Geosynthetics for waterways and flood protection structures – Controlling the interaction of water and soil

Abstract

The interaction of water and soil has been both a blessing and a curse in all times within living memory. Water is the origin of life but is also threatening life when appearing unboundedly. Therefore mankind has always worked hard to benefit from water resources on one hand and to deal with the threat of flooding on the other hand. For both, to protect the land and to allow for beneficial uses like irrigation or navigation, often special measures are necessary to keep the water within certain bounds. Structures to achieve a permanently stable situation like irrigation and navigational canals, river training or flood protection measures need suitable material, carefully thought out design and accurate execution. Often a decision has to be made among competitive approaches to optimize such structures. In many cases, geosynthetics can support or improve the functionality and sometimes only with geosynthetics the desired result can be achieved.Geosynthetics can provide strength and flexibility, imperviousness and drainage, durability and robustness or controlled degradation. All these properties can be of use to handle the many occurrences of interaction of water and soil. Surface water has to be guided or to be kept off; percolating water should be controlled to avoid internal erosion effects should be restrained by appropriate filtration. To guarantee well functioning in general, also chemical and biological aspects have to be considered like ochre formation, root penetration and population by any kind of species. The German Federal Waterways Engineering and Research Institute (BAW) has gathered experience with geosynthetics in hydraulic applications since more than 40 years. These years revealed the capabilities of geosynthetic solutions and simultaneously emphasized the need of careful selection, design and execution.A large variety of geosynthetic fabric and structures is available. To control the interaction of water and soil many different attributes are required, e.g. membranes for impervious lining, filter sheets for erosion control, different kinds of mattresses or wrap-around structures, voluminous elements from sandbags to mega containers for protection, training or immediate repair. In many cases geosynthetics can be designed to control the interaction of water and soil according to the individual and local requirements to allow for an excellent execution of waterways and flood protection structures.