Cost Benefit Analysis of an Agricultural Adaptation (Irrigation) to Climate Change
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Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Cost Benefit Analysis of an Agricultural Adaptation (Irrigation) to Climate Change
Agha Akram Yale University
The views expressed are those of the presenter and should not be attributed to either UNDP or USAID. Furthermore, it is strongly recommended that both the PowerPoint slides and the videos of the presentation of content included herein are viewed in conjunction in order that statements appearing in the PowerPoint slides are not interpreted out of context.
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
“The prices of staple foods are at near historic lows, and stockpiles are adequate. This is a situation that would be inconceivable without the last half-century's investments in irrigation.”
“Irrigation is the largest recipient of public agricultural investment in the developing world.”
(World Bank (1995)
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Irrigation as an Adaptation to Climate Change
Climate change affects temperature and precipitation among other climate phenomena.
Changes in the hydrological cycle will be some of the most obvious changes that will affect agriculture.
Irrigation systems are a way to adapt to changes in the hydrologic cycle (especially changes in the quantity and timing of precipitation).
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Cost Benefit Analysis
Determine the cost of implementing a project and the benefits it accrues.
Often, benefits (and sometimes costs) arrive over a period of time (“stream of benefits”).
Difficult but useful to consider externalities – we must account for the complete set of costs and benefits including costs not in the budget and impacts not paid for in the market.
- this can be difficult; might require non-market valuation techniques.
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Senegal Irrigation Project
Nianga Irrigation Pilot Project (NIPP).
Life-span of about 30 years.
One of the analyses of this project provided a very clear schedule of costs and benefits.
Measured in thousands of 1975 CFA Francs (Senegalese currency)* Weiler, Edward M. and Wallace E. Tyner (1981). Social Cost-Benefit Analysis of the Nianga Irrigation Pilot Project, Senegal. The Journal of Developing Areas , Vol. 15, No. 4 (Jul., 1981), pp. 655-670.
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Cost and Benefit Stream of NIPP
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Should we go ahead with this project?
We need to determine if the total benefits exceed the total costs.
If benefits > costs then the project is worth doing.
However, need to think through a small but important issue: discounting.
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Discounting the Future
We need to convert future values into a present value.
To do this we discount the future back to the present.
Why? Because: money today is worth more than money tomorrow.
The discount rate is a product of society’s time value of money (composed of the pure rate of time preference and the goods
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Present Value
Use this formula to convert all future values to present values:
PV = FVt/(1 + r)t
Where PV is present value, FV is future value, r is the discount rate and t is time.
Using this we see the following stream of benefits and costs for NIPP…
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Result
Year Period
Total Agricultural
Benefits Total Cost
Benefits without Project
Net Benefits
Discount Rate PV(TB) 5% PV(TC) 5%
BC Ratio
1973 0 0.0 31,320.7 7,248.0 -38,568.7 0.05 0.0 31320.7 .
1974 1 0.0 354,174.0 7,248.0 -361,422.0 0.05 0.0 337308.571 .
1975 2 43,781.3 512,089.9 7,248.0 -475,556.6 0.05 39710.9 464480.635 .
1976 3 157,552.7 124,573.8 7,248.0 25,730.9 0.05 136099.9 107611.532 .
1977 4 164,809.6 144,853.9 7,248.0 12,707.7 0.05 135589.3 119171.662 .
… … … …. … …. … … … …
1998 25 215,364.2 113,642.0 7,248.0 94,474.2 0.05 63597.6 33558.7976 .
1999 26 215,364.2 113,642.0 7,248.0 94,474.2 0.05 60569.2 31960.7596 .
2000 27 215,364.2 113,642.0 7,248.0 94,474.2 0.05 57684.9 30438.8187 .
2001 28 215,364.2 113,642.0 7,248.0 94,474.2 0.05 54938.0 28989.3511 .
2002 29 215,364.2 113,642.0 7,248.0 94,474.2 0.05 52321.9 27608.9058 .
Sum: 2,746,329.56 2,490,685.93 1.10
PV of TB: 2,746,329.56PV of TC: 2,490,685.93BC Ratio: 1.10
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Graph over Time: No Discounting and Discounting
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Agricultural Productivity and Climate Change
Benefits in NIPP are those of agricultural output (rice and tomatoes)
What if future climate change reduces the possible output?
This will require careful study – farmers may adapt their crop and input choice to a changed climate.
For the moment, let’s make some simple assumptions:
50% chance that climate change induces a 25% decline in agricultural revenues per year.
50% chance that climate change induces a 25% increase in agricultural revenues per year.This change comes about in the 15th year of the project.
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Graph over Time: High, Low and Expected Benefits with Climate Damages
Result: E(B)/C = 1.10264 But,
BH/C = 1.226883
BL/C = 0.978396
Capacity Building Programme on the Economics of AdaptationSupporting National/Sub-National Adaptation Planning and Action
Scenario: High Benefits with Climate Damages
Result: BH/C = 1.35