Rapid Assessment for Resilient Recovery and ... - GFDRR

Barrages. There are a number of large barrages in the lower Chao Phraya Basin to
control and divert the water in the canal systems that provide irrigation water to some
1.0 million hectares in this area. The most important barrages in the delta area are
the Rama VI barrage, which was completed in 1924, and the Chao Phraya (Chai Nat)
Diversion Barrage on the Chao Phraya River, which was constructed in 1957. These
barrages divert water to a complex system of inter-connect canals serving the lower
Chao Phraya Basin irrigation system. These large canals have the dual function of
irrigation and drainage – flood control.
Surface Water Storage. The government has constructed over 3,000 dams to store
the monsoon flows for release in the dry-season to exploit the Chao Phraya Basin’s
vast agricultural potential and to meet the growing demands of industrial and urban
users. The two largest dams: the Bhumibol and Sirikit Dams supply stored water
for electricity generation, irrigation, and domestic and industrial water use. Together
these two dams control the runoff from 22 percent of the area of the entire basin.
Bhumibol Dam on the Ping River has a live storage capacity of 9.7 billion cubic
meters (bm 3 ), compared to the average annual inflow of 6.6 bm 3 from a drainage
basin of 26,400 km 2 . The installed hydroelectricity generation capacity is 713 MW.
The dam was completed in 1963, and filled for the first time in 1970. Sirikit Dam on
the Nan River was completed in 1972 and has a live storage capacity of 6.0 bm 3
compared to the average annual inflow of 5.9 bm 3 . The installed hydroelectricity
generation capacity is 500 MW. Several other large dams (Pasak, Kiew Lom, Mae
Ngat, Mae Kuang, Mae Chang, Thap Salao and Kra Sieo) have also been built during
the last 20 years to increase the total surface water storage in the Basin.
Characteristics of Major Reservoirs in Chao Phraya Basin
Reservoir
Name
Sub-basin
Maximum
Retenon
(MCM)
Normal
Retenon
(MCM)
Minimum
Retenon
(MCM)
Effecve
Storage
(MCM)
Bhumibol Ping 13,462 13,462 3,800 9,662
Sirikit Nan 10,640 9,510 2,850 6,660
Pasak Pasak 960 785 N/A 785
Mae Ngat Ping 325 265 10 255
Mae Kuang Ping 263 263 14 249
Mae Chang Wang 108 N/A N/A N/A
Thap Salao Sakae Krang 198 160 8 152
Kra Sieo Tha Chin 363 240 40 201
Dam Safety. The majority of the dams in Thailand are owned by the RID and are
below 1 MCM in capacity and are thus classified as small dams, unless they are
over 15 meter high. The remaining medium (1-20 MCM) and large (> 20 MCM) dams
present potential hazards if they fail. Large dams are also owned by the Electricity
Generating Authority of Thailand (EGAT) and Department of Electric Power
Development (DEPD). The Dam Safety Department of the Royal Irrigation Department
are responsible for the dam safety and developing unified dam safety procedures
based on international standards.
THAI FLOOD 2011 RAPID ASSESSMENT FOR RESILIENT RECOVERY AND RECONSTRUCTION PLANNING
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