The Application of GIS and Remote Sensing Technologies in Mapping River Basins, Case Study of the Sanaga River in Cameroon

The Sanaga River is the largest river in Cameroon. It flows from its source on the Adamawa Plateau, down through the southern plateau which is a hilly landscape with volcanic domes to the very low depression where most of Cameroon's rivers join the Atlantic Ocean. Since the Sanaga is highly solicited for economic purposes detailed delineation of its drainage networks is important for natural resource management studies and Water management projects. The Shuttle Radar Topography Mission (SRTM) imagery covering the Sanaga area was used to extract drainage basins and define streams orders. The DEM threshold values of Flow Accumulation were used to delineate stream network, while the Strahler's and Horton's method of stream ordering was used to exact order of streams in the basins. It was found that Sanaga tributaries are of 9th order. Total 155011 streams are identified of which 77.939 are first order, 36.923 are second order, 20.127 are third order, 9.975 are fourth order, 4.606 are fifth order, 2.964 are sixth order, 1.321 are seventh order, 608 are eighth order and 548 are ninth order Stream. According to the results of this research, the Sanaga covers a drainage basin of 142,412 km². The drainage basin was divided into 5 drainage divides following the pattern in which channels merge with smaller tributaries to join the larger trunk stream. According to this research analysis, the Sanaga River channels covers an area of 1.257 km² and has a lenght of 877,577 km. The SRTM, DEMs provides greater detail in the extraction of the stream ordering system and drainage networks which can be applied in the analysis of hydrologic processes.

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