Mapping and Analysis of Hydro-Morphometric Parameters of Otammiri River Basin in Owerri, Imo State, Nigeria Using Geospatial Technique

Abstract

Notwithstanding that Otammiri river basin is one of the most important watersheds in Imo State, its hydrology is not well known. Good understanding of a basin drainage system and morphometry is fundamental for watershed management. Therefore, the aim of this study is to investigate the morpho-hydrological attributes of Otammiri watershed using geospatial technique. Landform, sub-catchment, drainage mapping, linear and areal morphometry analysis of the basin has been carried out by analyzing SRTM DEM-30 data using ArcGIS10.5 and supher11. Strahler (1964) stream order method was used for stream ordering. This study revealed that the basin is divided into 3 wings as a result of the confluence of Otammiri and Nworie river. The study area is rough and situated in surface of elevation range of 10m to 140m above mean sea level with total number of 82 streams of total length, 105 kilometers draining a landed area of approximately 113 square kilometers. The elevation of the basin decreases from north eastern part to the southern part with a large portion of the surface situated in a terrain of slope between 1 degree and 90 degrees. Results revealed that there are one (1) fourth order streams, three (3) third order streams, nineteen (19) second order streams and fifty-nine (59) first order streams. The river network revealed a dendritic pattern and a stream frequency of 0.7257, drainage density 0.9292 km-1, circulatory ratio of 0.320 and elongation ratio of 0.770. These digital derivatives attest that geospatial technique is effective in characterization of hydro-morphometric attribute of a river basin.