Untouched catchment area in the Caucasus mountains in Georgia. Credit: David Hetherington

+ If we act, and learn from nature, then we can repair the damage we’ve done to the landscape.

Large swathes of our landscape have been greatly altered after centuries of detrimental human activity. I believe the damage can be successfully repaired relatively quickly – but only by managing water in a way that restores or mimics natural processes.

In natural catchment systems (without human intervention) densely vegetated areas with deep, absorbent soils catch and hold rainwater. It can then slowly seep through the land and recharge groundwater reserves.

Activities that have taken a toll on the landscape include deforestation, drainage, surface mining, straightening and embanking rivers, dewatering wetlands and, critically, intensive agricultural practices. 

Our changes have stripped away many of the natural environmental and ecological systems. They have drained and degraded our catchments, increasing pollution, flooding and drought. The result is an unsustainable landscape that does not work economically.

The problem is an urgent one. Recent academic studies and national press articles have suggested that we may only have 100 harvests left in the UK if we let this continue. The reduction in the volume of water stored on land (as opposed to in the oceans) has even been linked by some academics to more frequent and severe extreme weather and natural disasters.

Managing the flow of water is key in repairing damaged catchment systems within a generation. By using innovative approaches to catchment management we can restore or mimic natural processes (physical, chemical and ecological) to create multiple benefits that cater for increasing societal needs. 

To properly understand and restore processes takes a top-down, catchment-scale approach. Attempting to fix localised catchment problems on a smaller scale improves habitats but isn’t an overall solution. For example, focusing on restoring a river reach without considering the catchment means that the symptom is being patched over, rather than the cause of the problem being tackled.

At Arup we’re working on ways to increase the rate at which catchment processes are restored or improved. In upper and rural catchments natural flood management (NFM), river and wetland restoration and land-use change are key techniques in restoring or mimicking natural processes. 

In towns and cities, green infrastructure uses the principles of ‘greening’ to better reflect natural processes. It regulates the local temperature, and brings air and water quality and aesthetic benefits. 

These approaches can be applied incrementally – for example by adding NFM features over a period of years to account for increasing flood risks or susceptibility. This means that catchment restoration approaches can be used to adapt to changing and/or unexpected climate conditions.

The basic principles of catchment restoration are not complex: attenuation and buffering capacity (essentially, the ability to slow, store and filter water) seem to be the key loss within our degraded landscapes. The difficulty is convincing local communities, policy makers and water professionals that there is a need to change governance and funding frameworks in order to enable widespread positive change.

This is a global concern with implications beyond the catchments where the problems were originally caused. I hope that ongoing education, the publication of sound science and lobbying will result in sufficient catchment restoration activity.  

Healthy catchment systems feed positive and sustainable inputs to other systems, such as the climate and oceans. So to me, repairing our damaged landscapes is clearly cost-effective.