An integrated framework for prediction of climate change impact on habitat suitability of a river in terms of water temperature, hydrological and hydraulic parameters

The continuous warming observed in recent decades as a result of climate change is posing significant threats to the environment, particularly for freshwater ecosystems. Therefore, it is highly important to predict the impact of this phenomenon on habitat suitability. However, such prediction requires the use of an integrated framework in which different parameters can be incorporated. While 1D modelling has been commonly used in river habit suitability simulations, most 1D mathematical models either do not provide enough information for the area along the rivers or do not consider the impact of river basin management on the river flow characteristics. This study seeks to develop such an integrated framework is in which water temperature and hydrologic-hydraulic parameters are jointly applied to simulate habitat suitability. The modeling setup is based on a combination of the Soil and Water Assessment Tool (SWAT) and international river interface cooperative (iRIC) models, and, due to the importance of the water temperature, the water temperature module in SWAT was modified. To examine the effectiveness of this method, Kikuchi basin is selected as the case study, and two different general circulation models, namely HadGEM2-ES and MICRO5, under two representative concentration pathways are applied to evaluate river habitat suitability under climate change conditions. The results showed a reduction in the river flows, water depths and velocities that have slightly positive effects on the habitat suitability of the Kikuchi river. However, this reduction causes some parts of the river to become dry, so that some of the habitats may disappear as a result of climate change. Moreover, it is shown that the downstream section of the Kikuchi river is more vulnerable to climate change. Therefore, migration of fishes to its upstream section is predicted. Finally, the proposed methodology is strongly recommended for use in modeling of other regions suffering water scarcity.