1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. Develop a better understanding of your river basin
#10
Develop a better understanding of your river basin

8. 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

9. 10. Develop a better understanding of your river basin.

10. 10. Develop a better understanding of your river basin.

11. 10. Develop a better understanding of your river basin.

12. 10. Develop a better understanding of your river basin.

13. 10. Develop a better understanding of your river basin.

14. 10. Develop a better understanding of your river basin.

15. 10. Develop a better understanding of your river basin.

16. Evaluate surface water availability#9
Evaluate surface water availability

17. 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?

18. 9. Evaluate surface water availability
How do upstream discharges affect surface water availability?

19. 9. Evaluate surface water availability
How do upstream discharges affect surface water availability?

20. 9. Evaluate surface water availability
How do upstream discharges affect surface water availability?

21. 9. Evaluate surface water availability
How do upstream discharges affect surface water availability?

22. Determine the likelihood of a water shortage#8
Determine the likelihood of a water shortage

23. 8. Determine the likelihood of a water shortage
Average Monthly Flows > 10 CFS 90% of the time
< 10 CFS 10% of the time

24. #7
Test alternative water management strategies, new operating rules, and “what-if” scenarios

25. 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%?

26. 7. Test alternative water management strategies, new operating rules, and “what-if” scenarios

27. 7. Test alternative water management strategies, new operating rules, and “what-if” scenarios

28. Evaluate the impacts of future withdrawals on instream flow needs#6
Evaluate the impacts of future withdrawals on instream flow needs

29. 6. Evaluate the impacts of future withdrawals on instream flow needs

30. 6. Evaluate the impacts of future withdrawals on instream flow needs

31. Evaluate interbasin transfers#5
Evaluate interbasin transfers

32. 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

33. #4
Support development of Drought Management Plans and evaluate the effectiveness of drought mitigation measures

34. 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?

35. 4. Support development of Drought Management Plans and evaluate the effectiveness of drought mitigation measures
Catawba-Wateree basin example (Low Inflow Protocol)

36. 4. Support development of Drought Management Plans and evaluate the effectiveness of drought mitigation measures
Catawba-Wateree basin example (Low Inflow Protocol)

37. 4. Support development of Drought Management Plans and evaluate the effectiveness of drought mitigation measures
Catawba-Wateree basin example (Low Inflow Protocol)

38. Compare managed to natural flows#3
Compare managed to natural flows

39. 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

40. 3. Compare managed flows to natural flows
Pacolet
River

41. 3. Compare managed flows to natural flows

42. Provide a scientific basis to make permitting decisions#2
Provide a scientific basis to make permitting decisions

43. 2. Provide a scientific basis to make permitting decisions

44. Support Basin, Regional and State Water Planning#1
Support Basin, Regional and State Water Planning

45. 1. Support Basin, Regional and State Water Planning
Demand Projections
Basin Planning
State Water Plan

46. 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

47. South Carolina Rural Water Association Annual Conference
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