Investigation of flood risk areas by using gis: Case study Murat River (Agri)

With the rapid increase in the population in our country and in the world, the number of floods and damages caused by the negative impacts such as unplanned construction, improper land use, floodplain opening for construction, building, road and similar constructions and impermeability of the soil surface have increased in recent years. This warrants to determine risk regions of potential floods for residential areas and to take appropriate measures. Ağrı province, which is study area, was a safe settlement in terms of floods since the first settlements were away from river beds. However, the province of Ağrı has become a place where the flood frequencies have increased and flood risks should be determined as a result of the increase of population in the period of 40-50 years and the occupation of low terraces and river beds together with the distorted urbanization and the increase in the construction. In this thesis, the flood risk maps of Murat River passing through the Central District of Ağrı province in order to determine the risky areas were obtained by using geographic information systems (GIS). Murat River, which passes through settlements and agricultural lands, causes floods especially in April-May. The region's TIN map which has the region with 1/1000-scale maps with streams was prepared with the ArcGIS and NetCAD softwares. The HEC-GeoRAS program, which is a module of ArcGIS software, has been digitized on TIN map and critical sections have been determined. The hydrometric data obtained from the 8th District of DSI Q2, Q5, Q10, Q25, Q50, Q100, Q500 and Q1000 flood repetition calculations were carried out with HEC-RAS software, and the surface elevations and flood limits were determined. The analyzes carried out with HEC-RAS software were transferred to the ArcGIS software and combined with digital maps and satellite images.. Flood risk areas were identified and flood damage calculations was performed. Flood risk maps and flood damage calculation were performed in this study; With the help of GIS, suggestions have been made for the realization of realistic results for risk analysis and for preventing the damages caused by floods.