The increase in temperature of surface waters in the eastern tropical Pacific Ocean, as a consequence of the presence of El Niño, causes meteorological hazards like floods, avalanches, landslides, among others, especially in the coastal area of the Peruvian mainland. A chronological long-term ground-based data analysis has allowed identification of major flooding events occurred in the last century along the Peruvian coast, specifically in the areas near to Lima (Capital of Peru), which is characterized by a Desert-Arid Sub-Tropical climate. Two main events occurred in 1997-1998 and 2017-2018, and were selected as focus of this study because they caused significant damage in the urban area. Satellite Synthetic Aperture Radar (SAR) data stacks were exploited in this study, as an alternative to optical imaging due to the main climatic characteristic of the study area, that for most of the day presents a dense cloud coverage preventing observation of ground features with visible imaging. Specifically, European Space Agency’s ERS-1/2 SAR Image Mode Single Look Complex (SLC) data were used for the event 1997-1998, and Copernicus Sentinel-1 Interferometric Wide (IW) swath mode Ground Range Detected (GRD) data for the event 2017-2018, and all of them were analyzed using a data processing workflow including radiometric calibration, precise co-registration, terrain correction and geocoding to map coordinates using the SNAP 6.0 software and Sentinel-1 toolbox (S1TBX). Among all the data available in the SAR catalogues, pre-, cross- and post-event ERS-1/2 and Sentinel-1 SAR data pairs were formed. Change detection products based on SAR amplitude, such as color composites and ratio maps, allowed the identification of flooded areas and other hazard-related landscape changes occurred in the study area. Through the use of satellite SAR data, that is the key to environmental monitoring, and with the help of ground-based information, it was possible to create flooding maps for the two events aforementioned. The flooding maps obtained via this methodology represent a great contribution for organizations in charge of land use planning and policy makers, as well as for the emergency managers, to better understand where a particular hazard event is most likely to occur, in order to have a clearer vision of the areas that were most affected by flood events in the past, and thus prevent damage in the future.

Area A - Board 154

Coastal zones are increasingly exposed to human exploitation and environmental forcing from sea level rise and more frequent storms caused by emergent climate change. Regardless of our actions now on climate change we are committed to adapting to sea level rise over the next hundreds, if not thousands of years. Coastal ecosystems and landforms, such as salt marshes, mudflats and sand bars, are critical parts of resilient coastlines, buffering environmental hazards of flooding and erosion, sequestering carbon, providing natural habitat for wildlife and exploited species, and providing recreational space and livelihoods for millions of people. Global policy instruments, national governments and NGOs steer coastal ecosystem management towards the Sustainable Development Goals, providing governance that conserves biodiversity and ecosystem functioning / services.
Approaches towards this type of management of the coastal zones range from holding the line with the construction of hard defences to managed realignment where previously reclaimed land is given back to the intertidal zone. A relatively new approach, the sand engine (or sand motor), has been part of an experiment in the management of dynamic coastlines in the Netherlands. A large sandbar-shaped ‘beach peninsula’ was artificially created covering about 1 km². As was expected, waves, wind and currents moved the sand over the years and realigned the coast, providing a range of societal and economic benefits. While beaches in this area had been artificially replenished every five years, the sand engine is expected to make replenishment unnecessary for the next 20 years. Over time this method is thus likely to be more cost effective than current practices and also helps nature by reducing the repeated disruption of sensitive habitats caused by replenishment.
As with any major environmental or infrastructure project it is vital that novel interventions, such as sand engines, are monitored over time to assess the impact of the management practice and understand its effectiveness at achieving the required outcomes. Sand engines are extensive enough to be easily mapped by Earth Observation (EO) data and the water, sand and vegetation combinations represent spectrally distinct targets. However, their highly dynamic nature requires spatially detailed daily monitoring to capture morphological and surface cover changes effectively.
Satellite EO is the only viable option to regularly acquire data over large areas.In the past, the paucity of EO data due to low spatial resolution, long time periods between revisits, cloud cover alongside the non-linear and complex behaviour of coastal processes, has made such an approach impossible. Fortunately, over the last four years we have entered what some are describing as the ‘golden era’ of EO where the increased observational capacity is providing sufficient EO data with spatial and temporal resolutions suitably aligned with coastal processes to make the deployment of operational monitoring services a realistic option.
Conventional space-based EO has become a success story, as evidenced by the European Copernicus programme, with systems such as Sentinel-2 acquiring optical super spectral 10 m data every 2 to 3 days in northern Europe. Even though Sentinel-2 is a very capable system, the monitoring of highly dynamic coastal features requires increased sampling frequencies and level of redundancy in the acquisitions to guarantee enough measurements for operational applications. Fortunately, EO is also currently undergoing further fundamental changes that epitomise the “New Space” paradigm, such as the operation of large constellations of small satellites by commercial companies that address specific requirement envelopes. In particular, Planet has a constellation of Doves which support their Planetscope products acquiring visible and near infrared 3 m spatial resolution data globally on a daily basis. In this environment new ideas are emerging around the use of publicly funded satellites, such as the Sentinels, to act as well-calibrated reference systems, thus allowing the commercial constellations to fill in the temporal and spatial gaps with more regular measurements.
In the case of monitoring large scale coastal adaptations, such as sand engines, even accounting for cloud cover it is likely that multiple images will be acquired of any site during a single spring-neap tidal cycle. Also, as satellite images are usually acquired at the same time each day, but the timing of high and low water changes, the acquired images will sample a range of different water depths.
The project outlined here is using a combination of PlanetScope and Sentinel-2 data, plus local tidal information, to provide quantitative information on the 3D geomorphology and habitats associated with the sand engines on a regular basis. Multiple images within a short monitoring period (e.g. 1 month) and at different water depths will be analysed using the water contour method to estimate the 3D structure of the intertidal surface covered by the sand engine. Differences in the 3D structure between monitoring periods will be used to show volume changes and the structural impacts of sediment movements. The Planetscope and Sentinel-2 data at the lowest water levels will be analysed to provide surface property (vegetation cover, sediment type) information and habitat maps.
It will be possible to provide information products multiple times per year to assess seasonal, interannual and episodic (caused by storm events) changes. From this information it should be possible to address many of the monitoring requirements of the coastal managers responsible for these features. This evidence would then be used to predict future changes and take additional action if needed. Also, this type of data yields visually appealing results that aid the promotion of such schemes in their area of operation and at potential future sites.
We will present result from an initial analysis of data for the Dutch sand engine, established in 2011, and further expand on this to cover the full development cycle for other sand engines, such as that planned for Norfolk, United Kingdom. As this coastal management approach is gaining interest globally, a service built on Sentinel-2 and Planetscope data could be deployed in any part of the world.

Area B - Board 158

Sea-level rise is an unavoidable consequence of climate change. Among the various components controlling sea-level changes, vertical motion trends of the coastal area play quite a significant role and their impact needs to be anticipated by coastal planners.
Subsidence phenomena can exacerbate the local consequences of sea-level rise in terms of hazard (flooding and erosion) and coastal vulnerability. At wider scales, ground surface deformation can affect the link between the global sea level evolution and its local expression measured by the tide gauges. Thus, the correction of in-situ measurements of sea-level change for vertical motion of the coastal zones is crucial to accurately reconstruct past-sea-level trends or even validate results of satellite altimetry.
Imaging geodetic techniques, such as SAR Interferometry (InSAR), have been proven an irreplaceable tool for measuring surface deformation, especially when lacking other ground-based geodetic networks (GNSS, DORIS etc.). Where such networks exists, the monitoring of spatio-temporal variability of vertical ground motion by InSAR consist a complementary source of information covering wide area at relatively low cost.
While the long SAR archive from ESA’s historical missions provided in several cases valuable insights on the behavior of coastal regions, the systematic acquisition planning of the Copernicus Sentinel-1 mission offers a unique opportunity to better constraint linear motion rates as well as to investigate in a more robust way temporal patterns of coastal deformation. The continues flow of data from Sentinel-1 contributed to the convergence of the performances of various processing techniques while meeting, in terms of precision, observations of sea-level rise.
In the current work we present the contemporary vertical motion trends along the coastal zones of Buenos Aires, illustrating apart from the utilization of this technology to sea-level change domain, the actual need to routinely consider ground deformation when assessing sea-level rise.

Area B - Board 159

In the current context of climate change, intensive water resource scarcity has been predicted. Consequently, improving groundwater monitoring and management has become a priority for human communities, especially in arid and semi-arid environments. Since 1992 SAR satellites have helped in the monitoring of land subsidence processes triggered by the exploitation of groundwater resources. In order to prevent major problems responsible authorities and water management agencies are beginning to increase their interest in methodologies involving surface deformation, especially in coupled methodologies involving surface deformation measurement and groundwater data. The Alto Guadalentín aquifer-system is located in the Spanish Mediterranean Arc, an area prone to severe drought periods aggravated in the last decades due to the impact of climate change. This detritic aquifer-system has been exploited intensively since 1960, generating a 150 m piezometric level drop until 2012 and one of the highest subsidence rates measured in Europe (around 12 cm/year). In a previous study, 20 years of historical SAR data (ERS, ENVISAT and Cosmo-SkyMed) were used to upgrade a new 52 years groundwater model. This model reproduces the evolution of the aquifer-system with an average error below 10% and calculates an empirical model connecting groundwater changes, soft soil thickness and ground surface deformation. New InSAR subsidence results using Sentinel-1 and Cosmo-SkyMed images have been used to improve an existing MODFLOW groundwater model of the basin and to calibrate the pumping pressure in the 2012-2016 period. The integration of remote sensing data in groundwater models allows to use them as a validation dataset but also as a modelling input when one of the boundary conditions lacks or is poorly defined, improving the aquifer management possibilities. These models are also useful to integrate future climatic series derived from the Intergovernmental Panel on Climate Change (IPCC) scenarios to predict the consequences of climate change and anticipate management plans to mitigate water scarcity and subsidence problems.

Area B - Board 160

In the present study, starting from existing literature, the relationship between climate change and mountain environment is investigated, with particular attention to skiing activities, in order to have sufficient knowledge of the state of the art of this topic. Spatial contextualization and analysis of the time series of temperature, precipitation and snow data specific for the focus area (area of Antagnod, Brusson, Champoluc, as well as Monterosa ski) has been performed using different datasets and techniques. Some of the main questions that this research aims to answer are which areas of Monterosa ski resort will be reliable in a context of climate change, and if ski-based tourism will still be sustainable for the valley in the future.
Therefore, remote sensing techniques to detect snow have been used. The methods are based on well-tested concepts (Normalised Difference Snow Index; additional criteria in order to detect snow in shadowed areas), but the spatial and temporal resolution of snow maps is nevertheless highly innovative: the implementation of the Sentinel-2 mission (global coverage with resolution up to 10 m every 5 days) allowes to obtain new perspectives for snow cover monitoring.
Thanks to the elaboration of selected satellite images (two images per month, because of the frequency in winter clouds cover above this area), it has been determined the snow cover extension from 2015 winter season until now. Then, a comparison between monthly snow cover extension on Monterosa ski area and number of ski tickets sold has been conducted. Furthermore, from existing scientific analysis, the altitude of the natural snow-reliability line has been related to future temperature and precipitation scenarios at local scale.
Finally, a possible link between the line of natural snow-reliability and sensitivity of Monterosa ski resort has been investigated in relation to the altitude.
The joint investigation of snow cover evolution with economic-tourist analysis is essential to evaluate best strategies for adapting to climate change’s impacts. With regard to temperature increase, Monterosa Ski area, thanks to the high altitudinal range of its slopes, is less sensitive than other European resorts. Nevertheless, adaptation measures that take into account not only changes in temperature and availability of water resources, but also consequences in the variation of precipitation and increase of intense meteorological phenomena are necessary.

Area B - Board 161

Extreme meteorological events are already affecting the Alpine regions, recording changing seasonal climatic parameters, such as in temperature or rain and snow precipitation amount. In the region of South Tyrol, temperatures are increasing and total snow amount is generally decreasing over time with snow line observed in higher elevation. Changing rainfall trends are also observed recording more precipitation in summer season. Natural hazards affecting this area, damaging population and infrastructures every year, are either water or cryosphere-related. These mountainous hazards are mainly debris and mud flows, landslides, avalanches, rock falls, and (flash) floods. While some natural hazard events have been recorded since the beginning of the 20th century, the completeness of the punctual hazards inventory, mainly recorded by the Civil Protection and the Geological Survey of the Autonomous province of Bolzano, is supposed since 1995. So far, Earth observation and remote sensing data has been barely exploited to complete this existing inventory and investigate the influence of climate perturbation on potentially dangerous natural phenomena.
The research aims to (i) collect and analyse long time series of data related to climate variations and hazard occurrence in South Tyrol, (ii) measure the spatiotemporal evolution of climatic and damaging events recorded, and (iii) explore potential relations between meteorological conditions and the hazard occurrence. In this context, in-situ and satellite-based climate data will be exploited to study some hazard triggers. The potential of remote sensing data (when available and relevant) will be also evaluated for hazard detection and monitoring changes in magnitude. Synthetic Aperture Radar techniques, provided by the ESA Geohazards Exploitation Platform (GEP), will allow for a spatiotemporal monitoring of natural hazard hotspots. Spatiotemporal behaviour of slow Earth surface deformations will be detected using the Copernicus Sentinel-1 images for checking and completing the actual landslide inventory. Whilst their limitation will be cautiously established, other radar and optical satellite sensors (such as the European remote sensing satellite, ERS) will be also used to measure changing slope dynamics in the past. Hazard-related changes in the South Tyrolian landscape will be analysed in relation to particular meteorological events at a regional and a local scale in order to detect the various actual and past trends. The outcomes will be of benefit for possible early-warning systems and further multi-hazard assessment for disaster risk reduction in the area.

Area B - Board 162

Carbon monitoring in regional and global scales is of significant importance for the comprehension of the global carbon cycle. About 45% of the terrestrial carbon is stored into forest biomass; therefore, the development of methodologies and models for the monitoring and the quantification of Above Ground Biomass (AGB) in different types of forest ecosystems arises as a key mechanism for carbon monitoring. Satellite remote sensing techniques constitute a powerful and promising source of information, providing global data with spatial and temporal continuity. In order to proceed to the modeling and mapping of AGB, with the use of satellite remote sensing techniques, the relationship between AGB and satellite derived parameters has to be investigated. The relationship between the backscatter coefficient of the radar signal (σ⁰) and the AGB has been proven to be effective for carbon modeling, for several vegetation cover types. In this study, a preliminary approach is being attempted on the relationship between the backscatter coefficient of a C-band SAR sensor and the AGB that was estimated from in situ data, collected in four Mediterranean conifer forest sites, of Abies cephalonica Loudon, at different locations in Greece. For the purposes of the study, in-situ data of forest structural parameters (diameter at breast height and tree height) were collected in the field and were then used in allometric equations, for the estimation of AGB. Sentinel – 1 GRD products were processed for the retrieval of the SAR backscatter coefficient values. Two empirical models were then applied, for the investigation of the relationship between the in-situ measured AGB and the C – band SAR backscatter coefficient. First results demonstrate the existence of a moderate relationship between the VH polarized SAR backscatter coefficient, of the ascending pass of the satellite and the AGB, while no significant relationship is found between either the VV polarized SAR backscatter coefficient of both passes, or the VH polarized SAR backscatter coefficient of the descending pass and the AGB.

Area B - Board 163