Helen lecture 1 Flashcards
5 main observations from the earthquake
groundwater response river flow change liquifaction well head damage springs
three types of springs that formed
springs relating to disruption of 3m confining layer
springs relating to port hills
old wells reactivation
remediation techniques for new springs
pumping-reduce head
permeation grouting
bit of info about he port hill springs
located at the interface between the loess covered hills and the colluvium valley floor
basalt water source
5 diffrernt response types of the groundwater level
slope change spike offset step spike no response
what is the order of the last list
increasing likelihood of long term effects
difference between lower and higher groundwater
deeper groundwater changed more drastically-sustained
shallow not changed much
four reasons for the sustained rise
lower horizontal permeability
higher vertical permeability
reduced storage
impact from basement
three methods used to test these
field work
modelling
statistical analysis
what did step tests show
lower horizontal transissivity
lower yeilds
increase turbulent flow losses
what were the results of modelling
increase Kh, showed positive offest from groundwater
decrease in Kz- greater variablility of result
reduced Storage- no change
basement-same as Kh
compare results from west and eastern side
western- decreased permeanbility/ injection from basement
eastern- increased leakage
(thoughts, western has increased heads- hence perm and injection, eastern has lower heads? so leakage from higher head wells upward?)
proof of increased leakage between layers
multi level piezometer
deeper wells, larger head increase (head gradient going down?)
what were the variables used to determine the driving force of gw change
dynamic shaking (PGA) static stress strain- volumetric change depth to water
used regresssion analysis
what did regression analysis show
distance important
tipping point in shaking
all depends on subset of data
WL change is not a surrogate for aquifer damage
