WATER RF PROJECT 4468: Comprehensive assessment of the impacts of climate change on reservoir water quality in a range of climatic regions

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1 Investigators: WATER RF PROJECT 4468: Comprehensive assessment of the impacts of climate change on reservoir water quality in a range of climatic regions Mike Burch & Leon van der Linden Australian Water Quality Centre (SA Water) Adelaide, SA, Australia Tsair-Fuh Lin Department of Environmental Engineering, National Cheng Kung University Tainan City, Taiwan John Little Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University Blacksburg, VA, USA Justin Brookes School of Earth and Environmental Science University of Adelaide Adelaide, SA, Australia Project management: Water Quality Research Australia Limited 250 Victoria Square, Adelaide SA, Australia WEB: 15 November August 2015 (2.5 years) Project Value $650,000 USD Award Funding Water Research Foundation $150,000 Water Quality Research Australia $50,000 Taiwan Water Corporation $50,000

2 Aims and Objectives Review information available internationally Downscaling the impacts of climate change from global to reservoir scale Consistent approach for three case studies representing different climatic zones: Temperate climate zone (Occoquan Reservoir USA) Humid Sub-tropical climate zone (Hsin-Shan Reservoir, Taiwan) Mediterranean climate zone (Myponga Reservoir, Australia)

3 Major Risks to Water Quality Algal growth and cyanobacterial blooms increased average temperature frequency and duration of heatwaves increases in nutrient loading (extreme run-off events ) Increased pathogen loads greater variability in inflow events increased temperature (reduced inactivation) Increased turbidity greater flood and drought risk Increased frequency of blackwater changes in temperature, inflows and land use change Changes in DOC load and chemistry increased temperature and run-off Increased risk of salinity spikes increased drought risk Risks arising from different source waters (inter-basin transfer demand) Increased frequency of wildfires Unknowns and unexpected events

4 Case Study Sites Myponga Reservoir (MR) Occoquan Reservoir (OR) Hsin-Shan Reservoir (HSR)

5 Risk MR OR HSR Algal growth and cyanobacterial blooms - increased average temperature - frequency and duration of heatwaves - increases in nutrient loading (extreme run-off events ) Increased pathogen loads - greater variability in inflow events - increased temperature (reduced inactivation) Increased turbidity - greater flood and drought risk Increased frequency of blackwater - changes in temperature, inflows and land use change Changes in DOC load and chemistry - increased temperature and run-off Increased risk of salinity spikes - increased drought risk ++ + (improvi ng) ++ + ± ± Risks arising from different source waters (inter-basin transfer demand) ± - - Increased frequency of wildfires Unknowns and unexpected events ± ± ±

6 Site Characteristics Characteristic Myponga Occoquan Hsin-Shan FSL (ML) 26,800 31,400 9,700 Mean depth (m) Maximum depth (m) Annual precipitation (mm) Natural catchment (km 2 ) 124 1, ( ) Population serviced > 50,000 >1.5 M (Fairfax Water) 400,000 WTP supply rate (ML/day) ~ Historical water quality issues Pathogens Cyanobacteria/Algal blooms DOC -> DBPs Fe & Mn Pathogens, Algal blooms, Hypoxia, Mn Cyanobacteria/ Algal blooms, DBPs Management interventions Aeration Mechanical mixers Copper sulphate Variable offtake Aerator, oxygenation, UOSA Water Reclamation plant, BMPs catchment works, variable offtake Floating aquatic macrophytes, ozonation, biomanipulation (mussels), variable offtake

7 The Occoquan Model Complexly-linked watershed-reservoir model Virginia Tech CEE Department 7 HSPF (Hydrologic Simulation Program Fortran) Lumped parameter hydrologic model runoff based on universal soil loss equation, water budget (surface and groundwater) and rainfall 2 CE-QUAL-W2 for reservoir simulation 2D hydrodynamic and water quality model Models are linked and calibrated together to observed hydrology and water quality in watershed and reservoir

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11 Calibration and Verification HSPF Flow Balance Sediment Loads Water Quality Orthophosphate Phosphorus Ammonium Nitrogen Nitrate Nitrogen Organic Matter (BOD) CE-QUAL-W2 Surface Elevation (~Flow) Heat Balance Water Quality DO Orthophosphate Phosphorus Ammonium Nitrogen Nitrate Nitrogen Algae 11

12 Jhongfu pumping station Masu Creek catchment area 28.2 km 2 Masu Creek Hsinshan Res. catchment area 1.3 km 2 Hsinshan WTP Badu pumping station Keelung River Badu sta. catchment area km 2

13 Badu pumping station

14 Badu pumping station

15 Hsinshan Reservoir

16 Myponga - Catchment - Land Use

17 Myponga Reservoir

18 Skilled GCM Climate Projections Change Statistics Distributions Variable correlation Weather Generator Historically valid coupled model Catchment Data Hydrological Model Hydrodynamic Model Reservoir Data Water quality Model Multidimensional Water quality scenarios Catchment and Reservoir Planning Options Expert knowledge Climate change impacts on water quality

19 Δ Precipitation Climate variables Δ Temperature Sensitivity analysis of key uncertainties Δ Wind Multidimensional Water quality scenarios Δ Land use and management Constituent parameters Water Quality Risks with Climate Change

20 WQ variable Risk Assessment Methodology Magnitude Threshold 2 Frequency Threshold 1 Duration of threshold exceedance

21 Threshold 1 Threshold 2 WQ variable Frequency Change in risk evaluated by change in magnitude and frequency of threshold exceedance Observed Projected Magnitude Frequency Threshold x N = Duration of threshold exceedance Magnitude

22 Qualitative risk analysis matrix (WQRA 2009) Almost Certain Insignificant Minor Moderate Major Catastrophic Moderate High Very High Very High Very High Likely Moderate High High Very High Very High Possible Low Moderate High Very High Very High Unlikely Low Low Moderate High Very High Rare Low Low Moderate High High

23 Output and deliverables Water quality projections for each of the case study reservoirs Simple rule sets on the responses of reservoirs to climate change under a range of climatic conditions, and under a range of future climate scenarios. A framework and guidelines on how reservoir management techniques and catchment management can be used to mitigate the risks of climate change to water quality in reservoirs based upon: Climate zone Catchment condition Reservoir size Nutrient inputs Fact sheets on the above