Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2021-01-25 Cooperative journals: 《干旱区研究》
Abstract：为研究残塬沟壑区苹果园不同果农复合种植模式下土壤入渗能力及其影响因素，采用野外双环入渗法测定了永寿县果-荒（CK）果-草（M1）果-蔬（M2）果-粮（M3）复合种植模式下苹果园的土壤水分入渗参数，使用相关性分析和线性冗余分析研究了土壤入渗特征参数的影响因素。利用3种常用的土壤入渗模型对4种果园入渗过程进行拟合。结果表明：4种果农复合种植模式下果园土壤初始入渗速率在7.18~13.57 mm·min-1；稳定入渗速率在1.87~2.94 mm·min-1；平均入渗速率在3.36~5.65 mm·min-1；累计入渗量在260.51~423.65 mm，各果农复合种植模式苹果园初始入渗速率和平均入渗速率表现为M1>M3>M2>CK；稳定入渗速率和累计入渗量表现为M1>M2>M3>CK，M1样地各入渗指标显著大于其他管理模式样地，CK样地各入渗特征指标最小。相关性分析发现，土壤入渗特征指标与土壤容重、黏粒含量和粉粒含量呈负相关；与最大持水、最小持水量、毛管持水量、毛管孔隙度、非毛管孔隙度、总孔隙沙粒含量呈正相关。线性冗余分析结果表明，土壤粉粒含量、土壤孔隙度、土壤持水量、土壤容重是影响土壤入渗能力的主要的因素。主成分分析评价的土壤入渗能力排序为M1（2.75）>M2（0.04）>M3（-0.63）>CK（-2.17），苹果园林下种植作物能够有效的增加土壤入渗能力。比较3种模型发现，蒋定生模型对残塬沟壑区4种果农复合种植模式果园土壤入渗过程的拟合精度较高（R2=0.97），适用于描述该地区土壤入渗的实际情况。
Subjects: Mechanics >> Solid Mechanics submitted time 2024-02-07 Cooperative journals: 《应用力学学报》
Abstract：
The seepage direction inside the dam usually changes due to the different seepage positions and the fluctuation of upstream and downstream water levels.The infiltration angle of the seepage flow on the contact surface between the protected soil and the filter is not orthogonal.Because of the great difference of permeability coefficient between the dam material and the filter,the seepage angle causes the change of hydraulic properties of the contact surface,which will affect the filter performance.In this paper,the PFC-3D is used to establish the numerical models of 30°,45°,60° and 90° between the seepage direction and the contact surface.By simulating the real-time invasion rate of the protected soil particles and the depth of their movement into the filter,the contact erosion and filter effect under the action of different seepage directions are studied.The results show that in the initial stage of seepage,the difference of invasion rate and invasion depth of protected soil particles in different seepage directions is small; with the increase of seepage time,the invasion rate at 90°is relatively stable and the value is small,the invasion depth and seepage velocity at the contact surface are the smallest,and the filter has a strong ability to block the movement of protected soil particles.The filter effect decreases at 60°,45° and 30°,indicating that the larger the angle between the seepage direction and the contact surface,the better the filter effect.The reasonableness of the calculation results is discussed by using the principle of seepage refraction,and compared and analyzed with the experimental results of relevant literature,and it is considered that the change of seepage infiltration angle at the contact surface between the fill and the filter should be paid attention to in water conservancy projects such as embankment dams,especially the fact that the small angle of infiltration flow at the interface has a greater influence on the filter effect.
Subjects: Geosciences >> Geography submitted time 2021-06-13 Cooperative journals: 《干旱区研究》
Abstract：为了研究长期液膜覆盖对旱地土壤结构及入渗性能的影响，于2015—2018年在山西农业大学林业试验站进行了田间随机区组试验。试验设计有垄沟耕作和平作方式下的液膜和塑膜覆盖，以平作不覆盖为对照。结果表明：（1）液膜覆盖能改善土壤理化性质。和其他处理相比，PY、LY显著增加了土壤有机质含量和毛管孔隙度；与对照(CK)相比较，PY、LY、PS、LS的土壤容重均有显著降低。（2）液膜覆盖能改善土壤结构特性。和其他处理比较，LY显著提高了干筛、湿筛＞0.25 mm团聚体含量，PY、LY显著降低了土壤团聚体结构破坏率及显著提高了团聚体水稳性指数。（3）液膜覆盖提高了土壤稳定入渗性能。PY、LY的稳定入渗率和平均入渗率显著高于其他处理。（4）同种覆盖方式下，垄沟耕作较平作更有利于改良土壤结构特征，但二者对稳定入渗率的影响没有显著差异。（5）初始入渗率与土壤理化指标间没有显著相关性。稳定入渗率和平均入渗率与毛管孔隙度、＞0.25 mm水稳性团聚体含量、团聚体破坏率与团聚体水稳性指数间有显著或极显著相关性。
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： Soil moisture is indispensable for the growth and development of plants in arid zones and determines the dynamics and direction of the succession of arid plant communities. It is particularly important to investigate the dynamic characteri stics of soil moisture in different landscape types at the edge of the oasis in the middle reaches of the Heihe River and to develop effective, scientific, and reasonable measures to prevent wind and fix sand to prevent desertification. This study focused on three landscape types—protected forest landscapes, desert–oasis transition zone landscapes, and desert landscapes—at the edge of the oasis in the middle reaches of the Heihe River. HYDRUS-2D model simulation, LSD analysis, and Pearson correlation analysis were used to study the characteristics of soil moisture dynamics and the influencing factors of the three landscape types. The results were as follows: (1) the RMSE of soil volumetric water content ranged from 0.002 to 0.006 cm3·cm -3, MRE ranged from 4.22% to 5.20%, and R2 ranged from 0.72 to 0.97. The simulation results showed a high degree of agreement with the measured data, and the HYDRUS-2D model can be used for simulation studies of soil moisture in this study area. (2) The soil volumetric water content of protected forest landscapes and desert–oasis transition zone landscapes showed a trend of initial increase and subsequent decrease with increasing soil depth, whereas desert landscapes showed a trend of initial decrease and subsequent increase with increasing soil depth. (3) Effective precipitation plays a decisive role in the dynamics of the soil volumetric water content, and precipitation above 9.5 mm significantly increases the soil moisture content and infiltration depth over a short period. The depth of soil moisture infiltration in all periods after precipitation in desert landscapes was higher than that in protected forest landscapes and desert–oasis transition zone landscapes. (4) The soil volumetric water content of the three landscape types was related to factors such as precipitation, evapotranspiration, bulkiness, soil granular composition, and soil water-holding properties. The soil water-holding properties were significantly correlated with factors such as precipitation and evapotranspiration (P < 0.01). Of these, precipitation and clay-powder grain content were significantly positively correlated with soil volumetric water content, whereas bulk weight and sand grain content were significantly negatively correlated with soil volumetric water content. Thus, planting windbreak shrubs in the study area can increase the content of soil sticky powder particles, improve the ability of the soil to collect and utilize rainwater, and slow the process of infiltration, thus positively affecting the soil water-holding properties.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： After ecological restoration in Horqin Sandy Land, the soil moisture dynamics of the forest and its response to rainfall affect whether Pinus sylvestris var. mongolica(PSM) can be continuously used for the ecological restoration in the same type of area. To study the characteristics of soil moisture dynamics after vegetation restoration on the southern edge of Horqin Sandy Land, this study used the methods of in situ observation and numerical simulation and corrected the HYDRUS-1D model based on the measured data of soil moisture to explore its relationship with rainfall. We obtained the following results: (1) The regional moisture distribution was changed by the PSM plantation, deep soil recharge at 2.0 m in bare sand accounted for 44.16% of the annual rainfall, whereas deep soil recharge at 2.0 m in PSM land accounted for only 0.7% of the annual rainfall. (2) Soil moisture below a depth of 0.4 m had no response to light rain, but the response depth of soil moisture to moderate rain could reach 1.0 m. The response depth to heavy rain and rainstorm involved the entire observation profile. With increasing soil depth, a decreasing trend was observed in the variation in moisture fluctuation. (3) There was a strong correlation between rainfall and volumetric soil water content at shallow depth, and the cumulative rainfall at weekly and semi- monthly intervals was significantly correlated with the volumetric soil water content of each layer(P<0.05). Rainfall >50 mm can ensure the supply of soil moisture within 2.0 m. (4) The determination coefficient of the model was between 0.61 and 0.85, and the root mean square error ranged from 0.0061 to 0.0096 cm -3·cm -3. The accuracy of the deep layer simulation was higher than that of the shallow layer. These results have important implications for rain- fed vegetation afforestation in the Horqin Sandy Land.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2018-09-03 Cooperative journals: 《干旱区研究》
Abstract：干旱区地下水主要补给来源为河水入渗，评价干旱区地下水资源量需要准确计算河床的参数，包括垂向河床渗透系数（K）和垂向河水入渗速率（V）。本文描述了一种简化后的渗水仪和干旱区河床垂向渗透系数的计算公式，将该方法应用于新疆南部昆仑山北麓，测定了干旱区河流的河床参数。结果表明：此方法能够有效地测定干旱区河床垂向渗透系数，18个试验点的垂向河床渗透系数在0.864～14.832 m·d-1。根据试验结果总结了干旱区河水垂向入渗速率与河水深度的关系，提出了一个用于描述干旱区河流河水入渗速率与河水深度关系的经验方程，表明河水垂向入渗速率（V）与河水深度（M）正相关，河水入渗速率的增长率(dV/dM)与河水深度负相关，当河水深度很大时，河水入渗速率的增长率趋于0。
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Basic Disciplines of Agriculture submitted time 2017-11-08 Cooperative journals: 《中国生态农业学报》
Abstract：为探明不同耕作方式对土壤剖面结构、水分入渗过程等的作用机理, 采集田间长期定位耕作措施(常规耕作、免耕、深松)试验中的原状土柱(0~100 cm)及0~10 cm、10~20 cm、…、90~100 cm 环刀样、原状土及混合土样, 通过室内模拟试验进行了0~100 cm 土层土壤入渗过程和饱和导水率的测定, 分析了不同土层的土壤有机碳含量、土壤结构特征及相互关系。结果表明: 从土柱顶部开始供水(恒定水头)到水分全部入渗到土柱底部的时间为: 常规耕作>免耕>深松; 土柱土壤入渗速率和累积入渗量为: 深松>免耕>常规耕作; 土柱累积蒸发量为: 常规耕作>免耕>深松。土壤的饱和导水率表现为: 0~10 cm 和50~60 cm 土层, 免耕>深松>常规耕作;20~50 cm 和60~100 cm 土层, 深松>免耕>常规耕作。随土层的加深, >0.25 mm 水稳性团聚体含量和土壤有机碳含量均表现为先增加(10~20 cm)再降低的趋势。在0~40 cm 土层和80~100cm 土层, 均以深松处理>0.25 mm水稳性团聚体含量最高。在60 cm 以上土层, 土壤有机碳含量表现为: 免耕>深松>常规耕作, 而60 cm 土层以下土壤有机碳显著降低, 均低于4 g·kg1, 且在70 cm 以下土层, 常规耕作>免耕>深松。综上, 耕作措施能够改变土壤有机碳含量, 改善土壤结构, 促进土壤蓄水保墒; 深松更利于水分就地入渗, 而免耕则更利于有机碳的提升和水分的储存, 其作用深度在0~60 cm 土层
Subjects: Geosciences >> Geochemistry submitted time 2019-11-14 Cooperative journals: 《干旱区研究》
Abstract： 通过在锡林郭勒草原设置禁牧和放牧试验点，对气象、植被、土壤要素和5 cm、10 cm、15 cm、30 cm层土壤水分进行监测分析，揭示典型草原禁牧条件下降雨和土壤水分的变化及转化规律，结果表明：禁牧3 a后土壤垂向异质性增强，降雨过程中各土层土壤含水量差异显著，放牧区则相反；土壤水分对降雨响应的滞后时间随土层深度增加而增加，相对于禁牧区，放牧区浅层土壤（5 cm、10 cm）持水性能较弱，入渗完成用时较短；5 mm以下的降雨对禁牧和放牧区土壤水分均无明显补给作用，当降雨连续均匀且强度不超过5 mm·h-1时最有利于入渗，放牧区入渗深度达到15 cm和30 cm层分别需要7.9 mm和大于25 mm的降雨，而禁牧区大于5 mm的降雨就可以入渗到30 cm土层；强度5~6 mm·h-1的独立降雨只能入渗到表层土壤中（5 cm），强度大于15 mm·h-1的降雨在禁牧区能通过大孔隙快速入渗到30 cm及更深层土壤，放牧区则表层入渗较快（0~5 cm），深层入渗较慢，会形成地表径流甚至洪水灾害。该研究的结果可以为草地生态水文过程研究和制定合理的放牧政策提供参考。
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Basic Disciplines of Agriculture submitted time 2017-11-07 Cooperative journals: 《中国生态农业学报》
Abstract：为提高沙坡头地区造林过程中的水分利用效率, 制定最优化的灌溉制度, 在宁夏中卫沙坡头自然保护区, 两年生固沙梭梭(Haloxy lonammodendron)林展开直插式根灌节水试验, 分析和模拟直插式根灌过程中土壤水分入渗和消退规律。结果表明: 1)直插式根灌过程中, 土壤含水量随灌水时间的变化符合Logistic 曲线变化; 停灌后, 土壤水分消退规律符合幂函数模型变化。2)本试验条件下, 不同土层土壤水分最大入渗速率依次为60 cm>40 cm>80 cm>100 cm>20 cm, 达到最大入渗速率的时间40 cm 土层最短, 平均为1.22 h, 100 cm 土层最长, 平均为4.57 h; 1 m 深土层土壤水分最大入渗速率平均为1.65%·h1, 达到最大入渗速率的时间平均为2.16 h。3)根据模拟结果, 建议沙坡头区梭梭林直插式根灌灌溉周期为4 d 左右, 单次灌水时间以6~10 h 为宜。4)停灌2 h 后, 各土层土壤含水量消退速率随土层深度增加而增大, 停灌后48 h, 各土层土壤水分消退速率基本为零; 梭梭全生长期, 1 m深土层土壤水分消退速率在结实期最大, 为2.20%·h1, 休眠期最小, 为1.31%·h1。5)直插式根灌对20 cm 土层土壤水分的影响最小, 对60 cm 土层土壤水分影响最大; 灌溉过程中, 土壤水分等值线以60 cm 土层等值线为中心, 向表层和深层土壤辐射状分布, 灌后各土层平均土壤含水量, 20 cm 和60 cm土层与其他各土层之间差异显著(P<0.05)。研究表明, 直插式根灌的土壤水分入渗规律符合Logistic 曲线变化,消退规律符合幂函数曲线变化, 直插式根灌对20 cm 土层土壤水分的影响最小, 对60 cm 土层土壤水分影响最大, 沙坡头区梭梭林直插式根灌灌溉周期为4 d 左右, 单次灌水时间以6~10 h 为宜。
Subjects: Biology >> Ecology submitted time 2017-11-29 Cooperative journals: 《中国生态农业学报》
Abstract： The Loess Plateau suffers serious soil and water loss; resulting in a fragile ecological and environment and an intense deficit on available water resources. The groundwater is crucial to guarantee the regional social and economic development and maintain the ecosystem balance; however; the mechanism of groundwater transformation and recharge on the Loess Plateau is still not clear. The objective of this study was to investigate the water movement in deep soil profile and test the possibilities of rainfall in recharging the shallow groundwater in the water-wind erosion crisscross region on the Loess Plateau. Considering the restrictions of current equipment and techniques for deep soil profile moisture observation; HYDRUS-1D model was applied to calculate solute the soil hydraulic parameters and simulate deep profile 0~15 m soil water movement; by using of the data sets of meteorological factors and soil water contents in soil depth 0~600 cm in a Chinese willow field plot with aeolian sandy soil from 2013 to 2016. Upper boundary condition was set as atmosphere boundary conditions with inputs of rainfall and potential transpiration (Tp) and potential evaporation (Ep) which were partitioned from crops evapotranspiration (ET0); ET0 derived from Penman-Monteith method and the partition into Tp and Ep had used the measured leaf area index (LAI) in different growing periods; and lower boundary condition was set free drainage. The optimized hydraulic parameters were derived from repeatedly inverse solution process; and then these parameters were used to simulate soil water movement in 0~1 500 cm; and the depth of soil water infiltration and the possibility of recharging shallow underground water were analyzed. Results showed that soil water contents at the end and the beginning of the growth season in 0~600 cm had a slight deficit in 2014 (439 mm; normal precipitation year) and 2015 (371 mm; dry year). However; there had a surplus of soil water at the end of the growth season as compared with the beginning of the growth season in 2013 and 2016 (669 mm and 704 mm respectively; wet years); and the rainfall infiltration had exceeded the observing depth 600 cm. From the simulating results; soil water contents in deep soil profile had not change significantly in 2014 and 2015; and the water moves slowly into deeper soil layers; but rainfall could infiltrate to soil depths 11 m and 12 m; respectively; exceeding rooting zone at the end of the 2013 and 2016; which indicated the possibilities of rainfall in recharging the shallow groundwater. During the simulated period of 4 years; the mean value of water infiltration rate on aeolian sandy soil is 606.28 cm穌-1; average soil evaporation in 4 years is 14.87 cm; and average plant transpiration in 4 years is 33.71 cm; soil water contents were mainly lossed in the form of transpiration. Thanks to the high infiltration rate in coarse-textured soil in wet years; a large proportion of rainfall may transform into shallow underground water. Dry and wet years alternate on the Loess Plateau with intensive rainfall variations; the rainfall infiltration in wet years may be one way of shallow groundwater recharge.
Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： Pore size in the soil physical crust directly affects soil water infiltration and gas exchange. However,few studies have investigated the changes in pore size within the soil physical crust during rainfall events. Thisstudy has utilized Lou soil as the research object and artificial rainfall simulations, with microdisk infiltrationapparatus to study the infiltration of the soil physical crust under different rainfall intensities and the pore sizechanges. The results show that under the pressure head of − 0.5 cm, the infiltration rate of the structural crustdecreases with the rainfall duration and then increases after 20 min. As rainfall progresses, the proportion of largepores in the two types of crusts begins to decrease, and the proportion of medium pores increases. The proportionof small pores in the structural crust decreases at 20 min, and the proportion of medium pores in the sedimentarycrust remains unchanged at 10 min. The average pore size for the two types of crusts was found to decrease withthe extension of the rainfall duration. During the increase in the negative pressure head, the effective infiltrationcapacity of the soil crust decreased. When the soil crust developed completely, the infiltration rate tended to bestable.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Basic Disciplines of Agriculture submitted time 2017-11-07 Cooperative journals: 《中国生态农业学报》
Abstract：土壤含水量是影响半干旱区农作物生长的重要因素。为了准确测定土壤含水量的变化动态以指导农 业高效用水, 近年来, 利用地球物理测量方法研究高分辨率的水流入渗, 已经越来越受到欢迎和重视。本文以陇中半干旱区玉米田为例, 通过在土壤表面布置电极, 利用高密度电阻率成像法(ERT)对降雨前后土壤二维剖面进行电阻率数据测量, 实现对土壤二维剖面电阻率值和含水量监测, 解释不同条件下土壤含水量变化的原因, 建立陇中半干旱区农田土壤电阻率和含水量之间的相关关系。结果表明: 降水入渗使得二维剖面土壤电阻率整体呈明显降低趋势, 反演得到的电阻率图像局部电阻值“高低高”的变化过程, 与一次降水过程前后“干湿干”的循环过程一致。土壤含水量实测值与估计值之间有较为显著的线性关系(R2=0.651 8, n=96)。在0~2.0 m深度范围内, 总体估计偏差较小, 为0.74%; 土壤含水率的估计精度较高, 为2.64%。0~0.5 m 土层(H1)含水量监测探头分布密集, 数据采集较为准确, 故H1 层估计精度略高于0.5~2.0 m 层(H2)。相比之前利用实测工具进行野外测量, ERT 测量方法精度较高。本文提供了一个高分辨率的土壤结构二维分布与水分运移过程的图像,同时为实现精确和高效的农业用水管理提供一种新途径。
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