Topic - Under Ground Water Cities are home to about half of the global population and urban population has doubled in the last 50 years from 1.5 billion people in 1975 to 3.5 billion people in 2015. This urban population will rise to a predicted 5 billion people by 2050. So, it’s probable that most of us will be reading this from a city. So, city dwellers, do you know how deep your groundwater level is? And is it rising or falling? It is often written that groundwater is a hidden resource. But in urban areas, when there is a protracted fall in groundwater levels, subsidence may occur. A recent paper published in the journal Science mapped subsidence at a global scale and identified that the most common cause was excessive groundwater extraction. Many people don’t realize groundwater flooding can also occur. When groundwate...