| Table 4-13: Supply-side and demand-side adaptive
options: some examples. |
 |
|
Supply-Side
|
|
Demand-Side
|
|
Option
|
Comments
|
Option
|
Comments
|
|
| Municipal water supply |
|
|
|
|
| – Increase reservoir capacity
– Extract more from rivers or groundwater
– Alter system operating rules
– Inter-basin transfer
– Desalination
– Seasonal forecasting
|
Expensive; potential
environmantal impact
– Potential environmental impact
– Possibly limited opportunity
– Expensive; potential
environmental impact
– Expensive (high energy use)
– Increasingly feasible
|
|
– Incentives to use less (e.g., through pricing)
– Legally enforceable water use standards (e.g., for appliances)
– Increase use of grey water
– Reduce leakage
– Development of non-water-based sanitation systems
|
Possibly limited opportunity; needs institutional framework
– Potential political impact; usually cost-inefficient
– Potentially expensive
– Potentially expensive to reduce to very low levels, especially in
old systems
– Possibly too technically advanced for wide application
|
|
|
|
| Irrigation |
|
|
|
|
| – Increase irrigation source capacity |
– Expensive; potential
environmental impact |
|
– Increase irrigation-use
efficiency
– Increase drought-toleration
– Change crop patterns
|
– By technology or through increasing prices
– Genetic engineering is
controversial
– Move to crops that need less or no irrigation |
|
|
|
Industrial and
power station cooling |
|
|
|
|
– Increase source capacity
– Use of low-grade water |
– Expensive
– Increasingly used |
|
– Increase water-use efficiency and water recycling |
– Possibly expensive to upgrade |
|
|
|
Hydropower generation
|
|
|
|
|
| – Increase reservoir capacity |
– Expensive; potential
environmental impact
– May not be feasible |
|
– Increase efficiency of
turbines; encourage energy efficiency |
– Possibly expensive to upgrade |
|
|
|
| Navigation |
|
|
|
|
| – Build weirs and locks |
– Expensive; potential
environmental impact
– Potential environmental impact
|
|
– Alter ship size and
frequency |
– Smaller ships (more trips, thus increased costs and emissions) |
|
|
|
| Pollution control |
|
|
|
|
| – Enhance treatment works |
– Potentially expensive |
|
– Reduce volume of effluents to treat (e.g., by charging discharges)
– Catchment management to reduce polluting runoff |
– Requires management of diffuse sources of pollution |
|
|
|
| Flood management |
|
|
|
|
– Increase flood protection (levees, reservoirs)
– Catchment source control to reduce peak discharges |
– Expensive; potential
environmental impact
– Most effective for small floods |
|
– Improve flood warning and dissemination
– Curb floodplain
development
|
– Technical limitations in flash-flood areas, and unknown effectiveness
– Potential major political problems |
|
Most of these strategies are being adopted or considered in many countries
in the face of increasing demands for water resources or protection against
risk. In the UK, for example, water supply companies currently are pursuing
the “twin track” of demand management and supply management in response
to potential increases in demand for water (although there is a conflict between
different parts of the water management system over the relative speeds with
which the two tracks should be followed). These management strategies also are
potentially feasible in the face of climate change. Nowhere, however, are water
management actions being taken explicitly and solely to cope with climate change,
although in an increasing number of countries climate change is being considered
in assessing future resource management. In the UK, for example, climate change
is one of the factors that must be considered by water supply companies in assessing
their future resource requirements—although companies are highly unlikely
to have new resources justified at present on climate change alone.
The continuing debate in water management (Easter et al., 1998) is between
the practicalities and costs of supply-side versus demand-side options, and
this debate is being pursued indepedently of climate change. The tide is moving
toward the use of demand-side options because they are regarded as being more
environmentally sustainable, cost-effective, and flexible (Frederick, 1986;
World Bank, 1993; Young et al., 1994; Anderson and Hill, 1997). “Smart”
combinations of supply-side and demand-side approaches are needed, although
in many cases new supply-side infrastructure may be necessary. This is particularly
the case in developing countries, where the challenge often is not to curb demand
but to meet minimum human health-driven standards.
There do appear, however, to be numerous “no regret” policies that
warrant immediate attention. In this context, a “no regret” policy
is one that would generate net social benefits regardless of whether there was
climate change. Examples include elimination of subsidies to agriculture and
floodplain occupancy and explicit recognition of environmental values in project
design and evaluation. The effect of successful demand-side policies is to reduce
the need for supply augmentation, although they may not prevent such needs entirely
if changes are large. Such policy changes represent the minimum package of “anticipatory
policy changes” in response to climate change.
