Flowering plants, a Biological Quality Element (BQE) under the Water Framework Directive

Adaptive management

An approach to managing systems with inherent uncertainties that involves learning from the system’s responses to intervention, then using that learning to improve future management


In flood defence, any man-made or natural feature – such as a raised defence, retaining structure, channel, pumping station or culvert – that performs a flood defence or land drainage function

Bank Stability

The ability of a river bank to counteract erosion or gravity forces


The area between the banks of a river ordinarily covered by water


Relating to the bed of a water body or to the organisms that live there.


All the species living in a particular area


The total collection of organisms of a geographic region or a time period.


An embankment, typically earth


The land (and its area) which drains (normally naturally) to a given point on a river, drainage system or other body of water


An assemblage of two or more populations of different species occupying the same geographical area.

Cost Effectiveness Analysis

A technique which seeks to identify the least cost option for meeting a particular objective. It enables prioritisation between options, but ultimately does not assess whether an option is economically worthwhile (cost benefit analysis would be employed to do this)


Traditional management of trees and shrubs for wood production by cutting stems close to the base and removing regrowth periodically.


A closed conduit carrying a watercourse beneath an obstruction such as a road, railway or canal. The term ‘closed’ implies that a culvert has a hard soffit and invert. The term ‘conduit’ implies the conveyance of water some or all of the time, thereby excluding tunnels and underpasses for vehicles, pedestrians and animals.


Underwater excavation, usually including removal of the excavated material


A raised structure (as of earth or gravel) used especially to hold back water.


Process by which particles are removed by the action of wind, flowing water or waves (opposite is accretion)


The seaward-sloping area of a shore that lies between the average high tide mark and the average low tide mark.

Flood Risk Management

The activity of understanding the probability and consequences of flooding, and seeking to modify these factors to manage flood risk to people, property and the environment in line with agreed policy objectives


The scientific study of the evolution and configuration of landforms.


The hydrological and geomorphological elements and processes of waterbody systems (i.e. Lakes, Rivers, Transitional Waters and Coasts).


The area that is exposed at low tide and underwater at high tide.

Invasive Species

Non-native organisms that successfully establish themselves in native ecosystems


An animal without a skeletal structure.

Land drainage

Limiting the effect of flooding by maintaining surface water and land drainage systems.


Organisms that do not have a backbone and are visible without a microscope.


Large vascular aquatic plants that grow in shallow water along the shorelines of lakes or in the slow-moving reaches of river



Work that sustains the desired condition and intended performance of an asset

Managed realignment

The deliberate removal or breaching of existing seawalls or embankments in order to allow the waters of adjacent coasts or estuaries to inundate the land behind.


The form and structure of the land surface (of relevance to this manual being formed by fluvial, coastal or estuarine processes)


Route that enables a hazard to propagate from a s ‘source’ to a ‘receptor’, as in the ‘source-pathway-receptor’ concept

A pathway must exist in order for a hazard to be realised. Pathways can be constrained in order to mitigate the risks


The plants that live on the bed of the sea, lake or river


The photosynthetic or plant constituent of plankton


A method of managing trees, particularly willows, by periodically cutting back the trunk at head height or higher and letting it regrow


Any plant material used for the purpose of plant propagation


The process in which a dredging ship propels sediment in a high arc to a particular location.


Along the banks of a watercourse. Riparian zones support riparian vegetation and are of environmental importance, providing diverse habitats and supporting a range of ecological communities


Material ranging from clay to gravel (or even larger) that is transported in flowing water and that settles or tends to settle in areas where the flow slows down


The deposition of sediment in the bed of a channel or within a hydraulic structure


An artificial channel for conducting water, with a valve or gate to regulate the flow

Species Richness

The number of different species in an area.

River Corridor

The continuous area of river, riverbanks and immediately adjacent land alongside a river and its tributaries


Continuously submerged areas of coastal areas


The concept of development that meets the needs of the present without compromising the ability of future generations to meet their own needs

Taxonomic composition

The number and arrangement of distinct species that are found in an assemblage

Water Quality

The physical, chemical and biological characteristics of water


A low dam built across a river to raise its water level or divert its flow