土壤:水系统中被忽视的向度

Soil:the Unseen Layer of Water

健康的土壤在水文中扮演着调节水量与控制水质的重要角色,对于水与土之间相互影响的忽视,往往是造成水系统设计失败的原因。例如,土壤过度夯实或结构遭到破坏,会在雨洪管理中影响土壤的渗透率与保水力,因而增加地表径流;土壤中有机质的流失,会降低土壤的净水效能,破坏营养物质与沉积物,从而导致水污染。为了将土壤知识纳入景观设计工作中,本文建议在设计过程中增加土壤管理专项。其中与水系统相关的最佳实践包括:1)保护既有的土壤以保持原有水文;2)避免及改善土壤夯实以增加保水率;3)保存及重建土壤有机质以改善水质。

Healthy soil performs important functions in regulating water volume and controlling water quality.However,overlooking such dynamics between soil and water often leads to design misassumption and water system failure.For instance,the compacted soil and disturbed soil profile result in poor water retaining capacity and increased surface runoff.The organic matter loss decrease soil's effectiveness at binding and breaking down nutrients and sediments,which further pollute the water system.To incorporate soil sciences in design and construction processes,implementing a soil management plan is suggested.The best soil practices for water system includes 1) Protecting soil structure to conserve hydrological performance; 2) Avoiding and amending soil compaction to increase water retaining capacity; 3) Conserving and restoring soil performance in water cleansing.