ICWP October 10, 2018 Greg Gates, PE ggates@hazenandsawyer

1. http://www.flickr.com/photos/nicholas_t/3555542960 Improving Drought Planning Capabilities ICWPOctober 10, 2018Greg Gates, PEggates@hazenandsawyer.com

2. Outline • Background • How do we deal with drought? • NOAA project overview • Drought simulation results • Other cases of interest

3. The National Climate Data Center has estimated the costs of drought in the US since 1980 has exceeded $100 billion in adjusted dollars, second only to tropical cyclones (Smith and Katz, 2013)

4. Limited Drought Records Tree-ring reconstructions show frequent, severe droughts over the last ~500 years, some persisting over many years. 23-year “megadrought” of the 1500’s 1960’s drought of record Pederson, N. et al. (2013). Is an Epic Pluvial Masking the Water Insecurity of the Greater New York City Region? Journal of Climate, 26(4): 1339-1354.

5. Climate Change and Drought in the US • Drought planning isn’t just for California and Texas! Strzepek, K. et al. (2010). Characterizing Changes in Drought Risk for the United States from Climate Change. Environmental Research Letters, 5(4): 1-9.

6. Climate Change and Drought in the US • Drought planning isn’t just for California and Texas! Strzepek, K. et al. (2010). Characterizing Changes in Drought Risk for the United States from Climate Change. Environmental Research Letters, 5(4): 1-9.

7. 2001-2002 Mid-Atlantic Drought Prettyboy Reservoir, photo by Wendy S. McPherson, U.S. Geological Survey http://www2.ljworld.com/photos/2002/jan/30/25563/

8. Dealing with Drought • How do we identify a drought? • System understanding • Monitor drought indices and triggers • We want to catch possible/probable drought as early as possible • Look at climate, compare to history • Important to consider water demands • How do we respond to drought? • Proactive planning and operations • Reactive management (demand cutbacks, use restrictions, etc.)

9. Drought Indices • Drought indices are used to describe current conditions and trends to support decision-making • Reservoir elevation or storage • Recent streamflow • Historical streamflow • Forecasts • Groundwater levels • Cumulative inflow • Percent of Normal • Standardized Precipitation Index (SPI) • Palmer Drought Severity Index (PDSI) • Palmer Hydrologic Drought Index (PHDI) • Soil Moisture Index (SMI) • Crop Moisture Index (CMI) • Surface Water Supply Index (SWSI)

10. Drought Triggers • Thresholds or values of indices or forecasts that are used to trigger a response • Near term management • Maximize finished water storage • Source balancing • Modified operations • Bring new source online • Call for use restrictions (voluntary, mandatory) • Long term planning • Develop new storage • Seek alternative or emergency sources • Vulnerability assessment • Climate change analysis • Demand management • Leak reduction

11. Difficulty Forecasting Drought How do we know when we’re here? Namias, J. (1967). Further Studies of Drought over Northeastern United States. Monthly Weather Review, 95(8): 497-508.

12. Drought Planning Tool Goals • Step 1 • Monitor relevant drought indices and forecasts • Use triggers to initiate mitigation responses • We want to catch possible/probable drought as early as possible • We want to minimize occurrence of “false positives” • Important to consider water demands

13. Drought Planning Tool Goals • Step 2 • Emphasize proactive over reactive management • Continue to monitor drought indices/forecasts and re-evaluate management decisions • Modeling and scenario analysis can help managers evaluate alternative strategies based on current and projected conditions

14. Drought Planning Tool Goals • Step 3 • Use drought indices and forecasts to trigger demobilization of mitigation actions • We want to avoid costly mitigation actions when risk for adverse outcomes is reasonably low

15. Case Study Example • Water utility with primary source of drinking water from 6 BG reservoir • Secondary riverine source via a pump station on the Lower Susquehanna River • Baseline drought management plan: Initiate blending of riverine source with reservoir source when reservoir storage falls below 12% usable storage • System Description

16. Drought Planning Tool Platform:SRBC’s OASIS System Model

17. Drought Planning Tool: Alternatives Analysis • Alternate Indices, Baseline Operations • Climatic indices (cumulative precipitation, PDSI, etc.) • Hydrologic forecast indices (projected inflow and storage, days of supply remaining, etc.) • Alternate Indices, Operational Alternatives • Proactive pumping before low-flow season • Additional sources of supply • Demand reductions • Pattern-based conservation releases

18. Can Forecasts Help Improve Performance? • Days of Supply Remaining (DSR): Observed streamflow Weather (forcing) uncertainty in flow Hydrologic uncertainty Streamflow Total Forecast horizon HEFS conceptual figure courtesy of Seann Reed, Middle Atlantic River Forecast Center, National Weather Service

19. Base Run: Proactive Management Test • Total Baltimore storage and DSR are higher throughout the 2002 drought with proactive pumping • Time Series, 2001-2003

20. Base Run: Proactive Management Test • Prettyboy and Loch Raven elevations remain high or generally equal • Time Series, 2001-2003

21. Tradeoffs Between Pumping and Reliability • Alternatives Analysis Storage (% Usable)…..Avg of yearly min values Riverine Diversions (mgd)…..Sum of yearly avg values

22. Tradeoffs Between Cost and Reliability • Alternatives Analysis Storage (% Usable)…..Avg of yearly min values Total Annual Cost ($)…..Avg of yearly total values

23. Other Cases - Albuquerque • Groundwater Reserve

24. Other Cases – Ute Reservoir • Establishing a Prudent Reserve

25. Drought Response Plan Storage and Restriction Levels

26. Questions? Greg Gates, PEggates@hazenandsawyer.com