Dyakov O., Sizo R., AZBOS

The summarized length of the Azov and Black Seas coastline within Ukraine constitutes 3065 km. Five main biotopes (ecotones) can be distinguished along Ukrainian Azov-Black Sea coastline: 1) Sedimentary deposits (sand, mud, clay); 2) Rocky coasts; 3) Salt lagoons; 4) Limans and deltas; 5) Wetlands and salt marshes.

Determination of main drivers influencing on the state of the coasts and coastal biotopes of the Black Sea and the Sea of Azov

A main natural factor of ruination of the Azov-Black Sea coasts and transformation of relevant biotopes is abrasion processes (mechanical ruination of coasts under activity of waves and surf). Maximal harm from abrasive ruination is caused by landslides and shifts of rocks, connected with relief of the coastal zones, which depend on the slope profile, gravitation processes, geological structure of above-water and underwater parts, geological conditions and tectonic regime of the region. On flat areas of the marine coast the abrasive-landslide coasts transit, as a rule, to abrasive-shifting ones with the height of the coastal cliff over 20 m. Almost 50% of the Ukrainian marine coastline is under negative impact of washoff and erosion and has a high ruination level with abrasive and shifting processes.

Anthropogenic factors influencing on the coastal zone development can be divided into direct or indirect ones.

Direct factors are:

1. Development of the coastal zone. Industrial, communal, recreation constructions and port facilities, building of oil-gas and irrigation communications under certain conditions provide a negative impact on areas of abrasive and accumulative coasts breaking a settled dynamic balance.

2. Coast-protective constructions without proper calculation of hydrodynamic factors break balance of currents of detrital sand-seashells material and accelerate the washout of bottom and ruination of coasts.

3. Excavation of sand deposits of sea beaches, spits, underwater banks in most cases has broken the dynamics balance on considerable areas of Black Sea and Azov Sea coasts and, as a consequence, has led to the washout of adjacent bedrock coasts. The coasts in the region of Yalta Bay, Odesa, Henichesk, Mariupol, etc. suffered from the most ruination.

4. Construction of marine entrance channels to ports and dredging works create traps for sediments on a coastal slope which also increases the ruination intensity of bedrock coasts.

5. In recent years, in connection with increase of the number of recreants including unorganized ones, their influence on coasts and coastal biotopes has grown. Apart from garbage, an important factor is mechanical ruination of sand relief forms of the coastline and shifting coasts, destruction of vegetation and reduction of beach areas.

Indirect factors are:

1. Regulation of river systems and removal of continental runoff which on the one part change the balance of sand material, and on the other part biogenic and hemogenic components, cause reduction of accumulative formations and decline in biological productivity of coastal water areas. The runoff regulation has caused an evident increase of water salinity in the north-western part of the Black and Azov Seas (in 1970s-1980s) and reduction of bottom molluscs biomass; when dying these molluscs compose a main component of detrital material accumulating in the coastal zone.

2. Irrigation works, which were carried out in some agricultural areas of the coastal zone (Lake Sasyk area, etc) with usage of high-mineralized water, have led to structural changes, loss of soil fertility and withdrawal of these lands from usage. Some negative phenomena in land use are registered also along the North Crimean Channel; they are caused by rising ground water level.

3. Pollution of water and bottom sediments with communal, industrial and irrigation wastewater, vehicles, etc. As a result, the marine environment suffers from inflow of a wide spectrum of high toxic organic and non-organic substances and compounds including such heavy metals as mercury, lead, cadmium, zinc, copper, chrome. They are partly neutralized in the coastal strip on a geochemical barrier due to mix of fresh and salt waters, absorbed by bottom sediments and coastal hydrobionts. However, when harmful substances enter in extremely high concentrations, some coastal sites suffer from a critical ecological situation. The most frequent these phenomena are in the region of industrial and port cities – Odesa, Kerch, Mariupol, and also in the regions of rice growing (Kherson Region).

Assessment of transformation of the Black Sea and Azov Sea coasts

Assessment of the present transformation of the Black Sea and Azov Sea coasts were carried out visually using satellite images. The analysis was based on satellite images LandSat4-7 of the years 1999 and 2011 (October-November). The satellite images were ordered from glovis.gov.ua and received as archives with files of .geotiff format for each canal of survey. Using the programme ERDAS IMAGINE the canals were combined in one file. Thus, two .img-files were obtained for 2 years of the survey. To estimate changes, both images were opened in ArcGIS applying a standard combination of canals - "artificial colours" (4-3-2).

The coastline with the total length of 3065 km was divided into five types according to its transformation degree:

  1. Untransformed – a section of the coast without evident transformation, located far from settlements and recreation centres.

  2. Untransformed (low recreation pressure) – a section of the coast without evident transformation, located near settlements and recreation centres.

  3. Untransformed (high recreation pressure) – a section of the coast without evident transformation, located in the borders of settlements, health resorts or directly close to recreation centres.

  4. Transformed (developed) – a section of the coast with different buildings and structures.

  5. Transformed Changed (coast-protective and port constructions) – a section of the coast with coast-protective and/or port constructions

According to the analysis of the obtained results an expert assessment allowed to determine the transformation degree of the sea coasts (Fig.1 and Table 1).

Table 1. The length of the coastline of the Black Sea and the Sea of Azov with different degree of transformation

Type of coast

Length*, km

% of the total length

Untransformed

1019,00

33,25

Untransformed (low recreation pressure)

370,00

12,07

Untransformed (high recreation pressure)

1160,00

37,85

Transformed (developed)

254,00

8,29

Transformed Changed (coast-protective constructions)

262,00

8,55

Total

3065,00

 

* Note – total length of the coastline including Dnieper-Buh Liman and coasts of bays in the Black Sea and the Sea of Azov. Syvash Lagoon is not included.

 

Assessment of transformation of coasts and coastal biotopes has shown that only 33% of the Black and Azov Seas coasts in Ukraine are untransformed and remained in a natural state. Over 50% are under influence of recreation; of them about 40% are subjected to high recreation pressure.

Over 8% of the coastline is transformed as a result of coastal development including uncontrolled one, and lately the rate of this process considerably accelerated and is acquiring catastrophic characteristics.

Due to construction of port and coast-protection facilities over 9% of coasts are changed, and coastal biotopes are greatly transformed.

 

Fig. 1. Transformation degree of the Ukrainian coasts of the Black Sea and the Sea of Azov

 

Summarizing the obtained results we can say that about 17% of the Azov-Black Sea coast were essentially transformed or totally changed, 50% are under recreation pressure of different degree. Thus, over 67% of the length of Ukrainian Azov-Black Sea coastal biotopes are under intensive anthropogenic pressure and lost a great part of their natural characteristics and do not perform their ecosystem functions.

One of the most vulnerable are accumulative coasts – sand and gravel-sand bars, spits and terraces of different types located along approximately 1000 km of the Ukrainian Azov-Black Sea coastline. At the present time, due to the growing number of population, active development of recreation, industry and agriculture they are widely developed and involved into economical activity.

But at the same time they are unique ecosystems which give shelter to rare and vanishing species of fauna and flora, breeding and roosting areas of birds, reptiles, insects, arthropods, crustacea.

A particular attention should be paid to eolian relief forms (dunes, barchans, sand ridges) which are an important component of sand coasts since they maintain their stability and general resistance to destabilizing factors, mechanisms of vertical and horizontal deformation of coastal relief, retain integral structure of coastal landscapes, and are an important element of wetlands which support biological diversity at the Azov-Black Sea coasts.

These systems are extremely fragile and vulnerable and require especially scrupulous approach to organization of the territory, planning and management of the accumulative forms with eolian relief on the surface.

Assessment of transformation dynamics of coasts on the example of a model site

Assessment of transformation dynamics of the Black Sea coast was done on the example on a model (pilot) site "Sanzheika-Illichivsk-Odesa" for the period from 2003 to 2012. This site was chosen as a pilot due to availability of the oldest images suitable for work. Unfortunately there was not possible to analyse more prolonged period because the images of necessary resolution were not available for earlier years. The use of extensive free database of remote sensing is not possible because of low resolution of the available data.

Digitization of the coastline was done directly in the Google Earth interface. After that the data were exported in .kml files which allowed to import these data in .gdb format of geo database. As a result, in ArcGIS interface there were obtained 3 linear layers corresponding to situations in 2003, 2008 and 2012.

It was found out that in the pilot site there are 3, 4 and 5 types of transformation (see the text above). For each year it was calculated the length in km for each transformation type and also its per cent out of the total length of the site (fig. 3).

Fig. 3. Dynamics of length of different types of the coast in km per years

 

Thus, in the pilot site:

  • In the period from 2003 to 2008 the length of untransformed coast with high recreation pressure (type 3) reduced from 5.36 km to 2.94 km. From 2008 to 2012 the length of this coast type remained the same. The reduction of the type 3 coast was at the expense of its transformation into other types of coasts.

  • In the period from 2003 to 2008 the length of transformed coast with development without coast-protective constructions (type 4) increased from 8.56 km to 9.66 km at the expense of transformation of the type 3 coast into type 4.

  • In the period from 2008 to 2012 the length of type 4 coast reduced from 9.66 to 8.52 km km. It is explained by its transformation into the coast with buildings and coast-protective constructions (type 5).

  • In the period from 2003 to 2012 the length of the type 5 coast increased from 4.48 km to 6.94 km at the expense of reducing length of other coast types.

  • In the period from 2003 to 2012 the percentage of untransformed coast with high recreation pressure reduced from 29.13% to 15.96%. The percentage of transformed and changed coast increased, respectively, from 70.87% to 84.94%.

An overall conclusion on dynamics of the model sites relates to a general socio-economical direction of the coastline transformation which may be similar over the all Azov-Black Sea coast. It is expressed in a gradual reduction of the camping and tourism recreation pressure on the coastline and its replacement with a tougher transformation form of the coast with building of recreation centers and coast-protective constructions. It is a dangerous signal of a growing progressive urbanization of the seashore which can have negative consequences for ecotone ecosystems.