Groundwater is a treasured earth's resource. Unfortunately, the world-wide groundwater overdraft or aquifer depletion, declining well yields, drying up of springs, streamflow depletion, and land subsidence due to over-exploitation of groundwater as well as the growing degradation of groundwater quality by natural and/or anthropogenic pollutants and by saltwater intrusion are threatening our ecosystems. Groundwater modelling has emerged as a powerful tool to help managers optimise groundwater use as well as to protect this vital resource. This book highlights the geographic information system (GIS) and groundwater modelling as an integrated tool for sustainable management of groundwater resources under changing environments.