Understanding water-energy-ecology nexus from a coupled human-nature system perspective

Transcription

1 Understanding water-energy-ecology nexus from a coupled human-nature system perspective Hong-Yi Li 2017 Montana AWRA Conference, Oct. 20,

2 Increasing demands under climate change Source: Consultative Group for International Agricultural Research; Beddington,

3 Water-Energy-Ecology nexus Irrigation Harvesting Processing Storage Energy Pumping Treatment Redistribution Hydropower Cooling Bioenergy Water Irrigation Processing Fish survival/reproduction Fish survival/reproduction Water quality Food Ecology Landuse change Via Bioenergy 3

4 Overarching science questions How does climate change influence water, energy, ecology and their connections? How does human intervention (mitigation, adaptation, and management) alter climate change impacts? What are the regional characteristics of the above impacts and their drivers? 4

5 Previous river representation in earth system models Typical example: River Transport Model (RTM) in Community Land Model (CLM, v4.0 and v4.5) Oversimplification of important riverine dynamics (e.g., River Transport Model in Community Earth System Model) Lack of sub-grid heterogeneity representation Assuming constant, globally uniform channel velocity No representation of human impacts No representation of riverine energy and biogeochemistry Earth System Models (ESM, formerly climate models) 5

6 Scale adaptive river transport Real River Network Tributary Main channel Watershe d boundary Conceptualized River Network Model for Scale-Adaptive River Transport (MOSART) Hillslope routing: Account for impacts of overland flow on soil erosion, nutrient loading, etc. Sub-network routing: Scale adaptive across different resolutions to reduce scale dependence Main channel routing: Explicit estimation of in-stream conditions (velocity, water depth, etc.) Model streamflow and stream temperature Being extended to include river biogeochemistry 6 (Li et al. 2013; 2015 JHM; Li et al JAMES)

7 Global flow observations grouped based on the level of flow regulation 1674 GRDC stations with good daily flow records Three groups based on the level of flow regulation after Nilsson et al. (2005) 7

8 Impacts of reservoir regulations on streamflow simulation Qsim (m 3 /s) Qsim (m 3 /s) Each dot for a river station with good records Ensemble mean of simulations under four forcings Qsim (m 3 /s) 1.0E+06 Rivers not affected 1.0E E E E E E E E+04 Qobs (m 3 /s) 1.0E E E+06 Rivers moderately affected 1.0E E E E E E E E+04 Qobs (m 3 /s) 1.0E E E+06 Rivers strongly affected 1.0E E E E E E E E E E+06 Qobs (m 3 /s)

9 Adding human component to river modeling -- An Earth-Human modeling framework Precipitation CLM Hydrology MOSART Coupled CLM-MOSART Simulation Evaporation Transpiration Throughfall Sublimation Melt Evaporation Infiltration Surface runoff Soil Aquifer recharge Water table Saturated fraction Water Management Model Irrigation water demand (Voisin et al., HESS, 2013; Li et al., JAMES, 2015) Reservoir operations 9

10 Water management (WM) modeling Local water extraction: first from sub-network channel and then from the main channel storage Reservoir operations: based on generic operating rules Each reservoir has multiple purposes: Flood control; Irrigation; or Combined irrigation and flood control Generic release targets and storage targets for each purpose Configured independently for each reservoir based on hydro-climatological conditions and demand associated with the reservoir Irrigation Rules release targets Flood Control Rules release targets (Voisin et al. HESS, 2013) Monthly release targets at Grand Coulee for different rules scenarios 10

11 Numerical experiments Not just GHG and aerosol emissions; LULC and water use are important parts of the mitigation RCP4.5 ( ) RCP8.5 CESM RESM (Atmospheric forcing) HIST_NAT RCP4.5_NAT RCP8.5_NAT RCP4.5 RCP8.5 CLM (Runoff and soil temperature) MOSART (Streamflow and stream temperature) HIST_WM RCP4.5_WM RCP8.5_WM GCAM (Water demand) WM (Local extraction / reservoir operations) 11

12 Separating effects of climate change, mitigation and water management HIST_NAT Climate change effects RCP8.5_NAT Emission mitigation effects RCP4.5_NAT Water management effects Water management effects Water management effects HIST_WM Climate change effects RCP8.5_WM Emission mitigation effects RCP4.5_WM

13 Water-energy connections Emission mitigation reduce increase increase Local water extraction reduce Reservoir operations increase Surface warming reduce Irrigation water demand Streamflow??? Stream temperature Water availability???? Thermo-electricity Generation Fish Survival

14 Changes in stream temperature Climate change effects (future minus historical) Mitigation effects (RCP8.5 minus RCP4.5) Water management effects (with WM minus without WM) % change in seasonal amplitude 14

15 Emission mitigation reduces exceedance frequency Frequency changes for stream temperature > 27 o C Water management reduces exceedance frequency % change in number of hours with stream temperature > 27 o C 15

16 Impacts of cooling water availability on thermoelectricity production No consistent difference in cooling water availability between RCP4.5 and RCP8.5 due to large inter-decadal variability in precipitation Water management alleviates the duration of low water availability by 5%-14% Percentage of time when projected inflows (2040s and 2080s) are lower than the historical average ( ) during summer 16

17 Model-simulated impacts of climate and water management on stream temp. and flow (April-June) Climate-induced changes in stream temperature Climate-induced changes in stream flow Water-manag.-caused changes in stream temperature Water-manag.-caused changes in stream flow 17

18 Two characteristics of water management effects on hydrological droughts Local water extraction: reduce flow year round Reservoir operations: enhance summer low flow All grid cells Grid cells affected by reservoirs 18

19 Answers to science questions How does climate change influence water, energy, and their connections? Warming increases stream temperature reduces thermoelectricity generation and basin-average juvenile Steelhead survival rates Warming has variable effects on regional precipitation and cooling water availability How does human intervention (mitigation, adaptation, and management) alter climate change impacts? Emission mitigation reduces warming, but its impacts on regional water availability are variable Water management consistently alleviates high stream temperature and reduces thermoelectricity loss and alleviate the reduction in Chinook and Steelhead survival rates induced by climate change What are the regional characteristics of the above impacts and their drivers? Regional drivers: local water extraction, reservoir regulations, and water demand Impacts of different scenarios must account for LULC and water use 19

20 Questions 20