Contribution of GIS to the morphometric characterization of Karcia watershed

Abstract

The objective targeted here is, to establish the global portrait of physical environment of Karcia watershed. This is an essential step towards the control,  protection and planning of its water resources. In that respect, emphasis is placed on geometrical, topographic and hydrographic characteristics, such  information are necessary to predetermine watershed response to rainfall elements and characterize its flow. DEM of 30m of resolution was exploited  due to its suitability for surface water flow modeling, while using the GIS approach. We have initially delimited watershed, generated DAM and  hydrographic network. We have subsequently created the thematic maps and calculated physiographic indexes and parameters intervening in  hydrological behavior. Results obtained are overall reliable, convincing and promising. Thus, Karcia watershed presents an elongated form: its length is  11 times greater than its width. It presents low relief, its topography decreases from NE and South towards the center. Maximum altitude equal to 50 m is  located in upstream and minimum equal to 2m, in the downstream. More than 76% of topography has a slope less than 1.8% and the remainder varies between 1.8% and 7.2%. Karcia watershed is 3rd order stream and presents a poplar (or corridor) network type. It also presents a coarse drainage texture  type and limited drainage density type. Interpretation of the results revealed that Karcia watershed is more adapted to infiltration than to runoff.  These results provide interesting insights to watershed specialists for irrigation and flood protection projects.