Greenhouses, tree loss blamed for frequent Da Lat flooding

Da Lat, a popular hill resort town of Lam Dong Province, was severely flooded Thursday following a 30-minute downpour, with the downtown area being under nearly a meter of water.

The rains flooded many shops on both sides of Phan Dinh Phung and Nguyen Cong Tru streets, making it difficult for people to evacuate in time and damaging furniture.

A street in Da Lat is submerged after a heavy downpour on September 1, 2022. Photo by VnExpress/Khanh Huong

This is not the first time Da Lat has been inundated by rains, and the Central Highlands town and its surrounding areas are in fact often submerged after a downpour.

Vo Ngoc Trinh, vice chairman of the town people’s committee, said the flooding in recent days, especially on Thursday afternoon, only occurred in some low-lying areas and near streams, not across town as many people think.

There are many factors behind the recent flooding, such as greenhouses and others, and not just an inadequate drainage system, he said.

Experts said heavy rains in a short period of time do cause flash floods but that is not the main problem.

The problem is the sudden increase in greenhouses, especially in the agricultural areas on both sides of the Cam Ly Stream, they pointed out.

From having just a few scattered greenhouses in the late 1990s it has them covering 10,000 hectares out of a total agricultural land area of 18,000 ha.

They are in all wards and communes though some wards in the inner-city area have a high density of greenhouse.

Seen from above, the city clearly does not have a lot of green space, with glass greenhouses popping up amid pine forests all over the suburbs.

According to experts, the ability of greenhouses to absorb water is nearly zero while many lakes like Van Kiep, Thanh Nien, Tam Tu, Da Thien 1 and 2, and others have been wiped out or shrunk, causing poor drainage during rains.

Greenhouses cover most of the space by the Cam Ly Stream in Da Lat. Photo by VnExpress/Quynh Tran

After studying urban planning in Da Lat for many years, architect Ngo Viet Nam Son said for more than 10 years the town’s development has tended to be less sustainable amid rapid urbanization, affecting drainage.

His analysis has shown that deforestation, a sharp decrease in green space and an increase in urbanization cause flooding. Heavy rains and steep slopes cause water to concentrate in some places, and there are not enough sewers to carry the water out quickly enough.

He said authorities need to plan for the worst rainfall drainage scenarios.

Green spaces have the role of collecting water when it rains heavily and draining it when the rain stops. In heavily concreted areas, Son suggested that there is artifical “water space” such as reversoirs or canals.

He warned that Da Lat would have to pay a heavy price in the long run if it focuses too much on development and not enough on green spaces and places to store water.

Da Lat’s downtown lacks green spaces. Photo by VnExpress/Quynh Tran

Dr Nguyen Mong Sinh, former president of the Lam Dong Province Union of Science and Technology Associations, said Da Lat needs to take care of and protect its natural and man-made lakes and reservoirs to keep a healthy ecosystem.

To achieve this goal, the town must re-plan agricultural production zones and grow vegetables and flowers in appropriate locations, he said.

“It needs to relocate greenhouses from the center to more remote locations, replacing them with green areas.

“At the same time it is critical to continue to conserve forests and develop green areas in Da Lat, particularly pine forests.”