Chiang Mai and Nan step up flood watch as rivers rise
Heavy rain is lifting river levels across northern Thailand, prompting 24-hour monitoring and drainage operations in Chiang Mai and Nan
- The Royal Irrigation Department has initiated 24-hour monitoring in Chiang Mai and Nan due to heavy rainfall causing rising river levels in the Ping and Nan basins.
- In Chiang Mai, authorities are proactively lowering water levels in the Ping River to create more capacity for incoming runoff and protect economic areas.
- Water levels in some parts of the Nan River have surpassed normal bank levels and are continuing to rise, prompting close surveillance by officials.
- Residents in low-lying areas of both provinces have been urged to monitor official information, move belongings to higher ground, and prepare for potential flooding.
The Royal Irrigation Department (RID) has intensified 24-hour water monitoring in Chiang Mai and Nan after heavy rain increased river flows across two separate northern basins, prompting drainage operations in the Ping River system and close surveillance of water levels above normal banks at some locations in Nan.
In Chiang Mai, heavy rainfall across the upper Ping basin in Chiang Dao, Mae Taeng and Wiang Haeng districts has sent increasing volumes of water into tributaries and the Ping River.
Regional Irrigation Office 1 has accelerated water management and lowered levels in advance to create more capacity in waterways before the incoming runoff passes through economic and residential areas of Chiang Mai.
Chiang Mai lowers Ping levels ahead of incoming runoff
In the upper area around Mae Taeng district, the Mae Taeng River remained within its banks and its level was falling. Water from upstream areas was continuing to move towards the Ping River, where flows remained at levels that officials said could still be managed.
In Chiang Mai city, officials were accelerating releases through the Tha Wang Tan drainage gate to push the Ping River below its normal retention level. The operation is intended to provide more room for incoming upstream water and limit the impact on economic areas.
Further downstream, irrigation structures in Hang Dong, San Pa Tong, Doi Lo, Chom Thong and Hot districts were being used periodically to speed the passage of water towards Bhumibol Dam.
Regional Irrigation Office 1 has deployed officials to monitor water conditions around the clock and adjust discharge plans according to actual flows.
Residents of Chiang Mai, particularly those in low-lying areas and communities along the Ping River, have been advised to monitor official information closely, move important belongings to higher ground and plan travel in advance in case conditions change.
Nan gauges rise above normal bank levels
In Nan, the RID is also maintaining 24-hour monitoring after the Thai Meteorological Department reported on 9 August that thunderstorms were expected across 70% of the North, with heavy rain in several areas including Nan.
Water levels in parts of the upper Nan basin were also showing an upward trend, prompting irrigation authorities to prepare water-management measures aimed at limiting possible impacts on residents.
RID monitoring data recorded at 5pm on 9 August showed that the N.64 station at Ban Pha Khwang in Mueang Nan district stood at 6.73 metres, with a flow of 571.90 cubic metres per second. The bank level is 9.50 metres, leaving the water 2.77 metres below the bank, with the level falling.
At the N.1 station near the Northern Development Bridge in Mueang Nan district, the water level was 7.02 metres and the flow was 1,071.80 cubic metres per second. The water was 0.02 metres above the normal bank level and was still rising.
However, the level remained 1.48 metres below the reinforced bank level on the Mueang district side and 0.98 metres below the reinforced bank level on the Phu Phiang district side.
At N.13A at Ban Bun Nak in Wiang Sa district, the water stood at 8.49 metres, with a flow of 1,776.00 cubic metres per second. The level was 1.99 metres above the normal bank and was continuing to rise.
The department separately reported that the N.1 station, described as being in front of the forestry office in Mueang Nan district, had begun to stabilise. It said the Phu Phiang side could accommodate a water level of about 8.00 metres, while the Mueang side could accommodate about 8.50 metres.
Low-lying communities told to remain alert
The Nan Irrigation Project under Regional Irrigation Office 2 has prepared water-management operations and is monitoring both river conditions and the weather around the clock. Discharges will be adjusted to actual conditions to reduce potential impacts on communities.
Residents of Nan, particularly those in low-lying areas, along waterways and in locations at risk of flooding, have been urged to follow official water updates and warnings closely and prepare for possible changes in conditions.
The RID said it would continue monitoring both water and weather conditions and issue further information if significant developments occurred.
