The Union for the Morava River presents:


Environmentally Sustainable Flood Protection
Measures for the Morava and the Becva Rivers
in Central Moravia

(a shortened English version of a full report that is available in Czech at http://www.sweb.cz/uprm/po.html)

 

By Vaclav Cermak, Kamila Florova, Helena Kralova and Jaroslav Ungerman

 

    Introduction

The Morava River, with the Becva River as one of its main affluents, is the only major tributary to the Danube, which originates in the Czech Republic (see the map for the precise locations of the mentioned places and rivers with their tributaries in the central Moravian region of the Czech Republic). The catastrophic floods in 1997, during which almost the entire lowland areas of the Morava and Becva Rivers were inundated, invoked, after almost a hundred years, a serious discussion about the concept of efficient flood protection measures. It was clear then that the focus on arable land protection should be re-directed towards specifically targeted protection measures of towns and villages built on the bottomland.
[Picture 1  Gradual straightening and shortening of the riverbed of the Morava River between Napajedla and Veseli nad Moravou]
Water authorities in the areas of the Morava and Becva Rivers have been suggesting that the high-flood-water waves on these rivers should be intercepted in new large reservoirs at Hanusovice, Mohelnice and Teplice, and also that the controversial, yet-to-be ratified Danube-Odra-Elbe canal should be used for re-directing flood-water flows.
Environmentalists have argued that new large reservoirs and canals will have an extreme and largely negative impact on the countryside, do not provide reliable solutions to flood threats, and are very demanding from the financial point of view. In their views, the anti-flood measures have to respect ecological links and dynamics of the landscape. They also think that the economy does play a factor and that a financially reasonable solution will have to be found.
In 2002, experts from the Union for the Morava River created this study on environment-friendly anti-flood measures with the purpose of putting pressure on relevant authorities and politicians to implement these measures.

    Basic Principles of the Anti-Flood Measures on the Morava and Becva Rivers

Having considered all possible and feasible measures, the Union for the Morava River suggests the following basic principles accommodating all possible ecological as well as financial requirements:

  1. Increasing the water retention capability of the areas along the Morava and Becva Rivers threatened with peak flows, especially in the spring areas of these rivers.
    This may be achieved by:
    • applying afforestation and grassing-down measures, predominately on the soil erosion-prone surfaces of arable land,
    • applying soil protection measures,
    • renewing the natural state of forests around the rivers, and
    • creating wetlands and small reservoirs in order to change overland flows to ground water runoffs.
  2. Protecting the urbanised areas and major industrial and agricultural sites along these rivers by tailor-made anti-flood measures.
    According to this conception, each urban unit on the bottomland will be protected by anti-flood measures dimensioned for the maximal water flow reached during the floods in the year of 1997. Nevertheless, each urban unit may, on the basis of the ratio of flood protection costs and costs of possible flood damages, use not maximal measures such as lower-capacity riverbeds or lower levels of protective dikes.
  3. Keeping or increasing the water retention capability of the bottomland along the Morava and Becva Rivers in the maximal possible way. Creating space for water spillage.
    This may be achieved by:
    • applying afforestation and grassing-down measures on the bottomland, thus reducing flood damages and renewing the landscape character of the bottomland,
    • cultivating crops on arable land on the bottomland with regard to the frequency and timing of possible floods, and
    • keeping the non-urbanised surroundings of the water flows (where the natural state of the water course is advisable to be renewed) in reserve for active water-bed creating processes, for meandering and for creating deep pools and alluvial gravel deposits.
  4. Improving the information system on run-off conditions. Enabling wider access to information on run-off conditions in order to make flood forecasting and run-off adaptations possible.
    It is necessary to realise that all technical anti-flood measures may fail, therefore an emergency system adapted to specific local conditions has to be applied. The emergency system should be created considering the speed of the coming high-flood-water wave, its course and extent.
  5. Compensating lost floodwater storage space in the bottomland with measures improving the retention potential of the river basin and the bottomland.
    Due to building up facilities ensuring tailor-made flood protection of the urban units, the flood-water storage area will be decreased by about 15%, thus reducing the retention capability of the bottom land and increasing maximal flows down the river course. Therefore measures improving the retention potential of the river basin and the bottomland will be needed.

[Picture 2  Anti-flood protection of urban units by means of protective dikes]

All the above mentioned principles conform to current trends in flood protection in developed countries where, due to frequent floods with catastrophic consequences, views on the efficiency of previous anti-flood measures have been changing. The new trends are derived from a simple idea - to provide rivers with sufficiently large areas for water spillage during floods where possible. In Germany and the UK, bottomland forests around water flows are being renewed and anti-flood dikes are, like in Germany along the Rhine, being moved further away from riverbanks.

In European countries such as Britain, Denmark and even the Netherlands, rivers are being renewed to their natural state, including their meanders, while these adaptations intend to be an ingrained part of anti-flood measures there. Even in urban areas around the world, protective measures these days do not always seem to be purely technical - the emphasis is being put on creating a harmonised entity formed by rivers, people and their places of living.

Example of river revitalization

Photo 1    Example of river revitalization
Increasing waterbed capacity of currently regulated rivers in towns and cities will be linked to revitalization of those rivers, their embankments and areas between dikes (or earth banks). A revitalized river will then become a part of the city life - providing opportunities for recreation and leisure-time activities as well as playing an important role during urbanization processes. The photo shows the Saale River in the town of Hof in Bavaria, Germany, which is an example of such revitalization.

    Conception of the Anti-Flood Measures on the Morava and the Becva Rivers

The conception of the anti-flood measures has been derived from an analysis of floods in the area of these rivers since 1883. The main purpose for conducting the analysis was to find out how the river basins of the Morava and Becva Rivers behaved during inundating, how floods created and developed. The course of inundation on these rivers significantly influences high-flood-water-wave speed, transformation of the high-flood-water wave in inundation areas and collisions of these waves at confluences of these rivers with big affluents.

The conception consists of adapting run-off conditions on these rivers in a way that ensures:
  • the lowest probability of high-flood-water-wave collisions, and
  • the biggest possible interval between maximal high-flood-water waves coming to main valleys.
Due to different run-off conditions on the Morava and Becva Rivers, the proposed measures are divided into several sections of these rivers (see the map for the precise locations of the below-mentioned places and rivers).
  1. The upper part of the Morava River (from its spring to its confluence with the Becva River)
    The flood peak on the Becva River precedes the flood peak on the Morava River at their confluence by a few hours, therefore the adaptations of the run-off conditions at the upper part of the Morava River will have to:
    • ensure slowing-down and flattering the high-flood-water wave, and
    • compensate the loss of retention space at the urban areas of Olomouc and Litovel.

    [Picture 3  Removing protective dikes at the upper part of the Morava River and increasing the retention capability of the bottomland]

  2. The Becva River (from the confluence of the Roznovska Becva and Vsetinska Becva Rivers to its confluence with the Morava River)
     
    In order to protect the town of Prerov, the Union for the Morava River proposes lowering the water level on the Becva River by increasing the cross section of the river below Prerov (down the river flow) and raising the capacity of the riverbed in Prerov itself.
    This is in contrast to water authority proposals that suggest building a dry retention reservoir at Teplice so as to flatten out the high-flood-water wave and reduce its effect on Prerov.
    The Becva River at the town of Prerov

    Photo 2    The Becva River at the town of Prerov
    Conditions for active river-bed creating processes will be created at areas outside urban units, where there is no danger of significant flood damages. The riverbed of the Becva River will be widened during the river-bed processes. The river-bed maintenance will be adequate to the equivalent care of non-regulated rivers. Bottomland forests and meadows will be renewed in areas outside urban units.

    [Picture 4  Increasing the cross section of the Becva River below Prerov (down the river flow)]

  3. The central part of the Morava River (from its confluence with the Becva River to its confluence with the Dyje River)
    The Morava River in this part has already been adapted and also equipped with dikes in order to allow the water flow capacity of 550-700 cubic metres per second. Protective dikes and inundation areas along both sides of the river function as a dry retention reservoir that effectively cuts the peak of the high-flood-water wave. Until the 1930s, the water spillage at the widest part of the bottomland at the confluence of the Morava and Becva Rivers had a significant impact on flattening the high-flood-water wave. But since then, the retention effect of this area has been lowered due to adjustments and adaptations of the Morava River north of Kromeriz and by building a movable weir there.
     
    The Union for the Morava River's proposal related to dealing with run-off conditions in the central part of the Morava River assumes maximal utilisation of the current hydraulic structures on condition that the retention potential of the inundation area around Kromeriz is increased. The existing movable weir will function as a pilot object controlling water flows in the Morava River in a way that the flow in the river will not exceed the water bed capacity below the weir (down the river flow). Big water flows will be moved over by means of inundation around Kromeriz. The embankment of a planned road bypass of Kromeriz will be used for increasing the retention effect of the dry detention reservoirs there.
     
    The waterbed capacity and the capacity of protective dikes (supposing that they are moved further away from the riverbanks) will be kept for the water flow of 550-600 cubic metres per second. The movable weir in Nedakonice will be used for constraining water flows over Uhersky Ostroh, Veseli nad Moravou and Vnorovy. Water flows with higher capacities than 550-600 cubic metres per second will bypass the floodway of the Morava River from its right side (see picture 6).
     
    [Picture 5  Increasing the retention effect of the dry detention reservoirs along both banks of the Morava River and moving protective dikes further away from the riverbed]
  4. The lower part of the Morava River (from its confluence with the Dyje River to its confluence with the Danube River)
    The flood peak on the Morava River has preceded the flood peak on the Dyje River at their confluence by a few dozen hours in recent years. The high-flood-water waves on both rivers at the place of their confluence are largely flat. The culmination period ranges from several hours to several days. Therefore any adaptation of run-off conditions should not have any significant impact on slowing down floods in central Moravia. The influence of the Nove Mlyny Reservoir on the Dyje River on the flood protection measures will have to be assessed for several variants of the retention capacity of the reservoir in order to find solutions to run-off conditions in the lower part of the Morava River.
     
    [Picture 6  Adaptation of runoff conditions on the Morava River and its tributaries]

    Approximate costs (at 2002 prices)

  1. Total expenditures on tailor-made flood-protection measures in urban areas
     
    Urban areas at:Total expenditures:
    The upper part of the Morava River3.180 billion CZK (106.0 million EUR)
    The Becva River1.296 billion CZK (43.2 million EUR)
    The central part of the Morava River1.392 billion CZK (46.4 million EUR)
    Total5.868 billion CZK (195.6 million EUR)
  2. Total expenditures on building weir bypasses in order that the fish migration may be enabled
    30 million CZK (1 million EUR)
  3. Total expenditures on afforestation and grassing down
    • Grassing down parts of arable land, predominantly on sloped-down areas in the upper and central part of the Morava River
      We suggest grassing down nearly 172 000 hectares of arable land (about 18% of the total area of the Morava River Basin) within the next 10 years with the total cost of about 1.5 billion CZK (50 million EUR).
      Note: The share of grass on arable land in the Czech Republic is very low - around 20% in average, whereas the grass share in the EU countries reach about 40% in average.
       
      Example of a harmonious landscape

      Photo 3    Example of a harmonious landscape
      Proposed anti-flood measures should lead to reducing erosion threats and improving water quality in streams and rivers. The measures should also promote the development of the countryside, thus increasing its attractiveness. The photo shows a highland area lying on the Bohemian-Moravian border, which is an example of a harmonious landscape.

    • Afforestation
      The afforestation will concern specifically chosen areas (around 17 000 hectares) of arable land, which is about 2% of the total area of the Morava River Basin. About 9 000 hectares will be afforested at inundation areas of the bottomland (in order to slow down flood waves), the rest (8 000 hectares) will fall on the afforestation of extremely sloped-down areas.
      The total cost of a 10-year afforestation work will be approximately 1.7 billion CZK (56.7 million EUR).

    Possible financial sources

  1. Regional and local authorities
    Tailor-made flood protection of urban areas is a predominately political matter. The municipal and local authorities should take over at least the minimal share of the above-mentioned costs. The regional authority (and the state) should pay most of the necessary expenditures.
  2. EU funds
    The EU structural funds may be used on condition that the anti-flood measures are environment-friendly.
  3. Government subsidies
    The Czech government has been providing subsidies on the afforestation and the grassing-down of arable land (including its upkeep) for many years.
    In connection with the accession of the Czech Republic into the EU, the Czech government is currently preparing a new "grassing-down" programme which will provide subsidies for grassing down and subsequent 5-year upkeep of the grassed-down areas.
    The financial support for this specific utilisation of arable land has not yet been sufficient enough to persuade farmers to re-direct their effort towards carrying out activities other than mere production of agricultural crops. Unfortunately, an institution making preparations for afforestation and grassing down, organising and co-ordinating activities related to alternative farming or changes in arable land utilisation and motivating farmers towards performing these changes is still missing in the Czech Republic.

 

Authors:

Vaclav Cermak
Veslarska 254
637 00 Brno-Jundrov
Czech Republic

Helena Kralova
Ustav vodniho hospodarstvi a krajiny VUT
Zizkova 17
602 00 Brno
Czech Republic
tel.: +420 541 147 776
e-mail: kralova.h@fce.vutbr.cz

Kamila Florova and Jaroslav Ungerman
Unie pro reku Moravu (Union for the Morava River)
Panska 9
602 00 Brno
Czech Republic
tel.: +420 542 422 755
e-mail: unie.rekamorava@ecn.cz

This report is a shortened English version of a study called "Alternativni ekologicky navrh protipovodnovych opatreni v povodich rek Moravy a Becvy" (Environmentally Sustainable Flood Protection Measures for the Morava and the Becva Rivers) available in Czech at http://www.sweb.cz/uprm/po.html This study was prepared by the Union for the Morava River within the "Integrated Decision-Making at the Environment and Public Participation Support" PHARE project under No. CZ9705-0503.

The Union for the Morava River is a network of 18 mostly non-governmental environmental organisations and 25 individual members which operate in the Morava and Vlara River Basins in the Moravian region of the Czech Republic. The Union started in 1993 and it is represented by a council of spokesmen and spokeswomen, elected each year on a general meeting.
The Union for the Morava River is:

  • seeking, as its main purpose, to renew the natural character of water courses;
  • seeking to support all life forms in natural water as well as on riverbanks;
  • supporting efforts which will result in clean water courses;
  • initiating environment-friendly flood-preventive measures.
The Union has already gained the respect of hydro-specialists as well as the general public due to its publication activities, due to its specifically-aimed projects, and due to its active participation in discussions on flood protection measures. The Union collaborates with many natural-science and technical-science professionals and participates in administrative procedures related to investment projects on water management and the environment. Since 1999, the Union has been a member of the international Danube Environmental Forum, currently based in Bratislava, Slovakia.

Unie pro reku Moravu (Union for the Morava River)
Panska 9
602 00 Brno
Czech Republic
tel.: +420 542 422 755
fax.: +420 542 422 752
e-mail: unie.rekamorava@ecn.cz and jaroslav.ungerman@ecn.cz
URL: http://www.sweb.cz/uprm/