Climate Change Impacts on Some Hydrological Variables in the Zayandeh-Rud River Basin, Iran

Abstract

The chapter aims to estimate the climate change impacts on the climate variables in Iran’s Zayandeh-Rud River Basin. A multi-model ensemble scenarios framework is used to improve the reliability of the climate change impact assessment by considering the three main sources of uncertainties including uncertainties of GCMs, emission scenarios, and climate variability of daily time series. The probabilistic multi-model ensemble scenarios, which include the 15 GCMs, are used to project the temperature and precipitation for the near future period (2015–2044) under 50% risk level of climate change. In a general view, temperature will rise in the basin while the level of temperature increase varies between. Monthly precipitation changes may be positive or negative in various parts of the basin. Generally, temperature change shows an increasing trend from West to East and has an inverse relationship with height. Nevertheless, the maximum monthly precipitation reduction will occur in winter. This can be of considerable importance for the basin having a semiarid Mediterranean climate in which winter precipitation is the main source of renewable water supply. In a general view, precipitation change shows a decreasing trend from West to East and it has a direct relationship with height. The Zayandeh Rud River Basin has been constantly facing the water stress problem during the past 60 years. Therefore, the results of the climate change impacts on the basin’s climate variables can provide the policy insights for regional water managers to address well the water scarcity in the near future.