Areas that are inundated by surface or ground water with frequency sufficient to support a prevalence of vegetative or aquatic life that requires saturated or seasonally saturated soil conditions for growth or reproduction.
Wetlands provide both stormwater attenuation and treatment, comprising shallow ponds and marshy areas covered in aquatic vegetation.ﾠ Wetlands detain flows for an extended period to allow sediments to settle and to remove contaminants.ﾠ They also provide runoff attenuation and can provide significant ecological benefits.

Water retention covers a wide set of mechanisms (see synthesis document n°1) the effect of which are to increase the capture of water by aquifers, soil, and aquatic and water dependent ecosystems.
More precisely it refers to capabilities of catchments (including wetlands, rivers and floodplains but also other land areas) to hold or retain as much water as possible during periods of abundant or even excessive precipitation, so that water is available for use during dry periods and runoff peaks are minimized.

Urban forest parks or protected areas provide multiple benefits including increased water infiltration, pollutant filtration, reductions in peak flow and maintenance of base flows. Urban forests also have many other aesthetic, biodiversity and quality of life benefits.
- Based on Stella definitions, adapted by NWRM project experts and validated by the European Commission

Phosphates from agriculture are an important contributor to phosphorus loading on water bodies. Phosphorus is considered to be a limiting factor in the process of eutrophication that can generally be regarded as the enrichment of surface waters by nutrients which causes overgrowth of algae and weeds. The result is deoxygenation of waters that can kill fish and other aquatic life. Algae growth can also be a hazard to human health.

Ponds or pools with additional storage capacity to attenuate surface runoff during rainfall events.ﾠ Retention time of runoff can provide the capacity to remove pollutants through sedimentation and opportunity for biological uptake of nutrients.
- Based on Stella definitions, adapted by NWRM project experts and validated by the European Commission

Traditional terraces consist of nearly level platforms built along contour lines of slopes, mostly sustained by stone walls, used for farming on hilly terrain.ﾠ When properly built and well maintained, terraces can reduce erosion and surface run-off by slowing rainwater to a non-erosive velocity.ﾠ So-called traditional terracing involves less disturbance of the terrain than modern terracing, as it does not involve significant levelling or cutting using heavy machinery.ﾠ
- Based on Stella definitions, adapted by NWRM project experts and validated by the European Commission

The management of land to minimise soil erosion to maintain soil and water resources, and provide sustainable benefits in the long term.

"Approaches to manage surface water that take account of water quantity (flooding), water quality (pollution)ﾠ and amenity issues are collectively referred to as Sustainable Drainage Systems (SuDS).
SuDS mimic nature and typically manage rainfall close to where it falls. SuDS can be designed to slow water down (attenuate) before it enters ﾠstreams, rivers and other watercourses, they provide areas to store water in natural contours and can be used to allow water to soak (infiltrate) into the ground or evaporated from surface water and lost or transpired from vegetation (known as evapotranspiration)." (Source: susdrain)

Meadows are areas or fields whose main vegetation is grass, or other non-woody plants, used for mowing and haying.ﾠ Pastures are grassed or wooded areas, moorland or heathland, generally used for grazing. Due to their rooted soils and their permanent cover, meadows and pastures provide good conditions for the uptake and storage of water during temporary floods. They also protect water quality by trapping sediments and assimilating nutrients.
- Based on Stella definitions, adapted by NWRM project experts and validated by the European Commission

Natural Water Retention Measures (NWRM) are multi-functional measures that aim to protect and manage water resources and address water-related challenges by restoring or maintaining ecosystems as well as natural features and characteristics of water bodies using natural means and processes. Their main focus is to enhance, as well as preserve, the water retention capacity of aquifers, soil, and ecosystems with a view to improving their status. NWRM have the potential to provide multiple benefits (see benefits table), including the reduction of risk of floods and droughts, water quality improvement, groundwater recharge and habitat improvement. The application of NWRM supports green infrastructure, improves or preserves the quantitative status of surface water and groundwater bodies and can positively affect the chemical and ecological status of water bodies by restoring or enhancing natural functioning of ecosystems and the services they provide (see ecosystem services). The preserved or restored ecosystems can contribute both to climate change adaptation and mitigation.