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As a whole, the study on snow cover/frozen soil preservation mainly stays in the description of this phenomenon, and the study of laws and mechanisms needs to be strengthened. One of the important reasons for this reality is that the basic data from related monitoring experiments are not yet abundant. Based on this, on the basis of combing the relevant monitoring test results, the snow/frozen soil conservation monitoring monitoring program was analyzed and designed from four aspects of the test environment, monitoring projects, monitoring instruments, and monitoring methods, with a view to providing further access to basic data. reference.
Harbin winter (11-March) lasted for as long as 15 years, forming a continuous layer of frozen layers below the surface; the form of precipitation is mainly snowfall, which often forms a large area of ​​snow cover on the ground, which is a typical seasonal frozen soil area. The snow-covered and frozen soil monitoring monitoring experiment is planned to be carried out in Harbin. It is planned to monitor the soil moisture content and environmental change parameters of the frozen soil within 1.5 m below the ground under different snow thicknesses of 10, 15 and 20 cm. Analyze and summarize the monitoring data to provide basic information for summarizing the laws and ascertaining the mechanism. Through the multi-point soil moisture monitoring system, the existing research methods are analyzed, combined with the existing research experience, comprehensive consideration of the authenticity of the test environment, controllability and ease of comparison, according to the specific conditions of the test and the actual needs of the test The choice of program.
The program is characterized by its full openness, pure field, and full respect for the original structure of the soil and the authenticity of the environment. The drying method is considered to be the most classic and most accurate method. It is an internationally accepted standard method for determining soil moisture, and all other soil moisture measurement methods are calibrated using this method as a standard. However, this solution is time consuming, laborious, and difficult to sample in deep layers. When the soil texture is unevenly distributed, it is difficult to take out representative soil samples and damage the field soil, making it difficult to perform long-term positioning observations.
Through the monitoring and analysis of multi-point soil moisture monitoring system, from the monitoring environment (test site, soil type, snow conditions, upper vegetation coverage, detection point layout, detection time period, etc.), monitoring items (soil moisture content, soil temperature, freezing The amount of swelling, soil water potential, etc.), monitoring equipment (TDR, neutron gauge, ground temperature gauge, negative pressure gauge, etc.), monitoring methods (drying method, instrumentation method, stagnant water, etc.) proposed a set of 4 aspects The test analysis method of "Snow monitoring and frozen soil monitoring" provides a favorable method basis for the analysis of the test. Based on the experimental contents and methods of existing studies, combined with existing research experience, three kinds of experimental design schemes have been put forward based on comprehensive consideration of the authenticity, controllability, and ease of comparison of the test, which can be based on the specific conditions of the test and The actual needs, the comparative choice of test program.
Measurement of Soil Moisture Content of Frozen Soil by Multi-point Soil Moisture Monitoring System
Because of the low temperature in Northeast China, it is often caused by permafrost. The snow and frozen soil in these permafrost zones have an important impact on the soil moisture of farmland. Snow cover has a significant impact on the soil moisture content. The most obvious feature of frozen soil is its ability to reduce permeability, water impermeability, and evaporative resistance, blocking the heat exchange between the soil and the atmosphere. Therefore, it has a significant effect on water storage, soil conservation and drought control. In short, the presence of snow and frozen soil has a positive effect on the maintenance of soil moisture. Multi-point soil moisture monitoring system has a very important role in the detection of soil moisture, and the results are very accurate and effective.