Question: where has irrigation been used by humans to alter biomes

title: Environmental impact of irrigation
text: rising water tables increased storage of groundwater that may be used for irrigation , municipal , household and drinking water by pumping from wells waterlogging and drainage problems in villages , agricultural lands , and along roads - with mostly negative consequences . The increased level of the water table can lead to reduced agricultural production . shallow water tables - a sign that the aquifer is unable to cope with the groundwater recharge stemming from the deep percolation losses where water tables are shallow , the irrigation applications are reduced . As a result , the soil is no longer leached and soil salinity problems develop stagnant water tables at the soil surface are known to increase the incidence of water - borne diseases like malaria , filariasis , yellow fever , dengue , and schistosomiasis ( Bilharzia ) in many areas . Health costs , appraisals of health impacts and mitigation measures are rarely part of irrigation projects , if at all . to mitigate the adverse effects of shallow water tables and soil salinization , some form of watertable control , soil salinity control , drainage and drainage system is needed as drainage water moves through the soil profile it may dissolve nutrients ( either fertilizer - based or naturally occurring ) such as nitrates , leading to a buildup of those nutrients in the ground - water aquifer . High nitrate levels in drinking water can be harmful to humans , particularly infants under 6 months , where it is linked to `` blue - baby syndrome '' ( see Methemoglobinemia ) .