Bangkok: The Royal Irrigation Department is using water from 5 reservoirs to release water to prevent saltwater from invading the Bang Pakong River and alleviating the suffering of the people of Paet Riew and Prachin Buri during the period of high tides and throughout this dry season. However, if it cannot be controlled at the control point at Wat Bang Tan, Ban Sang District, Prachin Buri Province, farmers and local agencies will be notified to build temporary dams to retain water and prevent saltwater from the Prachin Buri River from entering the area.
According to Thai News Agency, the Royal Irrigation Department, through the 9th Regional Irrigation Office, has monitored the salinity in the Bang Pakong River and found that the salinity has increased faster than normal. The salinity level of 1 gram per liter has reached the monitoring point at the Chachoengsao Irrigation Project, Ban Pho District (35 kilometers from the river mouth) since mid-November 2024, which is half a month earlier than expected. Therefore, the plan has been adjusted according to the appropriateness of the water situation, along with controlling the Bang Pakong Dam, according to the plan that has been approved by the Bang Pakong Basin Committee.
In the past, water from 4 reservoirs in the upper part was drained to remove salinity as follows: Narubadin Jinda Reservoir from 1 - 15 Dec 2024 at a rate of 2 million cubic meters per day; Khlong Si Yat Reservoir and Khlong Rabom Reservoir from 5 - 19 Dec 2024 at a rate of 2 million cubic meters per day; Khun Dan Prakan Chon Reservoir from 14 Dec 2024 - 13 Jan 2025 at a rate of 1 million cubic meters per day.
The management results can control the salinity in various control points according to the specified time period, including Control Point 1, Bang Pakong Dam (66 kilometers from the river mouth), which can slow down the advance of salinity. At this point, there are times when the salinity is lower than 1 gram per liter, allowing the upstream area to receive water according to the rise and fall of the sea level until December 31, 2024.
The second control point at the end of Khlong Bang Khanak (109 kilometers from the river mouth) can control the salinity level to prevent it from reaching this point before January 10, 2025, allowing farmers who grow rice on the right bank of the Bang Pakong River in Mueang Chachoengsao District, Khlong Khuean District, and Bang Nam Priao District, Chachoengsao Province, to use the water for cultivation without being affected.
During this period, there was a high tide, so the plan to control the salinity at Control Point 3 at Wat Bang Tan, Ban Sang District, Prachin Buri Province (115 kilometers from the river mouth) was adjusted by increasing the water discharge from the Naruebodindrajinda Reservoir from 5-9 January 2025 to 1.5 million cubic meters per day (previously 0.6 million cubic meters per day). It is expected that this will help prevent salinity intrusion until the period of the highest tide, and will continue to control until 1 February 2025.
The highest salinity today (13 Jan 2025) was measured at 0.8 grams per liter (controlled not to exceed 1 gram per liter) and tends to increase in line with the period of highest sea level on 13-15 Jan 2025 (according to the forecast of the Hydrographic Department, Royal Thai Navy). However, if Control Point 3 cannot control the salinity until 1 Feb 2025, a backup plan has been made for the Prachin Buri Irrigation Project to notify farmers and local agencies to build temporary dams to retain water and prevent saltwater from the Prachin Buri River from entering the area.