HCMC faces the risk of land collapse and lack of fresh water

According to the latest data, the groundwater level in Ho Chi Minh City has dropped to a depth of -46m. Talking to reporters of Saigon Tiep Thi newspaper, Associate Prof. Dr. Nguyen Viet Ky, head of the Department of Geology and Petroleum Engineering, Ho Chi Minh City University of Technology, said the data shows that the underground water reserves of The city also declined rapidly.

According to Ky, the data on the increasing decline of water levels in all aquifers in Ho Chi Minh City show many risks. The amount of water currently being exploited is greater than that of the aquifers. More specifically, the amount of natural water that the aquifer receives annually is much smaller than the amount of water we are exploiting. At the same time, the rapidly declining water level will accelerate the movement of saline boundaries (the line of 1 g / l mineralization value) into the area where exist fresh water, the fresh water distribution area of ​​the due layers That decreased rapidly, causing many good and fresh water wells to be canceled due to salinity.

Rapidly decreasing water levels to large depths (in the Pliocene layer to -37.5m) increase the risk of land subsidence of the city - a fairly common phenomenon occurring in many parts of the world. Ho Chi Minh City, which is considered one of the ten locations most affected by global climate change (losing the most land due to sea level rise), subsided the land surface due to water exploitation. effect of this phenomenon.

The water level of the aquifers decreases, changing the hydraulic relationship between the aquifers and the surface water system (increasing pressure difference). This also increases the ability of pollutants to penetrate the aquifers, thereby increasing the risk of contamination of aquifers, making water quality worse.

Rainwater is a good source of groundwater but has not been utilized.
Illustration.

Is there any way to improve water quality and water quality, sir?

One of the urgent measures implemented by the city is the prohibition, restriction and permission to exploit underground water together with the regulation of not allowing exploitation with lowering the water level to -40m . These This solution limits the decline and gradual recovery of water levels, thereby improving water quality (pushing back the salinity boundary).

Another measure is 'artificial supplementation', which means finding good quality surface water to bring to the aquifers, especially in areas where water levels are sharply lowered like Tan Binh and Hoc Mon . Ho Chi Minh City, surface water (rivers, canals, lakes, ponds .) of good quality is almost no longer available. The only solution is to collect rainwater to supplement reserves for aquifers, while reducing the amount of rainwater runoff on the ground, contributing to reducing flooding due to rain in the city. The solution to collect rainwater from the roof and put it into the aquifers was carried out by the research group of Ho Chi Minh City University of Technology and achieved a very good initial result.

If groundwater recession continues, what is the scenario?

If the situation continues, surely the water supply for all activities of the city will face great obstacles, especially when the quality of water sources from Saigon and Dong Nai rivers is increasingly threatened by the pollution from industrial zones and residential areas along these two rivers. Groundwater is exhausted, saline boundary is deep in the inner city, the ground collapses, water is heavily contaminated, the risk of losing area due to rising sea level . is the vision of the city if we still indifferent to this situation.

The ink and groundwater quality has reached alarming levels

According to the latest observation results from the Ho Chi Minh City Environmental Protection Department, compared to 2009, the water level of all monitoring stations decreased from 0.36 to 2.1m. This shows that the situation of underground water exploitation in HCMC is increasingly strong, especially in deep water layers.

Regarding groundwater quality, the content of heavy metals Cu, Pb, Zn, Cd, As, Cr at groundwater monitoring stations in 2010 in all aquifers increased compared to 2009, from 1.1 to 12 times, but still meet the standard.