Abstract: The impact of human activities on sensitive watershed terrains is a critical consideration in the management of urban ecosystems. Degradation of sensitive ecosystem features such as watershed land areas is often irreversible due to the extent and intensity. The vulnerability of 150 m watershed management zone of Otamiri river Owerri Imo State, Nigeria was studied by topographic analysis using 1977 Digital Elevation Model (DEM), 1977 aerial photos, shuttle radar topographic mission DEM of 2000, 2006 satellite imagery and the master plan of the study area. The impact of human activities in elevation change was observed in the parts of substantial human activities while topographical stability was recorded for areas of very low human activities. At the East banks of Otamiri and Nworie rivers where heavy human activities take place, average changes in elevation were -7.138 and -4.454 m, respectively, indicating eroded banks. While the West banks of Otamiri and Nworie rivers with sparse human activities measured +0.048 and +0.000 m in average changes in elevation. Along Otamiri and Nworie water courses from source to confluence, an average elevation increase of +3.616 and +5.159 m, respectively were recorded, indicating sedimentation and siltation. And a reduction (-7.028 m) in average elevation change, suggestive of erosive action was measured from Otamiri/Nworie confluence to the South, an area of intensive sand excavation. The study recommends enforcement of the watershed management edict that seeks to create a buffer zone around the river banks, so, as to protect the valuable ecosystem.
Ngozi AC-Chukwuocha, Sab A. Ngah and Akajiaku C. Chukwuocha, 2018. Vulnerability Studies of Sensitive Watershed Areas of Owerri South East Nigeria Using Digital Elevation Models. Research Journal of Applied Sciences, 13: 711-717.