State Water Resources Research Institute Program

Project ID: 2008NC113B
Title: Improved Drought Management Strategies for the Triangle Area Utilizing Climate Imformation based Probabilistic Streamflow Forecasts
Project Type: Research
Start Date: 3/01/2008
End Date: 2/28/2009
Congressional District: 2
Focus Categories: Drought, Hydrology, Water Supply
Keywords: Hydroclimatology, Hydrological Forecasting, Watershed Management, Risk Analysis, Climate Decision Models, Flood Control, Multi-Objective Planning, Optimization, Reservoir Modiling, Systems Analysis
Principal Investigator: Arumugam, Sankarasubramanian (North Carolina State University)
Federal Funds: $ 20,000
Non-Federal Matching Funds: $ 28,337
Abstract: Scope and Motivation: A prognostic approach to improve drought management in the Triangle Area is proposed here that integrates climate information based seasonal streamflow forecasts with the drought management plan of two major water supply systems - Falls Lake in the Neuse basin and Lake Jordan in the Cape Fear River basin. Two proactive water conservation measures - three levels of water restriction (voluntary, mandatory and emergency) and waste water reuse - that could be invoked contingent on climate forecasts are considered for reducing the regional water supply system's vulnerability to prolonged droughts. Invoking these proactive water conservation measures will also improve the system resilience - ability to bounce back from drought - which will ensure improved operation even after droughts. The ongoing project on improving the Falls Lake Management has shown that invoking different levels of restriction contingent on seasonal streamflow forecasts tend to ensure increased storages at the end of season. This study will combine the ongoing project's Falls Lake reservoir model with the proposed Lake Jordan Model to develop Triangle Area Water Management Model that explicitly considers the water supply contracts across the basins as well as downstream releases from each system. With the triangle area's annual population is expected to grow around 2% annually, the capacity of existing systems may be stressed in the future which will obviously lead to search for newer options such as capacity expansion and inter-basin transfers. Instead, this study promotes adaptive water management contingent on climate forecasts to ensure a coordinated management of region's two major water supply systems by invoking water conservation measures such as waste water use in reducing the demand-driven stress as well as during prolonged droughts. Objectives: Four specific objectives proposed are: (1) Develop climate-information based reservoir inflow forecasts for the winter (January-February- March) and summer seasons (July-August-September) for the Jordan Lake, (2) Develop a Triangle Area Water Management Model (TAWMM) that explicitly considers the water contracts and mandatory downstream releases from both systems,(3)Perform a retrospective analyses using TAWMM to understand the utility of climate forecasts in developing proactive drought management strategies - restriction and waste water reuse - under current demand and under increased demand potential, and (4) Disseminate the findings from the study by interacting with NC Drought Management Advisory Council (NCDMAC), NC Division of Water Resources (NCDWR) and State Climate Office of NC and by updating the current project web site. Methodology and Analyses: Retrospective (e.g. 1990-2005) 3-month ahead inflow forecasts for the two reservoirs will be developed by statistically downscaling the precipitation and temperature forecasts obtained from combining multiple General Circulation Models. Inflow forecasts developed for Lake Jordan and Cape Fear reservoirs will be forced into the TAWMM - a simulation-optimization model with two reservoirs in parallel - to quantify the reliability of meeting the water supply targets, water quality releases and end of the season target storage. By invoking proactive water conservation measures, the study will assess improvements in drought management and mitigation by quantifying the resilience, vulnerability, and reliability under climate forecasts operations as well as under no forecasts scenario. The study will also analyze the performance of the system to understand how future increased demand scenarios could be managed effectively using the retrospective forecasts and proactive water conservation measures, which could avoid potential investments in capacity expansion and inter-basin transfer projects. Benefits and Potential Impacts: Possible benefits from the study include: (a) a quantitative assessment of the reliability of meeting the water supply and water quality releases over the season in the region (b) dynamic rule curves that could be updated on a monthly basis as the streamflow potential changes (c) setting of trigger alarms estimated based on the climate forecast probabilities to invoke water restrictions and other conservation measures and (d) analyses focusing on reducing the demand-driven droughts using proactive water conservation measures and streamflow forecasts. Information from this project will also support other ongoing activities in the Neuse and Cape Fear river basins that includes Triangle Area Water Supply Monitoring Project, Neuse river basin planning program (supported by DENR), National Water Quality Assessment Program (supported by USGS) and NCDMC and State Climate Office (SCO). Analyses from this research will also promote identification of alternate river basin management plans during critical drought conditions that includes conjunctive use, instream flow maintenance and estuaries management. Informative web portal will be developed that summarizes the hydroclimatic predictability of the Neuse and Cape Fear River basins and provides updates on the streamflow potential for the seasons ahead. Potential benefits to other ongoing studies include quantitative representation of uncertainty in streamflows to support TMDL process, development of seasonal water management plans considering conjunctive use for the coastal zone and prediction outlooks for floods and droughts. We envisage that this effort for the triangle region will motivate other basins in NC to follow a prognostic, adaptive and climate-information driven approach towards drought management.

Progress/Completion Report, 2008, PDF
Progress/Completion Report, 2009, PDF

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