VietNamNet Bridge – The Department of Cultivation’s plan to expand the acreage of the 2016 autumn-winter rice crop, or the third rice crop, in the Mekong Delta to offset the losses in the winter-spring crop could lead drought and salinity in the region to worsen in the coming years, said experts.

A farmer uses an excavator to erect dikes to keep water for his rice field in the Mekong Delta in the previous third crop. The Department of Cultivation’s plan to expand the acreage of the 2016 autumn-winter rice crop, or the third rice crop, in the Mekong Delta could lead drought and salinity in the region to worsen in the coming years – Photo: Trung Chanh

The department, under the Ministry of Agriculture and Rural Development, plans to encourage farmers to start sowing paddy on 900,300 hectares in the third rice crop in the delta in July and early August, up 57,160 hectares year-on-year. Rice output is expected to exceed 4.9 million tons, up 361,000 tons from the same period last year.

The output rise is well above 180,000 tons of paddy damaged by drought and saltwater intrusion in the 2015-2016 winter-spring rice crop in the key rice producing region in Vietnam, according to the department.

However, Nguyen Huu Thien and other experts said the rice farming expansion might make matters worse in the region in 2017 because the construction of closed dikes to retain water for the third rice crop will severely affect water storage capacity in the Mekong Delta during the flooding season.

Thien said the Mekong River downstream has three natural water reservoirs, namely the Tonle Sap Lake in Cambodia and Vietnam’s Dong Thap Muoi (the Plain of Reeds) and Long Xuyen Quadrangle. The 700,000-hectare Dong Thap Muoi is on the left bank of the river in the provinces of Dong Thap, Tien Giang and Long An, while the Long Xuyen Quadrangle covers 590,000 hectares on the right bank of the river in An Giang and Kien Giang provinces.

Every year, floodwater from the Mekong River upstream flows into the Tonle Sap Lake, making the lake expand from approximately 300,000 hectares in the dry season to 1.5 million hectares in the wet season. Floodwater of the river also runs into the Dong Thap Muoi and Long Xuyen Quadrangle.

Thien said the three natural reservoirs regulate water flows of the Mekong River, store water to ease floods in the wet season and release water into the Tien and Hau rivers to help reduce salinity in coastal areas during the dry season.

However, the construction in previous years of closed dikes to keep water for the third rice crop has compromised water storage in the Dong Thap Muoi and Long Xuyen Quadrangle.

Statistics showed water volume in the Long Xuyen Quadrangle dropped from 9.2 billion cubic meters in 2000 to only 4.5 billion cubic meters in 2011 due to the construction of 1,100 square kilometers of such dike. As a result, more flooding hits the areas outside the dikes in the flooding season while drought and saltwater intrusion worsen in the dry season.

The wider area for rice farming in the third rice crop means more dikes would be built. Relevant agencies need to find ways to solve the drought and salinity problems caused by the third crop in previous years rather than planning to expand the acreage of the crop as this will result in more dikes being built.

SGT