Abstract—In recent years, geographic information systems (GIS) and remote sensing using has increased to estimate runoff catchment. In this research, runoff curve number maps for captive catchment of Tehran by helping GIS and also remote sensing which based on factors such as vegetation, lands using, group of soil hydrology and hydrological conditions were obtained. Runoff curve numbers map was obtained by combining these maps in ARC GIS and SCS table. To evaluate the accuracy of the results, the maximum flow rate of flood which was obtained from curve numbers, was compared with the measured maximum flood rate at the watershed outlet and correctness of curve numbers were approved. Keywords—Curve number, GIS, Remote sensing, Runoff. I. INTRODUCTION NE of empirical methods that is widely and global used by hydrologists, water project planners and water Engineering, is the curve numbers method that has been suggested and supported by the department of agriculture natural resources conservation service of USA [1]. Some applications of GIS are mapping curve number (CN) of catchment by using the digital data analysis, vegetation cover, land using and hydrologic soil groups; in this field, few studies had been done about the shortcomings and advantages of this approach and technology. Malekian et al (2004) used standard tables depending on factors such as vegetation cover, land using and soil hydrologic groups for mapping the curve numbers of the famous basin of Lighvan [4]. Khosroshahi and Saghafian (2004) made vegetation cover map Damavand watershed basin by using satellite images and then map of land using and soil hydrologic groups have integrated with GIS by using ILWIS software and curve numbers (CN) were calculated for the entire basin and sub- basins [2]. Molaei (2002) used SCS method to calculate the runoff volume in the watershed of Zanjan [3]. He combined the map of vegetation, soil hydrologic groups and using the field studies and applied some changes in the way of determination of CN, by using GIS and ILWIS software. This study focuses on the faster and more accurate ability of GIS in determining the CN. Poundi et al (1999) prepared catchment land using maps in Remi by using satellite imagery IRS-1B, then with a combination of land using maps and determined land cover, soil maps and soil hydrologic group; and finally basin area Abouzar Nasiri is in the Department of Information Systems and Technology, Moscow State University of Geodesy and Cartography, Moscow, Russia (phone: + +79251414375; e-mail: abuzarnasiri@gmail.com). Hamid Alipur is in the Young Researchers Club, Bojnourd Branch, Islamic Azad University, Bojnourd, Iran (e-mail: alipor.hamid@gmail.com). weighted curve number was determined according to the given surface by considering the available data and standard CN table in India [7]. The results of this study showed that no requirement exists for monitoring runoff basin Remy. Therefore the SCS curve number method can be used to predict runoff. In 2006 (InciTekeli), the curve number for the basin of Guvence in India was identified by using GIS and RS tools. In determining land using maps were used Landsat TM and for the density of the vegetation was applied the index NDVI [8]. Measured amounts of rainfall and catchment from 1987 to 2005 have been used for various return periods to calculate the flood discharge. The purpose of this study is preparing the map of curve number in catchment runoff Darband in Tehran by using land maps, the soil hydrology group and vegetation area with SCS table, and also is combining these maps in ARC GIS environment to estimate catchment runoff. II. METHODOLOGY A. The Studied Area The studied area is a part of the southern slopes of the Alborz Mountains, in which the cities of Tehran and Ray have been involved. Peaks of Tochal with a height of 3950 meters above sea level in the north part of this area and Shahr Rey with a height of 1,050 meters above sea level in the south of area are located. Flows resulting from rainfalls in the area are directed towards salt lakes through the above-mentioned rivers and along the north-south drainage. Catchment study is the part of the catchment area in north of Tehran which is located in the central basin in terms of overall watershed division in Iran. Catchment area is approximately 30 square kilometers and located in Tehran province. It is one of the important watersheds because its situation overlooks the political center of the country. The rivers of Glabdarreh and Darband are the main rivers within the project area. Glabdarreh catchment area is located in north of Tajrish and along the north-south flow. The river cross the street Darband after crossing near the village Glabdarreh and joins to the Draband river in bridge of Tajrish. Darband river catchment is located in the north of Shemiran and Darband square also at the west of Glabdarerh river. It is composed of the two main branches Jafarabad and Osun. Both branches have originated from the Tochal peak and are joined in Pas Qalee village and make up Darband River and enter to Tajrish and then Tehran. Then they cross the Sorkhe Hesarriver and flow to Shahre Rey. They tend to the southeast side after passing through the city. They enter to Jajrud near the Takhte Changi village. The studied area is Determination the Curve Number Catchment by Using GIS and Remote Sensing Abouzar Nasiri, Hamid Alipur O World Academy of Science, Engineering and Technology International Journal of Geological and Environmental Engineering Vol:8, No:5, 2014 342 International Scholarly and Scientific Research & Innovation 8(5) 2014 scholar.waset.org/1307-6892/9998929 International Science Index, Geological and Environmental Engineering Vol:8, No:5, 2014 waset.org/Publication/9998929