Flashcards in Runoff Variation And The Flood Hydrograph Deck (9)
How can river flow be measured?
River regimes and hydrographs.
How does an area influence a hydrograph?
Large basins produce higher peak discharges,
Small basins experience a shorter lag time (can be known as 'flashy') - because the water has less distance to travel.
How does shape influence a hydrograph?
Circular basin will be flashy because all boundaries are an equal distance away from the river at any one point.
peanut shaped basins will produce a double peak discharge as the water flows from the lower section, and then the upper section.
How does relief influence a hydrograph?
Steep relief causes a higher surface runoff, however infiltration rates are lower on steep slopes, and this is opposite for shallow slopes.
How does geology influence a hydrograph?
Permeable rock allows percolation which stops soil becoming saturated, causing a longer lag time, so the hydrograph would appear flat.
How does soil influence a hydrograph?
Saturated soil causes rapid surface runoff which results in a flashy hydrograph.
How does land use influence a hydrograph?
Urban land use - there is more concrete (impermeable) so more surface runoff, and less infiltration - so a shorter lag time and a flashy hydrograph result.
How does drainage density influence a hydrograph?
High drainage density - more channels - so there is a faster transfer of water so the hydrograph is flashy.