Many livestock regions, and centers of human population, obtain
water from groundwater or surface water sources other than lakes and
rivers. The water is being withdrawn from the same broad hydrological
cycle, but from a different source within that cycle. The important con-
sideration here is the balance between recharge rates for such groundwa-
ter resources compared with water removal rates. There is concern that
some aquifers are being drawn down at a rate that exceeds recharging,
resulting in depletion of reserves with very serious consequences in the
long term (Terrell et al., 2002; Konikow and Kendy, 2005). Inevitably,
this will result in competition for limited water resources among users
in the future