基于Hydrus-2D滨海盐碱地控盐排水暗管布设参数研究

为研究滨海吹填土地区控盐排水暗管布设对当地水盐运移的影响,以天津滨海新区为研究区选定典型试验区域建立现场试验,运用试验数据建立并验证了Hydrus-2D数学模型,土壤含水率RMSE范围为0.0042~0.0062 cm^(3)/cm^(3),R2为0.9167~0.9773,NSE为0.7606~0.7931;土壤含盐量RMSE范围为0.7178~1.1694 g/kg,R^(2)为0.9732~0.9861,NSE为0.7140~0.9240,所建立的模型能够准确模拟淋洗和暗管排水协同作用下的土壤水盐运移规律。模拟结果表明,当将30 cm土层土壤含盐量降低至0.3%,暗管布设深度固定时,总有一个暗管布设间距,其对应的耗水量为最大值,当布设间距增大或者减小时耗水量也随之减小;也总有一个暗管布设间距,其对应的0~500 cm土层脱盐率为最大值,当间距增大或者减小时脱盐率也随之降低。暗管布设宽度固定时,耗水量随暗管布设深度增加而减少,暗管布设宽度逐渐增加时耗水量受布设深度影响逐渐减小;排盐率随布设深度增加而增加。考虑淋洗耗水量与脱盐率提出了综合性暗管布设参数选取指标α,并运用指标确定了20种暗管布设深度与宽度组合中的最优组合参数为深度为120 cm、间距200 cm。研究成果可为海滨吹填土地区控盐排水暗管技术应用提供指导。

沟灌与暗管排水协同作用对水盐运移的影响

为探明沟灌与暗管排水协同作用对滨海盐土水盐运移的影响,选取滨海典型盐碱地区进行现场试验,通过试验数据滤定并验证了HYDRUS模拟效果,并利用验证完成的模型探究了不同灌水沟和暗管设置参数对滨海盐土水盐运移的影响。结果表明,沟灌与暗管排水协同作用下土壤水盐运移为垄沟灌溉与暗管排水特征的综合体现,靠近垄沟的浅层土壤受垄沟灌溉影响显著,同深度土壤层沟深位置含盐量低、垄处含盐量高。靠近暗管的浅层土壤受暗管排水影响显著,距离暗管越近土壤含盐量越低。增加垄沟间距与深度可以提升淋洗深度,垄沟间距增加还可提升淋洗范围,同时垄上盐分累积增加。沟灌与暗管排水协同运用治理盐碱地时,应及时挖除垄上高盐分土壤,防止大量盐分冲淋下渗。研究成果可为盐碱地的改良与利用提供理论支撑。

Study on the Landscaping Technologies for Coastal Saline-Alkali Land in Tanghai County of Tangshan City

Tanghai County is one of the counties in Tangshan City with the highest saline-alkali degree, with 80% of its land being covered by saline-alkali soils. Through studying landscaping technologies for coastal saline-alkali land in Tanghai County, 3 dominant modes for landscaping engineering in such land were summarized as shallow underground pipe desalination technology, banding soil replacement technology and hole membrane soil replacement technology, which are different in application scope and also in cost (respectively 260, 210 and 170 yuan). 3 landscaping measures were also proposed, including promotion of suitable plant cultivation technologies, application of saline-alkali tolerant plants and biological improvement of soils. To explore economic and practical planting patterns for saline-alkali land, low-cost landscaping tests were conducted from the perspectives of improving landscaping engineering mode and optimizing landscaping measures, and the results showed that it was practical to apply low-cost landscaping patterns, and comprehensive ecological measures should be adopted to realize the sustained utilization of soil.

基于HYDRUS-2D模拟排水暗管布设参数对土壤水盐运移的影响

为探究排水暗管布设参数对土壤水盐运移的影响,以中国天津滨海新区为研究区域,选定典型试验区域进行现场试验,利用试验数据率定验证了HYDRUS-2D的模拟效果,并运用验证后的模型参数模拟了不同暗管布设参数下的水盐运移。模拟结果表明HYDRUS-2D能够较好地模拟暗管排水条件下土壤的水盐动态。当保持暗管埋深不变时,暗管间距越大淋洗之后土壤含水率与含盐量越高;当保持暗管间距不变时,暗管埋深越大淋洗之后土壤含水率与含盐量越低。在12种模拟暗管模拟情景中,最大暗管埋深140 cm与最小暗管间距300 cm的组合参数下土壤剖面含盐量区间为最低值0.47~7.81 g/kg。因此,当暗管技术运用于盐碱地的改良时,应尽量减小暗管布设间距或增大暗管的布设深度以提高淋洗效果。

基于HYDRUS-2D模拟暗管排水条件下淋洗制度对土壤水盐运移的影响

为研究暗管排水条件下淋洗制度对土壤水盐运移的影响,本文以沿海盐碱地区为研究区域,选定典型试验地进行现场试验,利用现场试验数据率定了HYDRUS-2D模型参数并验证了模拟暗管排水的准确性,运用验证后的模型模拟了不同淋洗制度情况下的土壤盐分分布。结果表明:HYDRUS-2D能够较好地模拟暗管排水条件下的土壤水盐运移;在相同水量淋洗情况下,持续淋洗的淋洗效果优于间隔淋洗,间隔淋洗间隔时间越长淋洗效果越差。研究成果可为暗管排水条件下盐碱地淋洗制度的确定提供参考。

基于HYDRUS-2D模拟暗管排水条件下分区淋洗对土壤盐分分布的影响

为探究暗管排水条件下分区淋洗对土壤盐分分布的影响,以沿海盐碱地区为研究区域,选定典型试验地进行现场试验,利用现场试验数据率定了HYDRUS-2D模型参数并验证了模拟暗管排水的准确性,运用验证后的模型模拟了不同分区淋洗情况下的土壤盐分分布.模拟结果表明:HYDRUS-2D能够较好地模拟暗管排水条件下的土壤盐分分布.在暗管排水条件下,非分区淋洗土壤盐分分布均匀性较差,利用分区淋洗可以极大的提高土壤盐分淋洗的均匀性,在5种模拟情景中,F4模拟情景的土壤盐分淋洗均匀性最好,100cm土层的最大与最小含盐量差值仅0.79g/kg。

Effects of mosaic biological soil crusts on vascular plant establishment in a coastal saline land of the Yellow River Delta, China

Aims The effects of biocrusts on vascular plants are rarely evaluated in coastal saline lands.Our aim was to examine whether and how a mosaic of biocrusts affect seed germination of two typical herbaceous plants in a coastal saline land of the Yellow River Delta,to enhance our understanding by which substrate heterogeneity influences plant community dynamics.Methods We conducted growth chamber experiments to investigate the effects of biocrusts and uncrusted soil from bare patch-,Phragmites australis-,Suaeda glauca-and Tamarix chinensis-dominated habitats on seed germination percentage and mean germination time of two herbaceous plants:the perennial P.australis and the annual S.glauca.We also explored the mechanisms underlying the effects of substrate on seed germination.Important Findings Compared with uncrusted soil,biocrusts increased water content,nutrient accumulation and concentration of most salt ions,but they reduced soil pH value.Biocrusts with mosses directly decreased soil pH value and concentration of Mg2+,resulting in an indirect increase in seed germination percentage of S.glaucas.The low soil pH value also resulted in an indirect decrease in seed germination speed of P.australis in their own habitats.Bare patch directly increased accumulation of Cl?,resulting in an indirect decrease in seed germination speed of P.australis.These results suggest that biocrusts with mosses in P.australis habitats offer a window of opportunity for germination of S.glaucas.Biocrusts combined with habitat type have the potential to influence plant community structure through an effect on seed germination and establishment.