Irrigation is as much a problem as a solution to improved agriculture. The majority of the world's available freshwater goes to agriculture and inefficient irrigation systems waste a considerable amount of it. Waterlogging and increased salinity and/or alkalinity can defeat the very purpose of the irrigation scheme. In almost every irrigation zone, significant species shifts in soil fauna and plants can be found. Enlarged insect populations spread diseases such as malaria.
Not all water-related problems are associated with irrigation. In the Mekong Basin, natural leaching of rock salt into soils and saltwater intrusion in the delta area have degraded some of the most productive agricultural areas (MRC/UNEP 1997a).