University of Burgos1, IGME2, Burgos Council3
Impact of Climate Change Impact in Contamination Vulnerability of Mesozoic Karst Aquifers in Burgos Area (Spain). author(s): Luis Antonio Marcos University of Burgos, Spain, qplamn@ubu.es Laila Louajdi University of Burgos, Spain, louajdi_laila@yahoo.es Silvino Castaño Geological Survey of Spain (IGME), Spain, s.castano@igme.es Mónica Vazquez University of Burgos, Spain, movazm@gmail.com MarÃa Jesús Contreras Burgos Council, Spain, mjcontreras@aytoburgos.es keywords: karst aquifers, pollution vulnerability, hydrogeochemistry, climate change ABSTRACT. This study presents a methodological approach for the assessment of the Climate Change Impact in the vulnerability to chemical contamination of karst aquifers of Mesozoic age, located in Tierra de Lara (West of the Sierra de la Demanda, northeast of the Douro river basin) in the province of Burgos (Castilla y Leon, Spain). Karstic aquifers are well known for their vulnerability to groundwater contamination. This is due to characteristics such as thin soils and point recharge in dolines, shafts, and swallow holes. In karstic areas, groundwater is often the only freshwater source. The vulnerability of karst aquifers to contamination, both chemical and microbiological, is extreme, especially in high rainfall and a strong growth of the net movement of groundwater. There are very different methodologies to assess vulnerability to contamination of an, which are grouped into hydrogeologic methods, parametric or model-based simulation. In this study, we have chosen several methods (GOD, DRASTIC, EPIK and COP) for the assessment of the potential vulnerability. In this project we study the evaluation of climate change impact, below several hydrological hypotheses, on the quantity and quality of these groundwater with several hydrological hypothesis. The results are presented in the form of thematic maps produced using a GIS approach in order to identify areas of greater or lesser susceptibility to contamination. It also identifies areas of highest risk of pollution from chemicals. The karst environment consists of platform Cretaceous and Jurassic limestone and dolostone covered with thin layers of Tertiary and Pliocene-Quaternary rocks and soils. The carbonate rock is bedded, jointed, and subject to karst phenomena. The study site, is 200 km2 wide, and is characterized by developed karst landforms that form a network due to the chemical dissolution of limestone. As a result, an underground network of cavities, caves, and conduits has developed, some of which are very large. The landscape is typically low-relief karst, characterized by many dolines and by very flat-bottom valleys filled with thin alluvial deposits; mainly residual clayey deposits from karst processes (the so-called terre rosse) and detritus. There are, in the area, several big springs, usually associated to the birth of small rivers that occasionally dry up during the summer, sources that drain large bodies of water contained in karst aquifers and other low flow sources that drain fragmented small aquifers. Hydrogeochemistry and Stable Isotopes of Mesozoic Karst Aquifers are also studied, and different hydrochemistry zones are showed in relation to groundwater flow, recharge and discharge areas. Hypothetical evolution of their hydrochemistry is also studied. 55 spring waters and 24 small flow river have been sampled, chemically and in a stable isotopic way. Finally, both the chemical nature of the water and vulnerability to contamination of aquifers is studied under the potential impact of different assumptions and scenarios of climate change. References: 1.- Ekmekci, M., Tezcan, L. (2011) Management of Karst Aquifers under climate change: Implications for sustainable use. NATO Science for Peace and Security Series C: Environmental Security 2.- Ozyurt, N.N., Lutz, H.O., Hunjak, T., Mance, D., Roller-Lutz, Z. (2014). Characterization of the Gacka River basin karst aquifer (Croatia): Hydrochemistry, stable isotopes and tritium-based mean residence times. Science of the Total Environment Volume 487, Issue 1, 15 July 2014, Pages 245-254. 3.- Polemio, M.; D. Casarano, and P. P. Limoni (2009) Limoni Karstic aquifer vulnerability assessment methods and results at a test site (Apulia, southern Italy) Nat. Hazards Earth Syst. Sci., 9, 1461--1470, 2009. References: 1.- Ekmekci, M., Tezcan, L. (2011) Management of Karst Aquifers under climate change: Implications for sustainable use. NATO Science for Peace and Security Series C: Environmental Security 2.- Ozyurt, N.N., Lutz, H.O., Hunjak, T., Mance, D., Roller-Lutz, Z. (2014). Characterization of the Gacka River basin karst aquifer (Croatia): Hydrochemistry, stable isotopes and tritium-based mean residence times. Science of the Total Environment Volume 487, Issue 1, 15 July 2014, Pages 245-254. 3.- Polemio, M.; D. Casarano, and P. P. Limoni (2009) Limoni Karstic aquifer vulnerability assessment methods and results at a test site (Apulia, southern Italy) Nat. Hazards Earth Syst. Sci., 9, 1461–1470, 2009.