California drought short-term problems & long-term solutions. Roger Bales, Professor of Hydrology Sierra Nevada Research Institute

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1 California drought short-term problems & long-term solutions Roger Bales, Professor of Hydrology Sierra Nevada Research Institute 1. Current drought 2. Water security 3. Water information system 4. Forest management

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5 Long-term drought should be part of California s water planning Paleoclimate record shows year events in last millenium

6 Making a water-secure world the three I s Water security: the reliable availability of an acceptable quantity & quality of water for health, livelihoods & production, coupled w/ an acceptable level of water-related risks INFRASTRUCTURE to store, transport & treat water Stronger & moreadaptable INSTITUTIONS Better & moreaccessible INFORMATION Water security lies at the heart of adaptation to climate change.

7 Making a water-secure California INFRASTRUCTURE: planning INSTITUTIONS: collaboration & integration in planning, management More INFORMATIONintensive decision support Water management translates into managing ecosystem services. Adapting to climate change also means managing ecosystem services. Ecosystem services: managing forests, wetlands, rivers

8 ACWA Policy Principles on Improved Management of California s Headwaters managing California s headwaters is integral to optimizing water supplies Increasing water yield and quality; reducing the risk and impacts of catastrophic wildfire; and enhancing natural features and functions; are all benefits to be derived, locally and statewide, from improved headwaters stewardship. Enhancing the resiliency and adaptability of headwaters is overdue. California can no longer afford to relegate management of its headwaters to the margin. Natural Infrastructure

9 Envisioning a new water information system for California Current practice seasonal forecasts uncertainty can be high Mainly monthly, manual measurements Few automated, but non-representative measurements Statistical forecasts, vs. hydrologic models New, mature technology available now: blending data from satellites, aircraft, low-cost wireless sensor networks, advanced modeling tools

10 American R. basin hydrologic observatory (in progress) Platform for research & core element of new water information system Strategically place low-cost sensors to get spatial estimates of snowcover, soil moisture & other water-balance components Integrate these sensors with remotely sensed data, forecasting tools & decision support Goals: 1. Reduce uncertainty in water-supply forecasts 2. Potentially enable more-flexible operation of Folsom Dam 3. Enhance hydropower operations 4. Document & forecast impacts of forest management on water 5. Demonstrate basin-scale, real-time intelligent water information system

11 Forest & watershed management Basic montane water balance Precipitation = Evapotranspiration + Runoff Some recurring questions around water & forests 1. How will the post-fire water yield differ from that pre-fire? 2. What will be the water yield w/ climate warming? 3. What was the historical water yield, prior to fire suppression? 4. How different were forests prior to fire suppression vs. today, pre-fire & post-fire? 5. Can or should we take forests back to pre-fire-suppression conditions?

12 Water & Sierra Nevada forests What we know 1. Vegetation removal generally results in more runoff, initially 2. Vegetation regrowth means less runoff 3. Clear cutting or wildfire means more sublimation & earlier snowmelt 4. Less-dense forests (up to a point) can retain snow longer 5. Colder, snow-dominated areas produce more runoff that lower, rain-dominated areas Knowledge gaps 1. How much water is used by vegetation? 2. Interception, sublimation & evaporative losses? 3. Vegetation-thinning effects on the timing of snowmelt & runoff? 4. How to verify effects at small-watershed vs. landscape scale?

13 Some concluding points 1. Sustained forest management that provides measurable benefits for water supply will require investment, verification & maintenance Next step: do scalable demonstration project in Sierra Nevada 2. Better information is a critical foundation for water security, especially in a warming & more-variable climate Next step: incorporate research products into scalable water information system 3. Drought management is a critical water security issue for California Next step: continue development of technology & knowledge to meet emerging challenges