Floods are natural phenomena. Existing stream channels represent only the normal flow conditions and will, sooner or later, be overtopped by the unusual peak flow. By encroaching on the flood plain, man takes a calculated risk. Sometimes he pays the price of his occupancy. This paper discusses some of the physical relationships involved and indicates the importance and the limitations of land management.
Some experimental evidence is reviewed.
The others represent physical constraints which may have a completely overriding effect over man's efforts. The role of forest vegetation in water conservation is well known. Leafy canopies intercept rain, reducing both the amount and the impact of that which does reach the ground. The roots stabilize soils and form channels for rapid infiltration. Organic matter from roots and leaves improves soil structure and increases both infiltration rates and water-holding capacity.