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CLIMATE CHANGE SCENARIOS USING NON-
PHYSICAL RELATIONSHIPS FOR
GROUNDWATER IN COASTAL KARSTIC
AQUIFERS
C. Canul-Macario*, P. Salles*,+, J. A. Hernández-Espriú** and R. Pacheco Castro*,+
1. INTRODUCTION
Coastal aquifers are characterized by the interaction between the aquifer and the sea,
defining a mixing zone of saltwater-freshwater. Thus, coastal aquifers have a strong
synergy with hydrological forcings that govern the aquifer head (AH), the spatial
distribution of groundwater salinity (S) and the saline interface position (Werner et al.,
2013; Ketabchi et al., 2016). This work is a preliminary simulation of climate change
scenarios of the aquifer head (AH) and saline interface position (SI) associated with the sea
level (SL) rise, using numerical relationships in the karstic aquifer of northwest Yucatan,
Mexico (RNWY).
2. MATERIALS AND METHODS
Conceptual model
a. Field Data + Literature
IPCC climate change scenarios of sea-level rise: RCP 2.6, RCP 4.5 and RCP
8.5 (Church et al. 2013)
a. Aquifer head scenario SL vs AH
b. Aquifer discharge reduction scenario SL vs AH
c. Saline interface position scenario SL vs S; Glover (1959)
0
3. FIELD SITE
The NW Coastal Aquifer of Yucatán is located at SW of Mexican Republic in a Tertiary
and Quaternary rock (Fig. 2). The study zone is defined as a confined coastal karstic
aquifer. Regional groundwater flow is perpendicular to the coast with a low hydraulic
gradient 1X10-5 m/m (Villasuso et al., 2011). Precipitation, pressure, temperature, and
salinity data were used for the analysis, the data was collected in the northwest coast of
Yucatan during May 2017-May 2018 period.
4. NUMERICAL RELATIONSHIPS
Power spectra show a similitude between astronomical tide of SL, AH and S. Linear correlation of SL vs AH and
SL vs S shows significative correlation (Pearson r>0.7). The SL effects in the aquifer propagate toward the
continent until 11 km. Non-physical relationships suggest a direct relationship of AH and Sdue to increments of
SL (Fig. 3, Table 1). Precipitation and vertical recharge did not show significative correlation with AH and S.
5. RESULTS AND DISCUSSION
Non-physical relationships suggest that sea-level rise will express in the aquifer similar as the astronomical tide,
Fig. 4 show that AH increases towards the continent until 14 km, reducing the hydraulic gradient and the
aquifer discharge to the coast (RCP 2.6 and RCP 4.5). RCP 8.5 shows a reversal of the aquifer flow (negative
hydraulic gradient). Low elevation terrain would be vulnerable to flooding due to an outcrop of the aquifer.
Glover model shows that the aquifer discharges towards the sea until 2 km, but with the sea-level rise, the
saltwater wedge moves into the continent. RCP 2.6 and RCP 4.5 suggest a reduction between 5 to 20 min the
freshwater thickness of the aquifer. Local coastal populations are supplied with wells located between 5 to 10
km from the coast, therefore, these structures would be compromised by the reduction in the freshwater lens.
Seawater intrusion in coastal aquifers, similar as Yucatan, could be associated with an increment in the salinity
levels of the water supply from populations as well as an increase in household costs, ecological damages to
ecosystems and depletion of population health (Alameddine, Tarhini, and El-Fadel 2018; Shammi et al. 2019;
Williams 2010). Therefore, the population must be prepared for these affectations.
6. CONCLUSIONS
Climate change scenarios suggest affectations to the health, economy and environment of the coastal populations of RNWY due to the increment in the salinity of the aquifer and aquifer head rise.
Population in RNWY must considerate a future increment in the cost of the water supply associated with possible desalinization processes or/and pumping from several inland kilometres. Coastal
ecosystem of RNWY will experience flooding in zones where the confinement is fractured. In addition, the salinity in the groundwater will increase and the saline interface will be shallower. Several
species in the coastal lagoons may be lost due to their low tolerance to saline and/or brackish water.
It is important to understand how resilient the coastal populations are to the increase of salinity in the water supply and changes in their ecosystems. It is necessary to develop strategies to increase the
population capability to adapt to the possible environmental, social and economic impacts.
7. REFERENCES
Alameddine, I., R. Tarhini, and Mutasem El-Fadel. 2018. “Household Economic Burden from Seawater Intrusion in Coastal Urban Areas.” Water International 43 (2): 217–36. https://doi.org/10.1080/02508060.2017.1416441.
Church, J.A., P.U. Clark, Anny Cazenave, Jonathan Gregory, Svetlana Jevrejava, Anders Lebermann, Mark Merrifield, et al. 2013. “Sea Level Change.” In Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, edited by Jean Jouzel, Roderik van de
Wal, Philip Woodworth, and Cunde Xiao, 227. New York, USA: Cambridge University Press. https://doi.org/10.1017/CBO9781107415324.
Glover, R. E. 1959. “The Pattern of Fresh-Water Flow in a Coastal Aquifer.” Journal of Geophysical Research 64 (4): 457. https://doi.org/10.1029/JZ064i004p00457.
Ketabchi, Hamed, Davood Mahmoodzadeh, Behzad Ataie-Ashtiani, and Craig T. Simmons. 2016. “Sea-Level Rise Impacts on Seawater Intrusion in Coastal Aquifers: Review and Integration.” Journal of Hydrology 535. Elsevier B.V.:235–55.
Shammi, Mashura, Md. Rahman, Serene Bondad, and Md. Bodrud-Doza. 2019. “Impacts of Salinity Intrusion in Community Health: A Review of Experiences on Drinking Water Sodium from Coastal Areas of Bangladesh.” Healthcare 7 (1): 50https://doi.org/10.3390/healthcare7010050.
Villasuso-Pino, M., I. Sanchez y Pinto, C. Canul-Macario, G. Baldazo Escobedo, R. Casares Salazar, J. Souza Cetina, P. Poot Euan, and C. Pech. 2011. “Hydrogeology And Conceptual Model Of The Karstic Coastal Aquifer In Northern Yucatan State, Mexico.” Tropical and SubtroTropical Agroecosystems 13:243–60.
Werner, Adrian D., Mark Bakker, Vincent E.A. Post, Alexander Vandenbohede, Chunhui Lu, Behzad Ataie-Ashtiani, Craig T. Simmons, and D. A. Barry.2013.“Seawater Intrusion Processes, Investigation and Management: Recent Advances and Future Challenges.”Advances in Water Resources 51. Elsevier Ltd:3–26
Williams, Vereda Johnson. 2010.“Identifying the Economic Effects of Salt Water Intrusion after Hurricane Katrina.”Journal of Sustainable Development 3 (1). https://doi.org/10.5539/jsd.v3n1p29.
This project has received funding from the National Coastal Resilience Laboratory (LANRESC) and
CONACYT.
Numerical relationships
a. Power spectra (FFT) comparison of SL, AH and S
b. Non-physical relationships: SL vs AH and SL vs S
Figure 1. Methodology flux diagram.
Figure 3. Power sprectra comparison. (a) AH, (b) S
Figure 4. Climate
change scenarios
of AH.
Figure 5. Climate
change scenarios
of SI.
*Engineering and Coastal Process Laboratory, Sisal, Yucatan, Mexico. Engineering Institute, UNAM (e-mail:
CCanulM@iingen.unam.mx; PSallesA@iingen.unam.mx; RPachecoC@iingen.unam.mx)
+National Coastal Resilience Laboratory (www.lanresc.mx)
** Hydrogeolgy Group, Engineering Faculty, UNAM (E-mail: ahespriu@unam.mx)
H = freshwater aquifer thickness
q = unitary aquifer discharge
K = hydraulic conductivity
= ratio density salt-fresh water
Fresh water aquifer head
ID
Distance
from the
coast (km)
Astronomical Meteorological
slope r
t lag (hrs)
slope r
t lag (hrs)
P7a 0.80 0.809 1.00 0.00 0.612 0.82 0.00
P5 5.00 0.460 1.00 0.50 0.469 0.77 0.00
P8 12.00 0.140 0.99 2.00 0.398 0.71 3.00
P9 11.00 0.261 0.98 2.50 0.513 0.56 2.50
P7b 22.00 -- -- -- 0.354 0.38 59.50
P4 23.00 -- -- -- 0.050 0.07 34.50
Salinity
ID
Distance
from the
coast (km)
Astronomical Meteorological
slope r
t lag (hrs)
slope r
t lag (hrs)
P7aUSI
0.80 0.101 0.76 3.00 -0.113 0.17 0.00
P7aBSI 0.80 0.966 0.90 -2.50 -6.606 0.20 0.00
P8USI 12.00 0.126 0.93 7.00 -0.138 0.37 25.00
P8BSI 12.00 -- -- -- 1.644 0.51 25.00
Table 1. Linear correlation of fresh water aquifer head, salinity
and sea level.
Figure 2. Study Zone
