GLOBAL GROUNDWATER WELLS (Invited Presentation)

Groundwater well construction records provide locally relevant and widely available information about aquifer lithology and groundwater demand. Here, we present recent analyses of construction records for ~39 million globally distributed wells in ~40 countries around the globe. We show that many millions of wells are at risk of running dry should groundwater levels decline by a few meters. Additionally, we examine groundwater drilling depth time series in areas where groundwater levels are falling, and show that newer wells are not being constructed deeper than older wells in some of these areas. Our findings, in these areas, imply that newer wells are no more resilient to running dry than older wells are, should groundwater levels continue to decline. In places where groundwater reserves are being depleted and newer wells are being drilled deeper than older wells, we stress that this practice of drilling deeper to avoid loss of access to groundwater likely represents no more than a stopgap, as the effectiveness of drilling deeper wells is frequently limited by socioeconomic and hydrogeochemical conditions.