珠三角滨海小流域土壤水分吸力及特征曲线研究

Soil water content,suction and characteristic curves in the coastal watersheds of the Pearl River Delta

珠三角地区的中山、珠海等地下覆基岩多是花岗岩,花岗岩风化形成的土壤砾、砂含量高,其土壤水分特征曲线特点鲜明,但相关研究较少。本文以中山大学珠海校区滨海小流域为研究对象,利用马尔文粒径分析仪分析了小流域内的土壤质地,得出小流域内土壤基本属于砂壤土或砂土;在此基础上,根据小流域内实测的土壤含水量、土壤吸力数据,分析了土壤含水量、土壤吸力的变化及其对降雨、蒸发的响应特点。通过对野外实测数据的分析,发现小流域内径流试验场中各个深度土壤水分特征曲线(包括吸水过程和脱水过程)总体上呈"L"型,且含较多细小颗粒土壤的水分特征曲线(脱水过程)在"低含水量、高吸力"区呈现出"反S"型,根据此特点提出用Gauss、Dose res ponse(Bi-dose response)等函数对土壤水分特征曲线进行拟合的方法,并取得了良好的拟合效果。

The underlying bedrocks of Zhongshan and Zhuhai in the Pearl River Delta are mainly granite.Weathered granite soils in this region contain large proportions of gravel and grit,giving the soils a peculiar soil water characteristic curve （SWCC）.This literature focused on the coastal watershed of Zhuhai City and analyzed soil texture in the watershed using ＂Mastersizer 2000＂.The soils in the watershed are mainly sandy loam and loamy sand.On this basis,changes in the characteristics of the soil water content,suction,along with the responses to precipitation and evapotranspiration were analyzed.A scatter plot of the soil water content versus soil suction illustrates that SWCC （including absorption and desorption processes） at all depths of the experimental plot follows an L-shaped curve.For the desorption process,SWCC for soils with larger proportions of fine particles shows an inverse S-shaped curve for low water content and high suction sections.In order to obtain desired effects,we propose the use of ＂Gauss＂ and ＂Dose-response （Bi-dose response）＂ curves to fit SWCC.