runoff variation and the flood hydrograph Flashcards
how can river flow be measured?
river regimes and hydrographs
how does area influence a hydrograph?
large basins produce higher peak discharges, small basins shorter lag times (= flashy) because water has less distance to travel. vice versa
how does shape influence?
circular basin = flashy because equal distance away from river at any point.
how does relief influence?
steep = higher surface run off, however, infiltration rates are lower on steep slopes. opposite for less steep.
how does geology influence?
permeable rock = percolation which stops soil becoming saturated = longer lag time = flat
how does soil influence?
saturated soil = surface runoff = flashy
how does land use influence?
urban = more concrete (impermeable) = more surface runoff = less infiltration/interception and shorter lag time = flashy
how does drainage density influence?
high drainage density = more channels = quicker transfer of water = flashy
how does precipitation and temperature influence?
extreme temperatures = ground baked/frozen = less infiltration = flashy
high/intense rainfall = quick infiltration and saturation = flashy
