Knowledge Resource Center for Ecological Environment in Arid Area
| 膜下滴灌条件下土壤水盐运移规律及其模拟研究 | |
| 其他题名 | Regime and Simulation of Water and Salt Movement of Soil under Film Mulched Drip Irrigation |
| 刘春卿 | |
| 出版年 | 2007 |
| 学位类型 | 博士 |
| 导师 | 杨劲松 |
| 学位授予单位 | 中国科学院南京土壤研究所 |
| 中文摘要 | 采用实地调查、模拟试验与数值模拟相结合的研究手段与方法，对新疆灌耕灰漠土膜下滴灌条件下土壤水盐运移规律进行了研究和计算机模拟。论文按照面上调查－室内分析－模拟试验－数值模拟的技术路线开展工作。通过实地调查、采样和实验室分析，掌握了玛纳斯河流域和三工河流域灌溉水质与土壤盐渍化状况；根据土壤干容重及颗粒分析结果拟合得到van Genuchten型土壤水动力学参数；由水平土柱入渗试验、混合置换实验和等温静态平衡吸附试验获得了石河子垦区灌耕灰漠土饱和－非饱和土壤水动力弥散系数和平衡吸附常数；采用室内模拟试验研究了滴灌条件下水分和盐分的运移；通过温室模拟试验研究了作物生长条件下的土壤水盐运移；运用Hydrus-2D软件对滴灌条件下的土壤水盐运移进行了数值模拟。本论文为运用模型的方法研究二维土壤水盐运移规律，为荒漠绿洲农田可持续利用的研究提供了新的思路。主要研究内容和结果如下：\n1. 新疆玛纳斯河流域和三工河流域的灌溉水质和土壤盐渍化研究\n 石河子垦区各团场灌溉水矿化度大多在0.5g L-1以下，渠水属重碳酸盐型钙质水；井水多为钠质水。大部分灌溉水对土壤渗透性造成显著影响。当前的膜下滴灌促进了盐分淋洗出根区，但盐分累积于70cm或90cm以下深度。灌溉方式、灌溉水质和滴灌年限与0-40cm土壤含盐量显著相关。\n 三工河流域冲积扇上部灌溉水矿化度多小于0.5 g L-1；冲积平原中下部矿化度为2 g L-1或以上。土壤盐分含量平均值已达中度至强度盐渍化水平，离子组成以硫酸盐和氯化物为主。\n2. 石河子垦区灌耕灰漠土饱和－非饱和土壤水动力弥散系数和平衡吸附常数研究\n 试验研究获得了石河子垦区灌耕灰漠土非饱和土壤水扩散率和水动力弥散系数，饱和条件下水动力弥散系数和弥散度；等温静态平衡试验获得了静态平衡吸附常数，为应用数学模型对土壤水盐运移规律进行定量分析提供了基础数据。\n3. 膜下滴灌条件下土壤水盐运移及再分布的规律及模拟研究\n 土壤湿润体体积与总灌水量有关，而与滴头流量并无显著相关。滴灌结束后，水盐都经历了一个重要的再分布过程，进一步促进了盐分向深层和远离滴头处运移，再分布3天后盐分运移趋缓。\n 基于土壤水分运动方程和溶质运移对流－弥散方程，建立了地表滴灌条件下水盐运移二维模型，确定了相应的边界条件，运用Hydrus-2D软件对滴灌条件下的土壤水盐运移和再分布进行了数值模拟，利用实测数据对模型进行了验证。验证结果表明模拟结果较好地反映滴灌条件下的土壤水盐运移规律。\n4. 种植作物条件下土壤水盐运移动态及模拟研究\n 棉花根系有避开高盐环境的趋势。从本试验看，土壤电导率值低于7.5dS m-1时，对棉花根系的生长没有任何影响。当下层土壤电导率值高于7.5dS m-1时，棉花根系横向生长，并显示下层土壤盐分浓度越高，根系向下层扩展的时间越迟。\n 淡水滴灌盐土，可使上部土壤(20cm以上)逐渐脱盐。微咸水滴灌盐土，土壤表层盐分含量会有一定增加并基本稳定于一定数值。对于低含盐土壤，微咸水灌溉引入的盐分向土壤深层运移，主要增加深层土壤的盐分含量。对于高含盐土壤，微咸水灌溉携入的盐分主要积累于20cm处。\n 滴灌促进了盐分淋洗，随土壤深度增加，土壤盐分浓度增加，同一层中，盐分向远离滴头的方向运移。但对于土壤初始含盐高的处理2和处理3，棉花生长的前期和中期，最高盐分浓度出现在40cm深距滴头30cm处。对处理1和处理3，微咸水滴灌使40cm深距滴头15cm处的盐分含量持续增加，至生长后期超过其它各处成为盐分浓度最高的地方。\n 应用Hydrus-2D软件对各处理下的水盐运移规律进行了模拟和验证，结果显示，所选的参数和控制条件基本合理，较好地反映了水盐运移的实际情况，可以用来对滴灌条件下各种管理措施的水盐运移规律进行数值分析和预测分析。 |
| 英文摘要 | Based on the field method, experimental investigation and numerical simulation, a study on soil water and salt dynamic under film mulched drip irrigation was conducted and simulation was developed. The thesis was organized according to the technical route of investigation, indoor analysis, simulation tests and numerical simulation. Water quality and degree of soil salinization in Manasi and Sangonghe river basins were obtained via field method, sampling and analysing in laboratory. Hydraulic parameters of van Genuchten model from fitting soil bulk density and mechanical analysis, Hydrodynamic dispersion coefficient in saturated- unsaturated desert grey soil in Shihezi irrigated areas and equilibrium adsorption constant were obtained by horizontal infiltration experiment, miscible displacement experiment and isothermal static balance adsorption method. Movement of water and salt in soil under surface drip irrigation was conducted through indoor simulation tests in soil columns. Soil water and salt movements under plant growth in greenhouse were investigated and simulated by using Hydrus-2D software package. This thesis provided the new method for the study of sustainable utilization of desert oasis farmland. The following were the main contents and conclusions.\n1. Present status of irrigation water quality and soil salinization of Manasi and Sangonghe river basins were obtained.\n Mineralization degree of irrigation water in Shihezi irrigated area is below 0.5g L-1 in most cases. The major ions in ditch water are bicarbonate and calcareous. The major cation in well water is sodion. Most irrigation water put significantly impact on the permeability of soil. Current method of film mulched drip irrigation is favor of the leaching of salt out of root zone, but salt accumulated below 70cm or 90cm. Irrigation method, irrigation water quality and drip irrigation years are obviously correlated with 0-40cm soil salt content. \n Mineralization degree of irrigation water is below 0.5g L-1 in upper part of alluvial fan in Sangonghe catchment. Mineralization degree of irrigation water is above 0.5g L-1 in middle or lower part of alluvial plain. Mean of salt content in soil are moderate or high. The major salts in soil are sulfate or chloride.\n2. Hydrodynamic dispersion coefficient in saturated- unsaturated desert grey soil and its equilibrium salt adsorption constant were achieved.\n Soil water diffusivity and hydrodynamic dispersion coefficient under unsaturated soil and dispersivity under saturated soil were obtained. Static equilibrium adsorption constant was obtained through isothermal static equilibrium test. Above parameters are basic data for simulation using model.\n3. Study on movement and redistribution of water and salt in relation to emitter discharge rate and simulation were conducted.\n Wetted soil volume was related to total quantity of the irrigation water rather than emitter discharge rate. At the end of drip irrigation, water and salt had experienced important redistribution processes. Soil salt moved toward deeper soil layers and away from emitter. The movement of salt was the most active on the first three days of redistribution. \n Based on the theory of soil water dynamics and convection-dispersion equation, a two-dimensional model was developed and the boundary conditions were determined. Simulating the movement and redistribution of water and salt in soil by using Hydrus-2D software package, simulating results agreed well with measurement values.\n4. Soil water-salt dynamic and simulation under planting\n The roots of cotton had trend to avoid high-salt conditions. From this test, there wasn’t any influence on the growth of roots when the electrical conductivity in soil was below 7.5dS m-1. When the electrical conductivity in lower soil was above 7.5dS m-1, the roots of cotton extended along transverse direction. More high the salt content in lower soil, more late the roots of cotton expanded to lower soil.\n Drip irrigation with fresh water desalted the upper saline soil gradually. Brackish water irrigation increased salt content of topsoil at certain extent and kept at certain values. The salt introduced by brackish water moved to deeper soil layer in low saline soil. Salt introduced by brackish water mainly accumulated at 20cm because of the high salt content in lower soil.\n Drip irrigation promoted the leaching of salt. With the soil depth increased, soil salt content increased. Soil salt moved away from emitter at same layer. The highest salt content occurred at 40cm below the soil surface and 30cm apart from emitter before later phase of cotton growth period for treatment 2 and treatment 3 with high salt content. Brackish water irrigation made the position of 40cm below the soil surface and 15cm apart from emitter the highest salt content at later phase of cotton growth period. \n Simulation of the movements of soil water and salt under different treatments by using Hydrus-2D software package showed that the parameters and boundary conditions were appropriated to simulate the actual water-salt transport. It can be used for numerical analysis and forecasting of the movement of water-salt under different management measurements in drip irrigation. |
| 中文关键词 | 水盐运移 ; 数值模拟 ; 膜下滴灌 |
| 英文关键词 | water and salt movement numerical simulation drip irrigation under mulch |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 土壤学 |
| 来源机构 | 中国科学院南京土壤研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286572 |
| 推荐引用方式 GB/T 7714 | 刘春卿. 膜下滴灌条件下土壤水盐运移规律及其模拟研究[D]. 中国科学院南京土壤研究所,2007. |
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