river eden factors that affect hydrograph

Question 1

topography

Answer 1

• hard rock with thin volcanic soil in upper course = no infiltration so rapid runoff so short lag time
• wide, shallow valleys in lower course = infiltration so slower runoff more throughflow so longer lag time

Question 2

geology

Answer 2

• long and narrow basin = long lag time
• overridden by steep slopes and impermeable igneous rock upstream = shorter lag time, high peak discharge as water reaches river faster
• permeable limestone and sandstone in lower course allow some infiltration

Question 3

long profile

Answer 3

• fast flood responses in upper catchment due to steep gradient upstream of kirkby stephen = less lag time, steep rising limb

Question 4

land use - farming

Answer 4

1. intense farming = compacted soil from machinery and livestock = more runoff and less infiltration
2. 30% increase in cattle from 2000-2009 = further trampling

Question 5

land use - buildings

Answer 5

1. new developments on floodplain land = impermeable surfaces = more runoff, flood water can’t infiltrate, high peak discharge, low lag time
2. flood defences in carlisle = increase flooding in other areas = peak discharge may be lowered here but higher elsewhere

Question 6

land use - deforestation

Answer 6

1. deforestation for timber and farming = less interception and compacted soils = more runoff and flashy hydrograph