Rills in olistostromal melange in the Bologna Appenines)

Rainfall rate(intensity)mm/hr

Time (days)

Time (days)

Stream discharge(m3/sec)

Rainfall rate(intensity)mm/hr

Time (days)

Time (days)

Stream discharge(m3/sec)

Hydrograph:peak

Rainfall rate(intensity)mm/hr

Time (days)

Time (days)

Stream discharge(m3/sec)

Hydrograph:peak

Recession limb – period of falling stream flow after rainfall ceases

Rainfall rate(intensity)mm/hr

Time (days)

Time (days)

Stream discharge(m3/sec)

Hydrograph:peak

Base flow = low flow btwn storms, and their equivalent during storms

Rainfall rate(intensity)mm/hr

Time (days)

Time (days)

Stream discharge(m3/sec)

Hydrograph:peak

Base flow = low flow btwn storms, and their equivalent during storms

Storm runoff = runoff above projection of pre-storm flow

Rainfall rate(intensity)mm/hr

Time (days)

Time (days)

Stream discharge(m3/sec)

Hydrograph:

Base flow = low flow btwn storms, and their equivalent during storms

Lag to peak = Time from peak rainfall to peak stream flow

Storm runoff = runoff above projection of pre-storm flow

Response times altered by land use!

Build a parking lot ?

Irrigate a field ?

HOF

Sat. overland flow

Runoff coefficient – ratio of

total storm runoff (runoff above projection of pre-storm flow)

total storm rainfall

= Sum (rainfall) / Sum (runoff)

Qt = discharge at time t

Qp = peak discharge

Qt = Qp Kt

K = recession constant (small K = fast recession)

Qp : HOF > SOF > SSSF

Lag to peak: HOF < SOF < SSSF

K: HOF < SOF < SSSF

Darcy’s Law (groundwater discharge)

Porosity: measure of total pore space (not necessarily interconnected)

Permeability: volume fraction of interconnected pores Aquifer: permeable rocks and sediments that store

groundwaterWater table: upper surface of saturated zone in an

aquiferDarcy’s Law: groundwater discharge (Q) per cross

sectional area (A) of an aquifer is proportional to the hydraulic gradient (slope of water table surface)

To the board…

To the board…