3.6.4 Limits to adaptation and adaptive capacity

Adaptation in the water sector involves measures to alter hydrological characteristics to suit human demands, and measures to alter demands to fit conditions of water availability. It is possible to identify four different types of limits on adaptation to changes in water quantity and quality (Arnell and Delaney, 2006).

• The first is a physical limit: it may not be possible to prevent adverse effects through technical or institutional procedures. For example, it may be impossible to reduce demands for water further without seriously threatening health or livelihoods, it may physically be very difficult to react to the water quality problems associated with higher water temperatures, and in the extreme case it will be impossible to adapt where rivers dry up completely.
• Second, whilst it may be physically feasible to adapt, there may be economic constraints to what is affordable.
• Third, there may be political or social limits to the implementation of adaptation measures. In many countries, for example, it is difficult for water supply agencies to construct new reservoirs, and it may be politically very difficult to adapt to reduced reliability of supplies by reducing standards of service.
• Finally, the capacity of water management agencies and the water management system as a whole may act as a limit on which adaptation measures (if any) can be implemented. The low priority given to water management, lack of coordination between agencies, tensions between national, regional and local scales, ineffective water governance and uncertainty over future climate change impacts constrain the ability of organisations to adapt to changes in water supply and flood risk (Ivey et al., 2004; Naess et al., 2005; Crabbe and Robin, 2006).

These factors together influence the adaptive capacity of water-management systems as well as other determinants such as sensitivities to change, internal characteristics of the system (e.g., education and access to knowledge) and external conditions such as the role of regulation or the market.