Investigating the Effect of Climate Change on River Flow Using IHACRES Rainfall-Runoff Model

Since the importance of water in the durability and survival of life is clear to everyone, water issue has always been the focus of researchers and experts. Iran, having its own geographical and climatic location, has a small share of rainfall. Therefore, having an average annual rainfall of about 240 millimeters, one-third of the global average (860 millimeters), it is part of the dry and semi-arid climate (Alizadeh, 1997). Due to the lack of statistics, complexity of hydrological ecosystems and the impossibility of full recognition of the conditions in many catchment areas of the country, the use of methods that measure the amount of runoff from rainfall in non-statistical basins or those with incomplete statistics are of prime importance. One of these methods is the use of the capabilities of hydrological models in the simulation of hydrological processes which is one of the initial stages of water resources management and planning, and also the study of the hydrological effects of land use change and the way of exploitation of natural resources in a basin, where it is possible to simulate the hydrological processes, such as runoff, in the basins with complete statistics with the lowest cost and minimum time, and then use the information to estimate runoff in similar basins with no statistical data or incomplete statistics (Namdorost, 2002). LARS-WG5 is one of the generators of meteorological accidental data that is used to generate daily rainfall data, daily irradiance and maximum and minimum daily temperatures in a station under present and future climate conditions (Semenov and .Brooks., 1998). Zarghami et al (2001) reported a 2.3 degree increase in temperature and a 3 percent reduction in rainfall over the years 2020-2090 for East Azarbaijan province with the LRS-WG Exponential Meteorological Scale under the A1B, A2 and B1 scenarios using HADCM3 output.