Addressing Climate Change and Variability in the Development of Environmental Flows Paul Leonard , Lauren Elmore and Lawrence Wise Climate Change and Environmental Flows
Some important questions:
What is climate change?
What is the relevance of climate change to environmental flows?
How incorporate climate change predictions into streamflow management?
How have we been adapting to recent climate change-like patterns?
What are some impediments to incorporating climate change into environmental flow?
How can we incorporate uncertainty, risk management, and adaptive management?
What is climate change?
… .a significant variation in either the mean state of the climate or in its variability , persisting for an extended period (typically decades or longer)
IPCC - climate change refers to any change in climate over time, whether due to natural variability or as a result of human activity.
Climate change in the California?
Increased air temperatures
Overall precipitation unknown, but more variability expected
Increased frequency of heavy rainfall events
Increased frequency and severity of droughts
Decreased snowpack, more precipitation as rain in mountains
Decreased soil moisture and runoff in summer
Warmer water temperatures
Rising sea level
Five Riverine Flow Components (Instream Flow Council 2008)
Hydrology & Hydraulics
Water Quality Biology Physical Processes Connectivity Relevance of climate change to environmental flows: focus on hydrology
Effects on Aquatic Ecosystems
Changes in timing and magnitude of flows
Changes in thermal regime (warming)
Increased summer de-oxygenation
Increased primary productivity/nutrient cycling
Expansion of nuisance species
Increased pressure on water supplies
Rising sea level
U.S. Global Change Research Program 2003
Stationarity and hydrology
“ Stationarity—the idea that natural systems fluctuate within an unchanging envelope of variability…”
Changing hydrology and environmental flows
Analysis of historical flow records is central to most environmental flow methods
Flow time series, flow duration curves, habitat time series are widely used
Assumption of “stationarity” no longer valid
Need a new paradigm and models to simulate changing baseline and future climate scenarios
Incorporating climate change into streamflow management
Climate change simulations and scenario-based assessments using global and regional modeling
Pragmatic approaches focusing on drought management; inflow protocols
Risk-based assessments to address uncertainty
Uncertainty? Availability? Global Climate Model Projections GHG Emission Trajectories Downscaling, Regional Models Hydrologic Models Hydrologic Scenarios Planning / Impact Assessment based on Projected “Futures” Scenario-Based Climate Change Assessments
Climate change streamflow scenarios for water planning…
“ Without additional effort on the part of the academic community to translate information about regional climate change into a form compatible with the tools and objectives of the water resources management community, however, water planning studies are unlikely to address the implications of climate change in any more than a very cursory manner in the near term.”
Climate-Change Scenarios for Water Planning Studies 2003, Snover et al. 2003
Risk-Based Assessment Approaches
Knowledge of potential impacts and an associated probability of occurrence, enabling them to make informed, risk-based adaptation and planning decisions.
Uses scenario analysis, but considers climate probabilities, system modification options, adaptive capacities, resource threats, costs, and timing to suggest management priorities through time…
Probability-based planning and management – strongly interdisciplinary
How has California been adapting to recent climate change-like patterns?
Have historically managed consumptive uses and environmental flows based on water year type
Inflow-based operational and flow release rules
Identifying and incorporating known climate oscillations
Hydrologic or weather forecasting
Emphasis on drought management, water recycling, conservation
Development of new local supplies,
Identification of new storage opportunities
Hydrologicially Contingent Flow Releases
Forward-looking projections using meteorological forecasts “ Some weather patterns, such as El Niño-Southern Oscillation (ENSO), can now be predicted with some accuracy…”
Some Projects Incorporating Climate Change
CVP and SWP Long-term Operations Plan
Bay Delta Conservation Plan
San Joaquin River Restoration
Habitat Effects of Climate Change
Uncertain climate predictions; acceptance
Availability and uncertainty of regional climate downscaling models and predicted hydrology
Environmental flow standards based on historical hydrology
Need for basin hydrologic models vs. historical hydrology
Some practical considerations
Adequacy of existing instream/minimum flows
Effects will vary regulated vs. unregulated systems
Impacts may vary widely in regulated systems with low versus high storage ratios
Real-time operational and decision management is becoming critical
Existing regulations and requirements will need to be revisited
Planning vs. Permitting
Planning vs. permitting considerations
Climate change scenarios in permitting/impact assessment
Permanence of allocations
Infrastructure costs & ecosystem services
Availability of accepted climate change projections
Term of license or permit
Can we incorporate risk management?
Risk management fundamentals:
Thresholds for the system of interest
Understanding response of system to climate variability and/or change
Understanding probabilities associated with different climate futures
One or more management options or strategies for reducing risk