GEOL107 Lecture Notes - Fall 2018 Lecture 9 - Drainage divide, Drainage basin, Surface runoff
20 Sep 2018
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Document Summary
98. 26% of earth"s water is not a significant source of freshwater (water used for drinking, agriculture, and most industry. Evaporation water changing from liquid to gas (water vapor) driven by heat from sun. Condensation water changing from gas to liquid - driven by water vapor moving up in earth"s lowermost atmospheric layer (troposphere) and being cooled. Precipitation condensed water vapor in troposphere falling back to. Surface runoff water flowing on land surface downhill to oceans. Over the oceans - move evaporation than precipitation. Over land - more precipitation than evaporation. So, land should be flooded by water. But. equilibrium exists between these 2 excesses. Surface runoff (as rivers/streams and groundwater) of excess precipitation over land is equivalent to excess amount of evaporation over oceans. Rivers and streams (except for effects of changing global climate that we"ll talk about later) Area over which if precipitation falls it would be drained by river in that basin - drainage divide separates watersheds.
