Development of integrated tools for river basin management-DRRSM and GIS application

The use of computerized hydrologic models is increasing in water resources research for purposes of establishing a technical base to estimate the results of management decisions and to identify the underlying mechanism of the real hydrologic systems in watersheds. The developments in data collection and manipulation systems such as digital sampling equipments, remote sensing technologies (RS) and geographical information systems (GIS ) feed back the current hydrologic modeling systems to integrate them with the new complex algorithms and computation techniques. As new developments occur, new problems arise, such as over parameterization of the models and the difficulty in the use of complex models due to comprehensive data requirements. In this thesis, the basic concepts in hydrologic modeling systems are reviewed, and problems in watershed modeling studies are expressed. Then, as a new trend, the distributed hydrologic modeling systems are discussed in detail. In addition, a simple conceptual distributed hydrological model is introduced as developed in the scope of this thesis for simulating daily runoff, using only the daily rainfall and evaporation data which are commonly found everywhere. The developed model is called DRRSM (Daily Rainfall Runoff Simulation Model) and uses the spatially distributed watershed data such as land cover and soil types by integrating GIS algorithms. Hydrologic computations are carried out on Hydrological Response Units (HRU), which are obtained by overlaying rainfall, land cover and soil type distributions of the watershed. DRRSM computes surface, sub-surface, groundwater and total runoff components of a watershed as a continuous time series at the outlet of the watershed. The runoff generations are based on simple linear discharge-storage relationships, which may be changed to non-linear structures by the user, if desired, since the DRRSM is developed by means of Object Oriented Programming techniques (OOP).HI The application of the DRRSM is demonstrated on Demirci watershed, which is a sub-watershed of the Gediz River basin. After the calibration processes of the DRRSM, the verification of the model is realized. The results of the application in Demirci watershed shows that the developed model DRRSM can be used to simulate daily mean discharges of a watershed where comprehensive data do not exist. The simple forms of the equations in the hydrologic computations are shown to be satisfactory when the spatial distribution of the data are considered.