South-western Delta
How can we protect the safety and water quality of the South-western Delta against the long-range effects of climate change? And how can these measures contribute to reinforcing the area in ecological and economical terms? These are the key questions of the South-western Delta sub-programme.
The South-western Delta is the area comprising the province of Zeeland, the South Holland islands and Western Brabant. The Delta Works provided protection and brought safety following the flood disaster of 1953. However, the Delta Works also have their downsides for the natural environment, water quality and the economy.
Safe, resilient and vigorous
The South-western Delta sub-programme is working on a climate-proof, safe, ecologically resilient and economically vigorous delta area. Every area in the South-western Delta is faced with specific problems. Yet promising solutions are available. In the South-western Delta sub-programme, the state, provinces, municipal authorities and water boards collaborate with knowledge institutes, civil society institutions, the business community and citizens. The programme focuses on the medium term (2020-2050) and the long term (leading up to 2100).
The South-western Delta sub-programme is managed by the Ministry of Economic Affairs, Agriculture and Innovation.
Bottlenecks to be expected
The three national sub-programmes – Safety, Freshwater and New Urban Developments/Restructuring – pertain to the whole of the Netherlands, including the South-western Delta. In addition, the Delta Decision on the “protection of the Rhine-Meuse delta” is of major importance to the South-western Delta. In order to map out future bottlenecks, the Ministry of Economic Affairs, Agriculture and Innovation has commissioned the South-western Delta steering group to refine and broaden the South-western Delta problem analysis and develop possible solution strategies.
Salinisation
The delta scenarios and the short-term 2010-2015+ implementation programme have contributed to identifying the main bottlenecks with regard to water safety and the freshwater supply. The demand for freshwater may increase as a result of internal salinisation. Large parts of the South-western Delta have salty groundwater. This brackish water seeps up and salinifies the ditches. As a result, the ditchwater may become too salty to use for agriculture, horticulture and industry purposes. The freshwater supply in the area is contained in the Biesbosch, Hollandsch Diep and Haringvliet waterways as well as the freshwater that collects in the dunes. Low river discharges put pressure on the supplies. Major obstacles are the soil salinisation of the islands and the salinisation of the freshwater inlets near Bernisse and Gouda, inlets on which the entire green heart of the Netherlands and the Rhine estuary area depend.
High and low river levels
According to the delta scenarios, the combination of a rising sea level and possibly higher river discharges in the future may result in increased normative water levels in the South-western Delta. The discharge or storage of additional water in the South-western Delta may cause bottlenecks with regard to water safety. Problems are also expected for shipping in case of low river levels. The current safety strategy for the Eastern and Western Scheldt rivers is adequate, for the long term as well. However, additional research is required into the development of sand flats and trenches in the two Scheldt rivers.
Approach and possible solutions
Strategies are being defined for the South-western Delta, encompassing a coherent exploration of the relationship between safety and freshwater, ecology and the economy. Possible strategies are: moving along, moving along with emergency stops and offering resistance. Projects being studied or prepared that could contribute to long-term solutions are:
• Volkerak-Zoommeer water storage;
• Volkerak-Zoommeer water quality, linked to a number of measures aimed at making the freshwater supply more sustainable;
• the Grevelingen exploratory study, with the option of a tidal plant and additional water storage;
• the exploratory study into the shipping capacity of the Volkerak locks.
Summaries of plans of approach for the Delta Programme sub-programmes
The Delta Programme sub-programmes have drawn up a plan of approach outlining the plans and decisions being prepared in the time ahead. A summary of the plan of approach for the South-western Delta sub-programme is presented below.
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