A multi-sensor-based evaluation of the morphometric characteristics of Opa river basin in Southwest Nigeria
International Journal of Image and Data Fusion
Studies have shown that many river basins in the sub-Saharan Africa are largely unmonitored, partly because they are poorly or totally ungauged. In this study, remote sensing products (Landsat, Advanced Spaceborne Thermal Emission and Reﬂection Radiometer; ASTER and Shuttle Radar Topography Mission; SRTM) that are freely availableintheregionwereharnessedforthemonitoringofOpariver basin in southwestern Nigeria. The remote sensing products were complementarily used with topographical sheets (1:50,000), ground based observation and global positioning systems to determine selected morphometric characteristics as well as changes in landuse/ landcoveranditsimpactonpeakrunoﬀ intheOpariverbasin.Results showed that the basin is a 5th order basin whose land area has been subjected to diﬀerent natural and anthropogenic inﬂuences within the study period. Urbanisation is a major factor that threatens the basin with degradation and observed changes, and the threats are expectedtobecomeworseifrestorationisnotconsideredfromsome tributaries. The study concluded that commentary use of available remotesensingproductsintheregionwillprovideanimportantlevel of decision support information for management and monitoring of river basins.