The area of concentrated extraction in Ca Mau province is shown in Figure 6. The colored lines represent the level of water in a well, relative to the mean sea level (i.e., the hydraulic head of water in the confined aquifer). The arrows show the consequent direction of groundwater flow toward the area of low pressure caused by excessive extraction. Changes in the direction of groundwater flow have caused seawater to enter the aquifer in coastal areas
(Phuc, 2008, DWRPIS, 2009).