Drentsche Aa

Project description: 

Meandering streams along heaths, hay meadows and villages form the iconic and historic landscape of the Drentsche Aa. A unique and extensive network of streams and tributaries in the provinces of Groningen and Drenthe. Due to the diversity in the ecosystem, the area is home to many different species of flora and fauna. Because of the persistent drought and warm weather, the area suffers from desiccation in summer and is slowly deteriorating.

To improve the ecological quality and strengthen the fragile environment, the stream bed has been raised at three different places in the Drentsche Aa: Zeegscherloopje, Anloërdiep and Taarlosche Diep. The measures aim to improve water collection in times of extreme precipitation and and water storage for dry periods. As a specialized contractor for inland dredging and nature restoration, Knoop BV was asked to devise an innovative method. The project had a few challenges: preventing damage from transport (also for residents and landowners in the vicinity), limited carrying capacity of the soil and limited accessibility of banks. This required an adapted implementation method in order to place little to no burden on the vulnerable nature. To achieve this, we have developed a method especially for this project whereby sand is mixed with water and spread through the stream by means of a pressure pipe. A unique system with which stream bed elevation has been achieved for the first time like this in the Netherlands.

Equipment:

• Waterking WK 20
• Waterking WK 55
• Waterking WK 95
• Hose reel
• Winch system
• Sand press set
• Various dredging equipment