Huay Ma Nai catchment

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 km^²).

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

Climate

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.

Hydrology

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

Geology

The most common rock types are siltstone and sandstone.

Soils

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Since 1999, soybean and fruit trees cultivation has been replaced by intensive corn.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.