The water quantity and temperature are well-known to influence on the availability of physical habitat for running water fish communities. This paper aims to forecast the changes in the suitability of fish habitat, caused by alterations in the flow regime under climate change scenarios.

The instantaneous flow in several streams in Central Spain was modelled from daily temperature and precipitation data. Previous studies on rainfall-runoff modelling used lagged data as inputs. Therefore these studies mainly used lagged flows and precipitations. However none of them were focused on forecasting running flows under climate change scenarios. The rainfall-runoff models were developed by means of M5’ model trees. This technique has previously demonstrated proficient results in modelling daily flows.

The results showed a high performance and very good capability to predict low flows. These models were used to simulate the running flows under the climate change scenarios. The selected climate change scenarios were RCP4.5 and RCP8.5 (5thIPCC).

Results forecast significant decrease in summer flow and increase in the frequency zero-flow events. Future significant declines in summer flow could exacerbate the negative impact of increased water temperature on trout populations by reducing both the suitable spatial habitat and the warming resistance of the water mass.