How can you manage water resources in a changing climate?

1 Water cycle and climate change

The water cycle is the continuous movement of water between the atmosphere, land, and oceans. It is driven by solar energy and influenced by gravity, topography, vegetation, and human activities. Climate change affects the water cycle by altering the patterns and intensity of precipitation, evaporation, and runoff. This can result in more frequent and severe floods and droughts, as well as changes in water quality and availability.

2 Water balance and demand

The water balance is the relationship between the inputs and outputs of water in a given area over a given period. It can be expressed as a simple equation: P = Q + ET + ΔS, where P is precipitation, Q is runoff, ET is evapotranspiration, and ΔS is change in storage. The water balance helps you assess the availability and sustainability of water resources in a given location. The water demand is the amount of water needed or desired by various users, such as domestic, agricultural, industrial, and environmental. The water demand depends on factors such as population, consumption patterns, technology, and regulations.

3 Water supply and distribution

The water supply is the source and quantity of water that can be accessed and delivered to meet the water demand. The water supply can be surface water (such as rivers, lakes, and reservoirs), groundwater (such as aquifers and wells), or non-conventional sources (such as desalination, rainwater harvesting, and wastewater reuse). The water distribution is the system of pipes, pumps, valves, meters, and other infrastructure that transports water from the supply to the users. The water distribution system must be designed and operated to ensure adequate pressure, flow, and quality of water.

4 Water quality and treatment

The water quality is the physical, chemical, and biological characteristics of water that affect its suitability for different uses. The water quality can be affected by natural processes (such as weathering, erosion, and biodegradation) and human activities (such as agriculture, industry, and urbanization). The water quality can be measured by various indicators, such as pH, turbidity, dissolved oxygen, nutrients, and pathogens. The water treatment is the process of removing or reducing the contaminants and improving the aesthetic properties of water. The water treatment can be physical (such as filtration, sedimentation, and aeration), chemical (such as coagulation, disinfection, and softening), or biological (such as activated sludge, trickling filters, and wetlands).

5 Water conservation and efficiency

The water conservation is the practice of using water wisely and reducing wastage and losses. The water conservation can be achieved by behavioral changes (such as fixing leaks, installing low-flow fixtures, and watering plants efficiently) and technological innovations (such as smart meters, drip irrigation, and water recycling). The water efficiency is the ratio of water output to water input for a given activity or process. The water efficiency can be improved by optimizing the design, operation, and maintenance of water systems and devices.

6 Water governance and policy

The water governance is the set of rules, institutions, and processes that determine how water is managed and allocated among different stakeholders and sectors. The water governance involves multiple levels of authority, from local to global, and multiple actors, from public to private. The water governance must be based on principles of equity, participation, accountability, and sustainability. The water policy is the framework of laws, regulations, plans, and strategies that guide the water governance and decision-making. The water policy must be informed by scientific evidence, social values, and economic incentives.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?