Causes of farmland salinization and remedial measures in the Aral Sea basin - Research on water management to prevent secondary salinization in rice-based cropping system in and land
Causes of farmland salinization and remedial measures in the Aral Sea basin - Research on water management to prevent secondary salinization in rice-based cropping system in and land
复制标题
DOI：
10.1016/j.agwat.2006.03.007
复制
发表时间：
2006-09-16
影响因子：
6.7
通讯作者：
Inosako, Koji
中科院分区：
文献类型：
--
作者：
Kitamura, Yoshinobu;Yano, Tomohisa;Inosako, Koji
在咸海盆地的下锡尔河地区，灌溉土地的次生盐碱化一直是一个严重问题。为了阐明土壤次生盐渍化的机理，在一个实施水稻种植制度的灌区进行了水盐行为研究。现场研究结果如下：（1）由于水稻种植的土地平整效果极差，水位维持在足以淹没每一地块最高部分的水平，这造成灌溉水的浪费和盐分的积累。(2)引入稻田的大部分水往往被排放到田间排水沟中。(3)由于微咸水灌溉稻田，溶解盐主要沉积在地块及其周边的高地。土壤盐分积累速率的变化取决于轮作过程中由高地向淹水条件转化的农田面积的年变化规模。(4)对水稻田饱和浅层土壤盐分行为进行了研究。浅层土壤水盐分的初始降低是由于初期入渗的淋溶作用，随后逐渐增加更可能是由于与残留在土壤细孔隙中的咸水混合，再加上作物吸水的浓缩效应，以及由于偶尔中断和恢复灌溉供水而从下层向上流动的结果。(5)由于稻田渗漏水在田间排水沟下方流动，加速了邻近高地地下水位的上升和盐分的积累。因此，基于灌溉区作物轮作制度的水旱混合种植加速了高地的水涝和盐分积累。在此基础上，提出了治理次生盐渍化的几项措施：（1）避免水旱混种，将高地统一在一个灌区内，控制地下水位;（2）通过改善渠道建设和管理绩效，采用渠道衬砌，（3）维修及操作排水渠以加强排水功能，特别是安装地下瓷砖排水系统以加强地下排水功能，以及管理排水口，以尽量减少咸排水在下游地区造成的环境恶化;（4）发展蒸发塘的设计及管理技术，以便更有效地管理污水，并在每个灌溉区的排水口再用排水;（5）减少供应稻米的用水及其他农作物的用水，或将节省的水放回河流，供下游用户使用，包括放回环境中;（6）在沿岸国家之间缔结国际水和/或排水权协定，并颁布全流域管理条例，以控制取水和排水。(c)2006 Elsevier B. V.保留所有权利。
In the 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 and salt behavior were conducted in an irrigation block where a rice-based cropping system has been practiced. Results of on-site studies are summarized as follows: (1) since the performance of land-leveling for rice cultivation was extremely poor, the water level was maintained high enough to submerge the highest portion of each plot, and this causes wastage of irrigation water and salt accumulation. (2) A large portion of water introduced to rice plots tends to be released into field drains. (3) Due to excessive irrigation of rice plots with slightly saline river water, dissolved salts were mainly deposited in upland plots in the block and its periphery. Changes in salt accumulation rates were dependent upon the scale of annual changes in the farmland areas that were converted from the upland condition to submerged condition in a process of crop rotation. (4) A remarkable finding was obtained on salt behavior in saturated shallow soil layers of rice plots. An initial decrease in soil water salinity in the shallow layer is due to the leaching effects of infiltration during the initial stage, and the subsequent gradual increase is more likely a consequence of mixing with the saline water that remains in the finer soil pores combined with the concentration effects of crop water uptake, and the upward flow from the lower layers due to occasional interruption and resumption of irrigation water supply. (5) Because seepage water from rice plots flows underneath the field drain, the rise of the groundwater table and salt accumulation were accelerated in the adjacent upland plots. Thus, mixed cropping with rice and upland crops based on a crop rotation system in an irrigation block accelerates waterlogging and salt accumulation in upland plots. Based on these results, several remedial measures were recommended to overcome problems on secondary salinization as follows: (1) avoid mixed cropping with rice and upland crops, and unify either upland crops or rice in an irrigation block to control groundwater table; (2) decrease conveyance and field application losses through improved canal construction and management performance, introduction of canal lining, and improved land-leveling performance; (3) maintain and operate drainage canals to enhance function, particularly installation of subsurface tile drainage for enhancing subsurface drainage function and management of drainage outfall for minimizing environmental degradation caused by saline drainage water in the downstream area; (4) develop a design and management technique of evaporation pond for better effluent management and reuse of drainage water at the outfall of each irrigation block; (5) reduce the water supplied for rice and its use for other crops, or returning the saved water to the river for downstream users including returning to the environment; (6) conclude international water and/or drainage rights agreements among riparian countries and enactment of a basin-wide management regulation to control water withdrawal and drainage. (c) 2006 Elsevier B.V. All rights reserved.