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.

Morphometric analysis of watersheds coupled with multi‐criteria decision making (MCDM) techniques is a widely used approach in identifying and prioritizing subwatersheds for flood risk assessment. Finding the appropriate weight for each morphometric parameter is one of the most important steps in MCDM methods. The present research focuses on analyzing the effect of using objective weighting methods in watershed prioritization in Daroungar Watershed in Northeast of Iran. To this aim, the weights of morphometric parameters were determined using six objective weighting methods and were used for ranking subwatersheds based on flood generation by a multi‐criteria model. Study results show that the highest weight in various methods belonged to different parameters. Comparison of flood susceptibility ranking maps indicated, except standard deviation method, there is a significant correlation among WM, preference selection index, criteria importance through intercriteria correlation, entropy, and method based on the removal effects of criteria methods; however, the distribution of flood susceptibility classes is not the same in the six weighting methods. The flood hazard ranking map using aggregation methods depicts that subwatersheds 6, 74, 27, and 67 which have high priority for flood hazard, have the same rank in all aggregation methods. Overall, in the present study, the importance of choosing the appropriate weighting method in prioritizing watersheds was emphasized.

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.