Search for my resource (mind map) 'Impacts of human activities on flooding.' That should cover everything (river flooding that is, coastal flooding probably has different reasons).
Answered Tue 7th May, 2013 @ 16:59 by Bethany Edited by Bethany on Tue 7th May, 2013 @ 17:00
Deforestation means there is less interception and evapotranspiration so more run off
Urbanisation leads to impermeable surafaces and drains so more run off
Channel straightening means river flows faster so increases flood risk downstream