Desertification

Desertification is the spread of desert-like conditions in arid or semi-arid areas, due to overgrazing, loss of agriculturally productive soils, deforestation, or climate change. Dredging - the practice of deepening an existing waterway; also, a technique used for collecting bottom-dwelling marine organisms (e.g., shellfish) or harvesting coral, often causing significant destruction of reef and ocean-floor ecosystems.