THREE DIMENSIONAL RIVER BASIN SIMULATION WITH DISTRIBUTED RUNOFF MODEL FOR WATER QUANTITY AND QUALITY

Abstract

Most of the existing distributed rainfall-runoff models simplify the interaction between the atmosphere and the groundwater processes. Nevertheless the correct representation of this interaction is very important in water resources management. The time scale of interaction between surface runoff and atmosphere is ranging from few minuets to few hours. The time scale of interaction between surface runoff and groundwater also has the range from few hours to few days (depending on the hydrological characteristics of the unsaturated and saturated layers). Because these scales are not the same, the hydrological modeling of the water cycle related processes is not straightforward. For lumped-typed runoff models, it is sufficient to simplify the interaction within large time scales. This creates the problem that large time scales in hydrological modeling do not include many of the physical processes that occur in small time scales. The objective of this research has been to make an integrated hydrological model through the simulation of the hydrological interactions in the surface, ground and atmosphere. This resulted in a new distributed runoff model for watershed. For spatial interactions, it appeared that the existing distributed runoff models outputs could be improved considerably through considering atmosphere and ground interactions. The temporal interactions add much to the reliability and accuracy of the integrated hydrological model. The methodology is based on the dynamic linking among the transient hydrological models at different time scales, which implies that the quantity and quality of the distributed runoff at every time step is affected by the impact of atmosphere and groundwater interactions. Static linking of hydrological sub-models is normally used in distributed rainfall-runoff models. It is shown that the assumption of steady conditions for groundwater model during small time scales will not affect the accuracy of the model outputs. This is valid for many geological formations in the world. Using integrated hydrological modeling with dynamic linking between different sub-hydrological models is useful for water resources management. The developed integrated hydrological model has been applied for the Yasu River basin, Japan, and for the Seyhan River basin, Turkey. The performance of this model has been also compared with the available measured data. Thus, as this dissertation gives a useful tool for simulating the hydrological interactions in the surface, ground and atmosphere. The developed approaches are important for integrated water resources management.