Minimizing hydrological impacts of smallholder drainage development

Abstract

A review of available literature on the hydrologic impacts of drainage is presented and management practices that reduce such impacts are identified. Factors that influence the impact of drainage include land use, soil type, drainage density, type and condition of the drains, size and duration of the storm, and extent and location of the drainage. Suggested options for minimising impacts include: appropriate land use (fish ponds, duck farming, harvesting natural products, dry season grazing or cultivation); controlled drainage through use of shallow drains, drainage for growing water-loving plants, land preparation (hilling, cambered beds), and blocking drains at the end of the rains; and water storage (dams along the river or farm ponds).