The harmful effects of sedimentation in the Da Do Riverbed.

The sedimentation of the Da Do River reduces its drainage capacity, causing localized flooding in communes during the rainy season and affecting agricultural production.

Leaders of the Da Do Irrigation Works Exploitation One-Member Limited Company, in coordination with An Lao commune, inspected the location affected by sedimentation in the Da Do River.

The harmful effects and causes are clearly understood.

Some residents in Kien Hung commune have just finished harvesting their rice crop and are preparing for the 2025-2026 Winter-Spring crop. However, they are worried because every Spring season, production faces many difficulties, mainly due to prolonged droughts and saltwater intrusion, which hinder water supply for production. Ms. Nguyen Thi Dao, from Kien Hung commune, said that during the dry season, saltwater intrusion penetrates deep into the Van Uc River, making it impossible to obtain water for production. Obtaining freshwater from the Da Do River is also difficult due to low water levels, and during the rainy season, prolonged drainage causes localized flooding.

Not only the Kiến Hưng commune area, but also several other areas in the communes of An Lão, An Hưng, Phù Liễn, An Lão, An Khánh... are facing difficulties due to the drainage problems along the Đa Độ river.

The cause is that the Da Do River has recently experienced numerous sedimentation points, narrowing the waterway, reducing drainage capacity, and prolonging drainage time, leading to localized flooding. Some major sedimentation sites also obstruct the flow of domestic wastewater, causing waste accumulation and seriously affecting water quality and the water intake of factories.

According to a review by the Da Do Hai Phong Irrigation Works Exploitation Company Limited, nine localized sedimentation points have recently appeared on this river at several locations where the flow is diverted, narrowing the river channel. These shallow sedimentation points have an average width of 30m to 80m and an average sedimentation elevation of (+0.3) to (+0.7), reducing the river's water storage capacity. Specifically, the section near the Cau Nguyet water treatment plant (from K20+250 to K21+350) (in An Khanh commune) has accumulated sediment in a strip of L=1,100 m, with an average sedimentation elevation of (+0.4) to +0.75) m and a sedimentation width of 50 to 70 m. This sedimentation is causing flow obstruction, reducing drainage capacity, slowing flow velocity, affecting water quality, and hindering the ability to draw water into the Cau Nguyet water treatment plant.

The section from Cau Tre sluice gate to Khuc Gian sluice gate (from K4+100 to K5+450), belonging to An Truong and An Lao communes, has siltation on the left bank of the river for a length of L=350 m, with a sedimentation elevation of (+0.35÷+0.5)m and a sedimentation width of 50÷60 m. This is a crucial location for rapid water supply and drainage for the Khuc Gian and Ngoc Chu canals, especially for flood control in the communes. The sedimentation reduces the drainage capacity of the canals, causing localized flooding in the communes during the rainy season and affecting agricultural production…

Leaders of the Department of Agriculture and Environment inspect the sedimentation site on the Da Do River.

Short-term and long-term solutions

The Da Do river system is tasked with maximizing water utilization through the Trung Trang sluice gate (An Truong commune) and draining water into the Co Tieu sluice gate (Kien Hung commune) to flush out excess water, remove acidity and salinity, and ensure water quality and quantity for production and daily life. The system also plays a role in drainage, disaster prevention, and flood control, contributing to social welfare.

Therefore, in response to the aforementioned sedimentation points, the unit has primarily implemented solutions such as dredging the sedimented areas, building embankments to increase flow rate, utilizing water intake time, and storing water in the system to ensure quality and quantity for production. During the dry season, saltwater intrusion becomes more complex. Therefore, to overcome this phenomenon, from 2024 onwards, Da Do Irrigation Works Exploitation Company Limited will always have to utilize time to increase the rapid water intake capacity into the Da Do River to push saltwater and polluted water out of the system.

In the long term, Do Van Trai, Chairman of Da Do Irrigation Works Exploitation One-Member Limited Company, stated that it is necessary to comprehensively plan the Da Do River as a freshwater reservoir for socio -economic development. Simultaneously, it is essential to dredge the entire riverbed of the Da Do River; build embankments on both banks to an elevation of +2.5 with a total length of 100 km to ensure sufficient water storage capacity; and construct sluices on the banks of the Da Do River to enclose the riverbanks, prevent waste and wastewater from entering the primary canals, minimize water pollution, and protect the water quality of the Da Do River. Therefore, the attention and support of the city and central ministries and agencies are crucial…

HO HUONG

Source: https://baohaiphong.vn/tac-hai-long-song-da-do-bi-boi-lang-528969.html