| Budget Amount *help |
¥9,370,000 (Direct Cost: ¥7,900,000、Indirect Cost: ¥1,470,000)
Fiscal Year 2007: ¥6,370,000 (Direct Cost: ¥4,900,000、Indirect Cost: ¥1,470,000)
Fiscal Year 2006: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Research Abstract |
1. Thamnop is an irrigation system for low-land rice in which an earthen bund higher than the banks crosses a stream so that the whole flow is dammed up and spills over the bank upstream of the structure.
2. The spilling water is spread as widely as possible by extended earthen bunds, the plot-to-plot flow, and other means, and part of water is returned to the original stream via the detour channel.
3. Thus, the thamnop system consists of three functions, namely, (1) the damming-up function, (2) the diffusion function, and (3) the detouring function. All three functions are traditionally performed by earthen bunds, but, after concrete materials became available, the over-flow sluices, pipes, and water gates were added. Despite of these modifications, however, the system's essential feature remained to be the bank spilling.
4. Local governments in Northeast Thailand recognized the meaningfulness of the thamnop in the early 20th century. In the latter half of the century, the weir irrigation became predominant, and most of the thamnop systems were replaced for the weirs.
5. In view of the hydrographical characteristics of the region, however, the thamnop should be re-examined.
6. In general, where the constant flow is expected, the weir system is installed, which takes in only the needed volume of water. Where the flow is limited in volume and/or unstable temporally, the reservoir or tank system becomes necessary. Hydrography of streams in Northeast Thailand is characterized by the storm-flow, somewhat similar to wadi flow in the arid region. The damming-up of the whole stream flow by the thamnop, and spread over wide rice fields can be regarded as a sort of water reserve.
7. The problems of the thamnop such as distribution of bank-spilling water and returning to the original stream could technically be solved. The thamnop system has a practical potential for the future.
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