wa e
A icle
Sen inel-2 Sa elli es P o ide Nea -Real Time
E alua ion o Ca as ophic Floods in he
Wes Medi e anean
Isabel Caballe o * , Ja ie Ruiz and Gab iel Na a o
Ins i u o de Ciencias Ma inas de Andalucía (ICMAN), Consejo Supe io de In es igaciones Cien í icas (CSIC),
A enida República Saha aui, 11519 Pue o Real, Spain; ja ie [email p o ec ed] (J.R.);
[email p o ec ed] (G.N.)
*Co espondence: isabel.caballe [email p o ec ed]
Recei ed: 18 Oc obe 2019; Accep ed: 25 No embe 2019; Published: 27 No embe 2019


Abs ac :
Flooding is among he mos common na u al disas e s in ou plane and one o he main
causes o economic and human li e loss wo ldwide. E idence sugges s he inc ease o loods a
Eu opean scale wi h he Medi e anean coas being c i ically ulne able o his isk. The de as a ing
e en in he Wes Medi e anean du ing he second week o Sep embe 2019 is a clea case o his
isk c ys alliza ion, when a eco d-b eaking lood (locally called he “Cold D op” (Go a F
í
a)) has
swollen in o a ca as ophe o he sou heas o Spain su passing p e ious all- ime eco ds. By using a
s aigh o wa d app oach wi h he Sen inel-2 win sa elli es om he Cope nicus P og amme and he
ACOLITE a mosphe ic co ec ion p ocesso , an ini ial app oxima ion o he delinea ed looded zones,
including ag icul u e and u ban a eas, was accomplished in quasi- eal ime. The obus and lexible
app oach equi es no ancilla y da a o apid implemen a ion. A composi e o p e- and pos - lood
images was ob ained o iden i y change de ec ion and mask wa e pixels. Sen inel-2 iden i ies no only
impac s on land bu also on wa e ecosys em and i s se ices, p o iding in o ma ion on wa e quali y
de e io a ion and concen a ion o suspended ma e in highly sensi i e en i onmen s. Subsequen
wa e quali y de e io a ion occu ed in la ge po ions o Ma Meno , he la ges coas al lagoon in he
Medi e anean. The p esen s udy demons a es he po en ials b ough by he ee and open-da a
policy o Sen inel-2, a aluable sou ce o apid synop ic spa io- empo al in o ma ion a he local o
egional scale o suppo scien is s, manage s, s akeholde s, and socie y in gene al du ing and a e
he eme gency.
Keywo ds:
Cope nicus P og amme; ACOLITE; looding; quasi- eal ime moni o ing; inunda ion
mapping; suspended ma e ; Spain
1. In oduc ion
Flooding is among he mos common na u al disas e s in ou plane and one o he main causes
o economic and human li e loss wo ldwide [
1
]. Du ing he pe iod 1980–2013, lood losses exceeded
$1 illion globally and esul ed in ca. 220,000 a ali ies [
2
]. In addi ion, he equency and scale o
loods a e likely o inc ease in nex decades no only due o clima e- ela ed ex emes and na u al
haza ds bu also because ongoing socio-economic de elopmen [
3
]. Se e al s udies o i e loods and
s o ms in Eu ope sugges ed ha he obse ed inc eases in losses we e p incipally due o economic
weal h, inc eases in popula ions, and de elopmen s in haza d-p one a eas, bu he inc ease in hea y
p ecipi a ion in some egions o Eu ope may ha e also in luenced hese [
4
,
5
]. Human ac i i y is
undoub edly con ibu ing o an inc ease in he likelihood and ad e se impac s o ex eme lood e en s.
The popula ion inhabi ing isky zones is g owing and, a he same ime, cons uc ion in lood plains
Wa e 2019,11, 2499; doi:10.3390/w11122499 www.mdpi.com/jou nal/wa e
Wa e 2019,11, 2499 2 o 16
and inapp op ia e i e managemen is educing i e s capaci y o abso b loodwa e s. Coas al a eas
a e also a isk o looding; acco ding o he Eu opean En i onmen Agency S a e o he En i onmen
and Eu osion, he o al alue o Eu opean economic asse s loca ed wi hin 500 m o he coas line,
including ag icul u al, beaches, land and indus ial acili ies, is cu en ly es ima ed a
€
500 o
€
1000
billion [
6
]. In 2007, he Floods Di ec i e o he assessmen and managemen o lood isk was adop ed
by he Eu opean Commission (EC), and wo h men ioning is he ope a i e moni o ing by he EC
Cope nicus Eme gency Managemen Se ice (Cope nicus EMS) [
7
]. In addi ion o social and economic
damage, loods may cause se e e en i onmen al impac s, as well as educe biodi e si y and des oy
we land a eas. In Eu ope, a clima ic-change signal in lood discha ges has been demons a ed in
ela ion o changes in he iming o loods wi hin he yea [
8
]. Howe e , he egional scale diagnose o
hese e en s is hampe ed by lack o a cohe en signal mainly due o he es ic ed spa ial co e age and
densi y o hyd ome ic s a ions [
9
]. A ecen s udy analysing co-occu ing hea y p ecipi a ion and
high sea le el (compound looding) in Eu ope showed ha he Medi e anean coas s a e a p esen
expe iencing he highes compound looding p obabili y, being c i ically ulne able o his isk [10].
The de as a ing e en in he wes Medi e anean du ing he second week o Sep embe 2019 is
a clea case o his isk c ys alliza ion, when a eco d-b eaking lood (locally called he “Cold D op”
(Go a F
í
a)) has swollen in o a ca as ophe o he sou heas o Spain (Figu e 1). This wea he e en
ypical o he all season, whe e a sudden all in empe a u es appea s along he eas coas caused
by he a i al o e y cold pola ai [
11
], is al eady being desc ibed as one o he wo s . Wide a eas
ha e d ama ically b oken his o ical eco ds o daily ain all and lash loods, c ea ed chaos on oads,
cu public anspo , blocked oads, des oyed homes, closed schools, collapsed i e s, and caused
six human a ali ies in Valencia, Alican e, Mu cia, and eas e n Andalusia (Figu e 1). These p o inces
emained on ed ale du ing se e al days. Spain’s wea he agency con inued o issue se e e wea he
wa nings du ing a ious days as s o ms b inging o en ial ain in excess o 300 L/m
2
, hail, winds up
o 100 km/h, huge wa es, and lood isk swep ac oss he Sou heas o he Ibe ian Peninsula. A clea
example o he ex eme ain e en could be obse ed a a me eo ological s a ion in he O ihuela egion
( ed s a in Figu e 1), whe e he daily p ecipi a ion a e du ing 12–13 Sep embe su passed ha o
p e ious yea s (Figu e 2). The go e nmen in o med he ma e ial and economic damages caused
by his ex ao dina y me eo ological phenomenon a e s ill unquan i iable owing o i s magni ude,
decla ing he egion a disas e a ea. On 13 Sep embe , he au ho i ies epo ed ha he Segu a Ri e
had bu s i s banks in O ihuela, a own o a ound 80,000 esiden s in Alican e p o ince. Thousands o
esiden s om di e en municipali ies we e e acua ed due o he ex eme wea he condi ions o one o
he mos spec acula loods in Spain, whe e cu en ca as ophic looding has a su passed p e ious
all- ime eco ds in he Wes Medi e anean.
Unde s anding he spa io empo al and physical cha ac e is ics o isk d i e s (exposu e, haza d,
and ulne abili y) is needed in o de o implemen e ec i e lood mi iga ion measu es [
12
]. As a means
o eme gency esponse a e a looding o inland inunda ion, lood mapping helps o iden i y he
ex en o he e en on a la ge scale as well as he a ec ed in as uc u e such as oads and se lemen s
and impai ed egions o in e es such as ag icul u al a eas. This in o ma ion can be used by disas e
managemen agencies and o he s akeholde s o unde ake he escue in a ec ed a eas, coo dina ing
app op ia e eco e y ac i i ies and p e en ion measu es o possible upcoming e en s. Cu en ly,
he ca as ophic impac s o looding can be e alua ed by means o emo e sensing echnologies, which
p o ide a unique sou ce o da a o he implemen a ion o Eu opean Union (EU) di ec i es [
13
]. Remo e
sensing echnologies a e one o he mos widely used pla o ms o eme gency managemen and
ex ended a ea mapping. Sa elli e images can be applied o assess he ex en o looded a eas and hei
impac on human, economic, en i onmen , and in as uc u e o e ing a synop ic iew o la ge a eas,
equen obse a ions, and his o ical a chi es. Se e al s udies ha e ocused on ob aining in o ma ion
using emo e sensing image y wi h he applica ion o di e en me hodologies [
14
–
18
]. Pa icula ly,
when op ical sa elli e da a a e a ailable be o e and a e a looding e en , iden i ica ion o looded
egions and wa e quali y de e io a ion in he coas al a eas would be much easie by means o change
Wa e 2019,11, 2499 3 o 16
de ec ion app oaches. These app oaches equen ly equi e he applica ion o p e-and pos - lood image
pai s o dis inguish pixels ha ha e been modi ied om non-wa e o wa e be ween image da es and
ha e been implemen ed using pos classi ica ion image di e encing [
19
]. Whe eas hese echniques
can o e use ul and accu a e esul s, he combined challenges o s o m- ela ed cloud co e and low
empo al esolu ion emain impo an limi a ions. Fo his e alua ion, high empo al and ine spa ial
esolu ion images a e equi ed in o de o comp ehensi ely gene a e accu a e maps.
Wa e 2019, 11, x FOR PEER REVIEW 3 o 16
classi ica ion image di e encing [19]. Whe eas hese echniques can o e use ul and accu a e esul s,
he combined challenges o s o m- ela ed cloud co e and low empo al esolu ion emain impo an
limi a ions. Fo his e alua ion, high empo al and ine spa ial esolu ion images a e equi ed in o de
o comp ehensi ely gene a e accu a e maps.
Figu e 1. Loca ion o he Spanish egions impac ed by he looding in Sep embe 2019 om sou h o
no h: Alme ia, Mu cia, Alican e, and Valencia. The ed s a co esponds o he loca ion o he
me eo ological s a ion in O ihuela (Figu e 2). Pho os showing he eco d-b eaking looding du ing
he Cold D op (Go a F ía) in Alican e (a) and (c), Mu cia (b) and (d), and Valencia (e), and ( ) du ing
11–14 Sep embe 2019. The pho os a e cou esy o Le an e, E e, España Dia io, REUTERS, and El
Con idencial.
Figu e 1.
Loca ion o he Spanish egions impac ed by he looding in Sep embe 2019 om sou h
o no h: Alme ia, Mu cia, Alican e, and Valencia. The ed s a co esponds o he loca ion o he
me eo ological s a ion in O ihuela (Figu e 2). Pho os showing he eco d-b eaking looding du ing
he Cold D op (Go a F
í
a) in Alican e (
a
) and (
c
), Mu cia (
b
) and (
d
), and Valencia (
e
), and (
)
du ing
11–14 Sep embe 2019
. The pho os a e cou esy o Le an e, E e, España Dia io, REUTERS,
and El Con idencial.
Wa e 2019,11, 2499 4 o 16
Wa e 2019, 11, x FOR PEER REVIEW 4 o 16
Figu e 2. (a) His o ical daily ain all (li e pe squa e me e, l/m2) in a me eo ological s a ion in he
O ihuela egion (Alican e, ed s a in Figu e 1) and (b) daily p ecipi a ion du ing Sep embe 2013–
2019, whe e he ex eme p ecipi a ion du ing he Cold D op e en on 12–13 Sep embe 2019 is
highligh ed in ed.
In his ega d, he Eu opean Space Agency (ESA), in pa ne ship wi h he EC, is de eloping a
new amily o missions called he Sen inels o he ope a ional needs o he Cope nicus P og amme.
Each Sen inel is based on a cons ella ion o wo win sa elli es o ul il e isi and co e age
equi emen s, p o iding obus da ase s o Ea h Obse a ion Se ices, beginning a new e a in
disas e moni o ing and eme gency managemen [20]. These missions ca y a ange o echnologies,
such as mul i-spec al imaging and ada ins umen s o ocean, land, and a mosphe ic moni o ing,
and a e designed o deli e he weal h o da a and image y ha a e cen al o imp o e he
managemen o he en i onmen , sa egua ding li es e e y day. Speci ically, he Cope nicus Sen inel-
2 mission comp ises a cons ella ion o wo pola -o bi ing sa elli es placed in he same sun-
synch onous o bi , phased a 180° om each o he . I aims a moni o ing a iabili y in land and wa e
su ace condi ions o p o ide image y o ege a ion, soil, wa e co e , and inland wa e ways. The 5-
day e isi o he pai o Mul i Spec al Image s (MSI) onboa d Sen inel-2 wi h 10 m spa ial esolu ion
in isible bands, combined wi h eely a ailable da a, is unp eceden ed, p o iding new insigh s in o
he obse a ion o nea ly any coas al place on Ea h [21]. This enables o new endea ou s in
moni o ing, change de ec ion, and mapping o coas al zones.
In he p esen con ibu ion, a demons a ion o a sa elli e-based ool as an e ec i e solu ion o
add ess and delimi lood-a ec ed a eas and o e alua e he e ec s o he lood on he wa e quali y
(suspended sedimen s) o he Spanish coas al egions ollowing he ca as ophic lood du ing
Sep embe 2019 was accomplished. A s aigh o wa d app oach has been applied using a ecen ly
eleased so wa e sui ed o a mosphe ic co ec ion (ACOLITE p ocesso ) wi h Sen inel-2A/B images
be o e and a e he e en , indica ing he po en ials b ough by he win sa elli e’s wide co e age and
high e isi o change de ec ion. The indings a e an example o add essing nea - eal ime looding
Figu e 2.
(
a
) His o ical daily ain all (li e pe squa e me e, L/m
2
) in a me eo ological s a ion in he
O ihuela egion (Alican e, ed s a in Figu e 1) and (
b
) daily p ecipi a ion du ing Sep embe 2013–2019,
whe e he ex eme p ecipi a ion du ing he Cold D op e en on 12–13 Sep embe 2019 is highligh ed
in ed.
In his ega d, he Eu opean Space Agency (ESA), in pa ne ship wi h he EC, is de eloping a
new amily o missions called he Sen inels o he ope a ional needs o he Cope nicus P og amme.
Each Sen inel is based on a cons ella ion o wo win sa elli es o ul il e isi and co e age equi emen s,
p o iding obus da ase s o Ea h Obse a ion Se ices, beginning a new e a in disas e moni o ing
and eme gency managemen [
20
]. These missions ca y a ange o echnologies, such as mul i-spec al
imaging and ada ins umen s o ocean, land, and a mosphe ic moni o ing, and a e designed o
deli e he weal h o da a and image y ha a e cen al o imp o e he managemen o he en i onmen ,
sa egua ding li es e e y day. Speci ically, he Cope nicus Sen inel-2 mission comp ises a cons ella ion
o wo pola -o bi ing sa elli es placed in he same sun-synch onous o bi , phased a 180
◦
om each
o he . I aims a moni o ing a iabili y in land and wa e su ace condi ions o p o ide image y o
ege a ion, soil, wa e co e , and inland wa e ways. The 5-day e isi o he pai o Mul i Spec al
Image s (MSI) onboa d Sen inel-2 wi h 10 m spa ial esolu ion in isible bands, combined wi h eely
a ailable da a, is unp eceden ed, p o iding new insigh s in o he obse a ion o nea ly any coas al
place on Ea h [
21
]. This enables o new endea ou s in moni o ing, change de ec ion, and mapping o
coas al zones.
In he p esen con ibu ion, a demons a ion o a sa elli e-based ool as an e ec i e solu ion
o add ess and delimi lood-a ec ed a eas and o e alua e he e ec s o he lood on he wa e
quali y (suspended sedimen s) o he Spanish coas al egions ollowing he ca as ophic lood du ing
Sep embe 2019 was accomplished. A s aigh o wa d app oach has been applied using a ecen ly
eleased so wa e sui ed o a mosphe ic co ec ion (ACOLITE p ocesso ) wi h Sen inel-2A/B images
be o e and a e he e en , indica ing he po en ials b ough by he win sa elli e’s wide co e age and
high e isi o change de ec ion. The indings a e an example o add essing nea - eal ime looding
Wa e 2019,11, 2499 5 o 16
moni o ing in la ge a eas p o iding a p elimina y aluable sou ce o synop ic in o ma ion o suppo
manage s, scien is s, s akeholde s, and socie y du ing and a e he eme gency.
2. Ma e ials and Me hods
In his s udy, he Sen inel-2A and 2B win pola -o bi ing sa elli es we e used. Bo h Mul ispec al
Ins umen s (MSI) on-boa d a e now ope a ional: Sen inel-2A was launched on 23 June 2015 and
Sen inel-2B ollowed on 7 Ma ch 2017. A ee, ull, and open da a policy has been adop ed by he EU
o he Cope nicus P og amme, which o esees access by all use s o he Cope nicus Sen inels co e
p oduc s. The adiome ic, spec al, and spa ial cha ac e is ics o he bands used in his s udy a e
speci ied in he Use Handbook [
21
]. A empo al examina ion p o ided Le el-1C Sen inel-2 images
ha we e ypically geo-loca ed wi hin wo pixels o each o he (20 m) which is wi hin he s a ed quali y
equi emen s o absolu e geo-loca ion [
22
]. Sen inel-2 Le el 1 da ase s (zone 30, sub- ile SXG and SXH)
we e downloaded om he ESA o icial websi e Cope nicus Open Access Hub [
23
]. The Cope nicus
Se ices Da a Hub is an access o Cope nicus Sen inels da a dedica ed o Cope nicus Se ices and
Eu opean Ins i u ions. Cope nicus Sen inel-2 da a a e sys ema ically p ocessed o L1C p oduc s and
made a ailable online be ween 2 and 12 h om sensing (on a e age, 7 h a e sensing) in he Cope nicus
Open Access Hub and Cope nicus Se ices Da a Hub. Only images wi h low cloud co e age (<20%
o e he egion o s udy) we e conside ed and downloading ime was gene ally a ound 0.5 h. A leas
wo images wi h he same o bi ack and he same co e age a e equi ed o change de ec ion, namely,
he e e ence image (p e-e en ) and he a ge image (co-e en ), espec i ely. The e e ence image was
selec ed as he la es a ailable image p io o he e en wi h minimum cloud co e age. The scenes
we e selec ed ca e ully wi h wo Sen inel-2A/B sa elli e images be o e (19 Augus 2B, 3 Sep embe 2A)
and wo scene-cap u es du ing o immedia ely ollowing (13 Sep embe 2A, 18 Sep embe 2B) he
e en (Figu e 2).
A s aigh o wa d app oach has been accomplished by means o he ACOLITE so wa e de eloped
by he Royal Belgian Ins i u e o Na u al Sciences RBINS ( e sion 20190326.0). ACOLITE bundles
he p ocessing so wa e and a mosphe ic co ec ion algo i hms implemen ed a RBINS o aqua ic
applica ions o Sen inel-2 (A/B) and Landsa (5/7/8) sa elli e in o ma ion. ACOLITE pe o ms he
a mosphe ic co ec ion and can p o ide se e al pa ame e s de i ed om wa e e lec ance. ACOLITE
was o iginally de eloped in IDL (2014–2017) and has been ansla ed in o Py hon (2018–2019). The Da k
Spec um Fi ing (DSF) a mosphe ic co ec ion was used [
24
]. This model was o iginally implemen ed
o wa e applica ions o ine esolu ion me e-scale op ical sa elli es bu p o ed capaci ies o use wi h
MSI due o hei ine spec al co e age [
25
]. The DSF compu es a mosphe ic pa h e lec ance based on
mul iple da k a ge s in he scene o subscene, wi h no a p io i de ined da k band. Fo each band,
he da kes objec is es ima ed om he o se i o he i s housand pixels in he his og am and a “da k
spec um”. A Con inen al o Ma i ime ae osol model is chosen based on he lowes RMSD be ween he
obse ed e lec ance and he e ie ed pa h e lec ance o he wo closes i ing bands. The se ings
selec ed o he DSF we e a iled pa h e lec ance op ion, which di ides he ull scene in app oxima ely
6
×
6 km iles and in e pola es e ie ed pa h e lec ance. In his s udy, op ional image-based sun glin
co ec ion o he su ace e lec ance was also inco po a ed. To al ime o ACOLITE p ocessing was
~2.5 h (see wo k low diag am in Figu e 3). P ocessing speed and ime we e associa ed o a Windows
10 P o desk op machine wi h In e (R) Co e™i7.
MSI has spec al bands a di e en spa ial esolu ions, 10, 20, and 60 m and ACOLITE con e s
in e nally he bands o he same (use -speci ied) esolu ion. Fo bands a lowe esolu ion han he
p ocessing esolu ion, alues a e eplica ed by nea es neighbou esampling, i.e., no new pixel alues
a e compu ed, and o bands a highe esolu ion, pixels a e spa ially mean a e aged. By de aul , he
10 m g id is used, which means he alues om he 20 and 60 m bands a e eplica ed 4 and 36 imes
o o m a 10 m g id. In his s udy, ACOLITE p oduc s esampled o 10 m pixel size co esponded o
Remo e Sensing Re lec ance (R s, 1/s ) in all isible and Nea -In a ed (NIR) bands. The concen a ion
o o al suspended ma e ial (TSM, g/m
3
) was also calcula ed using a s anda d app oach [
26
], a model

Wa e 2019,11, 2499 6 o 16
which is sui able o any ocean colou senso . Theo y indica es ha use o a single band, i chosen
adequa ely, o e s a obus and TSM-sensi i e algo i hm. Re ie ing suspended ma e in op ically
shallow wa e equi es he use o spec al bands ha ha e limi ed dep h pene a ion in o de o
a oid subs an ial in e e ence om he bo om bu a he same ime a e sensi i e o u bidi y. Red
bands a e use ul o es ima ion o suspended ma e bu can ha e a s ong bo om signal in shallow
wa e s [
27
]. The abso p ion by wa e inc eases apidly om ed o he “ ed edge” NIR (700–780 nm).
This abso p ion limi s he ligh ecei ed om he bo om, while s ill e u ning ligh sca e ed om
ma e ials in he wa e . In his sense, he ed-edge NIR band 704 nm has su icien wa e abso p ion o
be a good comp omise be ween de ec ing u bidi y wi h limi ed de ec ion o he bo om, so i was
selec ed o he suspended ma e algo i hm [
26
] wi hin he ACOLITE p ocesso . Se e al s udies ha e
al eady indica ed hese ed-edge spec al bands a e app op ia e o u bidi y o suspended solids
moni o ing in op ically shallow egions [27,28].
Non-wa e pixels we e masked on he maps using a combina ion o h esholds and spec al es s
wi hin ACOLITE. Masking is pe o med a e he a mosphe ic co ec ion, using he e ie ed su ace
e lec ance. R smin and R smax ep esen he minimum and maximum e lec ance in he senso bands,
espec i ely. The da a we e masked i any one o he ou spec al es s used was ue: “B igh ” spec al
es , “NIR peak” spec al es , “Non-wa e ” spec al es , and “Whi e” spec al es (see mo e de ails
on [24]):
“B igh ” spec al es : Wa e pixels ha e a maximum e lec ance much less han 20%, and hence
pixels should be masked whe e:
R smax >0.2 (1)
“NIR peak” spec al es : Wa e pixels ha e a isible band e lec ance highe han NIR e lec ance
(excep o ex emely u bid wa e s), and hence, pixels should be masked whe e:
MaxR sblue,R sg een,R s ed<R sNIR (2)
“Non-wa e ” spec al es : The NIR o ed e lec ance a io is limi ed o a gi en a io o wa e
pixels (excep o ex emely u bid wa e s), and hence, pixels should be masked whe e:
R sNIR
R s ed
>0.9 (3)
R sNIR >0.05 (4)
“Whi e” spec al es : Wa e pixels ypically ha e a la ge spec al a iabili y in he isible and
NIR, and hence, pixels should be masked whe e:
R smax −R smin
R smax
<0.2 (5)
Based on he la e and while compu ing h esholds, he wo sa elli e image ies on 13 and 18
Sep embe a e change de ec ion we e cla i ied in o damaged and un-damaged a eas. These da a
we e p ocessed wi hin ew hou s, sa ing on ime and esou ces and enabling he nea - eal ime
quan i ica ion o he looded a eas and wa e quali y issues (see wo k low diag am in Figu e 3).
Mo eo e , in o ma ion on he his o ical daily ain all o a me eo ological s a ion in O ihuela, Alican e
( ed s a in Figu e 1, 38◦04004” N, 0◦58053” W) was ob ained om Aeme Open Da a [29].
Wa e 2019,11, 2499 7 o 16
Wa e 2019, 11, x FOR PEER REVIEW 7 o 16
Figu e 3. Diag am wi h wo k low and ime p ocessing o each s ep using Sen inel-2 images and
ACOLITE p ocesso .
3. Resul s
The Sen inel-2 images as ue colou composi e Red–g een–blue om he EO B owse [30] a 10
m spa ial esolu ion show he be o e on 3 Sep embe 2019 (Figu e 4a) and a e on 13 Sep embe 2019
(Figu e 4b) o he looding e en in Mu cia p o ince (Spain). The a ec ed and non-a ec ed zones
we e delinea ed, esul ing in a looded a ea o 1307 ha (Figu e 5) o e he Region o In e es on 13
Sep embe (ROI de ailed in Figu e 4b). This phenomenon has damaged he cul i a ed lands, mainly
in Los Alcáza es egion (Figu e 4b), whe e he excep ional ain all caused widesp ead looding and
damage o ag icul u al lands, much o hem a med unde ag i-en i onmen ag eemen s. While
looding in win e is a common e en in his egion, looding in la e summe o ea ly au umn
(associa ed o he Go a F ía) is unusual and much mo e damaging. The in o ma ion e ie ed can be
used o e alua e he impac s on looded a eas and help in o m s a egies o deal wi h changes in lood
isk in a eas o ag icul u al and en i onmen al in e es .
Mo eo e , Sen inel-2 iden i ies no only impac s on land bu also on wa e ecosys em and i s
se ices. Due o he la ge quan i y o sedimen s b ough by he lood, he a ec ed egions show an
ex eme inc ease o o al suspended ma e ial and se e e u bidi y le els, isible in he RGB image
(Figu e 4b), leading o a con amina ion and de e io a ion o he i e s and he coas al adjacen egion
(Figu e 2b). La ge po ions o Ma Meno ( he la ges coas al lagoon in he Medi e anean) showed
up o 200 mg/m3 o suspended solids on 13 Sep embe (Figu e 4d) compa ed o he s anda d si ua ion
en days be o e on 3 Sep embe wi h minimum concen a ion <10 mg/m3 (Figu e 4c). The e we e no
in si u da a o alida e he TSM algo i hm, bu ealis ic in o ma ion can be obse ed o he mapping
o suspended ma e using he TSM model [26] wi h he 704 nm band. A ecen s udy has con i med
ha Sen inel-2 ed-edge bands achie ed good accu acies when compa ed wi h suspended solid
concen a ions [31], in addi ion o he ed o NIR bands [32,33]. One o he main ad an ages o
Sen inel-2 o e Landsa -8 is he inclusion o hese h ee ed-edge and NIR bands, allowing o he
de e mina ion o chlo ophyll in u bid and p oduc i e wa e s and he e ie al o u bidi y o
suspended pa icula e ma e concen a ion, e en in na ow inle s and po s, p o iding an in aluable
da ase o se e al scien i ic and managemen pu poses [34]. The TSM model was no able o pe o m
accu a ely o e he ex emely u bid egion close o he coas and pa o he u bid in usion was
masked ou by ACOLITE p ocesso (simila esul s we e ound using o he TSM algo i hms wi hin
ACOLITE so wa e).
Figu e 3.
Diag am wi h wo k low and ime p ocessing o each s ep using Sen inel-2 images and
ACOLITE p ocesso .
3. Resul s
The Sen inel-2 images as ue colou composi e Red–g een–blue om he EO B owse [
30
] a 10 m
spa ial esolu ion show he be o e on 3 Sep embe 2019 (Figu e 4a) and a e on 13 Sep embe 2019
(Figu e 4b) o he looding e en in Mu cia p o ince (Spain). The a ec ed and non-a ec ed zones we e
delinea ed, esul ing in a looded a ea o 1307 ha (Figu e 5) o e he Region o In e es on 13 Sep embe
(ROI de ailed in Figu e 4b). This phenomenon has damaged he cul i a ed lands, mainly in Los
Alc
á
za es egion (Figu e 4b), whe e he excep ional ain all caused widesp ead looding and damage
o ag icul u al lands, much o hem a med unde ag i-en i onmen ag eemen s. While looding in
win e is a common e en in his egion, looding in la e summe o ea ly au umn (associa ed o he
Go a F
í
a) is unusual and much mo e damaging. The in o ma ion e ie ed can be used o e alua e
he impac s on looded a eas and help in o m s a egies o deal wi h changes in lood isk in a eas o
ag icul u al and en i onmen al in e es .
Mo eo e , Sen inel-2 iden i ies no only impac s on land bu also on wa e ecosys em and i s
se ices. Due o he la ge quan i y o sedimen s b ough by he lood, he a ec ed egions show an
ex eme inc ease o o al suspended ma e ial and se e e u bidi y le els, isible in he RGB image
(Figu e 4b), leading o a con amina ion and de e io a ion o he i e s and he coas al adjacen egion
(Figu e 2b). La ge po ions o Ma Meno ( he la ges coas al lagoon in he Medi e anean) showed up
o 200 mg/m
3
o suspended solids on 13 Sep embe (Figu e 4d) compa ed o he s anda d si ua ion
en days be o e on 3 Sep embe wi h minimum concen a ion <10 mg/m
3
(Figu e 4c). The e we e
no in si u da a o alida e he TSM algo i hm, bu ealis ic in o ma ion can be obse ed o he
mapping o suspended ma e using he TSM model [
26
] wi h he 704 nm band. A ecen s udy has
con i med ha Sen inel-2 ed-edge bands achie ed good accu acies when compa ed wi h suspended
solid concen a ions [
31
], in addi ion o he ed o NIR bands [
32
,
33
]. One o he main ad an ages
o Sen inel-2 o e Landsa -8 is he inclusion o hese h ee ed-edge and NIR bands, allowing o
he de e mina ion o chlo ophyll in u bid and p oduc i e wa e s and he e ie al o u bidi y o
suspended pa icula e ma e concen a ion, e en in na ow inle s and po s, p o iding an in aluable
da ase o se e al scien i ic and managemen pu poses [
34
]. The TSM model was no able o pe o m
accu a ely o e he ex emely u bid egion close o he coas and pa o he u bid in usion was
masked ou by ACOLITE p ocesso (simila esul s we e ound using o he TSM algo i hms wi hin
ACOLITE so wa e).
Wa e 2019,11, 2499 8 o 16
Wa e 2019, 11, x FOR PEER REVIEW 8 o 16
Figu e 4. Sen inel-2 images a 10 m spa ial esolu ion as ue colou composi e ( ed–g een–blue) om
he EOB oswe showing he (a) be o e (3 Sep embe 2019) and (b) a e (13 Sep embe 2019) o he
looding e en in Mu cia p o ince (Spain). The high concen a ion o suspended ma e ial (TSM,
mg/m3) in Ma Meno can be obse ed in he map (d) on 13 Sep embe wi h TSS > 200 mg/m3
compa ed o he no mal si ua ion (c) on 3 Sep embe 2019 wi h minimum concen a ion (10 mg/m3).
Whi e a eas co espond o land, clouds, o cloud shadows masked a e ACOLITE. Black ec angle
shows he Region o In e es (ROI) o looded a ea calcula ion. The TSS scales o each scene a e
di e en .
Figu e 4.
Sen inel-2 images a 10 m spa ial esolu ion as ue colou composi e ( ed–g een–blue) om
he EOB oswe showing he (
a
) be o e (3 Sep embe 2019) and (
b
) a e (13 Sep embe 2019) o he
looding e en in Mu cia p o ince (Spain). The high concen a ion o suspended ma e ial (TSM, mg/m
3
)
in Ma Meno can be obse ed in he map (
d
) on 13 Sep embe wi h TSS >200 mg/m
3
compa ed o
he no mal si ua ion (
c
) on 3 Sep embe 2019 wi h minimum concen a ion (10 mg/m
3
). Whi e a eas
co espond o land, clouds, o cloud shadows masked a e ACOLITE. Black ec angle shows he
Region o In e es (ROI) o looded a ea calcula ion. The TSS scales o each scene a e di e en .
Wa e 2019,11, 2499 9 o 16
Wa e 2019, 11, x FOR PEER REVIEW 9 o 16
Figu e 5. The lood-a ec ed a eas (yellow) in Mu cia on 13 Sep embe 2019 wi hin he Region o
In e es (ROI) de ined in Figu e 4b (black ec angle). The ed line ep esen s he coas al line.
In he Dolo es egion (Alican e), p e (19 Augus 2019, Figu e 6) and pos (18 Sep embe 2019,
Figu e 6b) Sen inel-2 alse colou composi e (nea in a ed–g een–blue) om he EO B owse
indica ed he a ec ed egions, wi h an es ima ed looded a ea o 3150 ha on 18 Sep (Figu e 7) wi hin
he ROI ( ec angle in Figu e 6b). This scene co esponds o some days ollowing he e en , hus some
lood a eas cloud no be well documen ed (scene 13 Sep embe o e Alican e egion has se e e cloud
con amina ion). The delinea ion o he looded zones, including ag icul u e and u ban a eas
impac ed as well as iden i ica ion o he a ec ed in as uc u es can be obse ed in he alse colou
image (Figu e 6b). Wa e quali y in ese oi s se icing human consump ion and ag icul u e was
also de e io a ed as can be obse ed in he u bidi y plume associa ed o he Segu a Ri e on 18 Sep
wi h concen a ion o suspended solids up o 150 mg/m3 (Figu e 6d) compa ed o he no mal si ua ion
on 19 Augus 2019 wi h minimum concen a ion <10 mg/m3 (Figu e 6c).
Figu e 5.
The lood-a ec ed a eas (yellow) in Mu cia on 13 Sep embe 2019 wi hin he Region o In e es
(ROI) de ined in Figu e 4b (black ec angle). The ed line ep esen s he coas al line.
In he Dolo es egion (Alican e), p e (19 Augus 2019, Figu e 6) and pos (18 Sep embe 2019,
Figu e 6b) Sen inel-2 alse colou composi e (nea in a ed–g een–blue) om he EO B owse indica ed
he a ec ed egions, wi h an es ima ed looded a ea o 3150 ha on 18 Sep (Figu e 7) wi hin he ROI
( ec angle in Figu e 6b). This scene co esponds o some days ollowing he e en , hus some lood
a eas cloud no be well documen ed (scene 13 Sep embe o e Alican e egion has se e e cloud
con amina ion). The delinea ion o he looded zones, including ag icul u e and u ban a eas impac ed
as well as iden i ica ion o he a ec ed in as uc u es can be obse ed in he alse colou image
(Figu e 6b). Wa e quali y in ese oi s se icing human consump ion and ag icul u e was also
de e io a ed as can be obse ed in he u bidi y plume associa ed o he Segu a Ri e on 18 Sep wi h
concen a ion o suspended solids up o 150 mg/m
3
(Figu e 6d) compa ed o he no mal si ua ion on
19 Augus 2019 wi h minimum concen a ion <10 mg/m3(Figu e 6c).
Wa e 2019,11, 2499 16 o 16
49.
Clemen , M.A.; Kilsby, C.G.; Moo e, P. Mul i- empo al syn he ic ape u e ada lood mapping using change
de ec ion. J. Flood Risk Manag. 2018,11, 152–168. [C ossRe ]
50.
E ena, M.; Dom
í
nguez, J.A.; Aguado-Gim
é
nez, F.; So ia, J.; Ga c
í
a-Galiano, S. Moni o ing Coas al Lagoon
Wa e Quali y h ough Remo e Sensing: The Ma Meno as a Case S udy. Wa e 2019,11, 1468. [C ossRe ]
©
2019 by he au ho s. Licensee MDPI, Basel, Swi ze land. This a icle is an open access
a icle dis ibu ed unde he e ms and condi ions o he C ea i e Commons A ibu ion
(CC BY) license (h p://c ea i ecommons.o g/licenses/by/4.0/).