Resilience in the water sector
In Study Sessions 1 and 4 you read about the limited availability of water in terms of both quantity and quality. By 2025, half of the world’s population will live in water-stressed river basins (World Wildlife Fund, 2015). You have also read about population growth, urbanisation, changing land use and the increasing demand for water for domestic, industrial and agricultural purposes. Climate change will aggravate these growing human pressures on water systems.
Improving resilience in the water sector means developing the adaptive capacity of the system. Countries need to adopt appropriate adaptation measures in their water supply sector that will reduce wastage, promote wise use of fresh water and improve water management practices. These adaptation measures include:
- Efficient use of water resources: ensure effective use and fair sharing of existing resources; develop new water sources and reservoirs; promote efficient use of water by consumers through education and tariff structures; develop water reuse and recycling; develop rainwater harvesting schemes.
- Leakage reduction: ensure that equipment and fittings of the water supply system are properly maintained to reduce the frequency of leakage, and that they are repaired promptly.
- Testing existing technologies for resilience: water and sanitation services should be robust enough to ensure that water quality, water quantity and sanitation systems can be maintained.
- Protecting ecosystem resilience: the impacts of natural disasters and climate change should be monitored to maintain the resilience of water and wetland ecosystems. Ecosystem resilience means that the effects of events like fires or drought do not make fundamental long-lasting changes to biodiversity within the ecosystem.
- Flexible management approaches: decision makers need to be able to adapt to the full range of climate scenarios and the demands they generate.
Following these principles for adaptation will help to ensure that increasing problems of water stress can be managed appropriately and that the water sector improves its resilience to future change. Many of these measures are about the sustainable use of water and require changes to the way water resources are managed. We will now look at three examples of water management practices that will help improve resilience: water conservation, water reuse and catchment management.
Water conservation covers a broad range of activities from using less water at home to national policies to protect freshwater ecosystems. Its purpose is to manage water sustainably by using less or using it more efficiently so that present and future needs of people and the environment can be met.
Freshwater conservation efforts are designed to protect and restore biodiversity in water and wetland ecosystems and the ecosystem services they provide. Ecosystem services are the benefits that people obtain from these systems, such as the provision of drinking water and food. Freshwater ecosystems support 12% of known species, while they account for only 1% of the Earth’s surface (Gleick, 2012). They include rivers, ponds, lakes, marshes, bogs and swamps, but they are becoming increasingly rare. Wetlands are also important carbon sinks but they are often drained to support agriculture or for human settlement.
An example of water conservation in agriculture is the use of drip-feed irrigation, which provides water directly to the soil near the roots of the growing crops (Figure 12.1). It requires a great deal less water than conventional methods of flood or spray irrigation in which much of the water is lost by evaporation. By using less water, the volume taken from rivers is reduced which helps to maintain the river ecosystem.
Other examples of water conservation from agriculture include changing the variety of crop that is grown to those that require less water and are more drought-resistant. Changing techniques for planting can also reduce water use, for example, creating a small hollow around the stem of a plant can ensure that water seeps into the ground close to the roots rather than running off over the surface.
Wastewater recycling will become an increasingly important source of new water resources. It means finding ways to use water more than once. Recycled water can be used to recharge groundwater aquifers, supply industrial processes, irrigate certain crops and supplement domestic supplies. Recycling helps provide usable water and reduces pollution of existing supplies. Many industrial and domestic processes do not require water of drinking standard. For example, water for flushing toilets does not need to be of the same quality as drinking water. There has been a significant increase in the availability and use of treated wastewater for a wide range of applications in different parts of the world and this is an area that is likely to grow.
In the past, responsibility for management of water resources has often been divided among several different agencies or administrative departments. For example, responsibility for providing water supply for domestic users would be entirely separate from water for irrigation, even though they would both be using the same resource. This lack of coordination creates problems because it does not recognise the processes and connections of the water cycle or the links between the various parts of the water resource system.
To overcome this problem, the natural boundaries of the water catchment should be recognised. The catchment area, also known as the watershed, of a river is the total area of surrounding land that slopes towards the river. Rainwater that falls in a catchment flows into the river and is therefore affected by the type of land over which it flows. Water can be contaminated by pollution sources in the catchment even though they may be some distance away. Adopting an integrated catchment management approachmeans that these connections are take into account. Integrated catchment management involves both water use and land use within the catchment area. It recognises the connections between water quality and water quantity and those between surface water and groundwater. Importantly, the needs of the environment are also taken into account. This integrated approach can improve resilience because understanding the connections within a system helps managers to predict impacts and identify strategies for coping with change.