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
•1998-2002 Southeastern US Drought amplified belief among climate scientists and policy makers that drought depiction and measurement is required on more local scales
Dam RelicensingDam 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
- 220 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 ManagementFish and Wildlife and Habitat Enhancement and Protection
Water Quality Water Supply
Recreation
0
50
100
150
200
250
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
% A
vera
ge D
isch
arg
e
Open Comment Period
Duke Consulting Studies
FERC Review & Relicensing
0
50
100
150
200
250
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
% A
vera
ge D
isch
arg
e
SC Governor’s 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 ProtocolLow 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
Stage Storage Index 1 Drought Monitor 2 (3-month average)
Monitored USGS 3 Streamflow Gages
04 90% < SI < TSI
0 ≤ DM
AVG ≤ 85%
1 75% < SI ≤ 90%TSI 1 ≤ DM AVG ≤ 78%
2 57% < SI ≤ 75%TSI 2 ≤ DM AVG ≤ 65%
3 42% < SI ≤ 57%TSI 3 ≤ DM AVG ≤ 55%
4 SI ≤ 42%TSI DM = 4 AVG ≤ 40%
Catawba-Wateree ProjectSummary of LIP Trigger Points
AND
OR
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, 1950-2004.
Empirical probability distributions of each index to allow stakeholders to create drought blends that address specific sensitivities to drought.
High Resolution Regional Drought MonitorHigh 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)
6-month SPI (1954-2003)
-4
-3
-2
-1
0
1
2
3
4
0 10 20 30 40 50 60 70 80 90 100
Percentile
SPI
D4 D3 D2 D1 D0
-0.51
-0.85
-1.3
-1.64
-2.11
PDSI Z Index SPI1 SPI3
50% -0.13 -0.22 0.05 0.00
30% -1.39 -1.21 -0.60 -0.61
20% -2.05 -1.88 -0.88 -1.06
10% -3.18 -2.56 -1.36 -1.35
5% -4.01 -3.62 -1.69 -1.78
Linking Probabilities to Indices
Difference Between 10%-20% Difference Between 20%-30%
PDSI 1.13 0.66
SPI1month 0.48 0.28
Stage Storage Index 1 Drought Monitor 2 (3-month average)
Monitored USGS 3 Streamflow Gages
04 90% < SI < TSI
0 ≤ DM
AVG ≤ 85%
1 75% < SI ≤ 90%TSI 1 ≤ DM AVG ≤ 78%
2 57% < SI ≤ 75%TSI 2 ≤ DM AVG ≤ 65%
3 42% < SI ≤ 57%TSI 3 ≤ DM AVG ≤ 55%
4 SI ≤ 42%TSI DM = 4 AVG ≤ 40%
Catawba-Wateree ProjectSummary of LIP Trigger Points
AND
OR
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 1953-2003
(Highest LIP stage according to Streamflow and Reservoir Storage)
Streamflow %
LIP Stage
Reservoir Storage Index
LIP Stage
Nov-54 0.33 4 Sep-02 40 3Dec-54 0.32 4 Oct-02 35.6 3Jan-55 0.31 4 Nov-02 39.2 3Jan-56 0.40 4 Dec-02 52.9 3Dec-78 0.38 4 Jul-02 46.2 2Oct-88 0.40 4 Aug-02 42.1 2Feb-01 0.39 4 Jan-03 79.6 2Oct-01 0.39 4 May-86 68.8 1Nov-01 0.38 4 Jun-86 44.2 1Dec-01 0.37 4 Jul-86 42.9 1Jan-02 0.39 4 Aug-86 45.1 1Feb-02 0.40 4 Sep-86 52.1 1Jul-02 0.38 4 Oct-86 50.8 1Aug-02 0.35 4 Nov-86 57.8 1Sep-02 0.32 4 Dec-86 67.4 1Oct-02 0.34 4 Sep-88 45.8 1
Catawba-Wateree Proposed Triggers
(During 2002 Record Drought)
Reservoir Storage Index Streamflow USDM
Jan-02 1 4 2Feb-02 1 4 3Mar-02 1 3 3Apr-02 1 3 3May-02 1 3 3Jun-02 1 3 3Jul-02 2 4 3Aug-02 2 4 4Sep-02 3 4 4Oct-02 3 4 4Nov-02 3 3 4Dec-02 3 1 3
Short Term Blend39% Z Index28% 3 Month Precip23% 1 Month Precip10% PDSI
Long Term Blend27% PHDI22% 24 Month Precip22% 12 Month Precip17% 6 Month Precip12% 60 Month Precip
US Drought Monitor vs Regional Drought MonitorUS Drought Monitor vs Regional Drought MonitorPros:
•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 Stage Comparison (2002)
Year
Reservoir Storage Index
Stream-flow USDM
PDSI Stage
PHDI Stage
Z Stage
SPI 1Stage
SPI 3 Stage
SPI 6 Stage
SPI 9 Stage
SPI12 Stage
Jan-02 1 4 2 2 2 0 1 1 1Feb-02 1 4 3 3 2 1 1 1 2 1 2Mar-02 1 3 3 2 2 1 1 2Apr-02 1 3 3 3 2 2 1 1 2 2 2May-02 1 3 3 3 2 1 1 2 1Jun-02 1 3 3 3 3 1 1 2 1 3 2Jul-02 2 4 3 3 3 1 0 1 3 3 3
Aug-02 2 4 4 2 3 1 2 2 2Sep-02 3 4 4 0 3 1 1 2Oct-02 3 4 4 2 1 1Nov-02 3 3 4 1 0 0Dec-02 3 1 3
Year
Reservoir Storage Index
Stream-flow USDM
12 Month Precip Stage
24 Month Precip Stage
Short Term Blend Stage
Long Term Blend Stage
Jan-02 1 4 2 1 2 2Feb-02 1 4 3 2 2 1 2Mar-02 1 3 3 2 2 2Apr-02 1 3 3 2 3 1 2May-02 1 3 3 1 3 0 2Jun-02 1 3 3 2 3 1 2Jul-02 2 4 3 3 3 1 3
Aug-02 2 4 4 2 3 2
Sep-02 3 4 4 2 3 2Oct-02 3 4 4 1 2 1Nov-02 3 3 4 0 2 0
Dec-02 3 1 3 1
Trigger Points Still Underdevelopment
Storage Index Drought 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 RelicenseYadkin-Pee Dee Relicense
Conclusions / Future ResultsConclusions / 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