Improving subsurface drainage design - minimising the environmental impacts

Abstract

This paper addresses how the design of subsurface drainage systems impact on the drainage volume and salinity of drainage water generated from these systems. The effects of drain depth and spacing are discussed along with the conceptualization of a subsurface drainage system which incorporates drainage water quality into the design. This system, known as a Multi-Level Drainage System, aims to minimise offsite impacts associated with subsurface drainage while still providing adequate protection from waterlogging and salinity of the plant root zone. This is achieved through the use of a shallow intensely spaced drainage system underlain by a deeper, widely spaced drainage system. The results indicate that by re-thinking subsurface drainage design to incorporate water quality aspects alternative designs can be formulated which begin to meet the present day environmental constraints placed on subsurface drainage systems.