Investigating the effect of climate change on river flow using HBV light rainfall-runoff model; Case study MohammadAbad watershed, Golestan

Overland flow is one of the main causes of erosion and decrease of soil fertility, sedimentation in reservoirs and decrease of water quality of rivers. Therefore, accurate prediction of catchment’s response to rainfall events is an important issue. Hydrologic models are simplified representation of a real hydrological system which helps us study the catchments reaction towards different inputs and better understand hydrological processes. Besides, the increase of greenhouse gases in future periods, and consequently, the aggravation of changes in climate parameters may have many negative effects on different systems, such as water resources, environment, industry, hygiene, agriculture, and all systems which are interacted with climate system. Considering simultaneous changes of fluctuations and average values of climate variables which influence runoff, will lead to more realisticresults. This study aims to consider the effect of climate change on overland flow in Mohammad-Abad Catchment, located in Golestan Province, during 2011-2040 periods. In this study, HBV-light model was calibrated for understudy region. Then, based on the output of HadCM3 model under A1B, A2 and B1 emission scenarios, temperature and precipitation data for 2011-2040 period were downscaled using LARS-WG model and used as input for HBV-light model to simulate surface runoff. The results in addition to verify the efficiency of LARS-WG model, showed that the temperature in the period of 2010-2040, will increase in comparison to the observation period (1982 2010), and also precipitation will increase in some months and will decreased in others in future in comparison to the observed period.