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Any interaction of water and soil at the streambed may cause erosion and scouring. Hydraulic loads on canal and river banks may origin either from natural hydrodynamic processes or from navigation. During flood events, water levels high above the normal lead to interaction of water and ground in often unprotected areas including the risk of erosion. In densely populated areas, the natural development of erosion and accretion cannot be accepted. Therefore special measures are needed to avoid scour and erosion and to guarantee stability of bed, bank and overbank zone. To avoid unfavourable actions of the water, either the action has to be reduced or the resistance has to be increased. Changing the action means to alter the flow for instance by river training works. Increasing the resistance is necessary if no alteration of actions can be realised, or the comparison of costs leads to such a decision. In many cases geosynthetics can support or improve the functionality. Sometimes only with geosynthetics the desired result can be achieved. Increasingly effort is put into bioengineering solutions, i.e. the integration of vegetation, at least in areas that are only temporarily drowned or loaded by hydraulic actions. Often the best solution is to combine vegetative with “technical” elements like hard armour or geotextiles. In all cases, placement of geosynthetic elements has to be done with care, especially if the installation has to be done under water, to provide strong and long lasting structures.