Is anthropogenic land subsidence a possible driver of riverine flood-hazard dynamics? A case study in Ravenna,Italy

ABSTRACT

We investigate possible changes in flood hazard over a 77-km² area around the city of Ravenna. The subsidence rate in the area, naturally a few mm year^?1, increased dramatically after World War II because of groundwater and natural gas extraction, exceeding 110?mm year^?1 and resulting in cumulative drops larger than 1.5?m. The Montone–Ronco river system flows in the southern portion of the area, which is protected against frequent flooding by levees. We performed two-dimensional simulations of inundation events associated with levee breaching by considering four different terrain configurations: current topography and a reconstruction of ground elevations before anthropogenic land subsidence, both neglecting and representing the main linear infrastructures (e.g. roads, artificial channels). Results show that flood-hazard changes due to anthropogenic land subsidence (e.g. significant changes in computed water depth and velocity) are observed over less than 10% of the study area and are definitely less important than those resulting from construction of the linear infrastructures.     

Geochemische Bedeutung des Sr und Ba beim Studium tertiärer Kalksteine

Zusammenfassung Die Untersuchung einiger eozäner und tortoner Kalksteine aus dem Siebenbürgischen Becken ergibt, daß sich Sr und Ba in den Kalksteinbänken derselben Fundstelle in der vertikalen Richtung nach gewissen Regelmäßigkeiten verteilen. Auf Grund einer Regelmäßigkeit der Verteilung von Sr und Ba in der Vertikalen können Kalksteine, welche sich unter ähnlichen oder gleichen Bedingungen gebildet haben, identifiziert werden. Ebenfalls mit Hilfe des Studiums der Kalksteinbänke in der Vertikalen kann man Angaben über die Migration des Sr im sedimentären Zyklus erhalten.

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The importance of the geochemistry of Sr and Ba in studies of tertiary limestones

Summary Investigation on Eocenian and Tortonian limestones from the Transsylvanian Basin showed in limestone-banks of the same occurence regularities in the vertical distribution of Sr and Ba. These regularities may be used for the identification of limestones formed under similar or identical conditions. The vertical study of limestone-banks also provides data concerning the migrations of Sr in the sedimentary cycle.

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Postglacial rebound and lateral viscosity variations: a semi-analytical approach based on a spherical model with Maxwell rheology

A spectral method is employed to study the response to surface loads of a Maxwell earth including lateral viscosity variations. In particular, we focus on the effects of lithospheric cratons on the long-wavelength time-dependent displacement field for simple earth models. The viscosity contrast of the craton with respect to the surrounding mantle is kept fixed, whereas its thickness is allowed to vary. We show that the long-wavelength vertical displacement is not greatly affected by the presence of a lithospheric craton, while the tangential displacement is severely modified for the case of a homogeneous mantle. With increasing harmonic degree and thickness of the craton, the load-deformation coefficients deviate from those pertaining to a homogeneous mantle with a viscosity of 10²¹ Pa s. These deviations are particularly enhanced on timescales larger than a few hundred years. These findings indicate that the interpretation of the viscosity structure of the mantle inferred from postglacial rebound signatures based on radially stratified models is affected by the presence of lateral viscosity variations.     

Lethal and estrogenic effects of 4-nonylphenol in the cockle Cerastoderma glaucum

The lethal and sublethal effects of the xenoestrogen 4-nonylphenol (NP) were evaluated in the cockle Cerastoderma glaucum. In a 96-h lethality test, bivalves were exposed to 0, 0+ acetone, 0.19, 0.38, 0.75, 1.5 and 3.0 mg NP/l. The 96-h LC₅₀ value was 0.3 mg NP/l. No mortality was observed at 0.1 mg NP/l. The potential estrogenicity of NP was studied in both sexually undifferentiated (resting phase) and differentiated (pre-spawning phase) cockles, exposed for 7 and 14 days to 0, 0+ acetone, 0.0125, 0.025, 0.05, and 0.1 mg NP/l. Vitellogenin (Vg)-like protein levels were determined in both haemolymph and digestive gland by the alkali-labile phosphate (ALP) assay. In the resting phase, exposure for 7 days to 0.1 mg NP/l resulted in significant increases in ALP in both haemolymph and digestive gland, compared with controls. A significant increase was also observed in digestive gland of animals exposed to 0.0125 mg NP/l-exposed animals. After 14 days of exposure, haemolymph ALP levels were significantly increased in exposed animals at all NP concentrations tested, whereas no difference was recorded in digestive gland. In the pre-spawning phase, exposure for 7 days to NP significantly increased ALP levels in haemolymph from males exposed at all NP concentrations tested, whereas no significant variations were found in haemolymph from females. NP (0.05 and 0.1 mg/l) was also shown to increase ALP concentrations significantly in digestive gland of males, but not in those of females. Likewise, after 14 days’ exposure, ALP levels significantly increased in haemolymph from males only at 0.1 mg NP/l. Conversely, NP caused significant increases in ALP levels in digestive gland from both males (at all NP concentrations tested) and females (at 0.025 and 0.1 mg NP/l). These results demonstrate that NP induces Vg synthesis in C. glaucum. Interestingly, males were more responsive to NP than females.     

Pumpellyite in low-grade metamorphic rocks from Ligurian and Lucanian Apennines,Maritime Alps and Calabria (Italy)

In the Ligurian Apennines and the Brianzonese area of the Maritime Alps (Northern Italy), and in the Lucanian Apennines and Calabria (Southern Italy), pumpellyite formed during the Alpine metamorphism is widespread in terranes of Late Paleozoic to Miocene age, particularly in mafic ophiolites (Tethyan ophiolites of Jurassic-Early Cretaceous age).Pumpellyite developed under variable metamorphic conditions, which include zeolite, prehnite-pumpellyite, pumpellyite-actinolite, lawsonite-albite and blueschist facies. Pumpellyite from rocks belonging to all these facies was studied in 30 specimens of different chemistry, derived mostly from ophiolitic basalt and gabbro, but also from gneiss, amphibolite, and greywacke protoliths.Microprobe data give evidence of strong compositional variations of pumpellyite. The ranges are extreme for Al and Fe^tot (Al₂O₃=18.74–30.91; FeO_tot=0.46–12.71), to a lesser extent for Mg (MgO=0.58–4.00), with a reciprocal variation of Al and Fe^tot which suggests that most Fe is Fe³⁺.Pumpellyite compositions can be related with the metamorphic conditions, particularly an increase of the Al/Fe^tot ratio with increasing pressure, but larger compositional variation for each facies in the Al-Fe^tot-Mg diagram than those previously described was recognized. Particularly the compositions of pumpellyite from the pumpellyite-actinolite and blueschist fades assemblages extend towards higher Fe^tot contents. Moreover, pumpellyites of the lawsonite-albite facies rocks result to be more aluminous than in blueschist facies; such relations appear to be inconsistent with that expected by the effects of pressure on the Al content.As the rocks are generally incompletely re-equilibrated, their bulk chemistry is not an important factor of pumpellyite composition; in fact the correlations of Al, Fe^tot and Mg are low. The local environment of crystallization, more evidently the composition of the precursor minerals, seems to be a major controlling factor. The observed topologic relations indicate that either the nature of the precursor mineral, or the presence of relict phases have a great influence on the pumpellyite composition. The observed variations within individual specimens, as well as the interspecimen ones, can be explained by small-scale inhomogeneities and in some cases by differences in the activity of O₂.It can be therefore concluded that the composition of pumpellyite often reflects disequilibrium crystallization and cannot be generally used as an indicator of metamorphic conditions.     

Evolution of river planforms downstream of dams: Effect of dam construction or earlier human‐induced changes?

When studying the evolution of landscape, it is difficult to discriminate the influence of anthropogenic from natural causes, or recognise changes caused by different sources of human action. This is especially challenging when the influence of certain sources is overprinted. For instance, although dam closure is the most common method of altering river courses, dam construction is often preceded by hydro‐technical works such as channel straightening, embankment construction or sediment mining. Both dam construction and the hydro‐technical works that precede dam closure can result in changes in the balance between sediment supply and transport capacity, and often, changes in river planform. The main objective of this study was to verify whether the works preceding dam closure are an important driver of river planform changes on the lower Drava River (Hungary). The case study is based on geological and geophysical surveys, as well as the analysis of historical maps covering an anabranching, 23 km long valley section. We show that channel straightening conducted prior to dam closure resulted in a transition from a meandering to sinuous planform with channel bars. Dam construction itself then caused enhanced incision, exposure of bar surfaces, vegetation encroachment and the formation of an anabranching planform. Based on this study, we developed models of alluvial island and channel planform evolution downstream of dams. Dam construction enhances channel incision, narrowing, and the reduction of flow caused by earlier hydro‐technical works. Many rivers downstream of dams experience episodes of anabranching or wandering, with a multi‐thread pattern replacing sinuous, braided and meandering courses. When incision continues, river patterns evolve from anabranching to sinuous via the attachment of alluvial islands to floodplains. However, the timing and sequence of these changes depend on hydrological and sediment supply regimes, geomorphic settings and anthropogenic actions accompanying dam construction. Copyright © 2018 John Wiley & Sons, Ltd.     

Disconnected policies and actors and the missing role of spatial planning throughout the risk management cycle

The present work addresses the problem of lack of coordination between policies and actors with joint competence for risk management, i.e., civil protection, spatial planning, and sectoral planning (e.g., forest policy in the case of forest fire risk). Spatial planning in particular is assigned a minor or no role at all though it might perfectly operate as the coordinating policy platform; the reason is that spatially relevant analysis and policy guidance is an omnipresent component of the risk management cycle. However, disconnected risk relevant policies turning a blind eye to spatial planning might cause several adverse repercussions: Breaks in the response-preparedness-prevention-remediation chain (which should function as a continuum), minimal attention to prevention, risk expansion and growth instead of mitigation, lack of synergies between involved actors as well as duplicated or even diverging measures and funding. The authors bear witness to the above suggestions by examining three cases of European (regional and local) risk management systems faced with failures when confronting natural hazards (floods and forest fires). These three systems are embedded in different types of political-administrative structures, namely those of the city of Dortmund (Germany) facing floods, Eastern Attica region (Greece), and Lazio Region (Italy) facing forest fires.     

Mineralogical and chemical evolution of ochreous precipitates from the Libiola Fe–Cu-sulfide mine (Eastern Liguria,Italy)

The mineralogical and chemical evolution of ochreous precipitates forming from acid mine drainage (AMD) from the abandoned Libiola Fe–Cu-sulfide mine (Eastern Liguria, Italy) was followed through a multianalytical approach (XRD, TEM, XRF, ICP) applied to surface precipitates and associated waters collected from several mine adits. The mineralogy of the precipitates changed significantly as a consequence of the variations of the chemical parameters of the circulating solutions (mainly pH, Eh, and sulfate concentrations) which, in turn, were mainly controlled by mixing with unpolluted stream and rill waters of the mining area. A progressive transition from jarosite-, to schwertmannite-, to goethite-, to ferrihydrite-, to amorphous-dominated precipitates was observed, mainly as a consequence of an increase in the pH of the associated solutions. This mineralogical evolution agrees well with the aqueous speciation and Eh–pH stability calculations performed on the waters associated with the different precipitate types. Furthermore, TEM analysis indicated that metastable pristine phases (schwertmannite) tend to transform progressively to well-crystallized more stable species, here represented by goethite. The comparison of the water chemistry and the crystal chemistry of the different precipitates showed a significant decrease in the Zn, Cu, Ni, Co contents in waters where the coexisting precipitates were almost exclusively composed of goethite. The distribution of V, Sr, As concentrations within the different precipitates showed that the most efficient scavenging phase for these elements was jarosite, whereas ferrihydrite efficiently took up Pb ions, and schwermannite acted as a natural sink for Cr.