In recent years, a vital part of water resources management plans is the implementation of hydrologic models. A wellknown example is the Soil and Water Assessment Tool most recognized as SWAT model. SWAT was applied in Thasos Island to simulate the water yield and highlight the most significant of the local torrents. The produced map identify four significant torrents: "Prinos" torrent, "Genna-Maries" torrent, "Limenaria-Kastrou Lakos" torrent and TheologosDipotamos" torrent. In addition, a field survey was conducted at the specific torrents to evaluate the results of the model and select the proper ones for further study and management plans in order to store surface water for other purposes and needs of the residents.Keywords: SWAT, field survey, torrent discharge, management plans, Thasos ____________________________________________________________________________________________ IntroductionHydrology is a science that requires spatial data in order to compose water resources management plans. The hydrological models are very important for this purpose and they are used worldwide and frequently in such applications [1]. The processing speed while using complex calculations to estimate the various hydrological phases is a major advantage of hydrologic models [2]. Various hydrological models have developed in recent years with the ability to directly incorporate geographic data through its integration with Geographic Information Systems (GIS) [3]. The GIS technology has the potential of the collection, storage, processing, analysis and visualization of different data sets with geographical reference. Furthermore, using GIS allows visualization of the spatial distribution of the components of the hydrological cycle and the simulation elements of geographic space as they are arranged in nature [4]. A wellknown model of this category is the Soil and Water Assessment Tool [5] through its interface with GIS (ArcSWAT). SWAT was developed for modeling hydrologic basins by taking into account the meteorological, geographical, geological and soil characteristics, land use and management practices. This study describes the application of SWAT in Thasos Island in order to simulate the torrent discharges of the local torrents. Materials and MethodsSWAT is a hydrologic model developed to predict the water yield and torrent discharge of a basin [6]. It is very useful software because it is manageable through a GIS interface named ArcSWAT [7]. The hydrologic cycle is given as the following (Eq. 1)where t is the simulation period, SWt is the soil water content after the simulation period, SW 0 is the soil water content at the beginning of the simulation period, and R day , Q surf , ET day , w day and Q gw are daily values (in millimeters) for precipitation, runoff, evapotranspiration, infiltration and return flow, respectively. SWAT requires the Digital Elevation Model (DEM) (Fig. 1) for the creation and the delineation of watersheds. According to the properties of the DEM, SWAT proposes a minimum threshold value which...