干旱荒漠区田间灌溉对区域尺度土壤水盐分异进程的影响研究

Water-salt transportation of artificial oases in arid desert area has unique characteristics. Field irrigation of different patterns has remarkable effect on regional water-salt differentiation, but it works slowly and the process is hard to manage in a short period. It is therefore of great importance for researches on the pattern of drastic environmental change in some regions to choose a specific experimental filed, reveal microcosmic water-salt transportation pattern as well as its impact, and postulate its status in the future, .Jingdian Irrigation Field, located on the southern margins of Tengger Desert, has been chosen as the experimental field. Based closely on regional water-salt differentiation and the pattern of drastic environmental changes , experimental simulation was adopted to demonstrate the inner mechanism and critical conditions; continuous location monitoring and remote sensing were utilized to generally reveal regional water-salt differentiation in time and space as well as its features during motion; the cloud-neural network model has been built to assess the multi-process coupling relationship between field irrigation and regional water-salt differentiation of soil and to predict the water-salt differentiation development as well as the potential drastic changes in water-soil environment. Hopefully, the research paper presented below would provide theoretic groundwork for the assessment of regional water-salt differentiation and the water-salt regulation in China.

干旱荒漠区人工绿洲的水盐运移具有典型性和独特性，不同模式的田间灌溉对区域尺度的土壤水盐分异进程的驱动表征十分明显，但其影响过程潜在而缓慢，短期内不能完全掌握。通过选定典型研究区，揭示田间微观的土壤水盐运移对区域宏观的水盐分异进程的驱动过程和影响程度，预测其演化态势，对区域水土环境激变的驱动机理研究具有重要意义。.本项目以地处腾格里沙漠边缘的甘肃景电灌区为研究区域，紧扣区域尺度的土壤水盐分异进程和空间变异的驱动机理这一关键性问题，通过实验模拟揭示田间灌溉驱动土壤微观水盐运移的内在机理和临界条件；通过连续的定位监测和遥感解译分析，揭示区域宏观尺度的水盐时空分异进程及其演化特征；建立云神经网络模型评估田间灌溉与区域尺度的土壤水盐分异进程之间的多过程耦合关系，预测区域未来的水盐分异态势和水土环境激变效应，为我国多尺度的土壤水盐分异过程评价和区域水盐调控提供理论依据。

干旱荒漠区人工绿洲的水盐运移具有典型性和独特性，不同模式的田间灌溉对区域尺度的土壤水盐分异进程的驱动表征十分明显。本项目以地处腾格里沙漠边缘的甘肃景泰川电力提灌灌区（以下简称“景电灌区”）为研究区域，紧扣区域尺度的土壤水盐分异进程、空间变异的驱动机理以及水土环境演化响应等问题，通过典型区的数值模拟、遥感影像解译、层次分析法、云理论、多级模糊评价模型等综合方法，研究分析了干旱荒漠区田间灌溉对区域尺度的水盐分异进程影响及水土环境响应。研究成果如下：1）运用HYDRUS-3D模型对畦灌和沟灌模式下水盐运移进行模拟，畦灌的土壤含水率值略高于沟灌，且含水率下降的趋势略低于沟灌；2）将与土壤水盐相关的重要因素进行空间处理和权重叠加，研究区总体水盐分布状况西低东高，西南向东北以弧线状递增；3）与未耕种盐碱荒地相比，耕种5a、10a、15a后0~80cm各土层盐分总量在剖面上随土壤深度的增加呈现先下降后上升的趋势；4）选取一期灌区东北部盐渍化较为严重的区域并利用灰色评估模型对其进行盐渍化风险等级定量评估，研究区域盐渍化风险等级以“一般风险”和“风险很大”为主；5）采用云理论改进的层次分析法开展干旱灌区水土环境响应评价，18个响应因子均为低敏感因子，其中，响应最为强烈的指标为灌溉提水量和灌溉用水量。灌区水土环境响应的4个状态层因素，响应最为强烈的是地表水，其次为地下水，响应最为微弱的为土地利用；6）将云理论引入到土壤盐渍化程度的多级模糊评价系统中，提出了基于云理论的土壤盐渍化程度的多级模糊评价模型，对干旱荒漠灌区的土壤盐渍化程度进行评价，该灌区区域土壤的盐渍土介于轻度盐化土和中度盐化土之间。本项目通过选定典型研究区，揭示田间微观的土壤水盐运移对区域宏观的水盐分异进程的驱动过程和影响程度，对区域水土环境激变的驱动机理研究以及推动干旱区人工新绿洲的可持续发展具有重要意义，对其它国家同类区域尺度的水盐分异过程的评估也具有重要示范作用。