High Resolution Regional Drought Monitor for the Carolinas USC Greg Carbone, USC-Regional Integrated Sciences Assessment Hope Mizzell, SC State Climate Office

Drought historically monitored on regional and statewide spatial scales Drought data readily available at climate division scale or larger Background Southeastern US Drought amplified belief among climate scientists and policy makers that drought depiction and measurement is required on more local scales

Dam Relicensing Federal Energy Regulatory Commission (FERC) has jurisdiction over all hydropower dams not owned by federal government. Rivers are owned by public. Developer may obtain license to dam river for purpose of hydropower generation. Licenses last 30 to 50 years Relicensing process gives stakeholders an opportunity to reconsider appropriate operations and land management for each project, taking into account current social and scientific knowledge. FERC State and federal resource agencies Conservation groups General public

FERC Projects: - 2,500 non-federal hydropower projects FERC hydropower licenses will expire this decade (one-third of FERC hydropower capacity)

Catawba-Wateree Project 11 Interconnected Reservoirs 2 states, 14 counties, 30 municipalities Regional and National profile Lasting impact to both NC and SC

Agencies and Interests in the FERC Relicensing Process Licensee Federal Agencies State Agencies Non-Agency Stakeholders

Study Groups Hydropower Shoreline Management Fish and Wildlife and Habitat Enhancement and Protection Water QualityWater Supply Recreation

Open Comment Period Duke Consulting Studies FERC Review & Relicensing

SC Governors Water Law Review Ad Hoc NC/SC Water Agreement El Nino Open Comment Period Duke Consulting Studies FERC Review & Relicensing SC Drought Act

Low Inflow Protocol Existing license does not address operation during low inflow periods. LIP establishes procedures for managing available water supply. Major elements include 3 triggers and response stages Success of LIP depends on diagnostic accuracy of trigger points, and effectiveness of Licensee and water users in working together to implement their required actions to achieve significant water use reductions. Additional considerations include –Consistency between Catawba and Yadkin LIP –Consistency with SC Drought Response Act Double regulations and requirements

StageStorage Index 1 Drought Monitor 2 (3-month average) Monitored USGS 3 Streamflow Gages % < SI < TSI 0 DM AVG 85% 175% < SI 90%TSI1 DM AVG 78% 257% < SI 75%TSI2 DMAVG 65% 342% < SI 57%TSI3 DMAVG 55% 4SI 42%TSIDM = 4AVG 40% Catawba-Wateree Project Summary of LIP Trigger Points AND AND OROR 1 Ratio of Remaining Useable Storage to Total Usable Storage 2 3-month numeric average of U.S. Drought Monitor 3 Sum of rolling 6-month average streamflow as percentage of period of record rolling average for same 6-month period 4 Stage 0 is triggered when any two of three trigger points are reached

To provide local scale drought monitoring tool Compute suite of monthly drought indices, Empirical probability distributions of each index to allow stakeholders to create drought blends that address specific sensitivities to drought. High Resolution Regional Drought Monitor Palmer Drought Severity Index (PDSI) Palmer Hydrological Drought Index (PHDI) Palmer Z Index Standardized Precipitation Index (1,2,6,9,12,24-month) Precipitation (1,3,6,12,24,60-month) 7-day Streamflow 14-day Streamflow Streamflow (1,3,6,12,24-month)

D4D3D2D1D

PDSIZ IndexSPI1SPI3 50% % % % % Linking Probabilities to Indices Difference Between 10%-20%Difference Between 20%-30% PDSI SPI1month

StageStorage Index 1 Drought Monitor 2 (3-month average) Monitored USGS 3 Streamflow Gages % < SI < TSI 0 DM AVG 85% 175% < SI 90%TSI1 DM AVG 78% 257% < SI 75%TSI2 DMAVG 65% 342% < SI 57%TSI3 DMAVG 55% 4SI 42%TSIDM = 4AVG 40% Catawba-Wateree Project Summary of LIP Trigger Points AND AND OROR 1 Ratio of Remaining Useable Storage to Total Usable Storage 2 3-month numeric average of U.S. Drought Monitor 3 Sum of rolling 6-month average streamflow as percentage of period of record rolling average for same 6-month period 4 Stage 0 is triggered when any two of three trigger points are reached

Catawba-Wateree Streamflow vs. Storage Index Comparison (Highest LIP stage according to Streamflow and Reservoir Storage)

Catawba-Wateree Proposed Triggers (During 2002 Record Drought)

US Drought Monitor vs Regional Drought Monitor Pros: Produced weekly by NOAA and USDA Incorporates quantitative indicators with input from experts Fujita or Saffir-Simpson type classification system for drought Uses percentile approach in determining severity thresholds Subjective adjustments based on local impacts Gained popularity among media, state and local officials Cons: Cannot regenerate historical values because local input not available Intended to display broad areas of dryness New Tool 1999-Present Difficult to compare with traditional drought indicators Use indicator that has a consistent long-term record (Steinman et al. 2005, Keyantash and Dracup, 2002).

Trigger Stage Comparison (2002)

Trigger Points Still Underdevelopment Storage IndexDrought Monitor Streamflow (3 month vs. 6 month) Yadkin-Pee Dee Project 6 Reservoirs 2 states, 24 counties, 83 municipalities Ran out of water 2002 Lasting impact to both NC and SC Yadkin-Pee Dee Relicense

Conclusions / Future Results Drought Triggers are Tools to Aid Decision-Makers LIP Creates a Drought Management Advisory Group (DMAG) Working with Licensee when LIP is initiated Meet as necessary to foster basin-wide response to LIP Meet annually during May, to review prior year activities, discuss data input from Large Intake Owners, and discuss other issues relevant to LIP Substitution of a Regional Drought Monitor for U.S. Drought Monitor are examples of items that may be re- evaluated Evaluation of Triggers Listed in SC Drought Response Act Regulations