【摘要】 为了查明盐碱地排水沟蓄水条件下农田与排水沟之间的水盐交换,基于两年现场观测试验数据,分析了农田与排水沟的水位响应以及电导率变化规律。结果发现:研究区排水沟蓄水条件下,相邻排水沟水位与农田地下水位变化基本一致,作物生长期较为强烈的蒸发蒸腾作用进一步降低了田间地下水位;排水沟水位变化可以直接或间接地影响周围农田的地下水位和水质状况,在无外界来水干扰的情况下,农田地下水和排水沟水样的电导率变化趋势一致,当排水沟受到外来淡水补给时,沟内浓缩的盐分得到稀释,电导率明显低于农田地下水。研究结果可为类似地区盐碱地治理和生态环境保护提供参考依据。更多还原

【Abstract】 The fast population growth and rapid urban development in China have made it necessary to develop marginal lands for agricultural use. One approach to meet such land requirement is to reclaim the existing salinized wasteland through engineering measures through artificial drainage. As salt content in soils poses potential threat to crop growth,understanding the relationships of salt and water exchange between farmland and drainage ditches is of great importance for salinity control in the saline agricultural environment. In this paper,we present a 2 year monitoring study on salt and water dynamics in a reclaimed salt affected farmland area in Shaanxi,China. In 2 strip fields of 100×400m,we observed water table depth and measured electrical conductivity( EC) of water samples taken from monitoring wells,those wells were installed at 1,2 and 3 m in depth in a cluster in each field; in the mean time,we measured the depth to water level in drainage ditches along the strip fields and sampled the ditch water for their salinity levels. Weather data analysis showed that the rainfall during the monitoring period was close to the long term average values. Rainfall pattern in the study area is generally in accordance with the potential evapotranspiration,making irrigation only necessary when prolonged dry period appears during the growing season. The monitoring data showed that the drainage ditches have effectively controlled the water table in the crop fields: the depth to water table varied between 1.69 to 2.27 in field A and between 1.24 and 2.18 in field B,while the depth to water level in drainage ditches varied between 1.84 and 2.05 by the field A and between 1.16 and 2.0 by the field B. The salinity of the groundwater in the fields,however,was less variable than that in the drainage ditches: the EC in groundwater varied between 4.72 and 7.51ms / cm in field A and between 6.58 and 11.4 in field B,while the EC in drainage ditches varied between 4.86 and 8.69 by the field A and between 1.9 and 14.75 by the field B. The greater variability of ECin the drainage ditches was caused by the dilution effect of freshwater recharge in the end of the irrigation season,when a large amount of irrigation return flow from an upstream irrigation district was discharged to the study area due to its lower elevation. The elevated water level in the drainage ditches had no significant impact on field water table depth due to the short duration. When no additional freshwater recharge is available,salinity in the drainage ditches increased with time due to evaporation concentration. Findings from this research may provide technical guidance for salinity management in the similar salt affected agricultural regions.更多还原