Dredging of harbor channel is a huge project, which is time-consuming and has a certain impact on the environment. Ordinary dredging measures cause widespread and violent agitation of the bottom sludge, leading to the spread of pollutants and deterioration of water quality. The waterway has the function of transportation and flood control. Dredging of the channel will lead to the pollution of the surrounding ecological environment and adversely affect its function. The environmental protection concept of port dredging projects requires the environmental protection of dredging equipment, the environmental protection of the dredging process, and the environmental protection of polluted sediment treatment. This paper analyzes the importance and impact of the port-channel dredging project on the environment and discusses the key points of port-channel dredging project supervision under the concept of environmental protection.

Considering the importance of environmental protection in today’s society, it is of great significance to analyze and discuss the dredging project of port-channel under the concept of environmental protection. In port, waterway dredging construction application of green concept not only can satisfy the demand of the protection of the ecological environment and realize the harmonious development of ecological environment and further but also can let the dredging construction companies keep up with the needs of the development of the era and increase their efficiency and core competitiveness.

1. The importance of port-channel dredging project supervision

The influence of harbor channel dredging projects on environment cannot be ignored, so the harbor channel dredging project under the environmental protection concept is analyzed carefully. The primary task of waterway dredging engineers is to strengthen the application of environmental protection concepts in port and waterway dredging projects and further strengthen the protection of the ecological environment. The concept of environmental protection refers to keeping the intact ecological environment as much as possible and taking effective measures to restore the damaged ecological environment to the natural state before the destruction. The concept of environmental protection has certain physical and chemical characteristics. The specific content of the environmental protection concept includes ecological protection within the concept of relative scope, there will be no absolute protection, only relative protection, ecological protection has dynamic characteristics. Ecological protection cannot be done once and for all. It is constantly changing with the change of the natural environment. In addition, ecological protection is closely related to the natural environment and social and economic development. And the two have certain coordination. The natural environment will not be destroyed because of social and economic development which will not be restricted because of the natural environment.

2. Environmental impact analysis of dredging project of the harbor channel

 2.1 The diffusion of pollution during the dredging project

Sediments are important depositing carriers of nutrients and pollutants. Sewage discharge, dust fall, the inflow of surface runoff and dead debris of aquatic organisms often lead to the gradual accumulation of nutrient salts in sediments in the channel, forming an internal load of nutrient salts. If there is a high temperature or flood, the pollutants in the sediment of the port-channel will continue to surface. Once the pollutants are too much to be independently evolved by the water body, eutrophication will occur and the organisms in the water will be polluted and die. The water quality will also change and smell bad. Once the channel dredging is carried out without effective treatment of the polluted bottom sediment in the waterway, the phenomenon of the polluted bottom sediment spreading in the water is easy to occur, which will worsen the water quality. Dredging abandoned soil should also be reasonably disposed of, and should not be directly filled, or it may cause adverse effects on groundwater.

2.2 Inorganic suspensions can damage aquatic ecosystems

In the dredging process of the harbor channel, the inorganic suspended matter is common pollution in the water area. Inorganic suspended matter mainly increases turbidity in water, and influences the growth and reproduction of a large number of aquatic organisms by its burial after settlement, leading to the destruction of the aquatic ecosystem. In the dredging process of the harbor channel, the concentration of suspended matter in the water is related to the position of the dredger.

 2.3 Noise pollution and ship pollution during dredging

During dredging and filling, the noise emitted by dredger will further affect the surrounding ecological environment. And the ships involved in the dredging process of the harbor channel will also have an adverse impact on the ecological environment. When a ship is sailing or stopping, it is easy to find sewage or oil at the bottom of the cabin. During the leakage process, such sewage and oil may be carried out in the surrounding area of the channel, which will affect the surrounding water quality. The sewage generated in the process of ship construction will also adversely affect the aquatic ecological environment.

3. Key points of port-channel dredging project supervision under the concept of environmental protection

 3.1 Time selection of ort channel dredging

It is necessary to select the dredging time of harbor and channel scientifically and reasonably. It is not suitable to dredge the harbor and channel in the season with the frequent biological activities in the nearby benthic habitat to prevent the adverse effects on the normal activities and survival of benthic habitat. From this point of view, the dredging project of port-channel should be carried out in the period with little risk and environmental impact as far as possible, and the best dredging period is winter. In addition, to minimize the impact on benthic organisms, the dredging of ports and channels should be carried out during the dry season to avoid the growth period of benthic larvae. At the same time, the flow rate at high tide and low tide should also be taken into account.  At this time, the precipitation of suspended and overflow is more difficult.

 3.2 The port-channel dredging plan should be scientific and reasonable

The environmental pollution near the port-channel should be closely examined to observe the causes and characteristics of the polluted sediment. Based on the analysis of the results, a specific dredging scheme for the port-channel should be worked out. The bottom sediment should be calculated according to the survey data, and then every link of the port and channel dredging project should be studied and formulated, and the scale, scope, and method of the port and channel dredging project should be formulated and divided respectively. In the dredging process of the harbor channel, the appropriate dredging equipment and tools should be selected. In view of the work management in the dredging process of port-channel, it is necessary to formulate certain management methods and regulations to ensure the normal operation of the dredging work of port-channel.

 3.3 Supervision of dredging construction of ports and waterways

The following three problems should be paid attention to the dredging process of port-channel to ensure effective control of the channel dredging construction.

(1) Further, improve the positioning of the dredging industry of port-channel and enhance the precision of excavation. The depth of pollutants deposited in the bottom layer of the water is usually 10 to 15 cm thick, ensuring a range of 1 m. In the process of harbor channel dredging, the concrete distribution of sand and stone polluted by the bottom should be analyzed and studied, so as to define the scope of dredging. In the course of dredging, the contaminated sediment should be completely removed, and the dredging quantity of the non-contaminated sediment should be controlled within a certain standard range. Under the concept of environmental protection, all aspects of the dredging work of the port-channel are different from the usual dredging requirements and significantly higher than usual.

(2) In the dredging process of the port channel, the possibility of secondary pollution must be reduced. A large part of the channel dredging does not pay attention to the re-emergence of suspended or deposited material after dredging, and on the premise of ensuring the amount of dredging work, often habitually ignore some of the leaked sediment. A small amount of fine sediment is rapidly added during the dredging of the channel, and after the dredging is completed, some of the suspended material will fall to the bottom or be taken out of the dredging area. In the dredging operation of ports and waterways under the environmental protection concept, in order to avoid the bottom sediment pollution or mud pollution, some relevant operation equipment in the dredging of ports and waterways should be installed and the use of certain methods should be used to completely eliminate most of the pollutants. At the same time, prevent the water ecological environment from suffering from secondary pollution.

(3) In order to deal with the pollution deposition materials removed from the dredging project of the port and waterway scientifically and reasonably, scientific and reasonable advanced technologies should be adopted to properly deal with the pollution deposition materials after the pollution deposition materials are removed, so as to prevent them from bringing different degrees of pollution to the groundwater around the storage yard and the new environment. In the sludge disposal site, the discharge of sewage concentration should also be effectively controlled.

4. Conclusion

The proposal of the environmental protection concept has brought a great impact on the construction of the dredging project of port-channel. Meanwhile, due to the characteristics of a long construction period and a large amount of engineering, the construction process often has different degrees of impact on the ecological environment. In order to integrate the environmental dredging project of port-channel, it is necessary to further strengthen the research on construction technology, combine with the characteristics and requirements of project construction, clarify its impact on the environment, take effective measures to reduce the impact and meet the requirements of environmental protection on the basis of guaranteeing the construction quality.