FACTORS AFFECTING THE SHAPE OF A RIVER FLOOD HYDROGRAPH
VEGETATION / SOILS (INFILTRATION CAPACITY)
LEVEL OF URBANISATION
LAND USE
GRADIENT / RELIEF
DRAINAGE DENSITY
ANTECEDENT CONDITIONS
SHAPE
GEOLOGY / LITHOLOGY
CHANNEL CHARACTERISTICS
PRECIPITATION INTENSITY / DURATION
CLIMATE
TIME OF YEAR
CONTRIBUTORY AREAS
Ensure that you know details about how each of these would make a hydrograph shape more 'flashy': with a quick and high peak, or delay the peak so that it arrived later, but didn't reach as high a level.
This is a common element of exam questions.
You can now download an excellent worksheet on this theme from the main page.