their work maps the distribution of the world s population with respect to relative water demand that is measured as the ratio of water withdrawals from industry domestic use and irrigated agriculture dia to the mean annual surface and subsurface shallow aquifer runoff q on an annual basis their results indicate that in many areas water stress is a serious concern their study also highlights the fact that water stress is not limited to poor counties or those nations with severely limited water resources but is also a serious concern in a number of oecd countries such as australia spain and the united states these studies consistently predict that some regions of the world will face water crises india northern china north and subsaharan africa the middle east and parts of eastern europe