The Use of geographic information systems (G.I.S) in water resources research and management

The complexity and uncertainty of management objectives and parameters involved in water resources management have led planners to consult intensively to mathematical models in the description of natural phenomena. However, such models are often found to be deficient due to the spatial variation of model parameters and inputs. Recently, a new technology called "the Geographic Information Systems" or GIS has been developed to effectively solve this problem. The technique has found a wide area of application in water resources planning and management as well as in various other fields where the spatial distribution of effective parameters is significant The study presented introduces various characteristics of GIS and discusses its applicability in water resources engineering. Current GIS applications are presented together with the case of erosion and erosion based pollution identification, pointing out to advantages of the technique, requirements for its application, and various types of information that GIS can process. For the case of erosion and erosion based pollution identification, GIS and USLE (Universal Soil Loss Equation) are integrated. USLE is a method which is used widely to determine soil loss in a small watershed. Due to the lack of sufficient spatial information in Turkey, the case study is carried out on a demonstrative basin. Basically, it is aimed in the study to develop a methodology which can be applied to a real basin if sufficient date are available. The parameters (R, K, LS, C, P) that USLE requires for soil loss estimation are derived in digital format by digitizing associate paper maps. The soil losses are computed by the USLE model where the manipulations of each digital-parameter-layer are realized in the GIS domain. Organic N pollution, which is transported by clay particles in sediment, is estimated by applying the enrichment concept of contaminants to sediment yield computed by USLE. As a result spatial distributions of erosion and organic N in the demonstration basin are obtained by using GIS functions. The case study has shown that GIS is a very powerful tool for analyzing the spatial properties of basin management components so that the best management decisions and practices can be obtained. On the other hand, the presented work has also deliniated the fact that the use of GIS at the most efficient level requires sufficient and suitable databases and an understanding of GIS system capabilities. Ill