Abstract
The conventional trapezoidal-shaped concrete-lined ditch (trapezoidal ditch) has been used for tertiary irrigation canals (irrigation ditches) in Thailand. The Modernization of Water Management System Project in Thailand (MWMS Project) introduced the U-shaped reinforced-concrete flume manufactured on the assembly line (U-shaped flume) into Thailand for the first time as an irrigation ditch. Advantages and disadvantages of the two types of concrete ditches are compared. Thus far, only dirt ditches have been constructed in deep-water rice areas and floating rice areas; therefore, experimental construction of concrete irrigation ditches, which are submerged under water for a long period in the latter half of the rainy season, were conducted for testing of suitable type and construction method. The results indicate problem-free construction of both types of concrete ditches using normal construction methods.
