1. Water Resources Planning and Management
River Basin Modeling
Water Resources Planning and Management
Daene C. McKinney

2. Water Resources Water at: What to do? Manipulate the hydrologic cycle
Wrong place, wrong quantity, wrong time
What to do?
Manipulate the hydrologic cycle
Build facilities? Remove facilities? Reoperate facilities?
Reservoirs
Canals
Levees
Other infrastructure

3. Scales Time Scales Water management plans Flood management
Consider average conditions within discrete time periods
Weekly, monthly or seasonal
Over a long time horizon
Year, decade, century
Shortest time period
No less than travel time from the upper basin to mouth
For shorter time periods some kind of flow routing required
Flood management
Conditions over much shorter periods
Hours, Days, Week

4. Processes Processes we need to describe: Precipitation Runoff
Infiltration
Percolation
Evapotranspiration
Chemical concentration
Groundwater

5. Data Measurement Reservoir losses Missing data Data sources
Flow conditions
Natural
Present
Unregulated
Regulated
Future
Reservoir losses
Missing data
Precipitation-runoff models
Stochastic streamflow models
Extending and filling in historic records

6. Hydrologic Frequency Analysis
Flow duration curves
Percent of time during which specified flow rates are equaled or exceeded at a given location
Pr{ X > x }

7. Central Asia
Syr Darya
Naryn River

8. Naryn River Annual Flows
Median flow
Min. flow
Glacier melt

9. Naryn River Annual Flows

10. Quantiles X is a continuous RV p-th quantile is xp Median: x50
equally likely to be above as below that value
Examples
Floodplain management - the 100-year flood x0.99
Water quality management
minimum 7-day-average low flow expected once in 10 years
10th percentile of the distribution of the annual minima of the 7-day average flows p xp X
FX(x)

11. Quantiles Observed values, sample of size n
Order statistics (observations ordered by magnitude
Sample estimates of quantiles can be obtained by using

12. Flow Duration Curve P(X>x)= Ranked Year Flow Rank 1-i/(n+1)= x i
1911
10817 1
0.99
6525
1912
11126 2
0.98
7478
1913
11503 3
0.97
8014
1914
11428 4
0.96
8161
1915
10233 5
0.95
8378 …
1997
10343 87
0.06
15062
1998
14511 88
0.05
15242
1999
14557 89
0.04
16504
2000
12614 90
0.03
16675
2001
12615 91
0.02
18754
2002
92=n
0.01
20725

13. Flow Duration Curve
Flow duration curve - Discharge vs % of time flow is equaled or exceeded.
Firm yield is flow that is equaled or exceeded 100% of the time

14. Increase Firm Yield - Add storage
To increase the firm yield of a stream, impoundments are built. Need to develop the storage-yield relationship for a river

15. Simplified Methods Mass curve (Rippl) method
Graphical estimate of storage required to supply given yield
Constructed by summing inflows over period of record and plotting these versus time and comparing to demands
Time interval includes “critical period”
Time over which flows reached a minimum
Causes the greatest drawdown of reservoir

16. Rippl method

17. Rippl Method Qt Rt Accumulated Inflows, Q Capacity K
Accumulated Releases, R

18. Sequent Peak Method

19. Reservoirs Hoover Dam 158 m 35 km3 2,074 MW Toktogul Dam 140 m
Grand Coulee Dam
100 m
11.8 km3
6,809 MW

20. Dams Masonry dams Embankment dams Spillways Arch dams Gravity dams
rock-fill and earth-fill dams
Spillways

21. Reservoir Qt Rt St K

22. Management of a Single Reservoir
2 common tasks of reservoir modeling:
Determine coefficients of functions that describe reservoir characteristics
Determine optimal mode of reservoir operation (storage volumes, elevations and releases) while satisfying downstream water demands

23. Reservoir Operation
Compute optimal operation of reservoir given a series of inflows and downstream water demands
where:
St End storage period t, (L3);
St-1 Beginning storage period t, (L3);
Qt Inflow period t, (L3);
Rt Release period t, (L3);
Dt Demand, (L3); and
K Capacity, (L3)
Smin Dead storage, (L3)

24. Comparison of Average and Dry Conditions

25. Results Storage Input Release Demand t0 15000 t1 13723 426 1700 t2t1
13723
426
1700 t2
12729
399
1388 t3
11762
523
1478 t4
11502
875
1109 t5
12894
2026
595 t6
15838
3626
637 t7
17503
2841
1126 t8
17838
1469
1092 t9
18119
821
511
t10
17839
600
869
t11
17239
458
1050
t12
16172
413
1476

26. Toktogul
Power = 1,200 MW
Height = 140 m
Capacity = 19.5 km3

27. Toktogul on the Naryn River in KyrgyzstanLt At
Evaporation
Toktogul on the Naryn River in Kyrgyzstan
Lt Losses from reservoir
A Surface area of reservoir
et ave. evaporation rate

28. Evaporation Lt At

29. Hydropower Production
Hoover Dam
2,074 MW
158 m
35 km3
Toktogul Dam
1,200 MW
140 m
19.5 km3
Grand Coulee Dam
6,809 MW
100 m
11.8 km3

30. Reservoir with Power Plant
earliest known dam - Jawa, Jordan - 9 m high x1 m wide x 50 m long, 3000 BC
Hoover Dam

31. Reservoir with Power PlantQt Rt St K Et Ht Qt

32. Power Production K Lt St Et Ht Qt Qt = Release (m3/period)
qt = Flow (m3/sec)
Pt = Power (kW)
Et = Energy (kWh)
Ht = Head (m)
e = efficiency (%)
timet = sec in period t Qt K St Et Ht Lt

33. Head vs Storage Relation
Toktogul on the Naryn River in Kyrgyzstan

34. Model Lt St Et Qt Rt K Rt = Release (m3/period)
Dt = Demand for water (m3/period)

35. K Qt Rt St Et Lt
Toktogul Operation