Climate and land-use scenarios Hadley weather series for 2070-2100, with 2.8 °C

1. Project 952211 ALTERRA ALTERRA temperature bank-full discharge geology valley slope vegetation management groundwater level soil water content upward seepage surf. water inundation U-scores (U1 ... U5) for low discharges O-scores (O1 ... O5) for high discharges groundwater composition surface water composition hydraulic geometry sinuosity carbonate content soil soil fertility hydraulics aeration moisture stress pH nutrients plant growth and reproduction • width, depth • water level gradient • velocity ecosystem types floristic composition 8Q50 4Q50 O3 Q50 Climate changes Changesin land use Changes in morphology Impacts on aquatic ecosystems Impacts on terrestrial ecosystems = • Effects of climate and land-use change on lowland stream ecosystems • P.E.V. van Walsum, P.F.M. Verdonschot, J. Runhaar, J.W.J. van der Gaast, A.H. Prins, Tj. H. van den Hoek, M.W. van den Hoorn, P.C. Jansen, F.J.E. van der Bolt, A.A. Veldhuizen Background During the past decades human interference in regional hydrologic systems has intensified. Water is an integrating medium, linking climate, human activities and ecological systems through groundwater and surface water interactions. An example is the lowering of watertables that has been caused by subsurface drainage of agricultural lands. Regional authorities are attempting to take measures aimed at achieving a sustainable economic development and restoring ecological systems to a more natural state.Climate change is a wildcard that perhaps could frustrate the attempts of regional authorities to achieve their goals. • Scientific Questions: • What are the possible hydrologic impacts of climate and land-use change on lowland streams? • What are the possible impacts on aquatic and stream-valley ecosystems? • What is the relative impact of climate change as compared to existing human influences? • Can the effects of climate change be neutralised by removing some of the existing human influences, e.g. by removing subsurface drainage and/or extractions for sprinkling • Project components • Use of Hadley GCM-data for downscaling to regional weather series (2070-2100) • Land and water use scenarios in a case-study region of • 40 000 ha • Integrated regional hydrologic modelling (soil water, groundwater and surface water) • Downscaling of results hydrologic modelling to pixels of 25 m * 25 m • Prediction of stream-morphological changes • Impacts on terrestrial stream-valley ecosystems • Impacts on aquatic ecosystems • Impact diagram • Indirect effects of climate change on ecosystems • through impacts on hydrology and stream • morphology • Direct effects on ecosystems through effect of • temperature rise • Climate and land-use scenarios • Hadley weather series for 2070-2100, with 2.8 °C • temperature rise • Downscaling of Hadley GCM-grid rainfall to regional scale • Extra scenarios in view of uncertainty about future climate • Had : downscaled Hadley weather series • HadPi : Had + increased precip. KNMI-rule-of-thumb • HadEr : Had + reduced transpiration (2X CO2-effect?) • HadPiEr: Had + increased prec. + reduced transpiration • Land-use scenarios: • new nature areas in the National Ecological Network • (series Ehs) • buffer zones around new nature areas • (series EhsBuf) • bufferzones and free meandering of streams • (series EhsBufM) Changes in hydrology • Regional integrated models • SIMGRO for integrated soil water, groundwater • and surface water modelling • StreaMES for natural stream morphology • NATLES (NATure oriented Land-Evaluation System) for indirect effects on terrestrial ecosystems through climate impacts on hydrology • Biogeographic study for direct effects of temperature rise • Discharge Dynamics Index DDI for indirect effects on • aquatic ecosystems through hydrology • Biogeographic study for direct effects of temperature rise • Discharge extremity classes: • Ri= Oi + Ui • Discharge Dynamics Index • DDI =  si·Ri • 1 < DDI < 5 • dynamic constant • Results • High sensitivity of peak discharges to precipitation • High sensitivity of pH-buffering by bicarbonate-rich upward seepage in stream valleys to evapotranspiration: ET  capillary rise to root zone   pH  • Indirect effects of climate change on terrestrial ecosystems in stream valleys are limited and mostly positive; effects of land-use change are more pronounced • Direct effect of temperature rise is increase of biodiversity • Indirect effects on aquatic ecosystems are siginificant; • lower values of Discharge Dynamics Index indicate more • extreme flows (high and low), and thus less abundance of • macro-invertrebrata that are used as indicator species • Direct effect of temperature rise is increase of biodiversity 2. 1. 1. the ranges are for the 2350 trajectories of the surface water model 3. 4. = ALTERRA Green World Research POBox 47, NL 6700 AA, Wageningen, Netherlands phone +31-317-474744 email r.w.a.hutjes@alterra.wag-ur.nl