Transboundary Floods over Meriç (Maritza/Evros)

02.02.2015
Yazar:Dursun Yıldız
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Dursun YILDIZ Civil Engineer -Hydropolitical Expert Introduction Meriç River Basin is located in Eastern Balkans within the borders of Turkey, Bulgaria and Greece. It is one of the large riversystems of the region and it both forms the boundary between those countries and it is a trans-boundary river. Therefore, water development and management issues for this river require the regional collaboration of those three countries. Up to now, desired level of collaboration has not been achieved, yet. Such a case result in water quality deteriorations in time in Meriç River and caused various flood damages in those three countries.

Of those three countries sharing Meriç Basin, Bulgaria and Greece are EU member countries, but Turkey is still dealing with EU accession processes.Besides, EU Water Framework Directive and European Flood Risk Management Directive ease the regional collaborations on prevention of water pollution and flood damages in Meriç Basin.But, except for small minor progresses, serious progresses have not been achieved in practice for long times.Such a case results in continues flood damages in Turkey.

Increase in water pollution and flood occurrences requires an urgent collaboration on Meriç Basin water issues.Such collaboration will also constitute a sample case for the practical effectiveness of EU Water Framework Directive and resultant outcomes.

Trans-boundary Floods of EU Serious social and economic problems have been experienced because of the increasing occurrences and rates of floods over boundary setting and trans-boundary Meriç River Basin.Turkey has a downstream position in this basin. Thus, agricultural lands and settlements have the largest damages from those flood cases. Floods of Meriç River influence Turkey, Bulgaria and Greece. However, since the sections of the river in Turkey are relatively short, Turkey does not have sufficient time to issue a warning and to take relevant measures. Therefore, Turkey is directly dependent on information to be supplied by Bulgaria to take measures against the floods, for flood estimation and to issue flood warning.

Bulgaria has an upstream position over Meriç River Basin and collaboration projects and construction of Suakacağı Dam were planned with Bulgaria to information share and to mitigate the flood damages of more frequent and severe floods over the basin. Sub-basin of Meriç River Basin has relatively smooth terrain and those lands are not available forthe construction of flood-prevention structures. Therefore, rather than prevention of floods through dam construction, operation and flood management, Turkey and Greece constructed embankments along the river sides in this region to prevent flood damages.

Discharge of water by Bulgaria from the dams during the flood seasons let us to think about insufficient flood storage capacities of those dams.If the sufficient flood offset volumes are not considered in dam reservoirs during the design phases of those dams, it is hard to pass the floods in a controlled fashion with post-design implementations. The basic measure is to get into the flood seasons with reduced dam reservoir levels.However, Bulgaria passed to market economy at the beginning of 1990s and dam operation and hydroelectric power generation processes were transferred to private sector after 1994.The private sector immediately implemented the measure of keeping the reservoir levels at upmost levels to increase hydroelectric power generation.Such a case resulted in large water releases from the dam gates to prevent embankment overflows during the flood seasons. Those dams do not have flood offset volumes. It means they have smaller reservoirs than the required volumes. For instance, in Ortaköy (Ivaylovgrad) Dam, the discharge released from the dam on 13 March 2006 was twice as much of the total reservoir volume. Such a case indicates that this dam was not designed for flood prevention and thus was not able to offset any floods.Such an offset volume brings significant financial load through project revisions, embankment raising and expropriations.

Photo - 1.Flood case in Ortaköy (Ivaylovgrad) Dam of Bulgaria on 13 March 2006[1] Scientific researches revealed that floods might have been prevented with proper implementations and operations of Bulgarian Dams[2]. The same research also indicated that improper operation of the dam resulted in artificial dam floods or overflows.The estimated damage caused by the floods of the year 2006 was about 100 million Euros both for Turkey and Greece (a total economic loss was calculated as 200 million € for the region). The amount to be waived from hydroelectric power generation to prevent the downstream floods of those dams was calculated as 88 thousand €[3].

Thus, just because of the above specified reasons, a comprehensive agreement should be made with Bulgaria to increase the reservoir volumes of those dams,built a new dams and/or implement proper operational measures.

Meriç floods have been dramatically increasing for the last 15 years.
Effectiveness of Suakacağı Dam in prevention of floods in Edirne is relatively at low levels, the main issue herein is to prevent floods from Meriç and Arda Rivers.

Meriç River is a trans-boundary and flood-generating river. Therefore, a package of measures is needed including complimentary measures within the scope of agreements among the basin countries to prevent the floods of Meriç River.
For a permanent solution forthe floods of Meriç River, a sustainable easy-to-implement agreement should be made among Bulgaria, Greece and Turkey for the cleaning and reclamation of the river bed. River bed cleaning works should periodically be performed in a schedule.

With regard to center of Edirne, about 97% of the drainage basins of Meriç Arda and Tunca Rivers are located within the borders of Bulgaria. Thus, the dams over those rivers should so be operated that total flow in Edirne should not pass over 1000 m³/s.

For the Bulgarian dams over Meriç River, a flood offset program should be defined by taking precipitation-flow relations, hydraulic conditions and hydroelectric power generation economy into consideration.

For efficient and permanent solution of the problem, Meriç River should be reclamated, Bulgarian dams over Arda River should be operated with a new program and/or a revision should be made to add flood offset volume to those dams.Otherwise, a new flood offset dam or reservoir should be constructed at the nearest available site to prevent possible floods.
Meriç and Tunca Rivers get into Turkey in a highly polluted fashion. Prevention of such decreases in water quality is as much significant as prevention of flood damages.

The above-specified urgent precautions and measures to be taken should be implemented as soon as possible with the comprehensive meetings and discussions with Bulgaria and Greece and progress should be achieved in those meetings. The items of 23 October 2007 dated and 2007/60/EC numbered directive of European Parliament and European Council on flood risk assessment and management (Annex) assign a clear responsibility to Bulgaria for the floods in Edirne and consequent fee damages. In case of not taking the relevant technical measures urgently, suffered people can appeal to European Human Rights Court. Besides, Turkey may demand the implementation of flood directive issued by European Parliament and then accepted by European Union through Turkish initiations within the scope of accession processes about the damages suffered over Meriç River Basin. All those problems obligate an international consensus and collaboration on Water Management in Meriç River Basin through comprehensive meetings among Turkey, Bulgaria and Greece. Measures taken to reduce flood risk and damage. Four telemetric hydrometry stations have been established in the Bulgarian part of the Meriç Catchments in 2006. These stations are recording continuoisly and supply real-time river flow data to Turkey and Bulgaria. Turkey and Bulgaria developed three joint project through the EU Cross Border Cooperation Programme,one for exchange of information and real time data and two for flood forecasting and warning in 2010.The information is shared on a common web site ,with real time information from two hydrometric stations.The transboundary forecasting and early warning system will be used as input for local and regional preparedness and emergency response plans. A hydrological model was also jointly developed in Meriç Catchments to reduce flood risk and improve preparedness and awareness of all actors in flood prone situations. Flood depths results taken from this model with Q₁₀ of Meriç River Flow in Edirne is given belove .

This has been a distinguish example of the cooperation between two countries for transboundary flood management . But these measures are not totally adequate flood risk management of the Meriç river. Conclusions and Recommendations In a transboundary flood prone area an accurate Flood Forecasting System is very important in terms of detecting timely high water levels and dissemination of information in order to reduce flood risk and damage. 1- In addition gauging and meteorologic stations must be established urgently at the Greece territory with cooperation between Turkey and Greece . İt must also be established "Early Warning Systems" during Meriç River route in Turkey . Using these stations and flood forcast models, occurences of floods could be forcasted in advance and inform Turkey so that damages could be eliminated or reduced considerably 2- %97 of the Meriç, Tunca and Arda rives drainage basins in Bulgaria where many dams are constructed. These dams has to be operated such that discharge at the center of Edirne Province should not exceed 1000 m³/s. 3. On 03.07.2006 a protocol was signed between Bulgarian and Turkish Delegation in Sofia as a result of meeting. According to this protocol a multi purpose dam on the Tunca river (flood control, energy and irrigation) will be constructed by Turkey. For the reduction of the Magnitudes of Floods Tunca Project must be realized by the benefits of both country in soon. 4-A cooperation project between Bulgaria and Turkey funded by EU fund with an amount of 4 000 000 € to increase the capacity of the river bed between the Maritza Bridge in the center of Edirne and Adakule by removing 29 islands formed in the bed is continuing. This projects should be initiated and realized as soon as possible. Cooperation between all three riparian states must be established not only to forecast the floods and inform riparians but also to take necessery measures at the upstream.