1 Introduction
-
Calibrate, verify and validate a HYSIM rainfall-runoff model for the Pong catchment;
-
Use the validated HYSIM model to simulate the historic runoff using the historic climate data;
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Derive optimized basic rule curves for the Pong using coupled SPA-GA approach
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Derive optimized hedging (trigger and rationing ratio) policy using GA for integration with the basic rule curves;
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Derive scenario-neutral future climate by applying reasonable delta perturbations to the rainfall and temperature; hence simulate climate-change induced runoff using HYSIM;
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Carry out reservoir behaviour simulations to assess the reliability, vulnerability, resilience and sustainability indices for the Pong with the simulated historic and climate change perturbed hydrology and make recommendations.
2 Methodology
2.1 Derivation of Basic Rule Curves
2.1.1 Sequent Peak Algorithm (SPA) Generation of Basic Curves
2.1.2 GA Optimisation of Rule Curves
2.2 Hedging Policy
2.3 Reservoir Behaviour Simulation and Performance Indices
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Reliability: this can be expressed either in the time-domain, R t (proportion of the total time period during which a reservoir can meet the target demand) or volume domain, R v (proportion of the total demand (volume) actually supplied) as follows:$$ {R}_t={N}_s/N $$(11)where N s is the total number of intervals (months) out of N (months) that the demand was met.$$ {R}_v={\displaystyle \sum_{t=1}^N{D}_t^{\prime }}/{\displaystyle \sum_{t=1}^N{D}_t} $$(12)
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Resilience: Resilience is a measure of the reservoir’s ability to recover from failure and the most widely used definition of resilience is due to Hashimoto et al. (1982):where φ is resilience, f s is number of continuous sequences of failure periods and f d is the total duration of the failures, i.e., f d = N - N s .$$ \begin{array}{ll}\varphi =1/\left({f}_d/{f}_s\right)={f}_s/{f}_d;\hfill & 0<\varphi \le 1\hfill \end{array} $$(13)
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Vulnerability: The definition of vulnerability used here is due to Sandoval-Soils et al. (2011) and is the average period shortfall as a ratio of the average period demand, i.e.,:where η is vulnerability (dimensionless) and all other terms are as defined previously.$$ \eta ={\displaystyle \sum_{t=1}^{f_d}\left[\left({D}_t-{D}_t^{\prime}\right)/{D}_t\right]}/{f}_d;t\in {f}_d $$(14)
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Sustainability: A sustainability index that integrates the three earlier defined indices was used (Sandoval-Soils et al. 2011):where λ1 is the sustainability. Because R v , unlike R t , is less likely to be dramatically affected by water scarcity, an alternative definition of sustainability index (λ2) using R v instead of R t was also explored, i.e.,:$$ {\lambda}_1={\left({R}_t\varphi \left(1-\eta \right)\right)}^{1/3} $$(15)$$ {\lambda}_2={\left({R}_v\varphi \left(1-\eta \right)\right)}^{1/3} $$(16)
2.4 HYSIM Rainfall-Runoff Modelling
Parameters | Sub-catchment | ||
---|---|---|---|
Upper | Middle | Lower | |
Channel roughness | 0.03 | 0.03 | 0.03 |
Reach gradient | 0.035 | 0.007 | 0.0025 |
Flood plain roughness | 0.10 | 0.10 | 0.10 |
3 Case Study & Data
Indices | Sub-catchment | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Upper | Middle | Lower | ||||||||||
Rainfall, mm/day | ETo, mm/day | Temperature, °C | Rainfall, mm/day | ETo, mm/day | Temperature, °C | Rainfall, mm/day | ETo, mm/day | Temperature, °C | ||||
Max. | Min. | Max. | Min. | Max. | Min. | |||||||
Mean | 2.77 | 1.97 | 10.85 | −1.42 | 3.76 | 4.62 | 26.12 | 13.40 | 4.12 | 6.58 | 32.78 | 18.45 |
Maximum | 96.44 | 6.31 | 25.75 | 12.24 | 119.44 | 9.70 | 40.03 | 25.74 | 136.83 | 15.92 | 50.30 | 33.16 |
Minimum | 0.00 | 0.27 | −6.31 | −23.07 | 0.00 | 0.53 | 6.87 | −1.24 | 0.00 | 0.73 | 10.71 | −3.05 |
Standard deviation | 6.69 | 1.03 | 6.31 | 6.32 | 9.00 | 1.80 | 6.59 | 5.81 | 10.04 | 2.65 | 7.77 | 7.62 |
5th percentile | 0.38 | 1.79 | −0.33 | −11.91 | 0.22 | 4.40 | 14.89 | 3.62 | 0.20 | 6.23 | 20.14 | 5.28 |
95th percentile | 13.83 | 3.87 | 19.51 | 7.51 | 19.28 | 7.94 | 35.42 | 21.60 | 23.19 | 11.36 | 44.46 | 28.56 |
4 Results and Discussion
4.1 1Hysim Calibration
4.2 Rule Curves and Hedging Policy
4.3 Simulated Performance for the Pong Reservoir Under Current Conditions
Policy | Total period demand (Mm3) | Total period release (Mm3) | Total period deficit (Mm3) | Max. single period deficit (Mm3) |
f
d
|
f
s
|
φ (Eq. 13) |
η (Eq. 14) | ||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
H0 | 55384.10 | 51817.06 | 3567.04 | 606.91 (0.686)a
| 13 | 5 | 88.0 | 93.6 | 0.385 | 0.606 | 0.508 | 0.519 |
H1 | 55384.10 | 49842.61 | 5541.49 | 392.12 (0.74)a
| 58 | 10 | 46.3 | 90.0 | 0.172 | 0.200 | 0.400 | 0.499 |
4.4 Climate Change Effects on Runoff and Reservoir Performance
4.4.1 Effects on Runoff
Temperature change, °C | Annual rainfall change, % | ||||
---|---|---|---|---|---|
−10 | −5 | 0 | +5 | +10 | |
Annual | |||||
0 | −12.11 | −6.25 | 0.00 | 6.70 | 13.77 |
1 | −7.08 | −1.63 | 4.17 | 10.21 | 16.44 |
2 | 6.98 | 12.41 | 18.19 | 24.27 | 30.51 |
Season: winter (December–February) | |||||
0 | −13.25 | −6.82 | 0.00 | 7.77 | 16.40 |
1 | −18.32 | −13.55 | −8.19 | −2.36 | 3.81 |
2 | −5.90 | −1.23 | 4.00 | 9.75 | 15.83 |
Season: post-monsoon (September to November) | |||||
0 | −10.80 | −5.54 | 0.00 | 5.83 | 11.93 |
1 | −7.60 | −2.80 | 2.30 | 7.54 | 12.81 |
2 | 6.88 | 11.63 | 16.71 | 21.99 | 27.29 |
Season: monsoon (June to August) | |||||
0 | −12.29 | −6.35 | 0.00 | 6.76 | 13.85 |
1 | −4.74 | 1.03 | 7.13 | 13.48 | 20.03 |
2 | 9.25 | 15.01 | 21.07 | 27.42 | 33.96 |
Season: pre-monsoon (March–May) | |||||
0 | −15.09 | −7.92 | 0.00 | 8.89 | 18.82 |
1 | −17.76 | −12.05 | −5.72 | 1.09 | 8.29 |
2 | −2.96 | 3.03 | 9.70 | 16.94 | 24.58 |
4.4.2 Effects on Reservoir Performance
Temp. change, °C | Rainfall change, % | Total period release (Mm3) | Total period deficit (Mm3) | Max. single period deficit (Mm3) |
f
d
|
f
s
|
R
t, (%) |
R
v
(%) |
φ
| η |
λ
1
|
λ
2
|
---|---|---|---|---|---|---|---|---|---|---|---|---|
0 | −10 | 48985.82 | 6398.28 | 642.74 | 20 | 6 | 81.5 | 88.4 | 0.300 | 0.656 | 0.438 | 0.450 |
(47504.75)
|
(7879.35)
|
(642.74)
|
(63)
|
(9)
|
(41.7)
|
(85.8)
|
(0.143)
|
(0.266)
|
(0.352)
|
(0.448)
| ||
−5 | 50527.22 | 4856.88 | 625.72 | 17 | 5 | 84.3 | 91.2 | 0.294 | 0.612 | 0.458 | 0.470 | |
(48830.63)
|
(6553.47)
|
(437.25)
|
(61)
|
(9)
|
(43.5)
|
(88.2)
|
(0.148)
|
(0.228)
|
(0.368)
|
(0.465)
| ||
0 | 51817.06 | 3567.04 | 606.91 | 13 | 5 | 88.0 | 93.6 | 0.385 | 0.606 | 0.511 | 0.522 | |
(49842.61)
|
(5541.49)
|
(392.12)
|
(58)
|
(10)
|
(46.3)
|
(90.0)
|
(0.172)
|
(0.200)
|
(0.399)
|
(0.498)
| ||
+5 | 52640.85 | 2743.25 | 586.10 | 10 | 4 | 90.7 | 95.0 | 0.400 | 0.547 | 0.548 | 0.556 | |
(50483.34)
|
(4900.76)
|
(320.50)
|
(54)
|
(11)
|
(50.0)
|
(91.2)
|
(0.204)
|
(0.193)
|
(0.435)
|
(0.531)
| ||
+10 | 52989.01 | 2395.09 | 564.23 | 10 | 4 | 90.7 | 95.7 | 0.400 | 0.493 | 0.569 | 0.579 | |
(51010.45)
|
(4373.64)
|
(228.41)
|
(48)
|
(10)
|
(55.6)
|
(92.1)
|
(0.208)
|
(0.181)
|
(0.456)
|
(0.539)
| ||
1 | −10 | 50045.58 | 5338.52 | 622.56 | 19 | 7 | 82.4 | 90.4 | 0.368 | 0.601 | 0.495 | 0.510 |
(48692.00)
|
(6692.10)
|
(399.05)
|
(64)
|
(9)
|
(40.7)
|
(87.9)
|
(0.141)
|
(0.227)
|
(0.354)
|
(0.458)
| ||
−5 | 51103.73 | 4280.37 | 607.08 | 17 | 6 | 84.3 | 92.3 | 0.353 | 0.582 | 0.499 | 0.514 | |
(49203.40)
|
(6180.70)
|
(391.76)
|
(63)
|
(9)
|
(41.7)
|
(88.8)
|
(0.143)
|
(0.205)
|
(0.362)
|
(0.466)
| ||
0 | 51961.39 | 3422.71 | 590.84 | 12 | 5 | 88.9 | 93.8 | 0.417 | 0.579 | 0.538 | 0.548 | |
(49679.29)
|
(5704.81)
|
(384.58)
|
(58)
|
(10)
|
(46.3)
|
(89.7)
|
(0.172)
|
(0.204)
|
(0.399)
|
(0.497)
| ||
+5 | 52356.35 | 3027.75 | 573.74 | 10 | 4 | 90.7 | 94.5 | 0.400 | 0.542 | 0.550 | 0.557 | |
(50010.58)
|
(5373.52)
|
(346.66)
|
(56)
|
(10)
|
(48.1)
|
(90.3)
|
(0.179)
|
(0.198)
|
(0.410)
|
(0.506)
| ||
+10 | 52619.77 | 2764.33 | 555.13 | 10 | 4 | 90.7 | 95.0 | 0.400 | 0.484 | 0.572 | 0.581 | |
(50532.90)
|
(4851.20)
|
(274.43)
|
(52)
|
(9)
|
(51.9)
|
(91.2)
|
(0.173)
|
(0.187)
|
(0.418)
|
(0.505)
| ||
2 | −10 | 52619.64 | 2764.46 | 519.99 | 10 | 4 | 90.7 | 95.0 | 0.400 | 0.543 | 0.549 | 0.558 |
(50454.57)
|
(4929.53)
|
(316.57)
|
(54)
|
(12)
|
(50.0)
|
(91.1)
|
(0.222)
|
(0.182)
|
(0.449)
|
(0.549)
| ||
−5 | 52830.79 | 2553.31 | 504.73 | 10 | 4 | 90.7 | 95.4 | 0.400 | 0.508 | 0.563 | 0.573 | |
(50829.99)
|
(4554.11)
|
(264.35)
|
(51)
|
(11)
|
(52.8)
|
(91.8)
|
(0.216)
|
(0.176)
|
(0.455)
|
(0.547)
| ||
0 | 53068.58 | 2315.52 | 487.58 | 10 | 4 | 90.7 | 95.8 | 0.400 | 0.475 | 0.575 | 0.586 | |
(51105.46)
|
(4278.63)
|
(203.46)
|
(48)
|
(11)
|
(55.6)
|
(92.3)
|
(0.229)
|
(0.175)
|
(0.472)
|
(0.559)
| ||
+5 | 53327.8 | 2056.3 | 468.3 | 9 | 4 | 91.7 | 96.3 | 0.444 | 0.474 | 0.598 | 0.608 | |
(51372.68)
|
(4011.42)
|
(164.76)
|
(46)
|
(10)
|
(57.4)
|
(92.8)
|
(0.217)
|
(0.175)
|
(0.468)
|
(0.550)
| ||
+10 | 53606.96 | 1777.14 | 446.38 | 8 | 4 | 92.6 | 96.8 | 0.500 | 0.472 | 0.625 | 0.635 | |
(51686.03)
|
(3698.07)
|
(164.76)
|
(43)
|
(10)
|
(60.2)
|
(93.3)
|
(0.233)
|
(0.171)
|
(0.488)
|
(0.565)
|