Lucia Mastrorillo

Groundwater of Rome

ABSTRACT This paper describes the contents of the new Hydrogeological Map of the City of Rome (1:50,000 scale). The map extends to the entire municipality (1285u2005km2) and is based on both the most recent scientific studies on the groundwater field and new survey activities carried out in order to fill the data gaps in several areas of the examined territory. The map is the result of a combination of different urban groundwater expertise and Geographic Information System (GIS)-based mapping performed using the most recent available data and has been produced with the intention of furnishing the City of Rome with the most recent and updated information regarding groundwater.

Water-table and discharge changes associated with the 2016–2017 seismic sequence in central Italy: hydrogeological data and a conceptual model for fractured carbonate aquifers

A seismic sequence in central Italy from August 2016 to January 2017 affected groundwater dynamics in fractured carbonate aquifers. Changes in spring discharge, water-table position, and streamflow were recorded for several months following nine Mw 5.0–6.5 seismic events. Data from 22 measurement sites, located within 100xa0km of the epicentral zones, were analyzed. The intensity of the induced changes were correlated with seismic magnitude and distance to epicenters. The additional post-seismic discharge from rivers and springs was found to be higher than 9xa0m3/s, totaling more than 0.1xa0km3 of groundwater release over 6xa0months. This huge and unexpected contribution increased streamflow in narrow mountainous valleys to previously unmeasured peak values. Analogously to the L’Aquila 2009 post-earthquake phenomenon, these hydrogeological changes might reflect an increase of bulk hydraulic conductivity at the aquifer scale, which would increase hydraulic heads in the discharge zones and lower them in some recharge areas. The observed changes may also be partly due to other mechanisms, such as shaking and/or squeezing effects related to intense subsidence in the core of the affected area, where effects had maximum extent, or breaching of hydraulic barriers.RésuméUne séquence sismiquexa0en Italie centrale entre Août 2016 et Janvier 2017 affecte la dynamique des eaux souterraines dans des aquifères carbonatés fracturés. Des changements dans le débit des sources, la position du niveau piézométrique, et l’écoulement ont été enregistrées pour plusieurs mois à la suite des neuf événements sismiques d’intensité 5.0–6.5. Les données de 22 sites de mesures, situés à moins de 100xa0km des zones des épicentres, ont été analysées. L’intensité des changements induits a été corrélée avec la magnitude sismique et la distance des épicentres. On a constaté que les débits post-sismiques additionnels des rivières et des sources étaient supérieurs à 9xa0m3/s, totalisant plus de 0.1xa0km3 de libération d’eaux souterraines sur 6xa0mois. Cette contribution énorme et inattendue a augmenté les débits des cours d’eau dans les vallées étroites montagneuses jusqu’à des valeurs de pics non mesurées auparavant. De façon analogue au phénomène de l’Aquila 2009 après le séisme, ces changements hydrogéologiques pourraient refléter une augmentation de la conductivité hydraulique apparente à l’échelle de l’aquifère, ce qui augmenterait les charges hydrauliques dans les zones de décharge et les abaisserait dans certaines zones de recharge. Les changements observés peuvent aussi être dues en partie à d’autres mécanismes, tels que les effets de secousse et/ou de compression liés à une subsidence intense dans le noyau de la zone affectée, où les effets ont une portée maximale, ou à la rupture des barrières hydrauliques.ResumenUna secuencia sísmica en el centro de Italia desde agosto de 2016 a enero de 2017 afectó la dinámica del agua subterránea en los acuíferos de carbonato fracturados. Los cambios en la descarga de los manantiales, la posición de la capa freática y el caudal se registraron durante varios meses luego de nueve eventos sísmicos de Mw 5.0–6.5. Se analizaron datos de 22 sitios de medición, ubicados dentro de los 100xa0km de las zonas de los epicentros. La intensidad de los cambios inducidos se correlacionó con la magnitud sísmica y la distancia a los epicentros. Se encontró que la descarga postsísmica adicional de ríos y manantiales era superior a 9xa0m3/s, totalizando más de 0.1xa0km3 de descarga de agua subterránea durante 6xa0meses. Esta enorme e inesperada contribución aumentó el flujo de las corrientes en los estrechos valles montañosos a valores máximos previamente no medidos. Análogamente al fenómeno de L’Aquila 2009 después del terremoto, estos cambios hidrogeológicos podrían reflejar un aumento de la conductividad hidráulica global en la escala del acuífero, lo que aumentaría las cargas hidráulicas en las zonas de descarga y las reduciría en algunas áreas de recarga. Los cambios observados también pueden deberse en parte a otros mecanismos, como temblores y/o efectos de compresión relacionados con un hundimiento intenso en el núcleo del área afectada, donde los efectos tuvieron la máxima extensión, o la ruptura de barreras hidráulicas.摘要2016年8月至2017年1月意大利中部的地震序列影响了断裂碳酸盐含水层的地下水动态。在9次Mw 5.0–6.5地震事件之后的几个月内记录了春季排水量,地下水位和河流的流量的变化。分析了位于震中区100公里范围内的22个测量点的数据。诱发变化的强度与地震的震级和震中距有关。发现河流和泉水的额外震后排水量高于9立方米/秒,超过6个月的地下水排放总量超过0.1立方公里。这个巨大而意想不到的贡献增加了狭窄山谷中的水流量,达到以前未测量的峰值水平。类似于拉奎拉2009年的地震后现象,这些水文地质的变化可能反映出含水层规模的分散水力传导性的增加,这将增加排放区的水头,并在一些补给区域降低它们。观察到的变化还可能部分归因于其他机制,如受影响地区核心的强烈沉降引起的震动和/或挤压效应,其中影响最大,或者破坏水力屏障。ResumoA sequência sísmica no centro da Itália de agosto de 2016 a janeiro de 2017 afetou a dinâmica das águas subterrâneas em aquíferos carbonáticos fraturados. Mudanças na descarga em nascentes, posição do nível freático e nos fluxos foram registrados por vários meses após nove eventos sísmicos com magnitude de 5.0 a 6.5. Dados de 22 locais de medição, localizados a 100xa0km das zonas de epicentro, foram analisados. A intensidade das mudanças induzidas foi correlacionada com a magnitude e distância dos epicentros. A descarga adicional pós-sísmica dos rios e nascentes foram encontradas acima de 9xa0m3/s, totalizando mais que 0.1xa0km3 de água subterrânea liberada em 6xa0meses. Essa enorme e inesperada contribuição aumentou o fluxo em vales montanhosos estreitos para valores máximos não registrados anteriormente. Analogamente ao fenômeno pós-terremoto de Áquila em 2009, essas mudanças hidrogeológicas podem refletir um aumento da condutividade hidráulica volumétrica na escala do aquífero, que aumentaria o nível potenciométrico nas zonas de descarga e diminuiria em algumas áreas de recarga. As mudanças observadas podem também ser em parte devido a outros mecanismos, como efeito de tremores e/ou compressão relacionados a subsidência intensa no núcleo da área afetada, onde os efeitos atingiram a extensão máxima, ou do rompimento de barreiras hidráulicas.

Effective infiltration variability in the Umbria-Marche carbonate aquifers of central Italy

The spatial variability of the effective infiltration parameter within the recharge areas of the main aquiferxa0complexes of the hydrogeological group of the Umbria-Marche ridge of Central Italy was assessed. This parameter usuallyxa0varies with respect to lithology and the extent of precipitation in the investigated area. The average effective infiltration,xa0expressed in millimeters/year, was directly computed by dividing the volume of water discharged on average from axa0hydrogeological basin by the extent of its recharge area. This method does not directly depend on the extent ofxa0precipitation, and therefore it is not biased by uncertainty in that value.xa0Effective infiltration was assessed for 15 hydrogeological units and ranges from 200 mm/year to 475 mm/year. Thexa0effective infiltration values for the “Scaglia” complex are always lower than those of the other aquifer complexes. Thexa0effective infiltration of the “Scaglia” complex increases southwards. This latitudinal spatial variation of effective infiltration isxa0nearly independent of the precipitation distribution. Because this trend is much more pronounced in the “Scaglia” complex,xa0it has been inferred that the spatial variability of the “Scaglia” fracturing is more significant than fracturing in any of the otherxa0calcareous lithotypes. The recharge area of the “Scaglia” complex is higher in the northern hydrostructures than in thexa0southern structures because the two areas have different deformation styles. When added to the spatial fracture variabilityxa0in the “Scaglia”, the effects of this differentiation in deformation are responsible for the different water resource amount ofxa0the hydrostructures. The occurrence of wide outcrops of the “Scaglia” complex with reduced infiltration capability justifiesxa0the existence of less productive aquifers in the northern hydrostructures.

Contribution of the Roccamonfina Caldera to the basal volcanic aquifer recharge: first considerations

A preliminary hydrogeological investigation of the Roccamonfina Caldera was conducted in order to increase the local knowledge of the multilayer aquifer hosted within the ignimbrite deposits. Three aquifer levels were distinguished according to stratigraphic data and according to the bottom well depth. The aquifer levels recharge punctual and linear springs with a total natural discharge of about 200 L/s. A preliminary groundwater recharge of about 300 L/s was calculated using the effective infiltration value (368 mm/y) suggested by Boni et al. (1986). A more detailed groundwater budget will be calculated afterwards, using the distributed method. Groundwater effective recharge will be calculated taking into account data about rainfall, land use, runoff and withdrawals values.

Hydrolithology of the area between Tuscany, Latium and Umbria regions (Italy)

Hydrogeological research lacks a standard methodology for supporting the management of groundwater resources in territory planning. The mapping of geological units in terms of their hydrogeological properties (such as permeability, effective infiltration, hydro-capacity) may provide a propaedeutical tool for calibration and validation of regional scale hydrogeological components (aquifer, aquiclude, aquitard). This work presents a hydrolithological map based on analysis of the 1:100,000 official cartography (provided by the Italian Geological Survey). The study area includes three distinct administrative regions (Tuscany, Latium and Umbria) and is a part of the central Apennines (Italy), an orogenic segment with distinctive tectono-stratigraphic sequences characterized by different degrees of permeability. A methodological approach is described that revises the geological information from the original cartography and builds a multicriteria database. The results are schematized in the attached map (at 1:100,000 scale) where the ‘hydrolithological complex’ (i.e. complex grouping lithologies with genetic and tectonic affinities and showing internal textural and compositional similarities that produce a comparable behaviour regarding groundwater flow and storage) is used as the key unit. Thematic maps illustrating permeability variation in the area and ‘macro-complexes’ are also included. The information is presented to outline the importance of revising, updating, and homogenizing geological cartography for providing direct multiscalar analysis suitable for territory planning.

Two-dimensional numerical modelling of the Roccamonfina volcanic aquifer to constrain the recharge from deep reservoir

2D model, hydrogeological properties, multilayered volcanic aquifer, inverse modelling calibration, FePest (PEST code).

Evidences of different salinization sources in the roman coastal aquifer (Central Italy)

The coastal aquifer of Rome is hosted in the Tiber River Delta depositional sequence, in a densely populated area, which was reclaimed at the end of the 19th century. Moderate salinization processes characterize this aquifer. Hydrogeological and hydrochemical surveys were carried out in October 2012 and February 2013 in the southern sector of the Delta. Hydrogeological surveys updated knowledge of groundwater morphology and a detailed conceptual hydrogeological model of the coastal aquifer was realized. Hydrochemical analyses helped to identify the salinization spatial distribution and to specify the main groundwater types. The most salinized water was not detected close to the coastline, where seawater intrusion processes would be expected, but in the inner areas. Moreover, the salinization processes resulted to be slightly marked. Results so far suggest that the source of salinization may be related more to a combination of land use and historical development of the Tiber River Delta, rather than to seawater.