城市绿地覆盖砂石后土壤水分入渗过程及模型分析

Investigating and modeling soil infiltration process with gravel mulch on urban green space

【目的】对城市绿地砂石覆盖土壤水分入渗过程进行研究和模型分析,为城市绿地水资源的合理利用提供理论参考。【方法】以银川城市绿地砂石覆盖土壤为研究对象,采用一维垂直定水头入渗法,选取砂石覆盖厚度为影响因子,设置5个覆盖厚度(0,2.5,5.0,7.5,10.0cm),观测湿润锋运移和累计入渗量变化规律,比较各处理土壤入渗特征,并用Horton、Kostiakov、Philip和通用经验模型模拟土壤的入渗过程,从中选出模拟效果最佳的模型。【结果】不同砂石覆盖厚度条件下湿润锋进程与入渗时间呈显著的函数关系,影响大小依次为10.0cm>7.5cm>5.0cm>2.5cm>0cm。砂石覆盖可以提高土壤初始入渗速率、稳定入渗速率、平均入渗速率和累计入渗量。与无覆盖相比,砂石覆盖厚度为2.5,5.0,7.5,10.0cm时的初始入渗速率分别增加了2.4%,5.2%,23.4%,27.6%;稳定入渗速率分别增加了6.0%,25.3%,32.8%,82.0%;平均入渗速率分别增加了12.5%,29.2%,39.6%,79.2%;累计入渗量分别增加了4.2%,11.7%,12.7%,17.0%。利用4种入渗模型拟合覆盖不同厚度砂石的土壤水分入渗过程,发现Horton模型拟合效果最好,Kostiakov模型次之,Philip模型和通用经验模型拟合效果较差。【结论】城市绿地覆盖砂石可以提高土壤入渗速率,增加入渗量,其中以覆盖厚度为10.0cm时最高,且Horton模型是拟合砂石覆盖与水分入渗关系的最佳模型。

[Objective] The study investigated and modeled soil infiltration process to provide basis for improving utilization of water resources for urban green space. [Method] Taking gravel mulch in Yinehuan green space as research object,one-dimensional vertical water infiltration method was used with five gravel mulch thickness levels （0,2.5,5.0,7.5, and 10.0 cm） to investigate the wetting front of water and cumula- tive infiltration. Soil infiltration characteristics were compared, and the infiltration process was simulated by Horton, Kostiakov, Philip and general empirical model. [Result] There were extremely significant power relationships among wetting front distance and infiltration time under different thicknesses of gravel mulch,with the infiltration capacity in order of 10.0cm〉7.5cm〉5.0cm〉2.5cm〉0cm. The initial in- filtration rate,stable infiltration rate,average infiltration rate and cumulative infiltration were improved bygravel mulch. Gravel mulch with the thicknesses of 2.5,5.0,7.5,and 10.0 cm increased the initial infiltra- tion rate, stable infiltration rate, average infiltration rate and cumulative infiltration by 2. 4%,5. 2%, 23.4%,and 27.6%;6.0%,25.3%,32.8%,and 82. 0%;12. 5%,29. 2%,39. 6%,and 79.2%,and 4.2%, 11.7%,12.7%,and 17.0% ,respectively. Fitting with four infiltration models showed that Horton model was the best followed by Kostiakov model,while Philip model and general empirical model were relatively poor. [Conclusion] Gravel mulch could improve soil infiltration rate,increase infiltration capacity,with the best thickness of 10.0 cm. The Horton model was the best to fit the relationship between sand gravel cov- erage and water infiltration.