The Quantification of Drought: An Evaluation of State and Local Drought Triggers Hope Mizzell, Greg Carbone, Jason Caldwell South Carolina Department of Natural Resources

WHY PLAN?

NOAA Paleoclimatology Program Dr. Edward Cook, Dr. David Meko, Dr. David Stahle Dr. Malcolm Cleaveland

Hydro-Illogical Cycle

Population 1 Dot = 10,000 People

South Carolina Drought Response Act Established procedures for monitoring, managing, and conserving water resources during periods of drought SC Department of Natural Resources – Land,Water & Conservation Division serves as primary agency Monitor drought conditions Coordinate States response

Local Drought Committee Local Drought Plans and Ordinances State Drought Program State Agency Drought Committee Drought Act and Regulations

Chairs D.R.C. & provides support SC State & Local Drought Committee SCDNR Coordinate response Issue Drought Declarations Consult with stakeholders Issue nonessential water curtailment declaration Review request for variance Curtail nonessential water use during severe and extreme droughts Health & safety threatened - Report conditions & recommend actions to Governor Mediate disputes Governor may declare drought emergency and issue emergency water curtailment regulations Water Systems implement drought response ordinances or plans

South Carolina Model Drought Mitigation Ordinance/Plan SCDNR, in cooperation with SC Water Utility Council and SCDHEC developed a model drought response ordinance/plan for water systems Reviewed by Municipal Association and SC Drought Response Committee SC Drought Response Act of 2000 requires that all municipalities, counties, public service districts, special purpose districts, and commissions of public works engaged in business or activity of supplying water for any purpose develop and implement drought response ordinances or plans.

Model Drought Management Plan and Response Ordinance Model Drought Management Plan and Response Ordinance Section I: Declaration of Purpose and Intent Section II: Definition of Terms Section III: Drought Management Plan A. Introduction B. Designation of Water System Drought Response Representative C. Description of Water System Layout, Water Sources, Capacities and Yields D. Identification of Water System Specific Drought or Water Shortage Indicators E. Cooperative Agreements and Alternative Water Supply Sources F. Description of Pre-Drought Planning Efforts G. Description of Capital Planning and Investment for System Reliability and Demand Forecasting

Drought Response Ordinance (or Resolution) A. Declaration of Policy and Authority B. Moderate Drought Phase C. Severe Drought Phase D. Extreme Drought Phase E. Rationing F. Enforcement of Restrictions G. Variances H. Status of the Ordinance Resolution of Adoption Resolution of Adoption

Importance of State and Local Drought Triggers 4 phases of drought established by regulation Incipient PDSI to -1.49CMI 0.00 to -1.49SPI 0.00 to KBDI 300 to 399DM D0 Avg daily streamflow 111%-120% of minimum flow for 2 consecutive weeks Static water level in aquifer is feet above trigger level for 2 cons. months Moderate PDSI to -2.99CMI to -2.99SPI to KBDI 400 to 499DM D1 Avg daily streamflow 101%-110% of minimum flow for 2 consecutive weeks Static water level in aquifer is 1-10 feet above trigger level for 2 cons. months Severe PDSI to -3.99CMI to -3.99SPI to KDBI 500 to 699DM D2 Avg daily streamflow is between minimum flow and 90% of minimum for 2 cons. weeks Static water level in aquifer is between trigger level and 10 feet below for 2 cons. months Extreme PDSI and belowCMI and belowSPI and below KBDI exceeds 700DM D3 or higher Avg daily streamflow less than 90% of minimum for 2 consecutive weeks Static water level in aquifer is more than 10 feet below trigger level for 2 consecutive months

Importance of State and Local Drought Triggers Water System Specific Triggers Moderate/Severe/Extreme Drought Phases 1. Reservoirs ________ full 2. Storage falls below ____ percentage of capacity 3. Stream-flow less than ______ cubic feet per second 4. Aquifer levels less than ______________ 5. ____________number of days of supply remaining 6. Average daily use greater than _____mgd for _____ consecutive days 7. Others: ______________________________________________

SJWD Water System

Percentage of Storage Volume Lyman Lake Drought Operating Curves

Drought Stage Thresholds Lyman Lake Drought Operating Curves

Operating Curve Performance (50-year Simulated Record)

Frequency of Drought Phase Indication (14.1 mgd Withdrawal) Drought Phase Percent of 54- year Historical Record for Lake Lyman Number of Weeks During 54-year Record Public Notices During 54-year Record Normal90.1%2544N/A Incipient Drought (Phase 1)1.1%3215 Moderate Drought (Phase 2)2.1%5915 Severe Drought (Phase 3)3.4%9714 Extreme Drought (Phase4)3.3%925 Frequency of Drought Phase Indication

Comparison of Lake Lyman Elevation, PDSI and 3 month SPI

Comparison of Lake Lyman Elevation, PDSI and 3 month SPI:

Frequency of Drought Phase Indication Drought Phase Percent of 54- year Historical Record for Lake Lyman Percent of 54- year Historical Record for SPI Percent of 54- year Historical Record for PDSI Normal 90.1%53.5%56% Incipient Drought (Phase 1) 1.1%31.5%13.2% Moderate Drought (Phase 2) 2.1%9.2%24.1% Severe Drought (Phase 3) 3.4%2.9%5.3% Extreme Drought (Phase4) 3.3%2.9% 1.2% Frequency of Drought Phase Indication

National Drought Preparedness Act of 2003 June 21, 2004, Western Governors, Creating a Drought Early Warning System for the 21st Century: The National Integrated Drought Information System (NIDIS) One Goal of NIDIS Create a drought early warning system capable of providing accurate, timely and integrated information on drought conditions at the relevant spatial scale to facilitate proactive decisions aimed at minimizing the economic, social and ecosystem losses associated with drought;

Future Work Compare additional state drought indices such as KBDI, Streamflow, Groundwater with several Local Water System Triggers such as those using wells Evaluate drought strength, frequency, mean and maximum duration of droughts of a given intensity, and trend in drought incidence as indicated by the local and State triggers