The removal of urban litter from stormwater conduits and streams: Paper 1 - The quantities involved and catchment litter management options
A large quantity of urban litter is finding its way into the drainage systems from where it is potentially able to travel via the stormwater conduits, streams, rivers, lakes and estuaries until it eventually reaches the open sea. Along the way items are entangled amongst the vegetation along the banks or strewn along the beaches to become an eyesore and a potential health hazard. The potential annual cost of cleaning South Africa's waterways of urban litter assuming current practices is conservatively estimated to be in the order of R2 bn. at current prices. The main factors influencing the quantity of litter finding its way into the waterways are identified, and suggestions are made for reducing this quantity through catchment litter management. Data from Australia and New Zealand are also reported to illustrate the potential for major reductions in the quantity of litter entering South Africa's waterways. On the assumption that it will take a while for effective catchment litter management to be implemented, some South African data on current urban litter loading rates related to land use, vegetation, the level of street cleaning and the type of rainfall are presented. The influence of these factors is then summarised in the form of simple equations to assist designers in the sizing of litter traps.