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Home >> Rivers >> Threats
  Threats
Pollution

Despite that strict legislation for the discharge of wastewaters from the industry and households is in place in Bulgaria, this type of pollution is the most important factor for the decrease of the water quality

Data about the water quality is available in the websites of the four Basin directorates:

- Danube region
- Black sea region
- Eastern Aegean region
- Western Aegean basin

The diffuse pollution from the agriculture used to be neglected in the past and therefore the data for its extent lacks. However a considerable loads of nutrients and pesticides are proven to exist in surface and ground waters in the areas with intensive agriculture.

The pollution of the rivers with solid waste become a serious problem during the last two decades. Nowadays garbage dumps and illegal deposing of solid waste exist along almost all of our rivers. This waste is transported downstreams by the high water discharges and the infiltrations from the rain waters worsen the chemical status of the waters. This problem is caused by the low environmental awareness of the population but also by the insufficient control by the municipalities and environmental inspectorates.

Habitats loss and fragmentation

- Transformations of the land use and construction on the river banks
- Training the river beds and drying floodplains
- Logging the vegetation on the river banks and islands
- Construction of hydropower plants and other hydro-engineering facilities

Morphological changes

Training the river beds has affected the hilly and flat country sections of the most of our rivers. The trend of maximal utilization of the lands for agriculture and urban areas has caused even the training of large rivers as Maritza, Iskar, Osam etc.

The ecological impacts from isolating the meanders and floodplains consist not only of habitat losses. The “canalizing” of the river between narrow dykes lead to increased velocity and shorten the length of theriver, considerable decrease of the flooded areas and the retention volumes.

Some negative consequences are:
- Decrease of the self purification capacity of the water ecosystem in case of pollution
- Decrease of the retention capacity of the river bed, important for the natural flood prevention.
- Increased erosion and carving down the river bottom

The observations over such effects from the river modifications and the experience of many European countries prove that straightening the river bed between narrow dykes is not effective and damaging the nature.
The trend is to restore the connections between the stream and the adjacent floodplains, providing natural retention volumes in case of torrent discharge. The dykes should be constricted at increased distance and designed in a way to protect the settlements and key infrastructure with highest priority.

Sand and gravel extraction

The intensive building over the last years creates large demand of sand and gravel, which are easily extracted from the river beds with a minimal investment. This activity is highly profitable but hardly controlled. The large volumes of alluviums, excavated from the river bottom recover at the expense of the increased transport of sediments. This cause regressive erosion and lead to under-digging and damaging of bridges, embankment walls and other infrastructure up to 20 km upstream.
Craving down the river bottom reflects in decreasing the level of the soil waters, degradation of humid riparian habitats and desertification of broad agriculture lands.
In spite of the obvious negative impacts, the permit licenses for extraction continue to be issued. In contrast to the present situation in Bulgaria, the most of European countries has already adopted legislation that forbids the sand and gravel extraction directly from the river. Permits are issued only for extraction from floodplains away from the main stream.

 
 
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