Answer:
a) The amount of freshwater available as groundwater, lakes and rivers, does not even reach one day the need for consumption for the current global population. ( t = 5.489 E-13 day )
b) The annual terrestrial precipitation, reaches to sustain the drinking water needs for the current global population
Explanation:
Let P = 7.7 billion people = 7.7 E12 person
∴ water needed for the total population for one day:
⇒ water amount = 7.7 E12 person * ( 15 L / person. day ) = 1.155 E14 L H2O /day
⇒ water amount = 1.155 E14 L H2O/day * 1 E1 Km² H2O / L H2O = 1.155 E15 Km² H2O/day * ( 365 day / year ) = 4.216 E17 Km²/year
∴ freshwater available:
freshwater = 6.34 E2 Km² H2O
how long will this water sustain the current population?
⇒ t = 6.34 E2 Km² * day / 1.155 E15 Km² = 5.489 E-13 day
this amount of freshwater does not even meet the need of the current global population.
∴ the annual terrestrial precipitation (Py) = 505000 Km³/year..........from literature
⇒ Py = 505000 Km³ H2O/year * ( 1000 m/Km )³ * ( 1000L/m³ )
⇒ Py = 5.05 E17 L H2O/year * ( 1 E1 Km² / L ) = 5.05 E18 Km² H2O/year
⇒ Py > water amount
the annual terrestrial precipitation of water, reaches to sustain the drinking water needs.
