Toward a Basin-Wide Drought Planning Tool in the Susquehanna River Basin

Transcription

1 Toward a Basin-Wide Drought Planning Tool in the Susquehanna River Basin 2016 AWRA Annual Conference November 13, 2016 Drought planning for water supply and forecasting drought conditions Josh Weiss, PhD, PE, D.WRE jweiss@hazenandsawyer.com

2 Acknowledgements and Agenda Co-authors: Kinsey Hoffman (Hazen and Sawyer) Ben Pratt, John Balay (Susquehanna River Basin Commission) Richard Palmer, Katie Booras, Alex McIntyre (UMass-Amherst) Clark Howells (City of Baltimore DPW) Background How do we deal with drought? NOAA project overview Drought simulation example

3 Susquehanna River Basin 27,500 sq miles of watershed Three states: NY, PA, MD Varies widely in topography, geology, climate Future climate conditions highly uncertain Wide range of drought responses/approaches

4 SRBC Drought Coordinating Committee Convened by staff as necessary based on hydrologic conditions Provides forum for signatories technical staff to communicate regarding drought monitoring data & potential response actions Intended for making recommendations to commissioners regarding drought declarations & response actions to be taken through resolution

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6 Mid-Atlantic Drought Prettyboy Reservoir, photo by Wendy S. McPherson, U.S. Geological Survey /jan/30/25563/

7 Drought planning isn t just for California and Texas! Palmer Drought Severity Index Original data from N. Pederson, Lamont Dougherty Earth Observatory -

8 Dealing with Drought How do we identify a drought? 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 NWS Hydrologic Ensemble Forecast Service (HEFS) Goal: quantify total uncertainty in flow Streamflow Observed streamflow Weather (forcing) uncertainty in flow Hydrologic uncertainty Total Forecast horizon HEFS aims to capture observed flow consistently So, must account for total uncertainty & remove bias Total = forcing uncertainty + hydrologic uncertainty Slide credit: Seann Reed, NOAA NWS MARFC

11 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

12 Drought Planning Tool Platform: SRBC s OASIS System Model Forecasts and Indices Demand Forecasts System Infrastructure System Operating Rules Water Quality Models Storage Projections Shortfall Projections Stream Flows at Key Locations Probability of Drought Status Water Quality Impacts

13 NOAA s Drought Mission SARP: Sectoral Applications Research Program Currently focused on water resource management initiatives for coping with drought, and extreme event preparedness NIDIS: National Integrated Drought Information System Objective is an integrated national drought monitoring and forecasting system at federal, state, and local levels NIDIS implementation plan: dis/nidis-ipfinal-june07.pdf

14 Objectives of the Drought Planning Tool Identify onset Implement mitigation actions Identify recovery 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

15 Objectives of the Drought Planning Tool Identify onset Implement mitigation actions Identify recovery 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

16 Objectives of the Drought Planning Tool Identify onset Implement mitigation actions Identify recovery 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

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18 Data and Models System Simulation Platform Analysis and Decision Support

19 OASIS Planning and Operations Support Tool will provide analytical platform for integrated basin planning Basin stakeholders

20 Given today s conditions, system indices, Forecasted Croton System Usable Storage and forecasted system inflows: What is the likelihood of entering drought? Should we initiate drought mitigation measures? What is the likelihood of use restrictions and can we avoid them? The objective of the SRB Drought Planning Tool is to enhance and integrate existing tools to improve predictive capabilities Observed storage

21 Forecasted Croton System Usable Storage Supply thresholds of interest (e.g. 25%, 30%, 35% storage) Observed storage

22 Forecasted Croton System Usable Storage Observed storage Forecasted storage

23 Forecasted Croton System Usable Storage e.g. Over the next 1-2 months, there is: 4% chance of dropping below 30% storage threshold 20% chance of dropping below 35% storage threshold Observed storage Forecasted storage

24 Case Study Example: Baltimore City Current Operations Pennsylvania Meet demand (~250 mgd) with storage in Prettyboy, Loch Raven, and Liberty Reservoirs Initiate Susquehanna diversions via Deer Creek PS when Prettyboy and Loch Raven are drawn down to 490 ft and 237 ft Maryland Liberty Reservoir Prettyboy Reservoir Loch Raven Reservoir Baltimore Conowingo Pond Intake Return to 100% Baltimore reservoir supplies when storage goes back above 490 and 237 ft

25 Operational Example: Baltimore City (cont d) Alternatives for Proactive Drought Management Initiate diversions before reservoirs are drawn down to 490/237 ft Maintain full reservoirs at the start of the low-flow season Avoid Susquehanna diversions during months with the lowest flows Tradeoffs: Water supply reliability, reservoir storage Pumping and treatment costs Water quality Use restrictions, curtailments

26 Scenario 1: Baseline operations to minimize pumping Reactive pumping triggered by extreme reservoir drawdown

27 Example Scenario 2: Proactive pumping based on Palmer Hydrologic Drought Index (PHDI) Earlier pumping triggered by PHDI

28 Example Scenario 3: Proactive pumping based on cumulative 6-month precipitation

29 Comparison of Example Scenarios 1, 2, and 3 How much water is pumped from the Susquehanna River?

30 Comparison of Example Scenarios 1, 2, and 3 How low does storage get during a drought?

31 Comparison of Example Scenarios 1, 2, and 3 Daily results over entire simulation period

32 Are there better water supply-specific indices? Days of Supply Remaining (DSR): DSR = Total Storage,t + NWS 3mo Forecast accum{demand, t + 1, t + 90} [mg] Demand [mgd] Streamflow Observed streamflow Weather (forcing) uncertainty in flow Hydrologic uncertainty Total Forecast horizon

33 Next Steps Case studies Baltimore, Capital Region Water, York Water Define key performance indicators Investigate alternative indices and thresholds Investigate alternative operating rules Develop Drought Planning Tool Dashboard Deliver Drought Planning Tool to SRBC Hold stakeholder workshops/training Project end date: August 30, 2017

34 Thank you! Josh Weiss Kinsey Hoffman