Résumé
Summary
Restoration of two wetlands along the Danube River within Persina Nature Park, through engineering works including sluices, channels, dykes and access roads, enabling controlled flooding, water flow to former wetlands, nutrient retention, and recovery of biodiversity and fish populations. Baseline data on water, birds, fish, mammals, reptiles and vegetation were collected for monitoring.
Implemented 2002–2008 by the Bulgarian Ministry of Environment and Water, with main funding from the Global Environment Facility (GEF) via the World Bank, the project also covered the Kalimok-Brashlen and Belene Islands Complex. Works improved hydrological connectivity and reduced pollution, supported by WWF Bulgaria and local communities.
Subsequent initiatives have continued restoration and management, including sluice maintenance, construction of a pelican nesting platform, and reintroduction of the white water lily. In 2025, the Persina4Nature project, under the DANUBEPARKS network, was launched to promote citizen science for wetland conservation and monitoring, further enhancing ecological and community engagement outcomes.
Photo gallery
Vue d'ensemble
Year of issue
2025
Project
NWRM
Implementation status
Completed
Contact
Jovanka Ignjatovic REC
Location of the project
Belene Island (2 280 ha) within the Persina Nature Park and Kalimok/Brushlen (1 755 ha) within the Kalimok
Country
Bulgaria
NUTS2 Code
Северен централен (Severen tsentralen)
Sponge measures implemented in the case study
Wetland restoration and management
Objectives
Project aim: “Create a model for reducing trans-boundary nutrient loads in the Danube and Black Sea basins and to preserve biodiversity in the protected sites through: restoration of wetlands, management plans for protected sites and support to the local people in adopting environmentally friendly economic activities.”
Involved partners
| Authority type | Authority name | Authority role | Comments | Authority responsibility |
|---|---|---|---|---|
| National water authority | Government of Bulgaria, Ministry of Environment and Water | Implementation | and Financing | — |
| Local water authority | Persina NP Directorate (NPD) | Monitoring | Long-term maintenance and monitoring of impacts | — |
| Regional / sub-national water authority | Dabube River Basin Directorate | Monitoring | Monitoring of WFD compliant quality elements, integration into RBMP | — |
| NGO | WWF Bulgaria | Monitoring | Partner in restoration/management follow-up (incl. work at Kaikusha; later practical actions such as infrastructure and habitat measures). | Supporting |
| NGO | BSPB (Bulgarian Society for the Protection of Birds) | Implementation | Co-implemented pelican platform with Persina NPD and WWF. | Supporting |
| Other | Belene Prison Administration | Other | Land user (agriculture/pasture) in western Persin; part of site jurisdiction. | Responsible |
Site Information
Climate Zone
Cool temperate dry
Precipitation
540.00 mm
Temperature (°C)
11.70 °C
Evapotranspiration
0.27 mm
Runoff
6000.00 mm
Runoff coefficient
0.15
Elevation range
15
Slope range
0.015
Vegetation class
Dominant wetland/floodplain types: riparian willow–poplar forests and extensive reed and cattail communities, with marsh macrophytes (e.g., water-lily/trapa communities) documented for the island marshes.
WFD Ecological status
Moderate
WFD Chemical status
Failing to achieve good
Water quality status
past conversion of alluvial forests to poplar plantations, planned/ongoing navigation dredging, potential industrial dredging, wild boar disturbance; within-site agriculture by the prison administration.
Design and Implementation
Project scale
Meso
Project scale specifications
Construction work and soft measures implemented in two protected sites, including one Nature park
Project area
4035
Principles
Primary goal of the project is connected with the reduction of nutrient pollution by restoration of wetlands and their respective nutrient capture capacity.
Besides this goal, the project design follows the objectives related to the biodiversity conservation and the principle of conformity with the management objectives of the protected sites.
Besides this goal, the project design follows the objectives related to the biodiversity conservation and the principle of conformity with the management objectives of the protected sites.
Factor constraints
Design of infrastructure facilities (dykes, sluices, channels, adjacent roads) was elaborated depending mainly on the topography of the island (for Persina) and the riparian bank and floodplain zone (for Kalimok-Brushlen).
Other key factors were the shape and depth profiles of the former wetlands, design of the old dykes, hydraulic parameters of Danube River (flow, water level and seasonal fluctuations) as well as the desired water regime for the wetlands biodiversity.
Other key factors were the shape and depth profiles of the former wetlands, design of the old dykes, hydraulic parameters of Danube River (flow, water level and seasonal fluctuations) as well as the desired water regime for the wetlands biodiversity.
Constraints
Possible appearance of disease because of mosquitoes
Favourable preconditions
Due to the hydrogeological conditions of the sites, parts of the wetlands continued to exist and have a high potential for restoration.
Financing
Total cost
9700000.00 €
Total cost information
Cost of restoration of Belene Island and K/B Marshes and other additional sites
Costs investment information
Cost of restoration of Belene Island and K/B Marshes
Costs capital
5480000.00 €
Costs capital information
Design & construction
Costs land acquisition
31000.00
Costs land acquisition unit
€ (total value)
Costs operation maintenance information
Operation of the facilities for regular flooding
Costs operational
600000.00 €
Costs operational information
Management and monitoring
Costs other
3600000.00 €
Costs other information
Protected areas management, capacity building, technical assistance
Economic costs additional
661000.00 €
Information on Economic costs additional
Restoration of additional sites
Administrative annual costs
3600000.00 €
Administrative annual cost information
Protected sites management planning, Capacity building, Monitoring
Compensations
Non
Policy and Governance
Policy description
Over the years, the wetlands and floodplain have been drained or dyked to create arable land and to reduce malarial mosquito habitats. Now the wetlands area is about 10 percent of its original size at the turn of the century, reducing the capacity of its ecological function of water purification.
Land ownership
State: 47%, Municipal: 10%, Private: 43%. Western Persin Island used for agriculture by the Prison administration (pastures; some hybrid poplar).
Policy targets
Pollutants Removal
Improved Biodiversity
Increase Water Storage
Target remarks
Natural assimilation (purification) of effluents through dilution, dispersion, and physic-chemical processes. Biodiversity and gene-pool conservation in riparian areas.
Policy pressure
| Directive | Relevant pressure |
|---|---|
| WFD identified pressure | 4.1.1 Physical alteration for flood protection |
| WFD identified pressure | 4.1.2 Physical alteration for agriculture |
| WFD identified pressure | 1.1 Point – Urban waste water |
| WFD identified pressure | 2.2 Diffuse – Agricultural |
Policy impact
| Directive | Relevant impact |
|---|---|
| WFD identified pressure | Nutrient pollution |
| WFD identified pressure | Altered habitats due to morphological changes |
Requirement directive
| Requirement directive | Specification |
|---|---|
| WFD-achievement of good ecological status | Mitigation of nutrient pollution and morphological alterations |
| WFD-restoring a HMWB | Lower Danube is described as HMWB in DRBMP |
| WFD-achieving objectives for Protected areas | Natura 2000 |
| The Birds and Habitat Directives | EU-Directive 79/409/EEC (Birds Directive 1979) EU-Directive 92/43/EEC (Habitats Directive) |
Requirement directive remarks
RBMP of Danube River District
National Wetlands Conservation Plan of Bulgaria
National Biodiversity Strategy
National Wetlands Conservation Plan of Bulgaria
National Biodiversity Strategy
Part of a wider plan
Oui
Wider plan
| Wider plan type | Wider plan focus | Name | Comments |
|---|---|---|---|
| National | Environment & Biodiversity | GEF Black Sea/Danube Strategic Partenrship-Nutrient Reduction Investment fund | Bulgaria's strategy for nutrient reduction, biodiversity and agriculture and rural development. |
Public consultation
Oui
Consultation activities
| Activity type | Comments |
|---|---|
| Public and media outreach | The aproach ensure public awarenes |
| Training and consulting of local | Local consulting in Belene, 30th of June, 2002, 25 participants and in Slivo Pole, 31th of June, 20. |
| Project promotion | Public support as well as support of public institutions and donor community in the country. |
| Environmental education | — |
Has contractual arrangements
Oui
Contractual arrangements
| Arrangement type | Name |
|---|---|
| Contractual agreement | Global Environmental Facility Trust Fund Grant Agreement |
Impacts and Monitoring
Monitoring System
Monitoring requirements
A comprehensive environmental monitoring program was developed with the financial support of the PHARE program.
Monitoring parameters
Nutrient load reduction: N and P monitoring on annual basis.
Biodiversity benefits: Monitoring of the total number of protected species and the quantitative status of target species.
Biodiversity benefits: Monitoring of the total number of protected species and the quantitative status of target species.
Maintenance
Maintenance requirements
Maintenance of the dykes, sluices and other hydraulic facilities on annual basis. Operation of the sluices on daily basis in order to ensure appropriate water regime – ensure by Park administration
Impact Assessment Methodology
Performance impact assessment method
Catchment outlet
Performance impact estimation information
N and P monitoring on annual basis. Biodiversity database carried out in the period 2001-2008
Socio-economic Impacts
Direct benefits information
Protection of the Danube river basin from nutrient pollution inccreasing and improving the water quality.
Ancillary benefits information
Increased economic benefits due to fishery and biomass production and farming practices.
Chance for future tourism development in the region, new employment opportunities and economic benefits due to fishery and biomass production as well as for protection of the Danube river basin from nutrient pollution inccreasing and improving the water quality. The project has also introduced a new idea that wetlands are not a necessary evil, making the landscape attractive.
Chance for future tourism development in the region, new employment opportunities and economic benefits due to fishery and biomass production as well as for protection of the Danube river basin from nutrient pollution inccreasing and improving the water quality. The project has also introduced a new idea that wetlands are not a necessary evil, making the landscape attractive.
Biophysical impacts: Hydrology
Retained water
9.00
Retained water unit
mio m3/month
Information on retained water
In total both sites
Information on increased water storage
The space for flooding is wider, with the selected situation of the dykes, with an area of 4035ha
Runoff reduction
5.00
Runoff reduction unit
% Percent
Information on runoff reduction
Runoff control by controlled flooding regime of the restored wetlands.
Peak flow reduction
1.00
Peak flow reduction unit
% Percent
Information on Restoring hydraulic connection
Area re-wetted/restored: 4,035 ha of former marshes (vs. 2,340 ha planned) were restored across the two pilot sites; Persina forms a major share.
Information on reducing flood risks quantity
Flood regime & buffering: Test flooding on Belene (Persina) was completed in April 2008; restored wetlands are noted to buffer flood waters in the lower Danube. Hydraulic control: Sluices, channels and dykes constructed; Persina Nature Park Directorate operates the sluices for Persina Island and nearby Kaikusha marsh.
Biophysical impacts: Biodiversity
Improved biodiversity
Oui
Information on improved biodiversity
Rapid post-flood response (Belene/Persina, 2008): Within ~2 months of the first flooding, 10 new fish species were recorded in the restored area; ferruginous duck nesting pairs increased from 5 to 50, and mallard from 16 to 400. Bird numbers of 22 species were found to increase. Colonial waterbirds: Dalmatian pelican breeding recorded on Persina/Belene for the first time in ~60 years (2016).
Aquatic macrophytes: Water lilies (protected species) were reintroduced and have returned to Persina’s marshes following restoration actions.
Aquatic macrophytes: Water lilies (protected species) were reintroduced and have returned to Persina’s marshes following restoration actions.
Biophysical impacts: Water & Soil Quality
Water quality overall improvements
Positive impact-WQ improvement
Information on water quality overall
The measure has impacted the overall water quality by nutrient reduction and capture (N, P) and capture of organic pollutants. Preliminary analysis indicates that the total nutrients reduction could reach 2.200 tons/year nitrogen and 284 tons/year phosphorus.
Soil quality overall improvements
N/A info
Information on soil quality overall improvements
No info available
Biophysical impacts: Others
Ecosystem impact climate regulation
No information available
Information on ecosystem impact climate regulation
No info available
Increased evapotranspiration information
Evaporation in the wetland will be as max about 1 m3/sec.
Lessons Learned
Key lessons
The Persina wetland restoration shows that large-scale floodplain reconnection on the lower Danube is possible even in heavily altered landscapes. Restoring controlled hydrological connectivity through sluices and channels re-established seasonal flooding over thousands of hectares and triggered rapid ecological responses. The sudden return of fish diversity and waterbird colonies after the first flooding illustrates the resilience of floodplain ecosystems once hydrology is restored.
When many stakeholders are involved, longer groundwork is essential. Participatory approaches to restoration design proved critical for success, as the project depended on changing people’s perceptions of wetlands and securing full support from authorities and local communities. The work of the Protected Area Local Consultative Councils and targeted public-awareness campaigns effectively supported this involvement.
Controlled restoration has provided a platform for large-scale experimentation and for studying nutrient-trapping processes under real conditions. This approach allowed managers to adjust operations based on ecological feedback and hydrological performance.
A solid understanding of both the baseline conditions and the desired future ecosystem state should be embedded early in the design phase. While baseline water-quality and biodiversity data were collected, the project itself recognised that long-term monitoring—10 to 15 years—would be needed to fully assess nutrient retention and other hydrological benefits. The absence of easily accessible long-term datasets today limits the ability to quantify these outcomes.
The case also shows that restoration is not a one-off action. Follow-up measures such as hydraulic-structure maintenance, reintroduction of aquatic plants, and creation of nesting platforms have been essential to sustaining ecological gains and adapting to changing environmental conditions.
When many stakeholders are involved, longer groundwork is essential. Participatory approaches to restoration design proved critical for success, as the project depended on changing people’s perceptions of wetlands and securing full support from authorities and local communities. The work of the Protected Area Local Consultative Councils and targeted public-awareness campaigns effectively supported this involvement.
Controlled restoration has provided a platform for large-scale experimentation and for studying nutrient-trapping processes under real conditions. This approach allowed managers to adjust operations based on ecological feedback and hydrological performance.
A solid understanding of both the baseline conditions and the desired future ecosystem state should be embedded early in the design phase. While baseline water-quality and biodiversity data were collected, the project itself recognised that long-term monitoring—10 to 15 years—would be needed to fully assess nutrient retention and other hydrological benefits. The absence of easily accessible long-term datasets today limits the ability to quantify these outcomes.
The case also shows that restoration is not a one-off action. Follow-up measures such as hydraulic-structure maintenance, reintroduction of aquatic plants, and creation of nesting platforms have been essential to sustaining ecological gains and adapting to changing environmental conditions.
Drivers
| Driver type | Driver role | Comments |
|---|---|---|
| Legal obligations | Main driver | The Environmental Program for the Danube River Basin as a `preemptive measure to prevent river Danube and Black Sea water pollution from reaching catastrophic proportions` |
| Legal obligations | Main driver | Danube Pollution Reduction program (DRP) |
Success factors
| Success factor type | Comments |
|---|---|
| Attitude of relevant stakeholders | The intensive stakeholder involvement during design and implementation created strong ownership and sustainable Project outcomes |
| Financing possibilities | The overall co-financing proveded by government substantially exceeded amounts agreed at appraisal. |
| Existing staff and consultant knowledge | Bank and Gobernment cooperation was in timely attention to critical implementation issues. |
Cost effectiveness
Reducing nutrient loads in the Danube River. Total cost-effectiveness ratios were estimated at US$1.3 to US$5.0 per kilogram of Nand US$28.9 to US$46.2 per kilogram of P removed annually.
Flexibility / Adaptability
Adaptation to changing ecological and hydrologic conditions of Danube River can be achieved by flexible operation of the hydraulic facilities (sluices) in order to maintain optimal water regime.
Transferability
Similar restoration works could be designed for other riparian (former) wetlands along medium and large rivers in their lower segments.
The first follow-up Project, “Kaikusha”, under EU LIFE+ program helps develop feasibility studies to restore the Kaikusha Marshes in the Danube River basin.
The first follow-up Project, “Kaikusha”, under EU LIFE+ program helps develop feasibility studies to restore the Kaikusha Marshes in the Danube River basin.
Basin characteristics influence
The low inclination and the plain landscape along lower Danube allow the achievement of relatively large flooded areas with low-head structures. The large mean discharge of lower Danube makes difficult to assess the measure relative impact due to scale.
Sources
Sources