Regional impacts of climate change on water resources quantity and quality indicators

The aim of this paper is to assess the impacts of climate change on water resources (surface runoff) and on water quality. Two GCM-based climate change scenarios are considered: transient (HadCM2) and equilibrium (UKHI). A conceptual, physically based hydrological model (WBUDG) is applied on a catchment in central Greece, simulating the effect of the two climate scenarios on average monthly runoff. A newly developed in the stream model (R-Qual) is applied in order to simulate water quality downstream of a point source under current and climatically changed conditions. Simulated parameters include monthly concentrations of BOD, DO and NH4+. Both scenarios suggest increase of temperature and decrease of precipitation in the study region. Those changes result in a significant decrease of mean monthly runoff for almost all months with a considerable negative impact on summer drought. Moreover, quality simulations under future climatic conditions entail significant water quality impairments because of decreased stream flows.