Environmental changes in the central Po Plain (northern Italy) due to fluvial modifications and anthropogenic activities

The fluvial environment of the central Po Plain, the largest plain in Italy, is discussed in this paper. Bounded by the mountain chains of the Alps and the Apennines, this plain is a link between the Mediterranean environment and the cultural and continental influences of both western and eastern Europe. In the past decades, economic development has been responsible for many changes in the fluvial environment of the area.This paper discusses the changes in fluvial dynamics that started from Late Pleistocene and Early Holocene due to distinct climatic changes. The discussion is based on geomorphological, pedological, and archaeological evidences and radiocarbon dating.In the northern foothills, Late Pleistocene palaeochannels indicate several cases of underfit streams among the northern tributaries of the River Po. On the other hand, on the southern side of the Po Plain, no geomorphological evidence of similar discharge reduction has been found. Here, stratigraphic sections, together with archaeological remains buried under the fluvial deposits, show a reduction in the size of fluvial sediments after the 10th millennium BC. During the Holocene, fluvial sedimentation became finer, and was characterised by minor fluctuations in the rate of deposition, probably related to short and less intense climatic fluctuations.Given the high rate of population growth and the development of human activities since the Neolithic Age, human influence on fluvial dynamics, especially since the Roman Age, prevailed over other factors (i.e., climate, tectonics, vegetation, etc.). During the Holocene, the most important changes in the Po Plain were not modifications in water discharge but in sediment. From the 1st to 3rd Century AD, land grants to war veterans caused almost complete deforestation, generalised soil erosion, and maximum progradation of the River Po delta. At present, land abandonment in the mountainous region has led to reafforestation. Artificial channel control in the mountain sector of the basins and in-channel gravel extraction (now illegal but very intense in the 1960s and 1970s) are causing erosion along the rivers and along large sectors of the Adriatic coast. These changes are comparable with those occurring in basins of other Mediterranean rivers.     

A glacial chronology for the Fish Creek drainage of Boulder Mountain, Utah, USA

Boulder Mountain, located in South Central Utah, is one of several mountain ranges on the Colorado Plateau that was glaciated during the late Pleistocene. Using ³He exposure-age dating (corrected for non-cosmogenic ³He with shielded samples), we determined ³He exposure-ages for boulders from the most well-preserved moraines in the Fish Creek drainage of Boulder Mountain. ³He exposure-ages indicate a last glacial maximum (LGM) advance ∼23,100 ± 1300 to 20,000 ± 1400 yr ago and a later and smaller advance ∼16,800 ± 500 to 15,200 ± 500 yr ago. This chronology is very similar to other cosmogenic glacial chronologies from the Western U.S. and suggests that the timing of glacial advance and retreat on the Colorado Plateau was generally in phase with the rest of the Western U.S. during the late Pleistocene.     

Cosmogenic He exposure ages of Pleistocene debris flows and desert pavements in Capitol Reef National Park, Utah

The Quaternary history of the Capitol Reef area, Utah, is closely linked to the basaltic-andesite boulder deposits that cover much of the landscape. Understanding the age and mode of emplacement of these deposits is crucial to deciphering the Quaternary evolution of this part of the Colorado Plateau. Using cosmogenic ³He exposure age dating, we obtained apparent exposure ages for several key deposits in the Capitol Reef area. Coarse boulder diamicts capping the Johnson Mesa and Carcass Creek Terraces are not associated with the Bull Lake glaciation as previously thought, but were deposited 180±15 to 205±17 ka (minimum age) and are the result of debris flow deposition. Desert pavements on the Johnson Mesa surface give exposure ranging from 97±8 to 159±14 ka and are 34–96 kyears younger than the boulder exposure ages. The offset between the boulder and pavement exposure ages appears to be related to a delay in pavement formation until the penultimate glacial/interglacial transition or periodic burial and exposure of pavement clasts since debris flow deposition. Incision rates for the Capitol Reef reach of the Fremont River calculated from the boulder exposure ages range from 0.40 to 0.43 m kyear⁻¹ (maximum rates) and are some of the highest on the Colorado Plateau.     

Using GB-SAR technique to monitor slow moving landslide

A Ground-Based SAR (GB-SAR) interferometer was employed to measure the surface displacements of a landslide occurring in the Carnian Alps, north-eastern Italy, which has affected a national road and seriously damaged a road tunnel still under construction. Moreover, since the landslide is located on the left bank of the Tagliamento River Valley, it is feared that this mass movement might dam the river, creating a basin that would increase natural hazard for the valley inhabitants. The data collected from December 2002 to July 2005 by a conventional monitoring system, consisting of a GPS network and boreholes equipped with inclinometric tubes, showed that the landslide was moving at a quasi-constant rate of about 3 cm per year. Due to the slow deformation rate of the landslide, a recently developed GB-SAR technique based on the analysis of a restricted ensemble of coherent points was used. Two surveys, each lasting two days, were planned in December 2004 and July 2005, in order to map and measure the surface displacements that occurred over time. The results from the radar were compared with the ones derived from the GPS monitoring network. An agreement was achieved among the data collected, showing the capability of the GB-SAR technique to measure displacements even within a time span of several months between the surveys.     

Multisource Data Integration for Fire Risk Management: The Local Test of a Global Approach

In this letter, we propose an algorithm to detect the presence of forest fires using data from both geostationary and polar-orbiting satellites. The very frequent acquisitions of the Spinning Enhanced Visible and Infrared Imager radiometer placed onboard the Meteosat Second Generation-9 satellite are used as main source for the algorithm, while the MEdium Resolution Imaging Spectrometer global vegetation index and the Advanced Along-Track Scanning Radiometer measurements are used to enhance the reliability of the detection. The problem is approached in a “global” way, providing the basis for an automated system that is not dependent on the local area properties. In cooperation with the Centre de Suivi Écologique (Dakar, Senegal), the proposed algorithm was implemented in a “Multisource Fire Risk Management System” for the Senegal area, as briefly described in this letter. A field campaign of one week was carried out in order to perform a validation of the system's detections, showing a good agreement with the fire coordinates measured on the ground. Furthermore, a consistency check was performed using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) Rapid Response System, showing that more than 76% of high-confidence MODIS events are detected by the algorithm.      

Vegetation and hydrogeomorphic features of a large lowland river: NDVI patterns summarizing fluvial dynamics and supporting interpretations of ecological patterns

The interactions among hydrogeomorphic features of large lowland rivers regulate the spatio-temporal fluvial dynamics and influence the occurrence and understanding of the ecological patterns in these systems. We studied the hydrogeomorphic features that explain the fluvial dynamics of the Paraná River floodplain and investigated the usefulness of NDVI patterns in summarizing these dynamics. Information layers related to elevation, drainage network, geomorphic units, runoff dynamics, and NDVI patterns of the study area were generated from multi-source remote sensing data and fieldwork measurements. All these layers were integrated and analysed in a GIS environment, and the statistical association among them was corroborated. In our study area, the interaction among hydrogeomorphic features determined a centrifugal flooding pattern through which inundation occurs when water from remote courses, fluvial lakes, and secondary tributaries reaches the main channel. The areas closest to the main channel are flooded only when it overflows. Five NDVI patterns statistically different in terms of their means and standard deviations were identified and characterized. These NDVI patterns were significantly associated with elevation, geomorphic units, and runoff dynamics, highlighting their usefulness to characterize the fluvial dynamics and support understanding of the ecological patterns. © 2020 John Wiley & Sons, Ltd.     

Soft proton flux on <Emphasis Type="Italic">ATHENA</Emphasis> focal plane and its impact on the magnetic diverter design

The experience gained with the current generation of X-ray telescopes like Chandra and XMM-Newton has shown that low energy “soft” protons can pose a severe threat to the possibility to exploit scientific data, reducing the available exposure times by up to 50% and introducing a poorly reproducible background component. These soft protons are present in orbits outside the radiation belts and enter the mirrors, being concentrated towards the focal plane instruments, losing energy along their path and finally depositing their remaining energy in the detectors. Their contribution to the residual background will be even higher for ATHENA with respect to previous missions, given the much higher collecting area of the mirrors, even if the instruments will likely suffer no significant radiation damage from this particles flux. As a consequence this soft proton flux shall be damped with the use of a magnetic diverter to avoid excess background loading on the WFI or X-IFU instruments. We present here a first complete evaluation of this background component for the two focal plane instruments of the ATHENA mission in absence of a magnetic diverter, and derive the requirements for such device to reduce the soft protons induced background below the level required to enable the mission science. We estimate the soft proton flux expected in L2 for the interplanetary component and for the component generated locally by acceleration processes in the magnetotail. We produce a proton response matrix for each of the two instruments of ATHENA focal plane, exploiting two independent Monte Carlo simulations to estimate the optics concentration efficiency, and Geant4 simulations to evaluate the energy loss inside the radiation filters and deposited in the detector. With this modular approach we derive the expected fluxes and spectra for the soft protons component of the background. Finally, we calculate the specifics of a magnetic diverter able to reduce such flux below the required level for both X-IFU and WFI.