International Journal of Applied Engineering Research ISSN 0973-4562 Volume 10, Number 3 (2015) pp. 9415-9423 © Research India Publications http://www.ripublication.com Comparison of A New Gis‐Based Method and A Manual Method For Determining Boundery Basin: Zayandeh Rood Basin In Iran Dr. Maryam Marani Barzani 1 Prof. Dr. Khairulmaini Bin Osman Salleh 2 Department of Geography,University of Malaya (UM),marani82@yahoo.com, Department of Geography,University of Malaya (UM), khairulo@um.edu.my Abstract We aimed coparision hydrologic model in a GIS as a means to determine the boundary of the basin and to compare by means of a hand drawing the boundary of Zayandeh Rood Basin, Iran. In this paper, the Arc GIS 9.3 software was used and the data included SRTM and 1:25000 topographic maps with a contour interval of 25 meters. The differences between the determining boundaries basins were derived from the two methods used for the basin. The study revealed that determining the exact boundaries of the basin on the contour maps is limited by the map scale and contour interval. In this study, the results are an exact boundary of the basin by GIS method. Gathering and analyzing the basin data for studies in mature regions have historically required the tedious and time‐consuming manual process of the boundary of the basin shown on topographic maps. Keywords: Basin, GIS Model, Zayandeh Rood Basin, Digital Model Elevation. Introduction The first step of geo-hydrological process study is to determine the boundary of the water shed. Land measurement which is surrounded by heights is referred to as the pouring water basin. Therefore, the running water which is the result of rain concentrates on the deepest surface and exits from the point that includes the lowest height watershed depends on the unit for planning. Rainfall and water resource produce the human units and human activities in the basins. Most human units are near the outlet or floodplain, especially in arid zones near quant or springs and the area is important for agriculture and settlement. Hillcrests are the boundary of basin in hydrology in close basins; water flow enters the ground and is saved as groundwater. The elevation data in a grid format can be used to delineate the drainage