water budgets Flashcards
what is evapotranspiration?
combined amounts of evaporation and transpiration
what are the two values that must be provided to create a water budget?
precipitation and potential evapotranspiration
what is potential evapotranspiration (eₚ)?
the total amount of water that could be evaporated or transpired based on the conditions for that month
potential maximum, not actual
what is actual evapotranspiration (eₐ)?
the amount of water that is actually evaporated and transpired, can come from both precipitation and storage
if p>=eₚ: eₐ=eₐ
if p<eₚ: eₐ=p+|△st|
what is storage (st)?
the amount of water stored in the soil left over
max of 100, min of 0
pm = past month
if pm st == 0 and p<eₚ: st = 0
elif pm st == 100 and p>eₚ: st = 100
else: st = pm st + (p-eₚ)
what is change in storage (△st)?
the change in storage from the past month and the current month
△st = st - pm st
what is deficit (d)?
the amount of extra evapotranspiration that doesn’t happen when st is 0
d=eₚ-eₐ
what is surplus (s)?
the amount of extra precipitation that is not absorbed when st is 100
s=p-eₚ-△st
what is usage?
when st is decreasing and 0<st<100
what is recharge?
when st is increasing and 0<st<100
what is deficit?
when st is 0 and eₐ>p (when there is a deficit)
what is surplus?
when st is 100 and p>eₐ (when there is a surplus)
what are contour lines?
lines that show points of equal elevation
how can you tell where a stream is on a contour map and how it flows?
if there are v shapes along a line
the river flows the opposite way from the v’s
how can you tell if elevation is decreasing on a contour map?
if the contour lines have little spikes on the inside
