Nigeria as a country is blessed with several resources which include: favourable weather, rich natural resources, human resources and enormous water resources. Globally, Water is widely regarded as the most essential of natural resources, yet freshwater systems are directly threatened by human activities which is further termed as the anthropogenic causes of climate change. Moreover, the water resources sector of Nigeria demands proper and adequate management of water in terms of quality and quantity. However, climate change is indeed a major regional and global challenge which is currently posing a serious threat to the water resources sector of the nation and the world at large. However, this global problem can be mitigated by putting precautionary measures in place. Considering the case study, River Ogunpa is one of the major rivers located in Ibadan, Nigeria. The watershed hydrology has changed considerably due to increased anthropogenic activities which often serves as one of the principal actors of climate change. The watershed was 6,680ha saved by 49 stream junctions. Rainfall data of 26 years (1984 – 2009) were collected in addition to some other meteorological data such as Relative humidity, sunshine hours, temperatures (1990-2009) etc. Besides, the river Ogunpa flow record (1990 – 1994) was collected and analyzed. The result of the data analysis using least square method and rank correlation formula generated the stimyulation equation thus: Y = 0.63 + 0.002x for determining flow or discharge from the available rainfall data. The flow- rainfall correlation was satisfactory as shown by the correlation coefficient of 0.84 from a collective sample of flow records and rainfall data  (1990 – 1994).

Keywords: Water Resources Management, Climate Change, Ogunpa River, Impact, Nigeria