Addressing monitoring needs for drought management

The record multi-year droughts impacting the Southeast over the last decade elevated the public's awareness and captured decision makers' attention to the challenges associated with managing the region's water resources. Persistent drought and increased water demand require that comprehensive drought planning, based on accurate drought indicators, guide future water resource management. Yet, drought indicators are often the weakest components of drought plans because drought affects different sectors at different time scales, making it difficult to define and measure. The Carolinas Dynamic Drought Index Tool (DDIT) was developed to address the need to display multiple drought indices for different time scales and across user-specified regions. Utilizing the DDIT this research evaluates the spatial and temporal distribution of drought intensity and frequency as detected by South Carolina's state drought indicators and the recently defined Federal Energy Regulatory Commission's (FERC) Low Inflow Protocol (LIP) indicators for the Catawba-Wateree and Yadkin-Pee Dee River Basins. The evolution and implementation of the drought plans or LIPs in FERC licenses identified or demonstrated the need for additional research on drought indicator validation. The LIPs were new to the relicensing process and the identification of drought indicators and trigger points presented challenges to the licensee (Duke Energy, Alcoa Yadkin, and Progress Energy) and the stakeholders.

Indicator discrepancies were identified and several major recommendations emerge from the research. First, statistical inconsistencies exist between the drought classes defined by the S.C. Drought Response Act regulations; these can be resolved by transforming the indicators from raw values to percentiles. Second, discrepancies in drought detection based on the LIP indicators were most acute during the drought recovery phase and for the Catawba-Wateree River Basin LIP, which is dependent on a recovery of all indicators to initiate a stage downgrade. Recommendations include shortening the streamflow average and replacing the U.S. Drought Monitor with the Standardized Precipitation Index. The addition of a recovery condition based on storage recovery should also be considered.

The research connects indicators based on scientific justification with operational relevancy by evaluating water systems' and power company's vulnerability to drought, their understanding of drought indicators, and their identification of indicator characteristics that provide the most effective drought response. The research identified that water systems and power companies value both local and state drought indicators, however, they have higher expectations and depend more heavily on their local indicators. Drought indicator(s) need to be multi-dimensional as indicator effectiveness is based on drought detection and indicator accessibility. The study implements the National Integrated Drought Information System initiative that calls for integrated drought research at relevant spatial scales to facilitate proactive decisions. The research results can be used to improve planning and coordination within and between levels of government and water users to help reduce society's vulnerabilities to drought and ensure sustainable water to meet growing demands.