Co-Working with Nature in the Kamchia River Basin

The RECONECT Bulgarian Collaborator is affected by pluvial, fluvial, and flash floods (generated by the emergency discharge of local dams), even simultaneously. Local communities fight against floods in every way they can, but their home-grown risk management lacks important elements to be fully operational. This is where RECONECT steps in.

11 min readJan 28, 2021


Authors: Lyudmil Ikonomov [1], Valeri Penchev [2], Antoaneta Kirova [2], Daniela Stoycheva [1], Sylvia Stoilova [1], Shirin Shukrieva [2]

[1] Regional Administration of Varna (a NUTS2 administrative unit) — project partner of RECONECT in Bulgaria; [2] Black Sea — Danube Association of Research and Development — lead project partner of RECONECT for Bulgaria;

The Kamchia River Basin is located in the eastern part of Bulgaria, covering nearly 5% of the national territory. Although not too big, Kamchia is the longest river on the Balkan Peninsula which flows directly into the Black Sea.

Figure 1: Topographic map of Bulgaria

The Kamchia Basin, consisting of 101 rivers and small creeks, is orientated in West-East direction towards the Black sea and is strongly influenced by the mild coastal climate. In winter and spring, frequent intensive rainfalls bring large amounts of sediments into the river; the water becomes quite turbid and the transport of suspended solids into the Black Sea is very high.

The amount of precipitation varies significantly within the catchment area. The average annual precipitation in the selected RECONECT focus area is around 700 mm a year (see fig. 2). In normal meteorological conditions, Kamchia is not too large a river in its middle course (see fig. 3). Even its lower course (fig. 4) and its Black Sea estuary (fig. 5) are not too impressive. However, due to its enormous catchment area, it becomes really dangerous in times of long-term continuous rains or in early spring during the snowmelt. For example, on 12ᵗʰ January 2021, the RECONECT sensors installed recently by BDCA registered a river level rise of 5.2 m only in a couple of hours in heavy rain conditions. Fortunately, the water didn’t flow over the dykes but the situation was quite dramatic.

Figure 2: Precipitation map (locations of the measuring stations and annual mean values). Figure 3: Middle course of the Kamchia River in normal meteorological conditions. Figure 4: Lower course of the Kamchia River. Figure 5: “Longoz” flood forests in the Kamchia Estuary Biosphere Reserve.

The zone around the Kamchia estuary is called Kamchia Biosphere Reserve”, a protected territory in which human activities are banned since the 1950s to protect the remnants of floodplain forests, which once covered a considerably larger area. The Kamchia Biosphere Reserve is, by itself, a huge Nature-based Solution for neutralising potential high flood waves. It comprises a vast flood plain and a big forest area which is being flooded almost every year, usually in spring. The “Longoz” forests, as they are called, are one of the best-preserved flood plain forests in Europe.

Water-related hazards affecting the area

Since 1914 until 2010 totally 241 floods have occurred in the Kamchia River basin. In 2015 and 2018 two heavy floods occurred in the middle course of the Kamchia River which, fortunately, didn’t cause human casualties and heavy material damage. Nevertheless, they caused the evacuation of the population in one town and one village and blowing up dykes in two places (see fig. 6) to avoid more severe flooding of the residential areas. Although these two floods happened in the Kamchia basin they were not riverine, but caused by storm waters flowing down the hills after days of heavy rains. The nature of floods in the middle and lower course of the Kamchia River has been quite diverse. There have been fluvial floods caused by high waters in the Kamchia and its tributaries, pluvial floods caused by storm waters and there have also been flash floods caused by the emergency discharge of two local dams. In the Kamchia estuary storm surge coastal floods are frequently occurring caused by high waves from the Black Sea. The most dangerous flood scenarios occur when two or more types of floods happen together at one and the same time. The simultaneous action of high river waters and heavy rains flowing down the hills doesn’t leave much chance for a safe life in the settlements in the middle course of the River. The situation becomes much more complicated in case of emergencies when the huge Tsonevo Dam has to be discharged to prevent even bigger disasters.

Figure 6: Dykes which have been blown up to prevent the flooding of residential areas in Dalgopol

So, which is the area with the highest natural demand for mitigating the flood risk using Nature-based Solutions and where is the RECONECT Area of Focus in the Kamchia River Basin?

The Kamchia River case study was initially based on two areas of potentially significant flood risk identified in the Black Sea River Basin Flood Risk Management Plan. The first one was the estuary of the Kamchia River and the second one lies some 20 km westwards.

Based on the data received from the Department of Mobilization Preparedness in the Regional Administration of Varna about the most dangerous floods caused by Kamchia in the last decade; on the suggestions made by the stakeholders during a practical discussion of flood scenarios held in May 2019; and on the information collected further in August 2019 from the Municipal administration of Dalgopol and the Mayor of Grozdyovo, the RECONECT team and the stakeholders decided jointly that the area around the City of Dalgopol must also be included in the RECONECT focus area in the Kamchia River basin. Thus, the designated Focus Area now covers a total area of over 20,000 hectares (see fig. 7).

Figure 7: Focus Area in the Kamchia River basin — the pilot area where the high flood risk will be mitigated using Nature-based Solutions

NBS in the area before RECONECT

People living in the RECONECT Focus Area have been anything, but passive throughout the years. They have struggled against the flood risk in every way they could. The residents of the town of Dalgopol and the village of Dabravino have built floodgates on the dykes near the Kamchia River and on the railway embankments in order to divert the floodwaters into the necessary direction. In facts, in case of fluvial floods, floodwaters have to go to the north to keep the settlements safe and, in case of pluvial floods, they have to be drained to the south. However, in the absence of water level sensors and a remote-control system, these floodgates are not very useful and the people do not know exactly how to operate them. Therefore, they keep them half-open in the area of Dalgopol and completely shut in the area of Dabravino which only shows that there are important elements missing from this “home-grown” flood risk management concept to make it really operational.

Figure 8: Floodgates in Dalgopol (half-open). Figure 9: Floodgates in Dabravino (fully shut)

Close to Dabravino, some 50 years ago a small barrage has been built on the Kamchia course to form a small dam for water-intake for irrigation. Today it only increases the flood risk and is one of the facilities which have to be removed. The Village Mayor is quite aware of this and strives for its removal. In the meantime, the people in Dabravino have invented a creative way to help the Black Sea Shad (Alosa pontica) overcome this barrage and go upstream the Kamchia River to throw its caviar. They have placed a small gutter to allow the fish to “climb” the barrage and continue its way upwards, against the river course (see fig. 10).

Figure 10: A small gutter helping the Black Sea Shad overcome the barrage and go upstream

The City of Dalgopol has built a special drainage canal whose purpose is to bring the waters into the Kamchia River in case of pluvial (stormwater) floods. This canal has gradually turned into a natural bio-swale (see fig. 11).

Figure 11: Southern drainage canal of Dalgopol — now an element of the green and blue infrastructure

The Municipality of Dalgopol has prepared a technical design for widening and deepening of this Southern Canal and lining it with stone plates for improving its conductivity and for preventing natural erosion. The RECONECT team is lobbying for strengthening its biological role as a green and blue corridor and as a part of the biodiversity-maintaining infrastructure in the area.

The dykes which have been built back in the sixties on both sides of Kamchia are also a part of the green and blue infrastructure because they control the river and keep its waters inside its bed, but they are also an important part of the green system with the vegetation on them. Today, the dykes are a little bit worn out and have sunk for nearly one metre and have to be strengthened and restored.

Figure 12: The dyke south of Dabravino has been considerably worn out and sunk by nearly 1 m

Why joining RECONECT?

The main reason is that the flood preventive measures currently applied in Bulgaria are not entirely effective. For the time being, there is a strong focus on hard engineering measures, mostly on river bed corrections and strengthening banks mainly by “casting concrete”. But those types of measures are in many ways ineffective: they are efficient at lower flood waves (of 10- and 20-year return period) but at higher waves (expected for the Kamchia) the effect is just the opposite — the damage is usually higher in rivers which have corrections and modifications compared to those which have not. It might be appropriate, instead, to take a more nature-based approach and designate lowland plots of arable land (and perhaps some large-area municipal facilities like sports grounds as well) as retention ponds in case of floods. And this is where RECONECT could help a lot.

What is RECONECT currently doing in the area?

RECONECT has carried out several surveys which pushed forward the flood risk reduction work in new directions. The stakeholder survey helped the Regional Administration develop a better view of the expectations of the local stakeholders about the potential goals to be achieved. Over 80% of them said that the hydro-meteorological risk, the water quality, the socio-economic and cultural contributions, and the human well-being are the primary areas where they wish to see positive results from the implementation of NBS in the Focus Zone. The collaborator survey helped get a better understanding of the role of NBS, of the practical ways to apply them and of their potential co-benefits. Through this survey, the local RECONECT team identified the project partners of both types (demonstrators and collaborators) which are dealing with similar issues and are most relevant to cooperate with for the Kamchia case. This survey was a major step towards developing a methodology for reaching out and up-scaling NBS in the Focus Zone and in the whole Kamchia Basin, well beyond the project’s lifespan. The survey on the demand for NBS gave an insight into the potential for NBS in the Focus Zone. This survey was instrumental in formulating a plan to support the co-creation work with other interested parties for increasing the positive impacts of NBS in the Focus Zone.

In September-December 2020 the Regional Administration of Varna launched two field surveys funded by RECONECT — one on potential retention and detention ponds in the area with regard to the forthcoming land-use planning (fig. 15) and one on the biodiversity in the Focus Zone with regard to the future measuring of the biological impact of NBS (fig. 16).

In November 2020 BDCA has undertaken the first practical steps towards creating an integrated flood management system in the Focus Zone by installing sensors in three different places for continuous monitoring of the Kamchia River level. The testing and validation of the sensors have already started, as well as the integration of the data in TeleControlNet — the ICT platform of RECONECT.

What has worked or hasn’t worked so far?

The stakeholder mapping methodology of RECONECT helped greatly to intensify the connections with the local key players and elaborate with them a common vision on the potential Focus Area and on the flood risk management concept. The early established relationship with the key interested parties was crucial for acquiring adequate information on the local flood hazards and for identifying jointly possible combinations of NBS which could reduce the flood risk considerably (see fig. 13).

Figure 13: The Regional Administration of Varna organised a training session for stakeholders on which they had to solve practical cases for reducing the flood risk in the Focus Area through NBS

The multi-criteria analysis of stakeholders’ interests (with 28 respondents) worked perfectly in the process of identifying the right project goals related to waters, nature and people and to outline the potential NBS which could be applied in the Kamchia River Basin.

Nature-based solutions are relatively new in Bulgaria and mostly for this reason they meet certain barriers on the way of their implementation. The first important barrier is the ownership of land. With so many small plots (see fig. 14) the local authorities will have to deal literally with hundreds of owners which makes the whole process extremely clumsy and lengthy. Another drawback is the (still) limited political recognition of NBS by the local authorities as a proper tool for mitigating flood risk. However, despite the barriers and the difficulties, the RECONECT project team is gaining speed quite fast.

Figure 14: Map of land ownership in the Focus Area. Figure 15: Potential retention ponds

Funding is always a problem. Therefore, BDCA and the Regional Governor of Varna have started a correspondence with the Bulgarian Minister of Environment to lobby for improving the terms and conditions of public funding programs, so that national funding can be provided for implementing NBS through the “Environment” Operative Program. The first reaction of the Minister was quite positive.

A remaining challenge is the promotion of a National Policy and a National Agenda for implementing NBS using the RECONECT replication and upscaling methodology. Another challenge is the Upgrading of the spatial planning practices and convincing the local authorities to include a new chapter called Adaptation to Climate Change” in their Municipal Spatial and Land-use Plans. This work is underway.

Why working for the environment?

The middle and lower parts of the Kamchia River Basin are well known for their unique biodiversity and for the “Longoz” forests which are considered a national bio-spheric wealth. For this reason, the biodiversity survey will be used as a baseline for the biological impact of the NBS on nature. Eight potential retention and detention zones have been designated in the Focus Area because they are effective and environment-friendly natural elements of the local flood management system.

Figure 16: Biodiversity survey in the Focus Area

Any lessons learned from working on RECONECT?

There is just one lesson learned so far, but a very important one: It is really hard to invent anything smarter than what has already been invented by Nature. Nature is our best teacher.




The RECONECT project demonstrates the effectiveness of Nature-Based Solutions for hydro-meteorological risk reduction in rural and natural areas