Water storage.

 

Globally, built reservoir capacity per person is decreasing, as reservoir expansion has not been able to keep pace with population growth, but also because storage capacity of existing reservoirs is decreasing, chiefly due to sedimentation. The Average annual storage volume losses equal about 1% of total built reservoir capacity, and the estimated costs for restoring these losses are approximately US$13 billion per year. An assessment of the value of storage capacity for Enhancing water security in the world’s 400 largest river basins identified water shortage risks in many parts of Africa, as well as in Australia, northern China, India, Spain and the western USA. There are widespread declines in total water storage and associated freshwater availability that are primarily attributed to the intensive overextraction of groundwater and an increasing Temperature-induced surface water loss.