Advisory report
RLG 01/4a: Storing water strategically
Advice on the implementation of water retention and water buffering
in policies and implementation plans - June 2001
Rationale
Motivated by some emergencies and stimulated by the expected climate change
and soil subsidence, the way of thinking about water has undergone sweeping
changes in the last few years. 'Room for water' is the new adage which
has meanwhile been embedded in policy memoranda (such as in the Vijfde
Nota Ruimtelijke Ordening) [the Fifth Memorandum on Spatial Planning].
Water issues are formulated, anticipation strategies explored. Steps are
being taken not only on the local level but also on the regional, national
and international levels to go ahead with the proposed adjustments in
the foreseeable future. Creating space for storing and buffering water
- preferably combined with agriculture, nature, recreation, housing or
employment - is now one of the most arduous and complex tasks in our densely
populated country.
Advice request and further details
At the request of the State Secretary for Agriculture, Nature Management
and Fisheries, the Council for the Rural Area explored the possibilities
for combining nature, landscape and recreation with creating space for
water. As space is scarce in the Netherlands, attempts are being made
to arrive at win-win situations by multifunctional planning and utilisation
of nature, recreation and agricultural areas that are already in existence
or are to be developed. The Council has carefully considered these options
and, where necessary, also the backgrounds and causes of the problems.
This has lead the Council to present the following summary conclusions
and recommendations:
1. Water issues and strategies
• Relocation or transformation of forms of land use at the national
level may contribute substantially to alleviate bottlenecks in water manegement.
• Attaining a certain acceptance of water nuisance and inconvenience
is necessary to arrive at a more sustainable way of dealing with water
in addition to adopting strategies that are aimed at more space for water
and additional hydraulic technologies. The development of standards for
'acceptable nuisance' may encourage such change.
• Possible climate change and changes in our water systems strengthen
the need for policies to improve the quality of water. Good water quality
is vital for our environment and is therefore the determining factor for
function combinations in water storage and water buffering.
2. Causes and effects
• Shaping the Dutch delta and restricting its extent and functioning
are the major causes of the lack of space and resilience to flexibly counter
the expected changes in water supply by rivers and precipitation.
• Resilience and sustainability cannot be restored as natural qualities
of future water systems. This aim is unrealistic. The measure and scale
of the Dutch spatial planning no longer match the measure and scale of
the natural hydrological systems. Resilience must primarily have an artificial
basis in space and technology. The sustainability of future water management
will be determined mainly by the standards of management of the adapted
system.
• Brackish water is only partly caused by a sea level rise and soil
subsidence. It is often caused by choices in the assignment of functions,
lack of space and water management in which the characteristic features
of the water system are not taken into account.
3. The water test
• The water test is an integral test of all major hydrologic aspects
(not only aspects of safety and flooding but also of water quality and
groundwater depletion) after which, depending on the location, administrative
consideration of the aspects must take place.
• Though an important instrument, the water test will only contribute
towards solving the expected problems in a procedural sense. It can prevent
deterioration of existing situations. Adequate testing may be conducive
to making indicated pressure points not more serious, or making them easier
to solve.
• The water test must be applied on all planning levels, and the
test results must bear upon all relevant policies and plans.
• The water test must be implemented promptly to make use of this
time of prosperity, of wealth and of planning large-scale operations (Fifth
Memorandum on Spatial Planning).
4. General aspects of water storage, water buffering and water quality
• Wet nature areas or watery farmlands (e.g. fen grasslands) are
not always the most suitable areas for water storage or buffering. On
the contrary, the storing and buffering capacity of these areas is relatively
restricted because of their permanent high groundwater tables and surface
water levels. The effectiveness of water buffering is further decreased
by relatively high water losses through evaporation and drainage of water.
• Drainage of water and inundation of nature and agricultural areas
may strongly affect the soil quality and the temporarily retained or semi-permanently
buffered water. These operations require sound hydrological and chemical
analyses be carried out beforehand.
5. Water retention and buffering combined with nature areas
• Moist or wet nature areas do not always benefit from water retention
and/or buffering, not even when they have to cope with dehydration. The
eco-hydrological reactions are often complex and vulnerable, their importance
as water buffer will be reduced by their own need for water and the water
quality requirements of natural habitats will limit the suitability to
retain water surpluses from elsewhere.
• Shifting polluted or over-fertilised water surpluses from urban
or agricultural areas on to nature areas may lead to consequential destruction
of capital (biodiversity, management costs) and to high expenses for many
years, if recovery is possible at all.
• Development of additional wet nature for the purpose of water storage
often generates yet higher water demands in periods of scarcity. This
'water balance' may turn out negatively.
6. Water storage and water buffering combined with agriculture
• The principles of sustainable water management are at odds with
the development perspectives for arable farming and horticulture in the
lower parts of the Netherlands and especially for chloride-sensitive crops
in the western and northern parts of the Netherlands. The 'Tweede Structuurschema
Groene Ruimte' [Second Spatial Plan for the Rural Area] should give a
further orientation on the desirable direction in spatial planning for
these sectors.
• The solution of water problems (including water becoming brackish)
in the western part of the Netherlands is not primarily to be found in
the water tables of fen grasslands. Relocation of chloride-sensitive crops
and drastic changes of functions of the polders offer better prospects
for recovery of a sustainable and resilient water system.
• Flexible water level management or permanent high-water levels
in fen grasslands make relatively heavy demands on the cultivation possibilities
of the land; i.e. in relation to contributing towards solving pressure
points in water management and in abating soil subsidence - and subsequently
on the agricultural output of existing enterprises.
• The potential of agriculture as 'water supplier' is limited from
the water quality angle. The (water) quality demands made will often stand
in the way of such a functional development for years at a time.
7. Water storage and buffering in relation to landscape and recreation
• Creating space for water will offer possibilities for restoring
broken relations in landscapes as well as historico-cultural elements
and patterns, when combined with new or renewed water functions.
• The development of water functions based on historical patterns
or new 'water landscapes' will offer prospects for high-quality recreational
areas.
• The combination of water functions and water recreation and tourism
will offer good prospects, but realisation and maintenance of sufficient
(swimming) water quality in summer may be an important complicating factor.
Design and management of waterside growth is quite a complicated task
with fluctuating water levels.
8. Water management and land use in relation with soil subsidence
• In the western part of the Netherlands, most soil hydrology problems
and risks of soil subsidence are not primarily caused by a drop in the
level of land in the fen itself, but mainly in the surrounding low polders
and reclaimed areas. It goes without saying that the solution of these
problems must be found there, where they occur.
• Without permanent inundation, the bog will continue to oxidise
and the surface subsides as a result of the evaporation surplus in summer.
• In boggy areas, deep drainage and agricultural forms of land use
other than grassland are very undesirable from the viewpoint of sustainable
water management and particularly of the restrictions of unequal subsidence.
Existing deep drainage's must be rounded off soon or stopped. (Semi)permanent
inundated deep drainage's may play an important role in water storing
and buffering on polder level, possibly combined with commercial reed
crops.
Final conclusion: 'room for water = space for water'
The possibilities for combining water storage or buffering with existing
nature and agricultural areas are relatively limited, at least when nature
or agriculture must continue to function according to fixed objectives.
There seem to be more possibilities for the opposite: combining green
functions in areas that are designed and intended for the main function
of water, especially for landscape and recreation. In this situation,
nature, agriculture and recreation will have to conform to the restrictions
which the water function entails. This will give another quality value
of nature and agriculture, different from the intended purpose of the
respective sector policy. This combination can therefore only have any
purport when added to the existing objectives. This also means that, within
the relatively restricted space our country has, political choices must
be made from time to time about what function will be prioritised at what
location.
For the policy, it means that:
1. the possibilities for function combinations with existing nature and
agriculture should not be overassessed, without infringement on the related
current objectives. According to this, the necessary capacity for storing
and buffering will only partly be realised and will therefore necessitate
pursuing other strategies at the same time.
2. the available possibilities for function combinations must be optimally
employed.
3. other spatial operations should not increase the existing and expected
water problems, but must, where possible, contribute to the solution (water
test).
4. substantial (extra) space must be reserved for the intended 'room for
water' policy, i.e. for the purpose of creating space for water retention
and water buffering as main function.
5. in this new 'room for water' policy, advantage should be taken of the
possibilities for multifunction purposes, taking into account the restriction
that the dual function is subordinate to the water function.