8 - Water Resources#
8.1 - Where Does Water Occur on the Planet?#
The circulation of water from one reservoir to another is called the hydrologic cycle.
Sublimation is when water molecules go directly from ice to vapor.
Groundwater flow describes water that falls below the roots of plants and becomes groundwater.
Transpiration describes precipitation and soil water that is taken in by plants.
8.2 - What is the Global Water Budget?#
Flux is a measurement of how much water moves in and out of a store, described in units of volume over time.
The length of time that a drop of water remains in a store is called its residence time.
8.3 - How Do We Evaluate Water Balances?#
The climatic water balance is an accounting of the amount of water in each store and its flux through the hydrologic cycle.
8.8 - What Are Problems Associated with Groundwater Pumping?#
As groundwater is overpumped, groundwater around the well cannot flow in fast enough to replenish what is pumped out. This causes the local water table to drop, forming a cone of depression around the well.
Overpumping near oceans or seas can draw salt water into the well in a process known as saltwater incursion or saltwater intrusion.