The following situations will affect the storm hydrograph by producing either a) a short lag time and steep rising limb or b) a long lag time and gentle rising limb

• a rainstorm in an area underlain by granite
• a long period of 'drizzly' rain during summer
• a snowstorm in the Highlands of Scotland
• a thunderstorm in a city
• a rain event in an area which is heavily forested
• a period of showers in an area where there is much newly ploughed, fairly level, arable land

For each of the situations listed above, select either (a) or (b) and give reasons for your choice.

Suggest how information from storm hydrographs could be used to assist flood control in a river basin.