GIS Based Flood Modeling of Laghman River

The research has shown that the reason of incensement of flood hazards is not the increment of frequency or magnitude of floods, but the intense use of flood terrains and limiting the river cross section by construction of (residential buildings, bridges etc.…) are the main reasons of hazardous floods creation. Respected to the thesis title and available data in our country, below are all the procedures which I have accomplished in my research. In this research GIS (Geographical Information system) has been used to specify flood hazard terrains according to hydraulic model in Laghman river territory which is of the most important parts of this research HEC-HMS software has been used for hydrologic modeling and for creation of flood hydrograph with frequency of (10,20,50) years for related catchment areas. Flow scheme for precipitation modeling is according to IDF (intensity duration frequency) curve which is developed from near station. HEC-RAS software has been used to simulate for cast flood on Laghman river. All mentioned models’ document has been developed in ARC MAP-GIS environment using their related extensions HEC-GEO HMS and HEC-GEO RAS, digital elevation models with 5-meter accuracy has been studied and analyzed according to site coordinates. One dimensional steady flow analysis has shown that a major area in river territory is under the flood hazard and destruction which draws a huge damage to our compatriots. In this research I have found that in 37-kilometer length of river, 1.7 square kilometers of the areas in river terrain which are generally agricultural lands that are under flood hazard and destruction. Thus, I recommend flood prevention and control structures in this area in order to improve living condition of residents in this area. By this, flood hazards are being prevented and a residential area along Laghman river which is a joyful area is being built. Flood frequency in 50 years has been derived from Gamble method with respect to 20 years’ flow from Tangi-e-Saidan hydrologic station.