SPECIAL ISSUE
Mapping o upli haza d due o ising g oundwa e le el
du ing loods
TomášJulínek | Da id Duchan | Ja omí Říha
Facul y o Ci il Enginee ing, Ins i u e o
Wa e S uc u es, B no Uni e si y o
Technology, B no, Czech Republic
Co espondence
TomášJulínek, Facul y o Ci il
Enginee ing, Ins i u e o Wa e S uc u es,
B no Uni e si y o Technology, Ve e i
331/95, 602 00 B no, Czech Republic.
Email: [email p o ec ed]
Funding in o ma ion
FAST-S19-5714 P obabilis ic Assessmen
o Soil Ins abili y Due o Seepage in Ea h
S uc u es and Thei Founda ions;
TH04030087 Tools o Op imisa ion o he
Managemen o Le ee Sys ems
Abs ac
Eu opean Di ec i e 2007/60/EC only b ie ly men ions he p oblem o haza d
a ising due o g oundwa e looding, and echniques o he mapping o haza d
occu ing due o ising g oundwa e ha e no ye been scien i ically de eloped.
The g oundwa e - ela ed h ea s ha occu du ing loods may include concen-
a ed leakage o g oundwa e behind le ees, hea e, o po en ial upli o he
opsoil laye a he p o ec ed a ea. The haza d co esponding o ising g ound-
wa e le el depends on a numbe o ac o s ela ed o he lood cou se, g ound-
wa e egime, geology, and opology o he p o ec ed a ea. The limi s a e
app oach is applied o he assessmen and mapping o haza d induced by is-
ing g oundwa e le el in he a ea behind lood p o ec ion ba ie s, and he
con ibu ing ac o s a e discussed, quan i ied, and inco po a ed in o he limi
s a e condi ion o opsoil laye upli (UPL). An o e -design ac o is exp essed
as a unc ion o he spa ial co-o dina es (x,y). Da a om geological and
hyd ogeological su eys and g oundwa e low modelling a e used o e alua e
indi idual e ms in he limi s a e condi ion. Unce ain ies in he inpu da a
a e exp essed ia pa ial ac o s. Da a collec ion and hei geog aphic in o ma-
ion sys ems analysis comple ed wi h hyd aulic modelling a e c ucial ech-
niques in he haza d mapping o po en ial UPL du ing loods. The a icle
includes a case s udy ea u ing a lood p o ec ion scheme o a shopping cen e
in he ci y o B no, Czech Republic.
KEYWORDS
Eu opean Di ec i e 2007/60/EC, looding, g oundwa e , haza d mapping, limi s a e, upli
1|INTRODUCTION
Floods a e cha ac e ised by a g ow h in i e low a es,
inc eased wa e s ages in s eams, o e banking, and he
inunda ion o loodplains. Inc eased wa e s ages du ing
he lood e en may signi ican ly a ec he g oundwa e
low egime in he aqui e adjacen o he i e . In he
case o he cons uc ion o lood con ol wo ks, hei
subsu ace pa s can a ec he na u al g oundwa e
egime du ing pe iods when looding is absen , a which
imes g oundwa e usually lows om highe -lying a eas
owa ds s eams which d ain adjacen aqui e s (Fe e ,
2001). The e o e, o main ain ee communica ion
be ween he i e and aqui e (Di ec i e, 2006), o exam-
ple, seepage ba ie s such as cu -o walls o injec ion
walls should be designed o be pa ially pene able.
Recei ed: 12 June 2019 Re ised: 4 Janua y 2020 Accep ed: 27 Janua y 2020
DOI: 10.1111/j 3.12601
This is an open access a icle unde he e ms o he C ea i e Commons A ibu ion License, which pe mi s use, dis ibu ion and ep oduc ion in any medium, p o ided
he o iginal wo k is p ope ly ci ed.
© 2020 The Au ho s. Jou nal o Flood Risk Managemen published by Cha e ed Ins i u ion o Wa e and En i onmen al Managemen and John Wiley & Sons L d.
J Flood Risk Managemen . 2020;e12601. wileyonlinelib a y.com/jou nal/j 3 1o 13
h ps://doi.o g/10.1111/j 3.12601
As a consequence o he ise in he wa e le el in a
s eam du ing a lood, su ace wa e empo a ily in il-
a es he banks o he i e and p opaga es in o he aqui-
e in he opposi e di ec ion o ha o no mal low. The
g oundwa e able (o piezome ic head) ises and may
cause one o he epo ed ypes o g oundwa e lood
e en s (CIRIA, 2013; Conan , Robinson, Hin on, & Rus-
sell, 2019; Fleckens ein, K ause, Hannah, & Boano, 2010;
Robins & Finch, 2012; Sophocleous, 2002):
•a ue “g oundwa e lood”in which he wa e able
ele a ion ises abo e he g ound ele a ion,
•a“g oundwa e induced lood,”which occu s when
in ense g oundwa e discha ge ia bou ne sp ings and
highly pe meable shallow ho izons discha ges o su -
ace wa e s and causes o e bank looding,
•inunda ion o subsu ace in as uc u e.
I impe meable opsoil co e s he aqui e , excess
upli may ac on he opsoil base and cause i s up u e,
ollowed by uncon olled concen a ed leakage a he
p o ec ed a ea behind lood p o ec ion measu es (FPM).
All o he men ioned cases may be ela ed o he local
looding o allu ial lowlands behind lood le ees o
loodwalls, which is caused when he g oundwa e able
o piezome ic head ises abo e he e ain. This phe-
nomenon is essen ially con olled by he local i e s age
(MacDonald, Bloom ield, e al., 2008; Robins & Finch,
2012), bu may also be a ec ed by g oundwa e in lows
om highe geological o ma ions like allu ial e aces.
Concen a ed o di use leakage mani es s i sel ia he
ponding o g oundwa e on he su ace (JACOBS, 2006).
Va ious aspec s o g oundwa e looding in he con ex o
mo phology, he geological composi ion o he subbase,
and so on ha e been a subjec o g ea conce n o au ho s
such as Adams e al. (2010), MacDonald, Hughes, e al.
(2008), and o he s.
A g oundwa e lood occu ing alongside s eams
du ing a lood a ec s (in ela ionship o he du a ion o
he lood) he a ea behind he lood p o ec ion line by
inc easing he s ages o he g oundwa e able. Mo eo e ,
uncon olled seepage may esul in a haza d bo h o lood
p o ec ion elemen s and o he subsu ace pa s o s uc-
u es like cella s, subsu ace ga ages, and so on in he e -
i o y p o ec ed agains looding (MacDonald, Dixon,
Newell, & Hallaways, 2012). The h ea is posed by he
p essu e o subsu ace wa e on he inunda ion and sub-
su ace in as uc u e (Abboud, Ryan, & Osbo n, 2017;
K eibich & Thieken, 2008), namely unde g ound pa s o
ci il s uc u es, and by he high hyd aulic g adien s along
he ounda ions o lood p o ec ion elemen s and a
places o g oundwa e leakage on o he g ound su ace.
Seepage in o he p o ec ed a ea is also un a ou able
du ing a lood as i inc eases he amoun o “in e nal
wa e s” ha mus be pumped back in o he s eam. How-
e e , up o now, losses caused by ising g oundwa e le els
ha e been neglec ed in lood isk s udies (K eibich &
Thieken, 2008). Acco ding o Di ec i e (2007), he scope o
lood haza d maps ela ed o g oundwa e looding shall
be limi ed o ex eme e en scena ios. Howe e , such
maps a e no ou inely p epa ed as a pa o lood isk
managemen plans.
Ma hema ical modelling has been employed in he
analysis o he seepage low egime o decades. Cu en
hyd aulic modelling me hods (Bea & Ve uij , 1992) and
he exis ing so wa e enable he e ec i e e alua ion o
g oundwa e egime changes due o changes in hyd olog-
ical condi ions and bounda y condi ions. The me hods
p o ide e ec i e assessmen o he impac o g oundwa e
on ounda ion soils, he ounda ions o lood p o ec ion
s uc u es, buildings in p o ec ed a eas and he seepage o
g oundwa e on o e ain (Mansou e al., 2013; Šol ész &
Ba oko á, 2014). Hyd aulic models linked o compu e -
aided design (CAD) o geog aphic in o ma ion sys ems
(GIS) sys ems p o ide spa ial da a o he e alua ion and
quan i ica ion o g oundwa e - ela ed haza d and i s ep e-
sen a ion using compu e mapping echniques (Büchele
e al., 2006; Hughes e al., 2001; MacDonald, Bloom ield,
e al., 2008; Mo is, Cobby, Zaidman, & Fishe , 2015;
Naugh on, Johns on, McCo mack, & Gill, 2015; Som-
me , 2007). Such echniques a e ou inely applied in
he de elopmen o lood isk managemen plans which
ake in o accoun su ace looding (A aul e al., 2016;
CDS, 2013; Di ec i e, 2007). Howe e , he e is a lack o
s udies ocused on he mapping o he haza d induced
by g oundwa e , namely due o he upli on he opsoil
laye s du ing lood e en s.
The e alua ion o he upli (UPL) limi s a e is
desc ibed in (Bond & Ha is, 2008; Eu ocode 7, 2004;
F ank e al., 2004). In he case o UPL a an a ea p o ec-
ed agains looding, all a iables en e ing he limi s a e
condi ion ha e a spa ial cha ac e . The o e -design ac o
(F ank e al., 2004) was in oduced as a unc ion o spa-
ial coo dina es o he assessmen o haza d. In his
s udy, all o he conce ned a iables (including he o e -
design ac o [OF]) a e exp essed using hema ic maps
p ocessed by GIS echniques.
2|MATERIALS AND METHODS
The me hod o e alua ing g oundwa e haza d due o
upli du ing loods consis s o he ollowing s eps:
•iden i ica ion and concep ual desc ip ion o haza d
a ising om UPL scena ios,
2o 13 JULÍNEK ET AL.
•limi s a e de ini ion,
•inpu da a collec ion, e i ica ion, and analysis,
•hyd aulic modelling,
•quan i ica ion o haza d due o UPL ia lood mapping.
2.1 |Iden i ica ion o haza d
Du ing a lood, he wa e le el in he s eam inc eases as
he piezome ic head o he g oundwa e in he aqui e
ises. In Figu e 1A,B, a scheme o g oundwa e low is
shown o wo scena ios. Figu e 1A shows he s a e jus
be o e a lood, when he wa e le el in a i e begins o
ise and s a s o in il a e in o he adjacen aqui e . In
Figu e 1B, a scheme o he lood peak is shown. The pie-
zome ic head ises signi ican ly abo e he e ain
(Jando a & Říha, 2008; CIRIA, 2013). Figu e 1A,B illus-
a e a si ua ion whe e a p o ec ed a ea is geologically
o med by an uppe opsoil laye composed o low pe me-
able ma e ials (allu ial loams) o e laying a pe meable
(e.g., g a el-sand) aqui e . The a ea behind he lood p o-
ec ion ba ie is hus endange ed by he inc ease in he
piezome ic head abo e he e ain and by he upli o
he less pe meable opsoil laye .
2.2 |The applica ion o he limi s a e
p ocedu e
In gene al, he in e nal e osion p ocess can be di ided
in o ou s ages. These a e ini ia ion, con inua ion, p o-
g ession, and ailu e (Fell & F y, 2007). In s anda d s ud-
ies on he sa e y o le ees, he ini ia ion phase should be
a oided and is subjec o he ( ecen ly ecommended)
pe o mance o an assessmen using he limi s a e
app oach acco ding o Eu ocode 7, 2004. In ou case, he
ini ia ion phase is ep esen ed by he up u e o he op-
soil laye a he “d y”side o FPM due o upwa d wa e
p essu e in he aqui e . This ype o in e nal e osion ail-
u e is classi ied as upli (Bond & Ha is, 2008; Eu ocode
7, 2004).
The gene al o m o he limi s a e condi ion holds:
Fds ,d≤Fs b,d,ð1Þ
whe e F
ds ,d
is he design alue o he des abilising o ce
and F
s b,d
is he design alue o he s abilising o ce ac ing
on he opsoil.
In he sa e y assessmen , i is necessa y o deal wi h
unce ain ies in he inpu da a which in he limi s a e
me hod a e inco po a ed ia pa ial ac o s (some imes
e e ed as eliabili y coe icien s; Eu ocode 7, 2004).
The design alues o he o ces a e ob ained by mul iply-
ing hei cha ac e is ic alues by he co esponding pa -
ial ac o s. Fo UPL assessmen , he design alues in
Equa ion (1) ac ing on he opsoil may be speci ied as
ollows:
Fds ,d=Fupl,d=γuplFupl,k,ð2Þ
Fs b,d=Fg,d=γgFg,k,ð3Þ
whe e F
upl,d
is he design alue o he des abilising o ce
due o he e ical wa e p essu e (upli ), γ
upl
is he pa -
ial ac o o a iable load om he po e wa e p essu e
in he aqui e , FQ
upl,kis he co esponding cha ac e is ic
alue o he upli o ce, F
g,d
is he design alue o he
o ce om he o al weigh o he opsoil laye , γ
g
is he
pa ial ac o exp essing unce ain ies in he opsoil laye
weigh , and FG
g,kis he cha ac e is ic alue o he o ce
om he weigh o he opsoil laye . In Equa ions (2–6)
all o ces a e exp essed pe uni a ea.
When in oducing he impo ance ac o γ
1
(exp essing he impo ance o he s uc u e and he
po en ial haza d o which i is subjec ) and subs i u ing
he design alues om Equa ions (2) and (3) o Equa-
ion (1), one ob ains:
(A)
(B)
FIGURE 1 The opsoil upli p ocess, (A) jus be o e a
loodand (B) du ing a lood
JULÍNEK ET AL.3o 13
γ1γuplFupl,k≤γgFg,k:ð4Þ
Using he no a ion in Figu e 2, he cha ac e is ic
alues o he o ces in Equa ion (4) may be exp essed as
ollows:
Fupl,k=γwhmax −LBS
ðÞ,ð5Þ
Fg,k=γsLT−LBS
ðÞ=γsb,ð6Þ
whe e γ
w
is he speci ic weigh o he wa e and h
max
is
he maximum piezome ic head eached du ing he lood
pe iod (Sec ion 2.4), L
BS
is he le el o he opsoil base, γ
s
is he o al speci ic weigh o soil in na u al condi ions,
L
T
is he le el o he e ain, and bis he opsoil laye
hickness. Va iables L
T
,L
BS
,L
BA
,b, and h
max
a e unc-
ions o spa ial coo dina es (x, y).
When implemen ing Equa ions (5) and (6) in o he
limi s a e ela ion (4) o he poin (x, y) one ob ains:
γ1γuplγwhmax x,yðÞ−LBS x,yðÞðÞ≤γgγsbx,yðÞ ð7Þ
Condi ion (7) is used o he limi s a e assessmen
pe o med o he a ea behind he FPM (see Sec ion 2.5).
2.3 |Da a
The inpu da a as well as haza d quan i ie s a y in space
(x, y), while he piezome ic head in he aqui e du ing
he lood a ies wi h ime ( ). In o de o e alua e
g oundwa e lood haza d a ising due o upli , he se o
inpu da a has o be aqui ed. The necessa y geological
and hyd ogeological da a a e ela ed o he opsoil laye ,
hyd aulic conduc i i y, and he hickness o he aqui e
(Figu e 2). A ypical geological composi ion alongside
s eams consis s o a ela i ely impe meable aqui e base
(e.g., Neogene sublaye s) co e ed by Qua e na y aqui e
laye s. Poo ly pe meable opsoil laye s o en o e lay aqui-
e soils. The basic in o ma ion abou he geological com-
posi ion o he a ea is aken om geological and
hyd ogeological maps, as well as om he cen al da a-
base o geological wo ks (CGS, 2019a), which is a cheap
sou ce p o iding all egis e ed geological su eys in he
Czech Republic. A mo e de ailed onsi e geological su ey
is usually necessa y o he design o FPM as well as o
modelling pu poses (Sec ion 2.4). The da a a e usually
ob ained in he o m o a poin da ase wi h i egula
placemen . The UPL assessmen employs he ollow-
ing da a:
•laye hickness is iden i ied in he bo eholes and is
speci ied by he le el o he base o he opsoil L
BS
and
he le el o he base o he aqui e L
BA
,
•geo echnical p ope ies o soils such as speci ic weigh ,
po osi y, g ain size dis ibu ion, and so on a e ob ained
om geo echnical analysis ca ied ou in he labo a-
o y on he samples aken om bo eholes,
• he hyd ogeological p ope ies o he soil, such as he
hyd aulic conduc i i y kand s o age So aqui e soils,
a e ob ained om pumping o in il a ion es s,
• he g oundwa e le els o a gi en ime a e aken
om moni o ing bo eholes; hese da a should be
comple ed by he co esponding wa e s age in adja-
cen wa e cou ses.
Geog aphic da a include:
•basic as e maps (including digi al e ain model
[DTM]) and ae ial pho os,
•geode ic su ey da a in he o m o poin da ase s o
ec o maps speci ying he spa ial cha ac e is ics o he
s udied a ea and ela ed objec s.
Hyd ological and hyd aulic da a o su ace s eams
a e used o he speci ica ion o bounda y and ini ial
FIGURE 2 Scheme o condi ions (4) and (7)
4o 13 JULÍNEK ET AL.
condi ions o seepage modelling. Da a ep esen ing he
ela ion be ween su ace wa e in s eams and he
g oundwa e le el in hyd ological moni o ing bo eholes
a e pa icula ly impo an . These da a, which a e p o-
ided by he Czech Hyd ome eo ological Ins i u e, a e
usually a ailable om he s a e g oundwa e moni o ing
ne wo k (CHMI, 2019).
The desc ip ion o exis ing and newly designed FPM,
which may signi ican ly in luence he g oundwa e
egime, is aken om he design o indi idual s uc u es
(le ees, loodwalls) and hei componen s (slu y walls,
cu -o enches, d ainage, e c.).
All spa ial da a mus be geo e e enced. The applica-
ion o CAD sys ems and/o GIS is a common p ocedu e
du ing he analysis, p epa a ion, and in e p e a ion o
inpu da a and esul s.
2.4 |G oundwa e low modelling
Ma hema ical modelling is a common ool o p edic ions
ega ding a gi en g oundwa e low egime and he
changes ha may a ec i due o hyd ological and
hyd ogeological condi ions, lood cou se, human ac ions,
and o he ac o s. Fo spa ial UPL assessmen , he piezo-
me ic head h(x, y, ) in he a ea behind FPM has o be
de e mined using he app op ia e g oundwa e low
model. Some simpli ica ions o eali y due o he com-
plexi y o hyd ogeological, hyd ological, and opological
condi ions ha e o be accep ed (Bea & Ve uij , 1992).
Dimensional simpli ica ions a e applied o he model
wi h espec o he hyd ogeological condi ions and
g oundwa e low egime (di ec ion o seepage, low
egime, e c.). Fo he de e mina ion o piezome ic head
wi hin la ge aqui e s, a gene al h ee-dimensional seep-
age low p oblem may be educed o a wo-dimensional
(2D) uns eady low model in a ho izon al plane. In his
case, he esul s a e ob ained in e ms o he piezome ic
head h(x,y, ), which changes wi h loca ion and wi h ime.
Fo he assessmen , he mos un a ou able si ua ion is
desc ibed by i s maximum alue h
max
(x,y) eached du ing
he lood.
Fo 2D, uns eady ho izon al low in con ined aqui e
he go e ning equa ion holds (Bea & Ve uij , 1992):
∂
∂xT∂h
∂x

+∂
∂yT∂h
∂y

−S∂h
∂ =0, ð8Þ
whe e Tis aqui e ansmissi i y (T=k.b
A
), kis hyd au-
lic conduc i i y, b
A
is aqui e hickness, Sis he s o age
coe icien , and his he piezome ic head.
Fo he bounda y i holds ha :
h ðÞ=
h ðÞ,ð9Þ
whe e 
h ðÞ is he known wa e le el in he adjacen
s eam du ing he lood. A a bounda y wi h p esc ibed
lux i holds ha :
k∂h
∂xnx+k∂h
∂yny=qð10Þ
whe e n
x
,n
y
a e di ec ional cosines ela ed o he ou e
no mal ec o o he bounda y wi h p esc ibed lux q(pe
uni wid h o he bounda y). Equa ion (10) may be
applied a he Neumann “no low”bounda y,
whe e q=0.
The ini ial condi ion exp esses he known piezome ic
head h
0
o e he low domain a he beginning o he
lood ( = 0). This may be aken om he calib a ed
s eady s a e solu ion:
hx,y,0ðÞ=h0x,yðÞ,ð11Þ
The maximum piezome ic head h
max
a he gi en
poin o he domain is aken om he esul ing piezome -
ic head ime cou se a he gi en loca ion:
hmax x,yðÞ= max hx,y, ðÞ
g
,ð12Þ
The model domain usually ollows local s eams wi h
known wa e le el o piezome ic head de e mined by
g oundwa e le el moni o ing (hyd ogeologic s udies). To
de e mine he bounda y condi ion in Equa ion (9), he
ime cou se o he discha ge and co esponding wa e
s age in i e s has o be modelled. The lood hyd og aph
may be heo e ical o aken om a eal lood e en .
The nume ical solu ion was done using he ini e ele-
men me hod implemen ed in he code HPV2D (2015)
de eloped a he Ins i u e o Wa e S uc u es, Facul y o
Ci il Enginee ing, B no Uni e si y o Technology.
2.5 |Quan i ica ion o haza d
The upli s abili y assessmen o he p o ec ed a ea is
pe o med using Equa ion (7) wi h h
max
de e mined by
Equa ion (12). Fo u he analysis, he OF is in oduced
(F ank e al., 2004) as he a io o he igh and le sides
o he Equa ion (7):
OF x,yðÞ=γgγsbx,yðÞ
γ1γuplγwhmax x,yðÞ−LBS x,yðÞðÞ
ð13Þ
JULÍNEK ET AL.5o 13

Sa e y agains upli is achie ed i OF ≥1. In he a ea
whe e OF < 1 measu es ha e o be adop ed, o example,
aising he e ain le el, o using elie wells.
The alues o pa ial ac o s may be de i ed using a -
ious me hods. Gene al guidance is p o ided by Eu ocode
7 (2004), whe e pa ial ac o s a e assigned acco ding o
he cha ac e is ic design si ua ion (see Eu ocode 7, 2004,
annex A. 3.1):
•Pe manen a ou able ac ion γ
g
= 0.9
•Va iable un a ou able ac ion γ
upl
= 1.5
In p ac ical applica ions, he alues o pa ial ac o s
a e equen ly de e mined using expe opinion based on
p e ious expe ience. In he case o a mo e ex ensi e
su ey, whe e a su icien amoun o da a is a ailable,
p obabilis ic me hods may be used.
3|HAZARD MAPPING
Inpu da a and he esul s o modelling and assessmen
can be e icien ly analysed, manipula ed, and displayed
using GIS mapping echniques. As a esul , he ollowing
maps a e g adually gene a ed o UPL assessmen in he
lood p o ec ion con ex :
1. maps ela ed o he inpu da a:
•map o he e ain le el (L
T
) compiled using a DTM
and geode ic su ey da a,
FIGURE 3 Flowcha o
spa ial upli assessmen ia
mapping
6o 13 JULÍNEK ET AL.
•map o he opsoil laye base (L
BS
),
•aqui e base (L
BA
),
•aqui e hickness b
A
=L
BS
-L
BA
,
•moni o ed g oundwa e le els (h) o gi en mea-
su ed wa e s ages in su ace s eams,
2. maps ela ed o des abilising ac ion con aining
hyd aulic modelling esul s (Sec ion 2.4) showing:
• he maximum piezome ic head h
max
du ing
looding o e all modelled scena ios (Equa ion (12)),
•map o h
max
−L
BS
di e ences deno ing he upli
p essu e head a he base o he opsoil,
3. map ela ed o s abilising ac ion displaying he opsoil
laye hickness b = LT −LBS,
4. haza d map displaying he o e -design ac o OF.
The lowcha in Figu e 3 summa ises he analysis
p ocedu es. I includes he p ocessing o inpu da a om
su eys, moni o ing, and hyd aulic modelling. Based on
disc e e spa ially o ien ed da a o indi idual pa ame e s,
he as e laye s a e p ocessed using s anda d GIS ools
o in e pola ion, calcula ion, and logical ope a ions. In
Figu e 3, he p ocedu e is di ided in o wo pa s o bo h
he s abilising and des abilising ac ion calcula ions. The
des abilising ac ion is in e p e ed by he hema ic map o
maximum piezome ic head h
max
and he map o p es-
su e head h
max
−L
BS
. The s abilising ac ion mapping
in ol es he analysis o land su ace and geological su -
ey da a and p o ides a map o pa ame e b(x,y) de e -
mined om he map o he e ain and opsoil base le el
(L
T
−L
BS
).
4|CASE STUDY
4.1 |Desc ip ion o he s udy a ea
The p ocedu es desc ibed abo e shall now be demon-
s a ed in connec ion wi h he lood p o ec ion scheme
o he Olympia shopping cen e in he ci y o B no. The
a ea o in e es is loca ed in he le -bank loodplain
be ween he S a ka Ri e and he no h-wes highway
be ween B no and B a isla a. Along i s wes e n side, he
a ea is p o ec ed by lood le ees, which a e subs i u ed in
places by loodwalls. F om he eas e n loodplain ela ed
o he S i a a Ri e and he I ano icky s eam, he a ea
is di ided by he highway (Figu e 4).
The geological composi ion gene ally co esponds o
he schemes in Figu es 1, 2, and 5. The impe ious base
FIGURE 4 A ea o in e es , g oundwa e low domain, and geological p o ile
JULÍNEK ET AL.7o 13
is abou 6.4 –8.4 m below he e ain (aqui e base L
BA
)
and is composed o Neogene clays. The base is o e laid
by pe meable Qua e na y lu ial g a els wi h an aqui e
hickness o 3.6 –4.7 m, wi h hyd aulic conduc i i y
anging om k= 3.010
−4
–4.210
−4
m/s and wi h a s o -
age coe icien o he con ined aqui e o 2.10
−4
[−]. The
aqui e is co e ed by he opsoil laye , which is composed
o ela i ely impe meable lu ial sil y clays o i egula
hickness in he ange b=3–5 m. The composi ion can
be seen in Figu e 5.
4.2 |Da a analysis, g oundwa e low
modelling, and mapping
The i s phase o he analysis includes da a collec ion
and analysis. Gene al da a on geology and hyd ogeology
we e ob ained om he map se e ope a ed by he
Czech Geology Se ice (CGS, 2019b). Geological da a
we e compiled om abou 40 his o ical bo eholes
included in he CGS (2019a) da abase and om 10 addi-
ional bo eholes d illed down o he aqui e base in he
p o ec ed a ea. The co esponding le els and soil
FIGURE 5 Geological p o ile
FIGURE 6 Map showing digi al e ain model and land
su ey poin s (L
T
)
FIGURE 7 Map o opsoil laye base L
BS
(CGS, 2019a)
8o 13 JULÍNEK ET AL.
cha ac e is ics we e iden i ied du ing he su ey and sub-
sequen geo echnical labo a o y es ing. Aqui e pa ame-
e s such as hyd aulic conduc i i y and s o age we e
de e mined by cons an - a e pumping es s ca ied ou a
wo bo eholes du ing he geological su ey.
The hyd og aph ela ed o a 50-yea lood was p o-
ided by he Czech Hyd ome eo ological Ins i u e
(CHMI, 2019). I was ans o med in o a ime-se ies o
wa e s ages in he S a ka Ri e in o de o de ine he
bounda y condi ion o he model (Equa ion (9)).
The mapping o he g ound le el L
T
(x,y), opsoil base
L
BS
(x,y), and aqui e base L
BA
(x,y) in ol ed he spa ial
analysis o he inpu da a om he su ey. A DTM o he
s udied a ea was compiled using a combina ion o lase
scanning da a a ailable o he whole e i o y o he
Czech Republic and a specially conduc ed geode ic land
su ey, which co e ed he a ea in mo e de ail (Figu e 6).
The map o he opsoil laye base (Figu e 7) and aqui e
base was in e p e ed om he his o ical and new bo e-
holes, which we e easonably well-sca e ed o e he
a ea. Fo u he p ocessing, a map o he opsoil laye
hickness b(x,y) was gene a ed using wo p e iously men-
ioned maps b(x,y)=L
T
(x,y)−L
BS
(x,y; see Figu e 8).
The accu acy o he spa ial dis ibu ion o indi idual
cha ac e is ics (L
T
,L
BS
,L
BA
) depends on he accu acy,
amoun , and loca ion o inpu da a. The g ound le el
ob ained om lase scanning has an expec ed accu acy o
± 0.2 m, and when supplemen ed by a su ace geode ic
land su ey he e o d ops o he magni ude o single
cen ime es. In he case o L
BS
and L
BA
, he e o o he
eading du ing he bo ehole d illing may be less han
0.1 m. Mo e signi ican e o may a ise du ing he in e -
pola ion p ocess in he case o sca ce ial bo eholes. In
ou case, due o he easonably dense ne wo k o bo e-
holes he expec ed e o is in he o de o single dec-
ime es (abou 0.2 m).
The gene a ion o maps depic ing L
BS
and L
BA
in ol ed da a il e ing and in e pola ion echniques. As
men ioned abo e, he accu acy o he hema ic maps
s ongly in luences he in e pola ion me hod. Since he
bo ehole da a co e he a ea o in e es easonably well,
he “na u al neighbou ”in e pola ion me hod (Bobach &
Umlau , 2007) was applied (Figu e 7). I s ad an age
(Dumi u, Plopeanu, & Badea, 2013; Ledoux & Gold,
2005) is ha i uses only a subse o samples ha su -
ound a que y poin . The esul s o in e pola ion do no
p oduce anomalies such as peaks, idges, and so on
unless hey a e ep esen ed by he o iginal inpu da a.
The deg ee o unce ain y in ol ed in he in e p e-
a ion o all laye s should be aken in o accoun and
FIGURE 8 Map o opsoil laye hickness b(CGS, 2019a)
FIGURE 9 Example o calib a ion esul s o a no- lood
pe iod
JULÍNEK ET AL.9o 13