Ecological aspects of waterway management in the Netherlands illustrated with examples from the IJsselmeer area

Ecological considerations play an important role in the management of waterways in the Netherlands nowadays. This article describes the legal aspects, technical possibilities, structural concepts and ecological objectives of the management of waterways. The article is introduced by a short description of the relevance of waterway management in the Netherlands and of Dutch government policy and legislation on the subject. A review in four sections is further given on the ecological aspects related to water quality control and to the maintenance and improvement works of structures such as locks, sluices and weirs, waterway banks, and bottoms (dredging). Several short and long-term effects of management and maintenance activities on the quality of water, the structural elements and sediments, and the more direct impact on flora and fauna are dealt with. These sections are illustrated with examples from the IJsselmeer area.