What are possible management actions that can address these challenges?

In a situation of water stress

Water stress, indicated by the ratio of withdrawal to availability over a particular period, is high in large parts of northern Africa, southern Africa, western and central Asia, the Indian subcontinent, northern China and Mongolia, Mexico and northern areas of Central America, the western coastal regions of South America as well as some areas of Argentina, Brazil and southern Thailand. (IPCC 2007, UNDP 2007) Here sustained rainfall deficits and increased water demand potentially increase water stress. When measuring water stress, not all aspects of vulnerability are captured, as it does not consider climatic variability. The most vulnerable areas in terms of climate-related water shortages are semi-arid and low-income countries with high annual variations and seasonal concentration of precipitation. Within these areas, people whose access to water supply is linked to rainfall, surface run-off and recharge of water bodies are most vulnerable. Adaptation interventions will consist of the following measures to increase water availability:

• Reduce water waste
• Increase efficiency in agriculture – ‘more crop per drop’
• Save water in domestic use

Measures to achieve these goals include:

• Water pricing (controversial as it may affect poor people’s access to water)
• Seasonal water rationing during times of shortage
• Adapt industrial and agricultural production to reduce water wastage
• Increase capture and storage of surface run-off
• Reuse or recycle wastewater after treatment
• Desalination of salty or brackish water (costly)
• Better use of groundwater resources (risk: siltation)
• Rainwater harvesting

In a situation of water quality risks

Climate change affects water quality. Increases in frequency and severity of storms and floods put water distributions systems at risk of damage. Inadequate drainage systems in many urban areas are likely to fail because of increases in the frequency of intense rainfall events. In lakes and reservoirs, an increase in water temperatures resulting from anthropogenic warming will affect water quality as a result of impacts on water chemistry. Increased temperatures in rivers reduce the oxygen content and therefore the capacity of rivers to purify themselves. Increase in rainfall may result in more nutrients, pathogens and toxins being washed into water bodies. Interventions will focus on reversing water quality effects associated with climate change, such as algal blooms as a result of higher temperatures or contamination because of higher precipitation.

Possible measures are:

• Improvement of drainage systems
• Upgrading or standardizing of wastewater treatment
• Better monitoring
• Special measures during high precipitation seasons

Adaptation interventions in water will require a combination of good practice and long-term measures to address specific climate change driven impacts on resources. (CAP-NET 2009)