干旱区盐渍化土壤热红外发射率特性及其含盐量反演研究

Salinization and alkalinization are the most common land degradation processes, particularly occurring in arid and semi-arid regions, where precipitation is too low to maintain a regular percolation of rainwater through the soil. Under such a climatic condition, soluble salts are accumulated in the soil, influencing soil properties and environment which cause lessening of the soil productivity. The consistent identification of the processes is essential for sustainable soil management. Identification, large scale mapping and monitoring of the salt-affected areas have been done using three different data and techniques. Remote sensing has been widely used to detect and map salt-affected areas, since thousands of medium to highresolution imageries from the earth surface are available.In practice, most of these studies have focused on severely saline areas and have given less attention to the detection and monitoring of slightly or moderately affected areas. The major constrain is related to the nature of the satellite images, which do not allow extracting information from the third dimension of the 3-D soil body e.g., where salts concentrate in subsoil. Solute transport modelling is another technique which is used to predict the salt distribution in the subsoil. Direct and precise estimation of salt quantities from optical remote sensing ，in particularly optical remote sensing is a difficult because of: Lack of specific absorption bands of some salt types(e.g. halite) and occurrence of spectral confusions;(2)Low spectral resolution of satellite bands;(3)Vertical, spatial, and temporal variability of salinity inthe soil mantle and substratum;(4)The presence of other soil chromophores (e.g. structural crusts, soil surface texture, soil colour, soil surface roughness as determined by different salt types). The research focus on the conceptual framework of a method where the data of the soil emissivitive obtained from field survery, revelation of relation between salinizied soil careteristies and its emissivity, reconstruction of the infrared soil surface emissivity,The approach of using the thermal infrared emissivity to retrieve the salt content.The goal to explain the rule of the relation between salinizied soil careteristies and its emissivity and provide the new methods to monitoring of the soil salinization of the arid land.

目前利用遥感技术提取土壤盐渍化信息方法大部分是利用盐渍地在遥感影像的可见光光谱信息。但是由于盐渍地的光谱信息与其它地物（沙地、砂砾等）的光谱信息较为相似以及光谱混合的存在，盐分在土壤中随时间、空间、垂直方向变化的复杂性和土壤理化性质的多样性(表层质地、土色等) 等对盐渍化遥感监测的干扰作用,利用光学遥感监测土壤盐渍化并且提高监测精度带来一定的困难。因此如何发掘盐渍化土壤的热红外光谱特征与其化学及物理参数的内在联系，并准确的建立二者之间的关系，对光学遥感土壤盐渍化遥感监测进行补充和发展，使得遥感克服现阶段土壤盐渍化遥感监测的限制因素是很有必要。 本研究对干旱区盐渍化土壤的热红外光谱野外测量方法、盐渍化土壤的热红外辐射特性、盐渍化土壤热红外光谱重建技术，含盐量反演等方面进行研究，揭示盐渍化土壤的热红外光谱特征及其变化规律,建立含盐量的反演模型，从而为干旱区土地盐渍化问题的解决提共新的技术手段。

新疆盐渍土总面积8.476×106 hm2，现有耕地中31.1%的面积受到盐渍化危害。随着人口的增加，耕地面积的不断扩大和水资源的不合理利用，盐渍化问题日益突出，尤其南疆农区耕地的土壤盐渍化现象, 虽在逐步减轻,但总体上并未得到根本遏制，对南疆绿洲农业的可持续发展构成严重的威胁。加强对盐渍化土地的科学管理和改善、提高土地资源利用率，是关系经济发展、民族团结、社会稳定，关系地区协调发展和最终实现共同富裕的重大举措，是涉及新疆发展全局和改善生态环境的重大问题。.针对目前利用光学遥感监测盐渍化土壤并且提高监测精度较困难等现状,本研究以塔里木盆地典型洲作为研究区域，在野外和实验室，利用102F 便携式傅立叶变换热红外光谱仪、多功能红外热成像仪PCE-TC和地物光谱仪（ASD Field Spec Pro FR 2500）等实验仪器对研究区域盐渍化土壤的辐射特性和光谱特性进行测定，采用光谱匹配模型等方法对土壤的热红外光谱特征进行重建，揭示了盐渍化土壤的热红外光谱特征的变化规律，在此基础上利用热红外遥感数据特征和地理综合因素，经过数据变换、融合、建立信息提取规则和模型实现对盐渍化土壤专题信息的提取。结果表明对盐渍化土壤热红外发射率光谱特征与机理、信息提取等研究是能够综合反映盐渍地在可见光-红外波段的辐射特性,使土壤盐渍化监测和识别过程变得相对简单, 准确率进一步提高。充分发挥了遥感在土壤盐渍化监测中的优越性。本课题的成果为干旱区土壤盐渍化监测提供新的技术手段，促进土壤盐渍化遥感定量化的发展，对有效治理盐渍化土壤进一步退化，合理开发利用盐渍土资源，发展区域经济和维持生态可持续发展具有重要意义。今后，该成果的应用，将使我区土壤盐渍化监测与治理技术水平一定提高，具有深远的社会效益。