Research on water management to prevent secondary salinization in arid land, 1: Water balance in an irrigation block under rice-based cropping system in Central Asia
2000
Kitamura, Y. (Tottori Univ. (Japan)) | Yano, T. | Yasuda, S. | Oba, T.
In die Lower Syr Darya region of the Aral Sea Basin, secondary salinization of irrigated lands has been a crucial problem. To clarify the mechanism of secondary salinization, studies on water balance were carried out in an irrigation block where a rice-based cropping system has been practiced. Results of on-site studies are summarized as follows. 1) The amount of water supplied to a block is dependent not so much upon the crop water requirement as upon the conveyance capacity of the canal system. 2) The conveyance losses in a distribution canal were estimated at around 5.8% km(-1). 3) The performance of land-leveling was extremely low in rice plots. Since the ponding depth is managed based on the highest portion of a plot, this brings about deep water which leads to wastage of irrigation water and salt accumulation. 4) The average for unavoidable losses of evapotranspiration and deep percolation in rice fields throughout the cropping season was estimated at about 9.3 mm d(-1). A large portion of water introduced to rice fields, excluding unavoidable losses, tends to be released into field drains
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