Silt in the Markermeer/IJmeer. A study on the effectivity and efficiency of proposed approaches concerning the deterioration of the lake and its surroundings.

Abstract

This thesis will provide an answer to the question what the most effective and efficient approach is to solve the silt problem in the Markermeer/IJmeer area, in perspective of the EU Water Framework Directive (WFD) and Natura-2000. The Markermeer, with a surface of 750 km2, was separated from the IJsselmeer in 1976 by the Houtribdijk and with its construction, the silt soils got isolated in this area. Since the Markermeer has a relatively limited depth, the wind waves have a free hand on the soil and a lot of re-suspension of silt is taking place. This creates difficulties for water plants to establish and negatively influences mussels, fish and birds. The amount of water plants has remained constant over the last decades, and the amount of zebra mussels, fish as well as birds have declined. Since the Markermeer/IJmeer area is listed as a Natura-2000 area and is also covered by the WFD, it should reach certain requirements, and if the area does not meet those requirements, as is the case for the Markermeer/IJmeer, it should be recovered. From 2007 until today, governments and social organizations are thinking about the future of the Markermeer/IJmeer area, and a plan for a ‘Toekomst Bestendig Ecologisch Systeem’ (TBES) was created. In 2012, an optimization report for the TBES followed, which led to an open-market-application for nature development plans. Those plans, in their turn, led to three approaches for possible measures, The Marker Wadden, lee structures and Innovative TBES. The first approach provides a plan for the creation of a large scale swamp area, the second focuses on lee structures in front of the coast of Noord-Holland and the last combines those plans with stepping stones and fish passages. From the Multi Criteria Analysis (MCA) performed on the approaches it can be concluded that the Marker Wadden project, proposing a large scale swamp area in the North-East of the Markermeer, is the most effective as well as efficient approach for solving the silt problem while reducing the costs as much as possible, taking Natura-2000, WFD and TBES requirements into account.