living thing is a kind of organism & as a population of organisms increases , the resources used by those organisms will decrease ->  as a population of living things increases, the resources used by those living things will decrease  as a population of living things increases, the resources used by those living things will decrease & living things require water for survival & water is a kind of natural resource ->  as a population of living things increases, the water used by those living things will decrease  as a population of living things increases, the water used by those living things will decrease & if the amount of something decreases then that something might be depleted ->  as a population of a living thing increases the water used by those living things might be depleted  a desert environment is low in availability of water / availability of food & if a resource is low in availability then it is more likely to be depleted ->  water is more likely to be depleted in a desert environment  as a population of a living thing increases the water used by those living things might be depleted & water is more likely to be depleted in a desert environment -> increased populations are likely to cause water to be depleted in a desert environment