Run Off Variation And Flood Hydrograph Flashcards
What is run off affected by
Precipitation
Seasons
Soil type
Type and density of vegetation
Relief
Soil water
Rock type
Type and density of run off
Human activities
How does precipitation affect run off
V heavy precipitation= less infil, more overland, more run off and faster
Low = less run off
How does seasons affect run off
Autumn leaf cover - intercept and infiltrate
Summer - higher temps = more evapotranspiration - less run off
Winter - less veg, less evap, and trans, more rain, so soil saturated - through flow - river
How does soil type affect run off
Impermeable dry soil - compact
Permeable - more infiltration, throughflow, groundflow - slower run off
How does type and density of vegetation affect run off
More dense veg - more trans - slower run off
Trees - more infil (roots, throughflow and more run off) and trans (less run off)
How does relief affect run off
Steep - faster run off, less infiltration
How does soil water affect run off
Saturated - slower infiltration - faster run off
Dry- greater infiltration, through flow, ground water flow SLOWER
How does rock type affect run off
Permeable (chalk pores, limestone cracks) = more percolation = slower run off? As groundwater slow
How does type and density of run off affect run off
Higher intensity - more run off, infiltration etc
Snow - set - slower run of - melts - infiltrate, or of fast - overland fl
How does human activities affect run off
Reservoir = big store
Impermeable surfaces inc runcoff
How does runcoff affect global water cycle
More runcoff = more in oceans
Hydrograph characteristics
Rising limb
Basin lag time
Peak flow
Recession limbo
Storm flow
Rainfall intensity
Peakflow compared to baseflow
Recovery rate back to base flow
Run off
What is the rising limb
Rising water from start of rainfall
What is basin lag time
Highest rainfall time to highest discharge in river
What is peak flow
Highest discharge in river
What is recession limb
Water dec after peak flow
What is storm flow
Made up of throughflow, channel and precipitation and overland flow
What is rainfsll intensity
How intense rain is - shown by bar chart - difference between bars
What is peakflow compared to base flow
Peakflow = highest discharge in river
Baseflow = flow of water in rocks high
What is the recovery rate back to base flow
Recession limb
How does a hudrograph show run off variation
Line
Drainage basin and precipitation characteristics
Basin size
Small - rapid water transfer
Large - slower water transfer
Drainage basin and prec characteristics
Drainage density
High density - speeds water transfer
Low - slow
Drainage basin and prec characteristics
Rock type
Imper - rapid overland flow
Permeable - enc slow transfer
Drainage basin and prec characteristics
Landuse
Urbanisation - rapid water transfer - forests slow due interception
Drainage basin and prec characteristics
Relief
Steep slopes = rapid overland flow
Dry soil = soaks up water and slows it’s transfer
Drainage basin and prec characteristics
Soil water
Saturated spike- rapid overlandflow
Dry soil - soaks up water and slow transfer
Drainage basin and prec characteristics
Rainfall intensity
Heavy rain - exceed infiltration capacity of veg and lead to overland flow
Light rain - transfer slowly
