考虑积雪覆盖的区域土壤春墒预报机理与模型研究——以松嫩平原黑土区为例

Aiming at low precision and bad applicability of pedon scale methods, small quantity and weak practicability of region scale methods and obtaining problems of large scale input data in current studies on soil moisture forecast, the mechanism and model of regional spring soil moisture forecast covered by snow, taking account of both physical mechanism and availability, will be researched by synthetically using remote sensing, spatial variability, fractal, etc. Firstly, snow depth and snow water equivalent retrieval will be conducted by using passive microwave remote sensing data, and snow surface temperature retrieval will be carried out by using MODIS data. Secondly, on the basis of fractal analysis on soil structure variables, a pedo-transfer function between soil structure fractal dimensions and parameters of van Genuchten-Mualem model will be studied to establish the estimation model of soil hydraulic properties. Finally, according to the division-and-integration thinking, based on numerical simulation of pedon soil moisture covered by snow and rational sampling number and location of regional soil moisture forecast, a regional soil moisture forecast method taking account of snow cover will be proposed by using spatial variability analysis and spatial interpolation. The research results have important theoretical values and practical significances to break through restriction of regional farmland soil moisture forecast, to complete theoretical system of soil moisture forecast, to improve operating capability of soil moisture and to reduce grain production risk in black soil area of Songnen Plain.

针对目前土壤墒情预报研究中存在的土体尺度方法精度低适应性差、区域尺度方法少应用性不强、大尺度输入数据获取困难等问题，综合运用遥感、空间变异、分形等多种技术方法，兼顾物理机理与实用性研究考虑积雪覆盖的区域土壤春墒预报机理与模型。首先，以被动微波遥感数据反演积雪深度与雪水当量，以MODIS遥感数据反演雪面温度；其次，在土壤结构变量分形分析的基础上，构建土壤结构分形维数与van Genuchten-Mualem模型参数的土壤传递函数，进而建立土壤水力参数估算模型；最后，按先分后总思路，基于考虑积雪覆盖的单点土壤水分数值模拟与区域土壤水分预测合理采样数量及位置的确定，通过空间变异分析与空间插值，提出考虑积雪覆盖的区域土壤春墒预报方法。研究成果对于突破区域农田土壤墒情预报限制，丰富与完善土壤墒情预报理论体系，提高松嫩平原黑土区土壤水分管理能力、降低粮食生产风险具有重要的理论价值与现实意义。

为解决寒区积雪覆盖下土壤春墒预报模型与方法在大尺度初始输入参数、土壤采样合理性、土壤水分运动关键参数、数值模拟数学模型等方面存在的问题，以松嫩平原黑土区为例，通过野外采样、室内试验和理论分析相结合的方法，对区域积雪覆盖下土壤春墒预报模型与方法开展了深入研究。通过项目研究，分别提出了基于多源数据的松嫩平原黑土区亚像元雪盖率遥感反演方法、基于被动微波亮温数据的松嫩平原黑土区雪深遥感反演方法、基于MODIS的松嫩平原黑土区雪面温度遥感反演方法、基于优先级指数的土壤采样设计方法，解析了离群样点对土壤特性空间变异性及合理采样数的影响，开发了空间分布数据集局部离群点挖掘算法，确定了松嫩平原黑土区土壤水动力学参数最优估算模型，构建了基于分形的松嫩平原黑土区土壤水力参数传递函数，揭示了松嫩平原黑土区积雪及土壤特性参数时空变异规律，建立了松嫩平原黑土区土壤水热耦合迁移模型，开展了积雪覆盖下区域土壤水热耦合迁移数值模拟。研究成果对于解决积雪覆盖下寒区土壤春墒预报问题，丰富和完善土壤水分运动理论体系，提高寒区土壤春墒管理调控能力等具有重要的科学意义。