Freshwater resources, whose distribution varies widely among and within countries, are of major environmental and economic importance. Various forces exert pressure on water resources. These include over-abstraction and degradation due to pollution loads from human activities (agriculture, industry, households), changes in climate and weather conditions, and the introduction of invasive species. Over-abstraction of water, in particular, can have significant environmental and socio-economic consequences. These range from low river flows, depleted groundwater and degraded water quality (including salinisation of freshwater bodies in coastal areas), to loss of wetlands, desertification and risks for both food security and economic production.