Huai Ma Nai is a small agricultural catchment (93 ha) of northern Thailand, 60 km from the city of Phrae, in a sloping land environment. The objective is to the impacts of land use changes, from mung bean and soya bean to maize, upon hydrological and sedimentary budgets. Agricultural practices are very intensive, based on high quantities of fertilizers, herbicides and pesticides, and mechanized cultivation. The mean slope is 12.9%%. Soils are thin Alfisols and Ultisols with sandy clay loam to clayey texture, high coarse fragment content, low pH, high bulk density and low-medium cation exchange capacity. Monitoring devices include an automatic meteorological station since 2001, and weirs and flume to monitor discharge from nested catchments, suspended sediment and bedload. More information is available on https://mtropics.obs-mip.fr/ and in the following paper: Valentin, C., et al., 2008. Runoff and sediment losses from 27 upland catchments in Southeast Asia: Impact of rapid land use changes and conservation practices. Agric. Ecosyst. Environ. 128, 225–238. https://doi.org/10.1016/j.agee.2008.06.004