ES9 - Filtration of pollutants

Ongoing climate change affects lake water quality through several mechanisms, including (1) changes in external and internal nutrient loads, (2) increased frequency of extreme events such as hurricanes, (3) temperature-induced changes in biota and biotic interactions, and (4) fluctuations in water levels.
Lakes function as important water retention systems, capable of storing water for flood control and providing water for multiple uses...

Swales are broad, shallow, linear vegetated channels which can store or convey surface water (reducing the rate and volume of runoff) and remove pollutants. They can be used as conveyance features to pass the runoff to the next stage of the SuDS treatment train and can be designed to promote infiltration where soil and groundwater conditions...

Riparian buffers are areas of land, predominantly covered with trees, shrubs, and sometimes grasses, along, and often up-gradient from, streams, watercourses, or water bodies. These natural or restored buffers serve multiple purposes. By maintaining a relatively undisturbed zone adjacent to open water, they play an important role in water quality and flow...

Streambed (or riverbed) represents the bottom of the river, including each bank. In the past, riverbeds have been artificially modified with concrete or big boulders, altering flows and reducing habitat for wildlife and vegetation diversity. The changes were aimed at preventing flood or supporting changes of agricultural practices for example. This has led to more...

Groundwater is the part of infiltrated water which composes the water resource for population and human activities.  Previous modifications of the landscape have reduced the infiltration capacity of many European soils, thereby limiting the rate at which precipitation is able to infiltrate and recharge groundwater aquifers. Restoration of natural infiltration to groundwater enables a lowering of run-off from surrounding land, and...

Seasonal streams or intermittent rivers are rivers for which surface water ceases to flow at some point in space and time. They comprise a large proportion of the global river network and are characterised by dynamic exchanges between terrestrial and aquatic habitats. These habitats support aquatic, semi-aquatic, and terrestrial biota. Seasonal streams provide essential ecosystem services to society, including flood control and irrigation....

A riverbank protection is an inert or living construction providing bank fixation but also an obstacle for the lateral connection of the river. Eliminating it consists in removing some parts of the bank protection, especially the inert one, in order to enhance lateral connections of the river, diversify flows (depth, substrate, and speed) and habitats, but also cap floods in the mainstream. It is a prerequisite for many other measures like re...

A river meander is a U-form taken by the river, allowing it to decrease water velocity. In the past, rivers have been straightened by cutting off meanders. Many rivers in northern and Western Europe have been straightened and channelized to, for example, facilitate log floating and/or speed up the drainage of water and control/limit the river bed movements. Channelizing was also a way to gain land for cultivation. River re-meandering consists...

An oxbow lake is an ancient meander that was cut off from the river, thus creating a small lake with a U form. Reconnecting it with the river consists in removing terrestrial lands between both water bodies, therefore favouring the overall functioning of the river by restoring lateral connectivity, diversifying flows and cleaning the river section of the present oxbow for a better water retention during floods. 

Recent literature...

A floodplain is the area bordering a river that naturally provides space for the retention of flood and rainwater.  Because of regular flooding, floodplain soils are generally very fertile and they have often been dried-out to be used as agricultural land. Floodplains in many places have also been separated from the river by dikes, berms or other structures designed to control the flow of the...