Letting nature (re)take its course

Letting nature (re)take its course

Allowing natural processes back into in rivers and catchments, collaboration, engagement and integrated measures are vital to ensure provision of ecosystem services and societal well-being

We all live in a river basin, a catchment. We might not be aware of this fact as we go about our daily lives, but it is a worldwide truth. River catchments vary in geology, orography and size. These factors, together with large scale drivers such as climate, latitude and orientation (north –south, east-west) come together to shape catchment soil types, availability of water and other natural resources, habitats and socio-economic human activity (read "Guns, Germs and Steel" by Jared Diamond).

Rivers, a living, continuous and dynamic thread of water, are providers and takers of life. They lap against cradles of civilization across the planet and are to be treated with respect. They provide us many services: water to drink and to irrigate our crops, food, transport and treatment of waste, means to produce energy and a sense of place, of well-being.

The catchments we live in are highly impacted and altered systems, detrimentally affecting the ecosystem services we take for granted. Natural headwater vegetation and forests - which provide nutrients and habitats for wildlife, prevent soil erosion and are an essential component of the water cycle - have been cleared to make way for agriculture and monoculture forestry. The flood plain, where rivers formerly spread to during periods of high flow, delaying and reducing peaks in flow while simultaneously recharging groundwater supply - are now intensively farmed or sit under ever more sprawling towns and cities. Wetlands - vital and biodiverse systems that slow the flow of water through the catchment, absorb pollutants and store carbon - have been built over by housing estates. Riparian galleries - highly dynamic systems that have myriad functions and provide a swathe of services - have been cleared to make way for development and agriculture. They have even been cleared in the past in the erroneous belief that riparian free river banks help prevent flooding by increasing conveyance from flood prone areas (conveyance describes the capacity of a river channel to carry or transport water). Well, conveyance may be increased from one area - but it will cause major flooding elsewhere downstream - where most urban areas are situated. Weirs and dams prevent flow of water, nutrients and substrates, migratory species cannot reach their breeding grounds, waterborne riparian seeds are prevented from travelling downstream to seed and maintain ecotone integrity.  

I have just described a litany of impacts, spread across the catchment, from the headwaters to the river itself. The river itself is no longer a dynamic continuum, no longer a reliable source of vital services. It is no surprise therefore that we suffer the consequences and lose a swathe of precious ecosystem services. River water quality is diminished through eutrophication and sedimentation from soil erosion and diffuse and direct sources of pollution. Wildlife disappears as habitats are lost. Rivers, straightened, channelled and contained by reinforced banks to prevent flooding of valuable land, have nowhere to go except thunder downstream, with devastating consequences of flood (check this video I shot of an urban stretch of my local river in spate this January to get some idea) in lower lying areas. In southern latitudes there is the double whammy of floods and wildfire, as previously existing fire adapted native vegetation is replaced by agriculture.

Society is increasingly finding that this lack of respect for rivers and catchments as a result of bad management decisions can and will ultimately wreak havoc, disrupting lives that have become too far removed from the natural world and its fundamental processes. The misery and destruction resulting from the Cumbrian floods in the UK this winter (and previous winters) are a real reminder of our impact on the living landscape. Further south, the problem of recurrent wildfire in countries with Mediterranean climates, such as Portugal, results in nutrients, ash and soils being swept into streams, killing off aquatic life and diminishing water quality.

This massive imbalance can only be redressed by reintroducing natural processes into “our” highly altered landscape to benefit both the environment (and the ecosystem services it provides us with) and society. This holistic, large scale approach implicitly involves many types of intervention at different spatial scales. These can involve tree planting and reintroducing green buffer zones in higher lying areas, reconnecting the river with the floodplain in key areas to reduce flood risk, promote biodiversity and improve water quality, reintroducing natural hydromorphological features such as meanders and riparian vegetation into river systems and removing obsolete instream structures, such as disused weirs, to promote river connectivity. Multiple benefits result from these measures, from reduced soil erosion to increased carbon storage (in planted forests and riparian stands), to better water quality and enhanced biodiversity.

The implications of such large scale interventions requires continued collaboration between a wide range of interested parties including academics, technical experts, land owners, statutory agencies, non-profit environmental and conservation organisations and the public, to name just a few. Established in 2001, the UK Rivers Trusts  are independent organisations – charities – that work for the benefit of the public to “co-ordinate, represent and develop the aims and interests of the member Trusts in the promotion of sustainable, holistic and integrated catchment management and sound environmental practices, recognising the wider economic benefits for local communities and the value of education.”  Social media positively crackle with news of their activities and accomplishments to bring life back to UK rivers and catchments by INVOLVING PEOPLE. If you want to be part of their activities, I suggest you have a “Google” and get in touch with one (or more) of them. I know I have.