Assessing Habitat Suitability of Adaptive Species to Climate Change Impacts in The Kikuchi River, Japan
Climate change is making significant threat especially on fresh waters ecosystems. The geographic location of Japan makes hydrological processes affected by this phenomenon substantially so that adverse impacts of climate change can be predicted for different parts of this country. In many studies, onlyhydrological and hydraulic parameters in a river basin are assessed to do habitat suitability simulation, however; water temperature is also influencing aquatic ecosystem which is affected by climate change. Zaccopatypus (Oikawa) is a dominant species in the Kikuchi River in Kyushu Island in Japan, which is known as an adaptive species to habitat characteristic changes. In this study, we seek to findout if this species is also adaptive to changes caused by climate change in order to have a better vision about river health in the future. In this regards, firstly we used two GCMs models including HadGEM2-ES and MICRO5 under two different RCPs (Representative Concentration Pathways) (RCP4.5 and RCP8.5) to get future meteorology data. At the second step, SWAT (Soil and Water Assessment Tool) model was used to simulate watershed hydrology in both baseline period (1986-2016) and future periods (2021-2040, 2041-2060 and 2061-208). Finally, using iRIC (International River Interface Cooperative) software; WUA was calculated with and without considering water temperature to find out which one of hydraulic parameters or water temperature is affecting more the habitat suitability. This study demonstrated different future projections, so that; it is expected to have decrease in discharge up to 6 (m3/s) under MICRO5 (RCP8.5) as well as increase in this parameter up to 2 (m3/s) under HadGEM2-ES (RCP4.5). The important result of this study was that changes in hydraulic parameter will not have notable effect on WUA for Oikawa in comparison with effects of this phenomenon when changes in water temperature is being considered.
Keywords - Climate Change, Water Temperture, SWAT, Aquatic Habitat Suitability, iRIC