1.2.4 Utilization of the choice related to the construction of a deep water navigable canal on the Bystroe channel (Choice 2)
According to this choice, the construction of the canal shall be carried out in two stages. In the first stage, the parameters of the deep water navigable canal envisage a 5.85 m ship depth.
The Reni - Vilkovo section of the deep water navigable canal (km 22) is common to both choices and necessary to be performed for this section have been examined above.
The Vilkovo - Bystroe channel section has a 8-12 m depth and, in the first stage, no works to deepen the river are envisaged. Works to deepen the river bed, as well as some other hydro-technical works, are to be performed in the second stage. The average volume of the depth, necessary for an adequate functioning of the canal is 506,500 cubic meters, on a 278,400 square meter area. The anua1 exploitation excavations in this area shall be 140,000 cubic meters.
The hydro-technical works to be undertaken in the second stage will consist in the strengthening of the banks, by constructing 13 semi-dams in three eroding sections of the Bystroe channel (between km 6 and 8), having a 1.05 km total length on the water surface.
All the works within this section shall be carried out outside the actual limits of the Danube Natural Reserve.
In the sand bank area, at the mouth of the Bystroe channel, in order for an adequate depth of the canal to be ensured (so that it can be adequately functioning), works to deepen the bottom shall be needed - 2,331,000 cubic meters on an 600,000 square meters area. In the first stage, the volume of the excavations shall be 1,948,000 cubic meters. In order to reduce the sand depositing, parallel surrounding dykes shall be built up in the second stage, having a 3,000 m length. When performing these works an approximately 100,000 square meter area shall be affected. According to the results of the research of the Academy of Science of Ukraine, the annual volume of soil excavation in order to preserve the depth envisaged by the project is 232,000 square meters.
When calculating the construction period, the previous data, used for choice 1 , were considered. 4 absorption dredges and an excavation dredge are recommended to be used for construction, concomitantly with the performance of hydro-technical works. In this case, the works would last for 41 months, including the 2 months needed for the preparatory works. The performance of the works in the first stage can be done during a year time.
The construction of the temporary deposits, where the excavated soil is to be placed is not examined in the Experts' Assessment for sections downstream Vilkovo. The soil excavated from this area shall be directly transported to and dumped in the deep sea.
The navigation during the exploitation and the traffic of the ships is used for the construction works and for the works to deepen the bottom.
The second and the third of the above-mentioned groups of factors will also determine a hydrologic impact on the surface waters (thus causing an alteration of the following regime of the surface waters). The factors within the second group can determine a redistribution of the water flow of the Danube River in the Chilia Delta, while the factors within the third group - the changing of the aquatic regime in the Jebriansk pools.
The impact of all the above-mentioned factors can be noticed from the beginning of the construction works and they are bound to persist during the exploitation of the canal.
The impact area of these factors on the hydraulic parameters is limited to the aquatic environment, either natural or artificial (channels or canals), while the impact area on the hydrologic regime can consist of all the area of the Danubian pools, belonging to Ukraine.
The physical and chemical impact factors that can affect the water environment, determining the alteration of the water compounds, as well as the alteration of the water and bottom deposits quality, are represented by the excavating works to deepen the bottom and the deposing of the excavated soil. These kinds of works are indispensable for the construction and exploitation of the canal.
When the deposits on the bottom of the canal contain radioactive substances, the radioactivity impact factor can be noticed.
Taking into account the fact that some of these substances can convert in a gas, one can reach the conclusion that the physical and chemical factor can also influence the atmosphere.
The impact of these factors on the environment is at its highest during the construction works and it is gradually decreasing after the depositing of the excavated soil in the permanent maritime deposits, after the elimination of temporary deposits next to the canal and the tilling of the land where quality is generally restricted to the sections of the canals and of the channels neighboring those on which the works to deepen the bottom are carried out, following the direction of the stream (the intensity of the impact is gradually decreasing, as the contaminated waters are mixing with the uncontaminated waters).
Another physical-chemical impact factor is represented by the infiltration in the water of the noxious substances from the ships to be used for the construction of the canal. In normal conditions of exploitation, the influence of this factor will be a minor one, but if damage were to be produced, its influence can have catastrophic consequences, from an ecologic point of view.
According to Choice 2, the works to deepen the riverbed in the Bystroe mouth area, can be considered an indirect physical-chemical impact factor on the aquatic environment, as it will cause the penetration of salted waters from the sea in the Bystroe Channel. The impact of this factor will be periodically noticed, during the high tide from the sea, and its area of impact is likely to be restricted to the water layers at the bottom of the Bystroe channel and in the delta area in the proximity of the mouth of the channel (although there are some prognostics envisaging the possibility of the extension of the salted waters in the larger area of the Danubian pools).
The gas emanations and the noise caused by the ship engines are the main physical and physical-chemical impact factors of the projected activity on the atmosphere. According to the calculations, these factors can affect a several hundred meters wide area, during the construction period. During the exploitation period, the impact of this factor will depend on the intensity of the navigation and can be as strong as during the construction period.
The main physical and physical-chemical factors, with a direct and permanent influence on soil, flora and fauna, causing their partial or total degradation, are represented by the lands to be used for construction or exploitation, the depositing of the excavated soil and the constructions of the installations to ensure navigation.
All the above-mentioned factors, affecting the water and air, indirectly affect the flora and fauna. This is a difficult evaluation, as the dimensions and the importance of an indirect impact generally cannot be evaluated according to the parameters of the main factors, but according to the ecological value and the vulnerability of the recipients to the alteration of the abiotic elements.
The next chapter will examine the impact on each of the environment elements.