Answer
All the circumstances and conditions listed indicate a need for water conservation.
Work Step by Step
Water is needed for community and social life, but industry and agriculture use most of the available water. We obtain by damming rivers, catching and storing rain water, and drawing water (wells) from aquifers. But the amount of water in any aquifer-- large or small-- is limited,and can be depleted unless recharged periodically. by rainfall or snow. If the amount of water withdrawn from an aquifer exceeds the ground water recharge ,then the aquifer will slowly be depleted.
Signs that an aquifer is being depleted include, subsidence the soil, sinkhole formation, and salt water intrusion .
Subsidence is the settling of the soil as water is withdrawn from it and it dries out. Large scale subsidence has been observed/detected over many parts of the world where fossil water, accumulated in aquifers over thousands of years, has been depleted to the point that cities and whole regions have subsided. Some examples are cities of Bangkok and Mexico City. Wider areas include the American Northwest ( Washington and Oregon) and the Chicago and Easter Wisconsin area which has subsided over 800 feet since 1864. The US desert South west (Arizona) -- subsided 300 feet since 1907 and as the Ogallala aquifer is a large shallow aquifer that underlies many of the states of the Great Plains in the US--Texas , Arizona, Kansas, Wyoming etc. It is probably the largest aquifer in the world but its water table is slowly falling. Subsidence damages buildings and canals, underground pipes and cables, Subsidence may also trigger earth movements including earthquakes
Sinkholes form when withdrawal of aquifer water leaves a cave or cavern which collapses because of the loss of water support of the roof. Buildings can lose round support and topple because of sinkholes; in addition, they may swallow motor vehicles when they form in roads and streets. They may otherwise impair transportation, and also damage communication installations.
The normal flow of water from streams and rivers usually inhibits the intrusion of sea water into aquifers near coastal areas. However, if water is being aggressively drawn from an aquifer--without adequate recharge--the water table gets lower and lower with time.. Eventually, a low point may be reached where sea water is able to flow into the stream bed and enter the aquifer. The mixing of sea water with fresh water produces brackish water which cannot support most terrestrial plants species, and cannot supply most human requirements for fresh water.
It is a human right to have pure drinking water, and there is enough water in the world to meet all human needs. However, some people live in semi-arid areas near to deserts, and they must get there water by damming rivers and drawing it from aquifers with artesian wells. But aquifers are being depleted, dams are silting up, and desalination of sea water is too expensive; therefore, wise conservation of water is essential if life in the heavily populated areas of more developed countries (MDC) is to be sustained in the current manner.
