An integrated framework for the hydrologic simulation of a complex geomorphological river basin

The purpose of this study was to simulate the surface and groundwater flow in a karstic river basin where flood phenomena appear from time to time. The Koiliaris River Basin is located east of the city of Chania on the island of Crete in Greece. This river basin has a complex hydrogeology that consists of temporary – ephemeral rivers (tributaries), high mountainous karstic areas, springs, downstream karstic areas and karstic channel parts. In order to simulate all of these processes, a combination of four models was employed. The four models used in the present study were: (a) a two-part Maillet karstic model, used to determine the spring discharge, (b) a GIS-based Energy Budget Snow Melt model, developed to simulate the snow melt rate and compute the snow melt flow that enters the karstic system of the high mountainous area, A matlab code developed in this work combines the previous two independent models, (c) an empirical karstic channel model, developed to simulate the flow in the downstream karstic part of the Koiliaris River Basin, and (d) the Hydrological Simulation Program – FORTRAN (HSPF) model was used to model the hydrology of the watershed. Besides the karstic model, developed in this work, a significant contribution is that for the computation of the snow melt rate the energy budget considers the topography of the area (using GIS) that is incorporated with seven important parameters: elevation, slope, curvature, aspect, illumination, land use, and radiation. The main steps of this study included calibration, validation and sensitivity analysis of the HSPF model. The simulated results are in a very good agreement with the observed field data.