Huay Ma Nai catchment

Location of the Huay Ma Nai catchment, Thailand

The 93.2 ha Huay Ma Nai catchment is located in northern Thailand, in the Phrae Province. Elevation ranges from 380 to 490 m above sea level and slopes range from 15 to 65%. Huay Ma Nai catchment is included in the Maethang watershed (121 km²).

The coordinates of the Huay Ma Nai catchment are 100°23’40’’E, 18°13’20’’N.


The climate is tropical sub-humid. It usually can be divided into 3 seasons: a dry and fresh season lasting from October to February, a dry and hot season lasting from March to April and a wet and hot season from April to October. The annual rainfall measured in the catchment over the past 15 years varies from 1028 to 1493 mm. In average, about 90% of rainfall occurs between May and October. At Phrae Airport the maximum annual rainfall recorded over the past 50 years is 1461 mm.


The stream flow is intermittent. Currently, 2 sub-catchments are monitored (Huay Ma Nai and Weir 1).

Flume at the outlet of the Huay Ma Nai catchment (photo: J.-L. Janeau)


The most common rock types are siltstone and sandstone.


The most common soils are Inceptisol (20%) and Alfisol (80%).

Vegetation and land use

Since 1999, soybean and fruit trees cultivation has been replaced by intensive corn. Corn is now grown as a single crop within the catchment since 2004.