• EU Water Initiative Plus (2016-2021)
• EU Water Framework Directive - integrated river basin management for Europe
• United Nation Economic Commission for Europe: Water Convention
• United Nations: SDG 6
• Water Resources Management tools - GWP Toolbox

A distinction is made between renewable and non-renewable water resources. Non-renewable water resources are either not replenished at all by nature, or not before a very long time. This includes so-called fossil groundwaters. Renewable water resources are recharged by the hydrological cycle, unless they are overexploited; they comprise groundwater aquifers and surface waters like rivers and lakes. Renewable freshwater resources are replenished by precipitation (minus evapotranspiration), which runs off into rivers and recharges aquifers (internal flow), and by surface waters and groundwater flowing in from neighbouring countries (external inflow or inflow from upstream areas). This indicator also includes the outflow of surface water and groundwater to neighbouring countries and to the sea. 

Water abstraction is the process of taking water from a surface (rivers, lakes) or underground (aquifers, etc.), either temporarily or permanently. Depending on the environmental legislation in the relevant country, controls may be placed on abstraction to limit the amount of water that can be removed. Excessive abstraction can lead to rivers drying up or groundwater aquifers depleting unacceptably.

(Source: European Environment Agency)

In contrast to water abstraction, water supply is the delivery of water to end users including abstraction for own final use. For example, a manufacturing plant might require 40,000 litres of freshwater a day for cooling, operating, and cleaning its equipment. Even if the plant returns 95 percent of that water to the watershed, the plant still needs all 40,000 litres to operate.

(Source: Eurostat, statistics explained).

Water use refers to the water actually used by end users (e.g. households, services, agriculture, industry) within a territory for a specific purpose, such as domestic use, irrigation or industrial processing. 

(Source: Eurostat, statistics explained) 

This is the portion of water use that is not returned to the original water source after withdrawal. Consumption also occurs when water is lost into the atmosphere through evaporation, or incorporated into a product or plant (such as a corn stalk), and is no longer available for reuse. For example, irrigated agriculture accounts for 70 percent of water use worldwide and almost 50 percent of that is consumed either by evaporation into the atmosphere or transpiration through plant leaves.

(Source:  World Resource Institute)

Integrated water resources management (IWRM) is a process that promotes the coordinated development and management of water, land and related resources, in order to maximise the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems. IWRM practices depend on the context; hence, regional and national institutions need to develop their own IWRM practices.

(Source: Global Water Partnership)

Aquatic ecosystem restoration, integrated management of storm water, and land use modification like buffer strips and hedges are some examples of water-related nature-based solutions. Water-related nature-based solutions have a positive impact on water quality and quantity. They can slow down runoff and increase infiltration, favour natural retention and purification, and restore and improve natural habitats. They are low-cost, efficient solutions but sometimes require time to show benefits. Usually they need some space, sound know-how for their implementation and local adaptation, as well as regular and tailored operation and maintenance. In case of extreme events, NBS may not be able to prevent any damage (nor may grey infrastructure). In addition, the best NBSs make use of existing, functional ecosystems that just need to be preserved. 

(Source: International Office for Water, France).