Studio idrogeologico sull’acquifero di Chiasso

Blick gegen Chiasso_16473088301_l Sto preparando la mia tesi al Master di idrogeologia e geotermia dell’Università di Neuchatel (CHYN) che avrà come oggetto di studio la piana di Chiasso ed il suo acquifero superficiale. Sarà uno studio sui suoi processi geochimici, in particolare attorno al pozzo di Pra Tiro (quello vicino allo stadio comunale). Una prima ricerca é già stata fatta ed esiste già un programma di monitoraggio preso in carica dall’Istituto di scienze della Terra di Trevano (IST).

L’acqua potabile di Chiasso é estratta unicamente dal sottosuolo. Si sono osservati dei valori di nitrati al di sopra della normativa svizzera di 25mg/l e si vuole capire l’origine e la fenomelogia di questi nitrati nell’acqua di falda.

Lavorero’ con il prof. Daniel Hunkeler (CHYN) ed il Dr. Pera (IST).

Aggiungo una presentazione piu’ dettagliata in inglese.

Situation

 

Chiasso, Switzerland Evening_6160275141_lChiasso is a town of about 8000 inhabitants prevalently occupied in the service and industrial business whereby the agricultural activities are limited. About half of the surface of the study area is occupied by the Swiss Federal Railways hub as part of the national second most important logistical center as it gradually developed[1],[2] from the opening of the Gotthard Tunnel (1882) until the contemporary dismantling.

The area is also the location of a 4x1km unconfined, pre-alpine, cross-border aquifer set in a quaternary sedimental plane which shows sequences of glacial, fluvial, marsh and lacustrine soft deposits (fig.1 from Gasperini, 2013). Highly organic deposits were also observed in several boreholes in the area, and the presence of hystorical gas seepage has been recognized (Greber et al., 1997)[3].

Chiasso and its railways

The plain is crossed by three rivers from West to East (fig.2): the tributaries Roncaglia, Faloppia and the main stream Breggia, which in turn flows into the 3 km distant Como Lake,in Italy. The rivers’ bed were completely cemented under the 1970-80s environmental policy and in theory do not play an important role for the recharge of the aquifer which is happening by snow and rainfall almost uniquely. We assume normal climatic values (i.d. 30% ) for evapotranspiration.

fiumi e pozzo e sorgente
Fig. 2 fiumi, pozzo e sorgente sulla piano di Chiasso

 

Since 2013, IST operates a groundwater observation network monthly measuring piezometric levels. Data are analyzed, interpolated to create a continuous surface and then published through web gis services for public administration use. According with those surveys, Pra Tiro well pumping strongly influences piezometric levels in the whole acquifer crating a large depression cone. In some observation points some artesian piezometric levels were also recorded in the west portion of the aquifer.

 

On the basis of this piezometric observation network, IST proposed a groundwater quality monitoring network currently operated by Sezione per la protezione dell’aria dell’acqua e del suolo (SPAAS) from Cantone Ticino.

 

On the Northern border of the plain a karstic source (“Rovagina”) in the calcalreous rocks of the Mount Generoso massif feeds substantially the 1914 firstly built aqueduct while in the middle of the plain is a well (“Pra Tiro”) which is in use since 1942 [4] and which was an extension to the original aqueduct (fig.2). Thus, the city of Chiasso (and the nearby city of Balerna) depends exclusively from groundwater from these two sources for its water supply. In order to fulfill quantitatively drinking water requirements the Rovagina Spring is now exploited by pumping.

 

Following the observation of NO3 values above the quality limits of 25 mg/ml fixed by the water protection ordinance[5] in certain abandoned industrial wells, public authorities performed in 2012 – 2013 an aquifer extensive groundwater quality survey. Collected data were successively used to conduct a hydrogeochemical study that was carried out in collaboration with IST – SUPSI and Pisa University[6]. The aim of the study was to do a description of the chemical characteristics of groundwater and the analysis of presence and spatial distribution of nitrogen related compounds.

situation - from gasperini et al

It has been concluded that the Nitrogen (and Potassium) comes from natural origin from interaction

of organic Quaternary lenses present in the alluvial plane[7] but other sources are envisaged (sewage discharge, fertilizers, wastewaters treatment facilities). Ion exchange processes ( Na – K) and calcite precipitation seems to play the major role and occur along paths. Thus the groundwater geochemical evolution is being controlled by oxidation of organic matter along the flow direction and water-rock interaction mechanisms6.

 

Study Objective

 

The fact that groundwater represents the only water source for the town of Chiasso explains the interest in studying and monitoring the hydrogeology of this densely populated area (up to >80 inhabitants/hectare[8]).

 

We aim at understanding more in detail the origin, behavior along flow paths, mechanisms of the oxidation process of the Nitrogen compounds around the well “Pra Tiro” by using environmental isotopes, in particular the N and O isotopes of the NO3 molecule and those of the water molecule (D,O). The role of artesian groundwater which is characterized by negative redox potential in releasing N related compounds will be also studied.

 

 

Chiasso_7885936504_l

 

Preliminary Bibliograhy

 

 

  1. Gasperini Greta, Geochemical Carachterization of the Chiasso Aquifer, Bachelor Thesis, University of Pisa, 2013. https://etd.adm.unipi.it/t/etd-06172013-161931/
  2. Istituto Geologico Cantonale (data). Idrogeologia del bacino di Chiasso. Rapporto interno
  3. Appelo C.A.J, Postma D., Geochemistry, Groundwater and pollution, 2nd Edition, 2010,CRC Press
  4. Glynn P.D, Plummer L.Niel, Geochemistry and the Understanding of Groundwater Systems, Hydrogeol J (2005) 13:263-287

 

  1. Greber E., Leu W., Bernoulli D., Schumacher M.E., Wyss R., 1997. Hydrocarbon Provinces in the Swiss Southern Alps – a gas geochemistry and basin modelling study. Marine and petroleum geology vol 14 no 1 pp. 3 -25.
  2. Krauskopf K.B, Bird, D.K, Introduction to Geochemistry, 3rd Edition, 1995, McGraw-Hill
  3. Sigg L, Stumm W., Aquatische Chemie, Einführung in die Chemie natürlicher Gewässer, 2011, VDF Verlag
  4. Geochemistry notes of the Master of Hydrogeology and Geothermy, CHYN, Université de Neuchâtel, 2013-2014
  5. Kendall C., Mc Donnell (Eds.), Isotope Tracers in Catchment Hydrology, 1998, Elsevier Science B.V.
  6. Clark I.D, Fritz P., Environmental isotopes in hydrogeology, 1997, CRC Press
  7. Churchod B., Gonthier J., Miéville P., Risse J., Introduction à la Chimie, 2011 Edition LEP

[1] SCUOLA CANTONALE DI COMMERCIO, I cento anni della ferrovia del San Gottardo, 1882-1982, Edizioni Casagrande SA, Bellinzona

[2] MARIO GILARDI, Saluti da Chiasso, Edizioni Tipo-Print, Mendrisio, 1971

[3] Greber E., Leu W., Bernoulli D., Schumacher M.E., Wyss R., 1997. Hydrocarbon Provinces in the Swiss Southern Alps – a gas geochemistry and basin modelling study. Marine and petroleum geology vol 14 no 1 pp. 3 -25.

[4] http://www.age-sa.ch/cenni-storici
[5] http://www.bafu.admin.ch/gewaesserschutz/10428/index.html?lang=en
[6] Gasperini Greta, Geochemical Carachterization of the Chiasso Aquifer, Bachelor Thesis, University of Pisa, 2013. https://etd.adm.unipi.it/t/etd-06172013-161931/

 

6 Gasperini Greta, Geochemical Carachterization of the Chiasso Aquifer, Bachelor Thesis, University of Pisa, 2013. https://etd.adm.unipi.it/t/etd-06172013-161931/
[7] Istituto Geologico Cantonale (data). Idrogeologia del bacino di Chiasso. Rapporto interno

[8] Population density map on the Swiss Geological Survey, https://map.geo.admin.ch

Larderello – geothermal field – geotermia

IMG_8336

I recently I visited the city of Larderello, Tuscany, Italy and the Museum of the Geothermal Energy.

Larderello is a tectonical extension area and the largest geothermal field in Europe. The main carachteristic is the presence of a batholit at low depth (10’000m) which warms up water infiltrating from the surface and creates vapour and gas vents on the te ground. The area is also called “The Devil Valley” and it has a bad reputation among locals.

 

The city itself is quite ok but it lacks of a proper Italian lifestyle which is so common in all nearby villages. The air is also affected by sulphur gas emissions and the only advantage of living here is that houses are directly heated with hot water coming from the geothermal field…and rents are very cheap. As for all villages in Tuscany, you need a car to move around or adapt to the reliable but spare runs of the public busses.

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La città di Larderello, in Toscana, non lontano da Volterra, é il piu’ grande campo geotermico in Europa. Ho visitato recentemente Larderello e raccolto per la prima volta dei commenti molto poco lusinghieri sulla geotermia, nota invece  in tutto il mondo come energia pulita e sicura tranne che qui. La spiegazione é semplice: a Larderello vi sono fuoriuscite naturali di vapori e acque calde, emissioni solforose e depositi evaporitici di bromo. Inoltre, vi sono tubi esteticamente brutti e in parte a vista per convogliare  il calore diretto alle case non solo di Larderello ma anche dei bellissimi borghi vicini come Pomarance a diversi cgilometri di distanza. La Valle, già anticamente é stata ribattezzata come “Valle del Diavolo”.

Parlando con gente di Volterra ho constatato di prima persona come sia abbia sul posto l’immagine di energia inquinante e malsana. Ovvia l’opposizione di nuovi impianti in nuove zone rurali ora incontaminate. Non si voglioni vapori pestilenziali né brutti tubi nella bella campagna toscana!

Ho cercato invano di spiegare che in Svizzera, a Bsilea e a San gallo si é cercato invece di fare della geotermia profonda proprio il piu’ vicino alla città, anzi a San Gallo anche proprio dentro una fattoria…

Il campo geotermico di Larderello é comunque davvero unico. La camera magmatica é circa a soli 10’000 metri di profondità perche la regione é tettonica in estensione. A 1500m la temperatura é di quasi 200 gradi. La visita del museo della geotermia di Larderello nell’impianto gestito dall’ENEL é davvero piacevole. Si cerca di essere il piu’ trasparenti possibili sulla geotermia locale e generale. C’é pero’ come un imbarazzo nel non dire la cosa piu’ semplice: Larderello é una città un po’ spettrale, senza una vera vita come nei villaggi vicini ma questo per il semplice fatto che la piccola vallata da sempre non é un luogo ospitale proprio per i fenomeni naturali appena descritti.

Per la cronaca, ho posato la mano su un tubo di riscaldamento di una casa un punto a gomito non coibentato) e davvero scottava, impossibile lasciarvi una mano sopra (penso almeno 80 gradi). Una signora del posto mi ha detto che anche se i riscaldamenti si possono regolare, i riscaldamenti in casa sono sempre accesi e che le finestre sono spesso aperte per rinfrescare la casa. Beh, chiaro, tanto é acqua calda naturale del sottosuolo.

Ecco un po’ di foto:

IMG_8331 IMG_8332 IMG_8337 IMG_8342 IMG_8343 IMG_8344 IMG_8346 IMG_8348 IMG_8352 IMG_8353 IMG_8354

 

Carotaggi su frana

Sabato e domenica eravamo occupati con la Foldtani con tre carotaggi su una frana in Italia. Si tratta di un deposito argilloso postglaciale eroso alla base dal fiume Bevera affetto che durante una piena di entità eccezionale ha visto una importante erosione dell’alveo con distruzione di un ponte in manufatto (cemento).

Si tratta di rimediare ora alla situatione dopo un primo lavoro provvisorio di contenimento dello scivolamento: un dreno per le acque superficiali a monte e impermeabilizzazione con teloni di plastica delle zone di distacco. La sistemazione dell’alveo con ripari antierosione e la ricostruzione di un ponticello tra le due sponde.

Dopo il carotaggio, abbiamo piazzato due piezometri, uno in testa ed uno al piede della frana.

carotaggio su frana in Italia, geologia ambientale

 

 

Neuchatel CHYN (hydrogeology and geothermy)

Kriging is a way of estimating spatial data where there is none. Easy said but it deals with high mathematics, probabilities, statistics and random variables. Do you have only a few points of data on a map but you want to create a reasonable contour area and even extrapolating values? Kriging is for that. Uses of kriging  are many: in environmental remediation, mineral and fossil fuels exploration, biology…to name a few.

Kriging maths

Another fundamental tool is FEFLOW of course: flow and mass simulation on a PC (actually I do it on my laptop). The learning curve is rather steep but little by little I am getting used here at teh University of Neuchatel (CHYN) where I am doing my master in hydrogeology and geothermy. We are using the old interface by the way…here it is:

feflow hydrogeology simulation numerical

 

 

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Geologia ambientale

Indagini ambientali in Italia, occorrono per un ordine municipale.

Servono 6 campioni in tre punti diversi del terreno in esame e a due profondità diverse (1m e 3m di profondità). L’indagine, relativamente semplice, si complica per la geologia del sottosuolo che é contraddistanta da ghiaie grossolane anche parecchie grosse, anche veri e propri “sassi” grandi come una mano o piu’ che rallentano o addirittura impediscono la campionature, onde spostare il macchinario per riprovare a poca distanza…

geologia-ambientale-desio-1 geologia-ambientale-desio-2 geologia-ambientale-desio-3 geologia-ambientale-desio-4

Come giustamente si dice, la geologia bisogna “vederla” sul campo, “sentirla” anche con questi tipi di esperienze…

 

 

Watsan For Emergency Situations

WATSAN, Water and Sanitation, is in demand

Learning how to take water from a possible natural source such a lake, making it drinkable and distribute it in a pipe network.
Learning how to take water from a possible natural source such a lake, making it drinkable and distribute it in a pipe network.

There has been one growing tendency in the last decades and this is the steady increase of refugees and internally displaced people because of international and national conflicts and unrest.

The ICRC (International Comitte of the Red Cross) and the Centre d’Hydrogeologie de Neuchatel, CHYN, (Université de Neuchatel, Switzerland), organized an intense 8 days of training on the subject (24-31 August 2013).

I participated as a geologist among other colleagues from the ICRC, the International Federation of Red Cross and Red Crescent Societies IFRC, NGOs, architects and professional: in total, we were a group of 20 people from all over the world.

Watsan specialist’s demand is growing and has been steadily increasing in the last years. Conflicts such as the one in Syria now with over 2 millions refugees are in fact a sad reality of the time we leave in. When somebody has to flee from home, the first thing you need is water (you can live for 3 weeks without food but no more than 3 days without water) and as soon as you settle down in a camp, be it an organized one (planned in advance or managed by the UNHCR, ICRC, OXFAM or else), the SECOND most important thing is to dipsose of the human excreta to prevent diseases.

And this is what we learned including topics in bacteriology and the main water and air-born disease such as malaria, dengue fever, worms and parasites, cholera (which is so easy to cure and nobody should die from it if water is available and the cure is fast!).

There was a lot to do with hydrogeology, too. We carried out a short-term pumping test in a nearby borehole and I could practice again the geoelectrical survey with a Schlumberger alignment of the electrodes.

A good, intense week, which didn’t make us Watsan experts at once (for this, as everything you need years of practice) but which contributed to raise awareness to topics and notions we were all familiar (we all had previous experiences in relief or third world countries activities)  with but never had the time perhaps to further investigate.

More pictures can seen here

Watsan week pictures, ICRC CHYN, Neuchatel, Switzerland, August 2013
Watsan week pictures, ICRC CHYN, Neuchatel, Switzerland, August 2013

 

 

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Geotermia a Milano, ma..l’archeologia viene prima!

geotermia a Milano

 

Milano
Milano (Photo credit: Wikipedia)

 

 

Siamo in agosto, gran caldo a Milano. Nel quadrilatero della moda, a due passi da via alla Spiga, eccoci insieme a Francesco (Foldtani) a seguire l’indagine archeologica prima della perforazione vera e propria per l’impianto geotermico a circuito chiuso che attimge alla falda (qui é circa a meno 30 metri dal piano di campagna).

L’indagine archeologica é d’obbligo essendo l’edificio nel centro storico e a un centinaio di metri dalle vecchie mura romane che spesso si trovano in scavi di cantieri a Milano ad una profondità di pochi metri.

Abbiamo trovato dei cocci di vasellame settecentesco e rinascimentale, una ghiacciaia medievale, qualche mattone di epoca romana, ma niente altro di importante. i lavori possono proseguire.

Un’esperienza in fondo rara, quella di osservare l’ispettorato dei beni archeologici al lavoro.

http://embed.animoto.com/play.html?w=swf/production/vp1&e=1376421078&f=0apmmu6sPbmwYa8C5jS0LQ&d=0&m=p&r=360p+480p&volume=100&start_res=480p&i=m&ct=Studio%20geologico%20FOLDTANI&cu=http://foldtani.it&asset_domain=s3-p.animoto.com&animoto_domain=animoto.com&options=

We are at the center of Milan (near via alla Spiga/Corso Venezia, just 5 minutes walking from the Duomo).

Before any drilling for the waterwell (the project is for a geothermal system in an old building) we need to go through an archeological investigation carried out by a state archeologist..

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