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