Ten Reasons to Use South Carolina’s Surface Water Quantity Models John Boyer, PE, BCEE September 14, 2016 2016 South Carolina Rural Water Association Annual Conference
Types of Water Quantity Models Preface Types of Water Quantity Models Precipitation-Runoff Models Convert rainfall volume into runoff Example: HEC-HMS Hydraulic Models Characterize the flow and routing of water in the river system Example: HEC-RAS The focus of this presentation is on Water Allocation Models Water Allocation Models Calculate legally and/or physically available water in a river system Examples: OASIS, CHEOPS, RiverWare and SWAM
Simplified Water Allocation Model (SWAM) Preface Simplified Water Allocation Model (SWAM) Developed in response to an increasing need for a desktop tool to facilitate regional and statewide water allocation analysis Calculates physically and legally available water, diversions, storage, consumption and return flows at user-defined nodes
Simplified Water Allocation Model (SWAM) Preface Simplified Water Allocation Model (SWAM) Object-oriented tool Resides within Microsoft Excel Point and click setup and output access Objects Tributaries Discharges Reservoirs Municipal Industrial Golf Courses Power Plants Agriculture Instream Flow Recreational Pool Aquifer USGS Gage Interbasin Transfer Input Forms Water User Objects
Model Access and Training Preface Model Access and Training Training will be offered once all eight models are complete Models will reside in the cloud (hosted virtual desktop) Consistent user experience Facilitates model improvements and updates Secure Users requesting access will be given their own account with designated storage
Ten reasons to use south Carolina’s surface water quantity models South Carolina Rural Water Conference Ten reasons to use south Carolina’s surface water quantity models
Develop a better understanding of your river basin #10 Develop a better understanding of your river basin
10. Develop a better understanding of your river basin. Streamflow & Unimpaired Flow CONSOLIDATED DATA MODEL Withdrawals/ Demand Discharges/ Return Flow Reservoir Levels/ Bathymetry/ Rule Curves/ Operating Rules/ Evaporation/ Precipitation
10. Develop a better understanding of your river basin.
10. Develop a better understanding of your river basin.
10. Develop a better understanding of your river basin.
10. Develop a better understanding of your river basin.
10. Develop a better understanding of your river basin.
10. Develop a better understanding of your river basin.
10. Develop a better understanding of your river basin.
Evaluate surface water availability #9 Evaluate surface water availability
9. Evaluate surface water availability How much surface water is available on the main branch, major tributaries, and minor tributaries? How much water is available for instream uses? How much water is available in the growing season? How much water is available during a drought? How does a reservoir affect surface water availability? How do upstream discharges affect surface water availability?
9. Evaluate surface water availability How do upstream discharges affect surface water availability?
9. Evaluate surface water availability How do upstream discharges affect surface water availability?
9. Evaluate surface water availability How do upstream discharges affect surface water availability?
9. Evaluate surface water availability How do upstream discharges affect surface water availability?
Determine the likelihood of a water shortage #8 Determine the likelihood of a water shortage
8. Determine the likelihood of a water shortage Average Monthly Flows > 10 CFS 90% of the time < 10 CFS 10% of the time
#7 Test alternative water management strategies, new operating rules, and “what-if” scenarios
7. Test alternative water management strategies, new operating rules, and “what-if” scenarios Does intake #1 provide a more reliable supply than intake #2? How will an increased minimum flow release impact reservoir levels during the summer? What if water supply demand throughout the basin increased by 40%?
7. Test alternative water management strategies, new operating rules, and “what-if” scenarios
7. Test alternative water management strategies, new operating rules, and “what-if” scenarios
Evaluate the impacts of future withdrawals on instream flow needs #6 Evaluate the impacts of future withdrawals on instream flow needs
6. Evaluate the impacts of future withdrawals on instream flow needs
6. Evaluate the impacts of future withdrawals on instream flow needs
Evaluate interbasin transfers #5 Evaluate interbasin transfers
5. Evaluate interbasin transfers 30 MGD Examples: Greenville Water’s export from the Savannah and the Saluda to the Broad Aiken Export from the Edisto to the Savannah Charleston Water System Export from Edisto to the Santee
#4 Support development of Drought Management Plans and evaluate the effectiveness of drought mitigation measures
4. Support development of Drought Management Plans and evaluate the effectiveness of drought mitigation measures What are appropriate reductions in water use given moderate, severe, and extreme drought conditions? What is the cumulative response in the river system if water use reduction goals are achieved by all users?
4. Support development of Drought Management Plans and evaluate the effectiveness of drought mitigation measures Catawba-Wateree basin example (Low Inflow Protocol)
4. Support development of Drought Management Plans and evaluate the effectiveness of drought mitigation measures Catawba-Wateree basin example (Low Inflow Protocol)
4. Support development of Drought Management Plans and evaluate the effectiveness of drought mitigation measures Catawba-Wateree basin example (Low Inflow Protocol)
Compare managed to natural flows #3 Compare managed to natural flows
3. Compare managed flows to natural flows Help understand cumulative impact of withdrawals, discharges, impoundments, and flow regulation Help understand the natural variability in flow within the system, which can be important in maintaining healthy aquatic ecosystems Source: The Natural Flow Regime. N. Leroy Poff et al. Bioscience, Vol 47, No. 11
3. Compare managed flows to natural flows Pacolet River
3. Compare managed flows to natural flows
Provide a scientific basis to make permitting decisions #2 Provide a scientific basis to make permitting decisions
2. Provide a scientific basis to make permitting decisions
Support Basin, Regional and State Water Planning #1 Support Basin, Regional and State Water Planning
1. Support Basin, Regional and State Water Planning Demand Projections Basin Planning State Water Plan
Models Will Always Have Limitations Models can’t incorporate all of the details of a river system Models must use approximations Water allocation models assume stationarity - the past is statistically the same as the future Models can be made more accurate, but at the expense of simplicity A good model is both as accurate as possible and as simple as possible
South Carolina Rural Water Association Annual Conference THANK YOU