CIRED laboratory
HYPATIA NASSOPOULOS, PATRICE DUMAS, STEPHANE HALLEGATTE
CLIMATE CHANGE, PRECIPITATIONS AND WATER MANAGEMENT
INFRASTRUCTURES
Water in Africa:
Hydro-Pessimism or Hydro-Optimism?
CEAUP, 2-3 October, Porto Portugal
1

Mediterranean r.+ CC + Water = ?
7% world’s population
3% world’s water resources,
temporal and spatial variability
Climate change: change in
precipitation patterns, decrease
2

Climate change and Hydraulic infrastructures
Present: stationary climate without taking into consideration climate change
When variability increases, increasing dam and reservoir dimensions allows to
capture more inter-annual variability until all is captured
How to keep a satisfactory level of reliability by optimizing the available resources?
Small mountainous catchments in Algeria and Greece
Sensitivity analysis of climate model choice on the hydraulic infrastructure’s
Optimal Dimension
Cost Benefit Analysis of different dam heights under climate change optimal
storage capacity
3

Simulation of dam operation
Simulate inflows under different constant precipitation and temperature
changes by using local run-off monthly coefficients
Simulate dam operations (monthly) using simple rules:
Serve fixed demand
Overflow when inflow exceeds storage capacity
If available water less than demand, consider that demand can not be
reliably satisfied
Compute demand at 95% reliability for different inflow changes
4

Inflow and demand under climate change
IPCC models output under A2 scenario linear trends of
precipitation change
Hypothesis of demand adapting to the available resources
Each year the annual demand at 95% reliability for this inflow
change is used
5

Investment decision, Cost Benefit Analysis
Cost: Rock fill dam, trapezoidal section, local height/volume geometry
Benefits:
Dt Demand at 95% reliability with climate change as computed previously
Water price per m3 p
Discount rate ρ
NPV= (∑(1/(1+ρ))t p Dt 0.95)-Cost
For each IPCC model, demand at a fixed level of reliability,water price
and discount rate, we find the storage capacity which maximises the NPV
6

Results
7

Results
8

Results
9

Results
10

Conclusions
Optimal storage capacity increases with increasing
precipitations
Optimal storage capacity increases with increasing variability
For the 12 models precipitation and variability are correlated
Wide range of optimal storage capacity
11

obrigada!
12