Land use change from rangeland and forest to agriculture and orchard areas which affected water regime, are widely occurred in many parts of Iran. The above mentioned problem has happened in Orumieh Lake basin for an area of 1146 km2 which is located in northwest of Iran. The recent land use map was resulted through satellite images of 1990, 1998 and 2006 as well as field observations and the previous period map was performed by using the aerial photographs of 1955 (which is considered as the oldest documents). In this period 14% of rangeland is changed into dry farming and 7% of irrigated farming is converted to orchard. The results show that due to land use change in this area, the mean annual discharge has not changed but maximum daily discharge increased and minimum daily discharge reduced.