Sirikit Dam

Sirikit Dam
Name	Sirikit Dam
Location	Thailand; Nakhon Sawan Province/Phrae Province border vicinity, Nan River
Coordinates	17°38′N 100°34′E
Country	Thailand
Purpose	Hydro-electric power, irrigation, flood control, water supply
Status	Operational
Construction began	1968
Opening	1972
Owner	Royal Irrigation Department (Thailand)
Dam type	Embankment, rock-fill with clay core
Dam length	800 m
Dam height	113 m
Spillways	Controlled service spillway
Reservoir name	Sirikit Reservoir
Reservoir capacity total	9.51 km3 (approx.)
Plant operator	National Electricity Generating Authority of Thailand
Plant capacity	240 MW

Sirikit Dam Sirikit Dam is a major multi-purpose embankment dam on the Nan River in northern Thailand. Built in the late 1960s and early 1970s, it forms one of Thailand's largest reservoirs and supports hydroelectricity, regional irrigation schemes, and flood control measures for the Chao Phraya River basin. The project was a centerpiece of national development plans involving Thai authorities and international advisers, and it remains significant for regional water resources and energy systems.

History and construction

Construction followed feasibility studies linked to post-World War II development policies and the Thai National Economic Development Board plans of the 1960s. The scheme advanced amid regional infrastructure programs alongside projects such as the Bhumibol Dam and the Sirindhorn Dam planning era. Groundbreaking occurred in 1968 with engineering and consultancy input from international firms and coordination by the Royal Irrigation Department (Thailand) and the U.S. Bureau of Reclamation advisors. Completion and initial impoundment were achieved in 1972, with official inauguration aligning with national rural development initiatives endorsed by the Thai monarchy and ministries including the Ministry of Interior (Thailand) and the Ministry of Energy (Thailand).

Design and specifications

The structure is an embankment rock-fill dam with a central impervious clay core, engineered to withstand seismic and seasonal hydrological variability common to the Thai highlands and the Luang Prabang Range. Its crest length and height provide a large storage head for the powerhouse downstream. The spillway and outlet works were designed to evacuate extreme floods modeled after historical events on the Nan River and the wider Chao Phraya River basin, integrating standards used by international civil engineering bodies and influenced by design approaches from projects like Bhumibol Dam and Mekong River Commission studies. The installed power plant uses vertical shaft turbines supplied by major international manufacturers and connected to the national grid managed by the Provincial Electricity Authority and the National Electricity Generating Authority of Thailand.

Reservoir and hydrology

The reservoir inundates extensive valley lands upstream, forming Sirikit Reservoir, which stores roughly 9.5 cubic kilometres at full supply level and alters seasonal flow regimes of the Nan River. It functions as a regulating basin for the Chao Phraya River hydrological network and interacts with tributaries originating in the Phi Pan Nam Range and the Phi Pan Nam-South watersheds. Hydrological management considers monsoon patterns driven by the Southwest Monsoon and inter-annual variability associated with phenomena like the El Niño–Southern Oscillation. Sedimentation rates, catchment land use changes in Phrae Province and Nan Province, and upstream deforestation have been subjects of ongoing hydrological monitoring by the Royal Irrigation Department (Thailand) and academic institutions such as Chulalongkorn University and Mae Fah Luang University.

Power generation and operation

The hydroelectric complex comprises turbine-generator units with a combined capacity near 240 megawatts, operated in coordination with national dispatch managed by the Electricity Generating Authority of Thailand and grid oversight by the Provincial Electricity Authority. Generation profiles are seasonal, peaking during reservoir releases in the dry season to meet regional electricity demand across northern Thailand and supply to load centers including Chiang Mai and Bangkok via high-voltage transmission corridors. Maintenance regimes follow standards from international manufacturers and national regulatory frameworks overseen by the Ministry of Energy (Thailand) and technical agencies like the Department of Mineral Resources (Thailand) for infrastructure safety.

Irrigation and water management

Stored water supplies irrigation schemes serving the Chao Phraya Delta feeder networks and paddy fields in provinces such as Phitsanulok and Nakhon Sawan, supporting rice production central to Thailand's agricultural exports linked to traders in Bangkok and port logistics at Laem Chabang Port. Water allocation policies are administered by the Royal Irrigation Department (Thailand), balancing irrigation deliveries, municipal water supply for towns like Phrae and Sukhothai, and environmental flow requirements set in coordination with the Ministry of Natural Resources and Environment (Thailand). Drought contingency and multi-year storage planning draw on basin models developed with inputs from international institutions including the Asian Development Bank.

Environmental and social impacts

Reservoir creation resulted in displacement of communities and transformation of terrestrial ecosystems, affecting ethnic groups and local populations in upper-valley districts where resettlement programs were implemented under state auspices and assisted by civil society organizations and academic researchers from Thammasat University and Chiang Mai University. Aquatic habitat changes influenced native fish populations tied to fisheries in the Nan River and altered nutrient dynamics, with studies by agencies such as the Thailand Institute of Scientific and Technological Research examining water quality and greenhouse gas fluxes from large reservoirs. Conservation responses have engaged protected area authorities managing nearby conservation landscapes like Doi Phu Kha National Park and reforestation initiatives promoted by royal projects associated with the Thai Royal Family.

Tourism and recreation

The reservoir and surrounding hills support recreational boating, sport fishing, and eco-tourism, attracting visitors from regional centers such as Chiang Mai and international tourists arriving via Suvarnabhumi Airport. Local attractions include scenic viewpoints, cultural sites in nearby towns, and community-based tourism programs developed in partnership with provincial tourism offices and the Tourism Authority of Thailand. Facilities have been expanded to host events tied to seasonal festivals and to provide visitor services integrating local handicraft markets and homestay accommodations promoted through provincial development schemes.

Category:Dams in Thailand Category:Hydroelectric power stations in Thailand