Climate change will accelerate the hydrological cycle, altering rainfall, and the magnitude and timing of runoff. The purpose of this paper is to assess the impacts of climate change on streamflow and sediment yield from the Gorganroud river basin in the North of Iran. To study the effects of climatic variations, the SWAT model was implemented to simulate the hydrological regime and the SUFI-2 algorithm was used for parameter optimization. The climate change scenarios were constructed using the outcomes of three general circulation models for three emission scenarios. The study results for 2040-2069 showed an increase in annual streamflow of 5.8%, 2.8% and 9.5% and an increase in sediment yield of 47.7%, 44.5% and 35.9% for the A1F1, A2 and B1 emission scenarios, respectively. This implies that the impact of climate change on sediment yield is greater than on streamflow. Monthly variations show that the increase in discharge and sediment yield is more pronounced in wet seasons and the decrease is more pronounced in summer (July-September). The results highlighted the strong impact of climate change and reflected the importance of incorporating such analysis into adaptive management.

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Assessing the effectiveness of conservation practices under changed climatic conditions has proven to be invaluable in selecting the adaptation practices. Conservationists are concerned that past effective practices may no longer be effective in the future climate change. This research is aimed at assessing the effectiveness of soil and water conservation practices under future climate change, with respect to sediment yield leaving a watershed. For this purpose, the Soil and Water Assessment Tool, SWAT, was applied to simulate various climate change scenarios with three soil and water conservation practices to assess possible changes in stream flow, and sediment yield of the Gorganroud watershed in the northern part of Iran. Study results demonstrated that the impact of climate change in the increase of watershed sediment yield is more than the stream flow and varies from 35.9 to 47.7% for the period 2040-2069. Implementing conservation practices under climate change can reduce the sediment yield of watershed up to 7.2% and for the sub-basin scale up to 46.4%. Range management practices were found to be the most effective practice in the decrease of sediment at the sub-basin scale and porous gully plugs and terrace construction, the most effective at the watershed scale. The results indicate that soil and water conservation practices will be more effective at reducing sediment yields under anticipated future climates. Though, implementation of each conservation practice solely was not sufficient to compensate for climate change-driven increases in sediment yield. This study provides valuable information for watershed managers and decision makers regarding selection of soil and water conservation practices for adaptation to climate change.

We evaluated the potential impacts of future land cover change and climate variability on hydrological processes in the Neka River basin, northern Iran. This catchment is the main source of water for the intensively cultivated area of Neka County. Hydrological simulations were conducted using the Soil and Water Assessment Tool. An ensemble of 17 CMIP5 climate models was applied to assess changes in temperature and precipitation under the moderate and high emissions scenarios. To generate the business-as-usual scenario map for year 2050 we used the Land Change Modeler. With a combined change in land cover and climate, discharge is expected to decline in all seasons except the end of autumn and winter, based on the inter-model average and various climate models, which illustrated a high degree of uncertainty in discharge projections. Land cover change had a minor influence on discharge relative to that resulting from climate change.