An inland shore is an area for water storage connected to a nearby lake or river in which ecosystem services are optimized for multiple land use, thereby creating new economic opportunities. Large water level fluctuations are taken into account in advance and optimizing sustainability is the main theme in the whole concept. Inland shores are connected to the lake or river through inlets in the dike. Connections to the regional water system are optional but advisable. Inland shores can store and release water if needed, allowing the area to function as a climate buffer and freshwater storage. In addition, the design takes into account the possibility to function as a helophyte filter to allow improvement of water quality which is considered to be essential for proper functioning. Additional functions (e.g. recreation, fishing, aquaculture, floating infrastructure for living and working, sustainable energy production by sun, wind and water, floating agriculture, nature development) can be added depending on the desires of stakeholders.
The concept is based on the idea that climate change will increasingly lead to extreme weather that can damage existing land use functions through floods and droughts, and on the idea that freshwater is a valuable resource that provides economic opportunities if properly managed.
The Netherlands has more than enough water due to a net rainfall surplus and inflow of river water from Rhine and Meuse. Still, water shortages are occurring as most of this water is directed towards the North sea and becomes unavailable when needed. A solution to this problem is to store water in large water bodies. Lake IJsselmeer is such a body but on the long term water level fluctuations are limited due to the presence of existing infrastructure. Another possibility is to seek extra storage capacity for water on land by construction of inland shores. This expands the storage capacity of the lake, but also brings additional benefits for the functioning of the lake and new prospects for economic development. For instance, at present the fish stock of lake IJsselmeer is low due to over-exploitation by the fishing industry. With the current design of the coastline of lake IJsselmeer possibilities for spawning and fish reproduction are limited due to a lack of suitable habitats. Inland shores can provide these suitable habitats with great potential for enhanced ecosystem services and recovery of commercial fishing.
Inland shores can also contribute to increased safety from flooding. Currently excessive pumping and drainage causes land subsidence in the Netherlands. In addition, accelerating sea level rise will increase water levels around us. One option is to raise and reinforce dikes but the question is to what level? Flood risk is expressed as the product of chance and consequences, and we are professionals in building dikes, but what if the dike still fails? Due to the high economic value of land and infrastructure behind the dikes the consequences will be very dire. In addition, huge dikes will detach the Dutch inhabitant from the water which harbours beautiful scenery and nature values and which has always been part of our history. Besides, with high and secure dikes we may still be confronted with flooding due to extreme rainfall events. Inland shores can be used to store the excess of water coming from the sky or from large water bodies. The concept is a fundamental breakthrough in current water management practices of ongoing pumping, drainage and land subsidence which in the end will not be sustainable.
Besides benefits for future robust water management and benefits for commercial fishing many other benefits are to be explored. For example, inland shores can become attractive areas where people can live and work. The Netherlands is experimenting with houses on water. Inhabitants of inland shores have lots of possibilities for nearby recreation on or near the water in beautiful scenery. Agriculture may benefit because in an inland shore there is a secure freshwater source despite more extreme floods and droughts. Floating glasshouses are possible, which can also be used to generate energy in a sustainable way using sun radiation. In addition, differences in water level can be used to generate sustainable energy.
Inland shores can support climate services if carbon is captured from the atmosphere and stored under water. Depending on the management regime, wetlands can be efficient ecosystems for carbon capture. Also these systems can be used for nutrient retention enhancing the water quality. Improvement of the water quality is important for the Netherlands which in many locations has enriched nutrient levels in water and sediments. In a warmer climate this constitutes a risk in relation to algae bloom. Inland shores can also contribute to nature conservation objectives linked to the WFD, Natura 2000 and national objectives for nature.
In all, these developments will open opportunities for regional and national economic development. However, bringing inland shores from theory to practice will need a transition in Dutch thinking on water management. Can we develop sufficient economic value by living with and on top of water? This will desire a whole suite of innovative concepts in living, working and transport.
There is no exact blueprint for an inland shore. It is a concept and active stakeholder involvement is needed on the regional level to fill in the details based on ideas of stakeholders about economic opportunities and desires. Eventually, a ring of high quality wetland areas can be created around lakes where ecosystem services are optimized for different land use functions, that provide more space for water in a world with a changing climate, and bring new opportunities for economy and quality of life in deltas like the Netherlands.
With this Building Solution description, anyone with a basic level of knowledge and/or working experience on inland lake systems can make a first order assessment.
The added value of this Building Solution within BwN-type projects is that it combines multi-functional use of space with utilizing the ecosystem services of wetlands. The Building Solution is mainly applicable in the planning and design phase.
How to Use
Inland shores (in Dutch "achteroevers") are possible along large water bodies where the water level is higher than the hinterland. Then water can flow into the inland shore by gravity. An extra dike is needed to keep the water within the borders of the inland shore. This needs to be a reliable construction. A sustainable energy source (e.g. solar, wind, water) is used to pump water back into the large water body and to control the water level fluctuation in the inland shore. The pump facility should be equipped with a fish-friendly migration facility (see www.fishflowinnovations.nl).
Pumping is also important in relation to water quality. Stagnant water is a risk, especially in relation to algae bloom. So, some movement is needed. Water moment is also needed to enhance the filtering capacity of the inland shore, e.g. as helophyte filters or constructed wetlands. Inland shores can be designed to remove N, P, BOD, COD, suspended solids and bacteriological pollution from the through-flowing water. The excess of riparian vegetation can be used in bio-mass energy plants as a sustainable energy source. Some kind of management of the vegetation will be needed.
Water levels fluctuations are allowed in an inland shore, but there should always remain permanent water to prevent loss of fish stock, other negative impacts on biodiversity and living conditions. The water level is managed in such a manner that the area can function as a climate buffer, taking in water when there is excess of water and release water when water supply is limited. The water level regime should simulate a more dynamic water system, but the regime should not be too extreme to the extent that it surpasses what is known as "natural".
The surface water needs to be clean and in good ecological condition to provide suitable habitat for predators that feed on mosquito larvae. That way potential discomfort of midges can be limited. Good water quality is also important to allow recreational use of the water and to create an optimal living environment. If there are activities within an inland shore that can pollute the water (e.g. with nutrients: aquaculture, agriculture) then this part of the water needs to be treated separately.
Floating structures can block the sunlight underneath in the water. This can seriously limit plant growth. Plant growth is important for habitats and water quality. This has to be taken into account in the design (e.g. enough separation between floating infrastructure).
The principle of an inland shore is already being practised at two locations.
In 2010 Rijkswaterstaat and Deltares joined forces with the Province of Noord-Holland, the regional waterboard Hoogheemraadschap Hollands Noorderkwartier, and the Government Service for Land and Water Management (DLG) to develop an unique project: pilot Koopmanspolder. Originally, the Province aimed at a wet nature development project, but Rijkswaterstaat and Deltares convinced the other parties, including Staatsbosbeheer and municipality Medemblik, to include new elements allowing innovation on water management. Koopmanspolder is located near the villages Andijk and Wervershoof along the border of Lake IJsselmeer.
The pilot includes an inlet so that lake water can enter the polder, which is situated a bit lower than the lake. Water flows through a long spirally shaped ditch inside the polder with gentle slopes and is gathered into a small pond from which it can be pumped back into the lake.
The pumping facility will be equipped with a fish-friendly axial pump and driven by a wind mill. After a year, to allow the growth of riparian vegetation on the gentle slopes of the ditches, a field test of several years will start in which water levels inside the polder will be varied considerably simulating periods with floods and droughts. Monitoring of water and ecology will take place during the field test. Due to the design, the polder will function as a helophyte filter improving the water quality. In addition, fish can encounter better conditions for spawning than presently available in lake IJsselmeer. Besides, the polder can function as a climate buffer, providing a place to store water when there is too much, and withdrawal of water when there is too little.
The polder is situated along the Westfriese Omring dike, a popular route for recreational biking. The public can enter the center of the pond by a special facility and experience the benefits of good water quality, and enjoy nature in a newly created habitat.
First price of the "Water meets Water" innovation contest
Artist impression of the new polder
All consortium partners are enthusiastic about this living laboratory because it combines knowledge from all partners and allows for learning together. In 2011 the design and the cooperative way of working resulted in winning the first price of the "Water meets Water" innovation contest. This procedure of “Learning by doing” is especially interesting because it allows us to quantify more precisely the ecosystem services of such a newly designed polder area. The project started in 2012.
Koopmanspolder is a first pilot within the broader innovative framework “inland shores”. The focus of the pilot Koopmanspolder is on the ecological benefits of an inland shore.
It aims at creating a zone of high quality wetlands around Lake IJsselmeer where ecosystem services are optimized for different land use functions. It is based on the idea that more space for water is needed in a world with a changing climate, and that water can create new opportunities for economy and quality of life in deltas like the Netherlands. From 2014 up to 2016 field tests were executed to analyse the impact of different water level regimes on water quality, water quantity, flora and fauna. In 2014 the impact of a 'natural water regime' was tested with high water levels during the winter and spring period and a natural draw down of water levels during the growing season as a function of evapotranspiration. In 2015 a drought situation was simulated with exceptionally low water levels and in 2016 a flood event with exceptionally high water levels. The results show that the system can handle water level fluctuations of up to 2 m, water storage did not lead to ground water problems in the hinterland, and the water quality is high and supports fish and waterfowl.
More information can be found below:
- General information on inland shores (achteroevers) (in Dutch)
- Monitoring results 2012-2013
- Final report 2016 (in Dutch)
A second pilot for the inland shore concept is the Wieringermeerpolder. This is a deep polder area in the north of the Netherlands which receives a high salt load through upward seepage. It borders Lake IJsselmeer and lies 4 meter below surface level. The polder is mostly mono-functional focussed on agriculture. Along the dike inland shores plans are developed for new business models focussing on water storage in combination with food production (floating cultivation beds, aquacultures, aquaponic systems) and recreational activities (e.g. fishing). In 2016 the pilot Wieringermeerpolder won the Water Innovation prize in the category "Sufficient water". The focus of the pilot Wieringermeerpolder is on economic benefits of an inland shore.
For illustrational purposes a movie has been developed on how such an inland shore could look like: movie
In the figure below a sketch of how this water-production landscape could look like:
- Report of workshop in Andijk in 2008 (Dutch only)
- Report of workshop in LEF Future Center in 2009 (Dutch only)
- Report of workshop in LEF Future Center in 2010 (Dutch only)
- Report in water - fish workshop Koopmanspolder 2010 (Dutch only)
- Article in visionair 2012 (Dutch only) - literature
- Monitoringplan (Dutch only)
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