. Further analysis also revealed that illegal construction of buildings along the floodplain and its corresponding informal settlements resulted to huge economic loss and increase in the number of affected persons during 2012 flood within the study area.
Keywords; flood, informal settlement, rainfall intensity, Gis, MODIS