THURSDAY, JAN 26, 2023: NOTE TO FILE
Module 3-16
Application of Sustainable Design Solutions
4.1. Land restoration through rehabilitation of riparian zones
A fully functional riparian zone alongside gullies, streams and rivers provides an essential ecosystem service for very little cost. However, once the biomass of trees and shrubs are removed from a riparian zone, the sheet flow of rainfall flows unchecked into water courses together with topsoil which is flushed downstream. Eventually, these water courses become deeply scoured through erosion which unfortunately results in the water table being lowered in lands adjacent to the water course, often with drastic consequences for trees and crops whose roots no longer reach the water table. Droughts are thus exacerbated through the removal of riparian zones and resulting erosion of water courses. The simple rehabilitation of riparian zones and restoration of water courses through incremental check weirs can raise and replenish the water table thus benefitting the adjacent lands as illustrated in Figure 4.2. The benefits from the rehabilitation of riparian zones can be summarised as follows:
· It acts as a buffer to reduce flooding and erosion.
· Stormwater surface flows are slowed down, spread and sunk into the groundwater.
· It acts as a filter to trap silt and absorb harmful chemicals from entering the water course.
· It provides biodiversity and habitat for wildlife as well as for the aquatic environment.
· It provides a wilderness area for people to appreciate.
Figure 4.2: The process of rehabilitating a riparian zone with eroded gullies
Module 3, lesson 17
