Proactively securing clean urban water sources.

Many challenges

According to Da Nang City's water supply plan until 2030, with a vision to 2050, the highest daily demand for clean water in Da Nang is over 801,000 m3 by 2030. However, the city's water supply system's capacity to meet domestic water needs at the end of 2022 only reached 210,000 m3/day.

Without supplemental water supply during peak periods, Da Nang will face a shortage of over 590,000 cubic meters of water. Simultaneously, saltwater intrusion continues to occur frequently during the hot season with increasing frequency and severity. The almost complete dependence on the Vu Gia River has led to long-standing water supply insecurity in Da Nang. Furthermore, water pollution from wastewater discharge poses a serious threat to the socio-economic development of the locality.

According to Mr. Ho Minh Nam, General Director of Da Nang Water Supply Joint Stock Company (Dawaco), the surface water quality in Da Nang during the dry season is often affected by salinity. At the intake of the Cau Do water treatment plant, the average salinity exceeds 1,000 mg/l. The highest salinity reached 8,192 mg/l (on August 29, 2023). Previously, before the An Trach salinity control pumping station was upgraded, the salinity contamination of the river posed a significant challenge to water security in Da Nang. However, since the An Trach salinity control pumping station, with a capacity of 420,000 m3/day, was put into operation, when salinity contamination occurs in the Cau Do River, the raw water from the pumping station is channeled to the Cau Do water treatment plant for processing, ensuring a safe water supply for the entire city.

Mr. Ho Minh Nam further stated that in Da Nang, rainfall during the dry season months will be much lower than in the same period last year, resulting in reduced river flow. It is predicted that the average flow rate on the Vu Gia River (the source of raw water for Da Nang) will be deficient by approximately 40-60%. The depletion of water resources in reservoirs will jeopardize the safety of ensuring domestic water supply for downstream areas during the dry season.

Optimized automatic control system at Hoa Lien Water Treatment Plant, Da Nang

In the event of a salinity level of 1,000 mg/l in the river, water will be drawn from the An Trach dam. However, if the water flow from upstream is insufficient, and the dam's water level drops below 1.6m, one of the two pumping stations will be unable to operate. This will then affect the water supply to the people.

Proactively securing clean water sources.

At the end of May 2023, the Hoa Lien Water Treatment Plant (Phase I), with a capacity of 120,000 m3/day, commenced operation, supplying water to residents of Lien Chieu district and part of Hoa Vang district, thus reducing the burden on the Cau Do Water Treatment Plant. According to calculations, in the near future, Da Nang will form a reservoir with a capacity of 50 million m3 on the Bac River (upstream of the Cu De River), and the Hoa Lien Water Treatment Plant will become the second largest water treatment plant serving the clean water needs of the city's residents. This will contribute to ensuring water security and the lives of the people, and ensure the synchronization of the development of Da Nang's water supply systems according to the set roadmap.

Mr. Ho Minh Nam, General Director of Da Nang Water Supply Joint Stock Company (Dawaco), said that when the city builds a water reservoir on the Bac River (upstream of the Cu De River) to increase the operating capacity of the Hoa Lien Water Treatment Plant, the company will also study the possibility of investing in a pipeline to bring this freshwater source to the Cau Do Water Treatment Plant. This will reduce the city's over-reliance on water from hydroelectric reservoirs upstream of the Vu Gia River, contributing to ensuring water security for the city.

In addition to providing water, the company must also ensure water quality that meets safety standards for consumers. The company conducts thorough monitoring to guarantee clean water quality that meets the requirements of Circular 41/2018/TT-BYT dated December 14, 2018, and Circular 26/2021/TT-BYT dated December 15, 2021, issued by the Ministry of Health .

Testing was conducted at the Analytical Testing Center (an ISO/IEC 17025:2017 accredited testing laboratory) with Group A parameters tested monthly, and Group B parameters tested monthly and every six months for all water samples subject to periodic monitoring as per regulations.

Therefore, to ensure water supply for the city under saline conditions, the salinity at the intake of the Cau Do water treatment plant must be maintained below 1,000 mg/l. With salinity below this threshold, the water intake at the Cau Do intake can reach approximately 60,000 m³/day. If salinity exceeds 1,000 mg/l, leading to a shortage of raw water, regulations will be followed to advise the City People's Committee to request hydroelectric reservoirs to release water and operate the An Trach dam to release water downstream to ensure raw water supply for pumping stations serving agricultural irrigation and domestic water supply in Quang Nam province and Da Nang city. In case of different salinity levels, appropriate scenarios will be considered to respond promptly.

According to the Da Nang Department of Natural Resources and Environment, the locality is currently actively implementing solutions to protect water resources, such as declaring a sanitary protection zone for the water intake area of ​​the Cu De River surface water exploitation project, part of the Hoa Lien Water Treatment Plant project, which is considered an important water reserve. This will help Da Nang strictly enforce regulations on environmental protection of the Cu De River, reducing dependence on the Vu Gia River and the operation of upstream hydropower plants. To better protect this water reserve, Da Nang will immediately implement measures to minimize the impact of agricultural, forestry, and fisheries production activities, as well as wastewater from ecotourism development.

Source: https://baotainguyenmoitruong.vn/da-nang-chu-dong-nguon-nuoc-sach-do-thi-368868.html