γ透射法在土壤水运动研究中的应用

Application of gamma-ray in research of soil water movement

在作者对γ透射法测定土壤含水量的精度与分辨率研究的基础上,首先介绍了利用γ透射法在室内外一维入渗实验过程中,同时测定几个土壤水分运动参数的原理与方法;其次对作者近十多年来,根据不同实验要求所研制的室内一维与不同类别的二维土壤水分运动实验装置的结构组成与应用情况做了介绍;最后对γ透射法用于大型称重式蒸渗仪的土壤水分剖面检测也做了概述。在上述各实验方法及实验装置中均采用了计算机对土壤水分的自动检测、控制与数据处理,从而为非饱和土壤水分运动的研究提供了重要条件。研究表明,在利用γ透射法进行土壤含水量测定时,当穿透土体后的射线强度记数率不小于104情况下,室内实验的测点间距为2.5cm,其误差不超过±2%;而大田试验的测点间距为5.0cm,其误差范围为3%～5%。

Based on previous discussions on the accuracy of measured soil water contents and the spatial resolutions by the gamma-ray approach, this paper focused on the applications of the approach in the soil water movement studies. The basic principle and the methodology for measuring the unsaturated soil hydraulic parameters with one dimensional experiment setup both in the lab and fields are given first. Then several systems which have been developed in the past decade for the study of one and two-dimensional soil water movement in the lab were described briefly in conjunction with their practical applications. Moreover, the application of the approach in detecting the soil moisture variation by a large scale lysimeter with a weighing system was introduced. All the applications given here were implemented with computerized systems in data acquisition, control and processing. It was shown that in measuring the soil water content, under the condition that the ray strength rate through the soil sample was more than 104, the gamma-ray approach was able to present good results with an error of less than ±2% in the lab and 3%~5% in the field respectively, where the measurement point separation was 2.5 cm in the lab and 5.0 cm in the field correspondingly.