Overview and Managing Risks of Wildfire for Drinking Water Systems: Results from two research workshops. Chi Ho Sham, Ph.D., The Cadmus Group, Inc.

Transcription

1 Overview and Managing Risks of Wildfire for Drinking Water Systems: Results from two research workshops Chi Ho Sham, Ph.D., The Cadmus Group, Inc. AWRA Annual Conference, Tysons Corner, VA November 6, 2014

2 Objectives Provide an overview of the impacts of wildfires on watersheds and drinking water utilities Summarize the results from two research workshops on the impacts on wildfires on drinking water supplies Acknowledgement: Water Research Foundation (Kenan Ozekin) and Canadian Water Network (Bernadette Conant, Katherine Balpataky, Alex Chik, and Katrina Hitchman) Special acknowledgement: Dr. Monica Emelko of the University of Waterloo (co-chair of the Kananaskis workshop) 10/22/2014 2

3 Wildfires & Watersheds Wildfire is a natural component of healthy forest ecosystems Severity and frequency of wildfires in the western U.S. have increased over the past decade Wildfires can produce dramatic physical and chemical changes in soils and hillslopes that negatively affect downslope and downstream hydrology and water quality 10/22/2014 3

4 Wildfires & Watersheds Magnitude of changes in soils and hillslopes is dependent on several factors including fire severity, intensity, and duration; topography; and post-fire precipitation amount and intensity 10/22/2014 4

5 Wildfires & Watersheds Post-fire changes Reduced interception Increased rain splash Decreased infiltration Reduced ET Hydrophobic soil Post-fire effects Increased total runoff Increased peak flow Increased flooding Increased sediment mobilization 10/22/2014 5

6 Wildfires & Hydrology Total Runoff higher post-fire annual discharge and water yield Peak Flows resulting from loss of vegetation and decreased soil infiltration, especially from hydrophobic soils Sediment Mobilization consumption of litter exposing soil to rain splash, lower infiltration, and increased overland flow 10/22/2014 6

7 Wildfires & Sediment Post-fire sediment transport up to 20 folds Dependent on geology, soil, topography, vegetation, fire characteristics, weather patterns, and land use practices Timing, magnitude, and duration of storms immediately after a fire a key factor 10/22/2014 7

8 Wildfires & Debris Flow Debris Flows triggered by severe fires followed by intense rain More often with steep slope, thick sediment and soil, hydrophobic soil, and heavy and prolonged rainfall Less predictable and can occur with little warning 10/22/2014 8

9 Wildfires & Water Quality Nutrients increase after fires Nitrogen (organic nitrogen, nitrate, and ammonium) increases immediately and peaks in the first or second year, slowly declines as vegetation re-establish Phosphorus (dissolved and sediment-associated) concentrations and export are greater 10/22/2014 9

10 Wildfires & Water Quality Organic Carbon increase after fires Particulate organic carbon (POC) may increase due to deposit of ash Dissolved organic carbon (DOC) may increase as rain and snowmelt percolate through ash DOC elevated into third and fourth year 10/22/

11 Wildfires & Water Quality Other Chemical Constituents may increase post-fire Ash contains oxides of calcium and magnesium, chloride, carbonates of sodium and potassium, polyphosphates of calcium and magnesium Leaching of ash can mobilize cations and chloride Mobilization of mercury 10/22/

12 Wildfires & Water Quality Suspended Sediments and Turbidity due to suspension of ash and clay-sized soil particles Total suspended solids (TSS) and turbidity may increase by orders of magnitude post-fire 10/22/

13 Quantification of vulnerability of water systems Burned Area Emergency Response (BAER) Values at Risk (VAR) calculation tool Emergency Preparedness and Response Plans (Pan American Health Organization (PAHO)) Mitigating Risks General scheme for vulnerability analysis and mitigation measures (PAHO, 1998) 10/22/

14 Mitigating Risks Source Water Protection and Forest Management Buffer strips (trapping and filtering sediments) Hazard fuels reduction (prescribed burn and mechanical thinning) LANDFIRE.gov for landscape-scale map data to support strategic vegetation, fire, and fuels management planning U.S. Forest Service s Spatial Analysis Project (SAP) on forest land for prioritization Community wildfire protection plans Funding 10/22/

15 Workshops April 4-5, 2013 in Denver, Colorado sponsored by the Water Research Foundation (WRF) and U.S. Environmental Protection Agency (EPA); Supported by The Cadmus Group, Inc. (Cadmus) and the Consensus Building Institute (CBI) September 18-19, 2013 in Kananaskis, Alberta, Canada sponsored by WRF and the Canadian Water Network (CWN); Co-chaired by Monica Emelko of University of Waterloo and Chi Ho Sham of Cadmus; Facilitated by CBI 10/22/

16 Findings and Recommendations Workshop 1: Need to conduct a detail review and synthesis of the effects of wildfire on drinking water quality, quantity, availability, and treatability (considerations of prevention and time scales) Assess relative costs, benefits, and effectiveness of various preventative forest management practices to reduce risks or impacts of wildfire on drinking water Evaluate the relative short and long term costs, benefits, and effectiveness of various post-fire management approaches to mitigate effects of wildfire on drinking water 10/22/

17 Findings and Recommendations Workshop 1 (continue): Assess the effects of wildfire on drinking water treatment trains and technologies Evaluate the effects of wildfire on groundwater-based drinking water supplies Compile lessons learned from integrating sciences, policy, politics, and community actions in water supply protection and wildfire prevention, emergency response, and longterm responses Develop a method of pricing ecosystem services provided by forests for drinking water protection 10/22/

18 Findings and Recommendations Workshop 1 (continue): Develop overall messages to communicate with the public about actions taken by utilities for watershed wildfire prevention and remediation Sponsor and support studies on the longer-term effects of wildfire on drinking water supplies (10 years or longer) Collect information on watershed resiliency to wildfire across various geographies, ecosystems, and climates 10/22/

19 Findings and Recommendations Workshop 2: Action related to fire suppression Develop strategic forest management plans focused on prioritizing and protecting key drinking water supplies Ensuring preparedness of drinking water providers Source water protection action within forested watersheds to manage wildfire risk Actions to reduce the impacts (extent and severity) of wildfire Actions to mitigate the impacts of wildfire on water quality and treatments to prevent burned materials from entering water supply systems (e.g., Burned Area Emergency Response or BAER) 10/22/

20 Findings and Recommendations Workshop 2 (continue): Water utility wildfire preparedness and response plan Identify potential alternate sources of water Assess the range of potential impacts of wildfire on water quality Identify additional drinking water treatment infrastructure and analytical capacity Develop treatment plan technological and operational response options Include a knowledge mobilization strategy for local stakeholders regarding the risks and actions to deal with wildfires 10/22/

21 Overall Summary Need opportunities for water industry and forestry professionals to work together to gain better understanding of the challenges (e.g., workshops) Wildfire risks are likely to increase due to climate change Strong expectation that management options can reduce wildfire risks but need further study Knowledge and tools exist to assess forest and watershed conditions and drinking water system capacity and vulnerability, but need to improve knowledge on the effectiveness, costs, and benefits of techniques Lexington Hills Community Hazard Rating Map Image courtesy of Anchor Point Group, LLC 10/22/

22 Questions? Chi Ho Sham, Ph.D. The Cadmus Group, Inc. Waltham, MA Resources: Workshop Workshop /22/