ABSTRACT
Life in northern Thailand has long been organized around the monsoon. Nearly 90 per cent of the annual rainfall falls between May and October. Stream flows rise several months after the start of the wet season, but decline rapidly after the rains end, underlining low storage capacities in soils and groundwater in the mountain catchments (Alford, 1992; Sharma et al, 2007). Water managers, thus must deal with periods of both excess and shortage each year. The Ping River drains much of the mountainous northern region of Thailand, flowing through a wide inter-montane valley that has a history of more than 700 years of communal and state-managed irrigation (Surarerks,1986, 2006; Cohen and Pearson, 1998). During the wet season farmers divert water to grow rice, and fish in the floodplains and wetlands. In the dry season only a few farmers with access to main river waters or large all-season tributaries can grow crops. The rest repair canals, build baskets and traps, and harvest products from community-managed forests.
