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2021 Report Open Access OPEN

SI-Lab Annual Research Report 2020
Leone G. R., Righi M., Carboni A., Caudai C., Colantonio S., Kuruoglu E. E., Leporini B., Magrini M., Paradisi P., Pascali M. A., Pieri G., Reggiannini M., Salerno E., Scozzari A., Tonazzini A., Fusco G., Galesi G., Martinelli M., Pardini F., Tampucci M., Buongiorno R., Bruno A., Germanese D., Matarese F., Coscetti S., Coltelli P., Jalil B., Benassi A., Bertini G., Salvetti O., Moroni D.
The Signal & Images Laboratory (http://si.isti.cnr.it/) is an interdisciplinary research group in computer vision, signal analysis, smart vision systems and multimedia data understanding. It is part of the Institute for Information Science and Technologies of the National Research Council of Italy. This report accounts for the research activities of the Signal and Images Laboratory of the Institute of Information Science and Technologies during the year 2020.Source: ISTI Technical Report, ISTI-2021-TR/009, pp.1–38, 2021
DOI: 10.32079/isti-tr-2021/009

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2020 Contribution to conference Restricted

Estimating Relative and Absolute Sea Level Rise and Vertical Land Movement Rates in the Adriatic Sea with in situ observations and the ESA SL_CCI altimetry dataset
De Biasio F., Vignudelli S., Scozzari A., Papa A., Zecchetto S., Baldin G.
Considerable efforts are made by space agencies and scientists to develop consistent and long-term satellitebased datasets: the European Space Agency (ESA) Climate Change Initiative (CCI) initiative Sea Level Project (SLCCI) is being producing climate-oriented altimeter sea level products optimized for the coastal zone, a monthly-mean gridded product covering the global ocean at 0.25x0.25 degrees (1993-2015). Based on this heritage, the operational production of climateoriented altimeter sea level products has been taken over by the European Copernicus Climate Change Service (C3S) with a daily-mean product gridded at 0.125x0.125 degrees covering the global ocean 1993-present. In parallel, refined products are expected in the second phase of the SLCCI project. We made a comparison of the SLCCI satellite altimetry dataset with sea level time series at selected tide gauges in the Mediterranean Sea, focusing on Venice and Trieste. There the coast is densely covered by civil settlements and industrial areas with a strongly rooted seaside tourism, and tides and storm-related surges reach higher levels than in most of the Mediterranean Sea, causing damages and casualties as in the recent storm of November 12th, 2019: the second higher water registered in Venice since 1872. Moreover, in the Venice area the ground displacements exhibit clear negative trends which deepen the effects of the absolute sea level rise. Several authors have pointed out the synergy between satellite altimetry and tide gauges to corroborate evidences of ground displacements. Here we exploit the long satellite-altimetry dataset duration and the high quality of sea-level time series at selected tide gauges of the Mediterranean Sea, to estimate the ground displacement rates. While in Venice, in the period 1993-2015, a relative sea level rise trend of about +6.17±1.51 mm y-1 has been determined from tide gauge at Acqua Alta Platform, 14 km offshore, in Trieste the tide gauge registered a trend of +4.10±1.38 mm y-1. Similarly, the altimetry product reports at the closest grid points absolute sea level rise rates of +4.02±1.27 mm y-1 (Venice) and +1.15±1.35 mm y-1 (Trieste). The estimated vertical land displacement rates, following the direct approach [Cazenave et al. 2009], resulted -1.79±0.72 mm y-1 (Venice), and -2.95±0.75 mm y-1 (Trieste). The estimated fitting slopes [Vignudelli et al., 2019] are the object of our investigation using the generalized least mean square procedure with constraints [Menke, 1989]. A partial validation of the resulting estimates has been made against Global Positioning System-derived (GPS) time series at selected stations. This work will contribute to identify problems and challenges to extend the sea level climate record to the coastal zone with quality comparable to open ocean, and also to assess the suitability of altimeter-derived absolute sea levels as a tool to estimate subsidence where permanent GPS receivers are not available. The Northern Adriatic is a laboratory to assess this tool, in particular considering the prospect of coming refined global products that are being generated within the ESA SLCCI extension (CCI+) project.Source: ESA Coastal Altimetry Workshop, ESA-ESRIN, Frascati, 4/2/2020-7/2/2020

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2020 Contribution to conference Open Access OPEN

Inland radar altimetry for intermediate scale water bodies with nadir specular echoes and a constellation of small satellites
Abileah R., Vignudelli S., Scozzari A.
We previously reported (COASTALT Workshop 8, Lake Konstanz, 2017; 25-years..., Ponta Delgada, 2018) on the prevalence of quasi-specular echoes from intermediate scale (50m to 250 m) inland water bodies. Specularity is a boon and bane for Inland radar altimetry. The boon is that specular echoes allow very precise range measurements with coherent 'zero-Doppler' summing of a few individual echoes (IEs). (Accuracy of <1 cm was shown with Envisat IEs.) Also, land interference is virtually eliminated. The bane is that such water echoes can only be detected when the satellite nadir is directly over the water surface. The echoes SNR fall perceptibly squinting off nadir. The implication is that with current large spacecraft altimeters only a very small fraction of water bodies are encountered. Also, water level slope (discharge) cannot be measured. Radar altimetry cannot fulfill the hydrologists' data requirements. Inland altimetry requires a paradigm shift away from large spacecraft. A wide range of Earth observations and other LEO uses are already migrating to swarms of small satellites (ESA APIES, NASA RainCube , and SpaceX Starlink). The same idea is appropriate for inland altimetry where specular echoes reduce the required radar power 20-40 dB and so much smaller satellites can be used. A constellation of 1000 can provide 100% geographical coverage, water levels and discharge, at 10-day repeat cycles. We used several Sentinel 3A/B data sets to evaluate water level measurements with specular echoes and extrapolate to smaller satellites. First set is of the Arno River which is 100 m wide, just wide enough to have one full S3 burst over water. Water levels over three years (45 revisits) are compared with river gauges maintained by Centre for Meteorological and Hydrological Monitoring, Tuscany Region, Italy. A second data set is multiple passes over Salar de Uyuni compared with surface topography measured by Borsa et al 2008. And a third data set of passes over 800 m wide Silsersee Lake (Switzerland) were there is no ground truth but multiple bursts provide inter-data accuracy and further insight on application to larger water bodies. We degrade SNR on these data sets to extrapolate performance with small sat radars. Details on the algorithms used in this analysis will be provided and illustrated in a companion poster presentation.Source: ESA Coastal Altimetry Workshop, pp. 24–25, ESA-ESRIN, Frascati, 4/2/2020-7/2/2020

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2020 Contribution to conference Open Access OPEN

The algorithm for processing specular echoes
Abileah R., Vignudelli S., Scozzari A.
The poster will be a companion to the Inland radar altimetry for intermediate scale water bodies paper to provide extra time and setting to explain the processing ('retracking') specular echoes. The processing flow will be described and illustrated step-by-step in the poster and with live in-the-cloud processing. [For live demo we'll need Wifi and a small stand for a laptop.] The processing is little changed since the 2017 paper. Steps in processing IEs into range measurements are (1A) a water map from EO images (such as Google Earth) , (1B) identify a string of consecutive echoes over water. (2) Verifying that there is actually water with Doppler (expected to be zero), echo power (exceeding a threshold), and coherence (~1). (3) Verifying surface roughness below threshold. (4) Coherently sum IEs into a waveform profile. (5) A parametric fit to two or three range gates to derive sub-gate range accuracy. For the intermediate water bodies (50-250 m) processing is based on one or two S3 bursts. There are special considerations for very narrow (<50 m), and wide (>250 m) rivers or lakes. For <50 there is a fair chance the water body will fall in the gaps between S3 bursts so there are no nadir water IEs. The algorithm can be nudged a bit to handle those cases. For >250 there will be several bursts to combine optimally and some probability that the water surface will have variable roughness scales.Source: ESA Coastal Altimetry Workshop, pp. 26–26, ESA-ESRIN, Frascati, 4/2/2020-7/2/2020

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2020 Conference article Open Access OPEN

Lake water level estimated by a purely radiometric measurement: An experiment with the SLSTR radiometer onboard Sentinel-3 satellites
Scozzari A., Vignudelli S., Negm A.
This work describes a preliminary study on the possible usage of the imaging radiometer SLSTR (Sea and Land Surface Temperature Radiometer) onboard the Sentinel-3 satellites for estimating quantitative parameters (extent and/or level) of inland water bodies. Various works in the literature propose a combination of optical imagery and radar altimetry to estimate water storage variations in inland water targets. This work wants to exploit the simultaneous acquisition offered by SRAL (Synthetic aperture Radar ALtimeter) and SLSTR instruments hosted by the Sentinel-3A/B platform. We present a practical case study, demonstrating how a strongly reduced subset of radiometric measurements can be enough representative of the status of the natural system under observation. In our approach, a subset of the collected radiance maps is extracted, based on the selection of the most variable pixels. Thus, a time series of average spectral radiances is built upon the reduced set of SLSTR data, and compared with satellite radar altimetry measurements. Preliminary results show a promising relationship between the timeseries generated by the two independent instruments, in terms of both general trend and seasonal dependence. Finally, by using the approximation proposed in this paper, a very light computational process can infer an estimation of water storage, when the natural system is fully identified on the basis of ground-truth data.Source: 2020 IEEE International Instrumentation and Measurement Technology Conference, pp. 1–6, 25-29/5/2020
DOI: 10.1109/i2mtc43012.2020.9128711

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2020 Contribution to conference Open Access OPEN

Synergy between optical imaging radiometry and radar altimetry for inland waters: an experience with Sentinel-3 on the Nasser Lake
Scozzari A., Vignudelli S., Elsahabi M., Galal N., Khairy M., Negm A.
It is currently well known that a combination of stressors, such as climate change, human activities and new infrastructures might influence the storage capacity of strategic surface water reservoirs at a global level. The Nasser Lake is the biggest and most important lake in Egypt, located in the southern part of the Nile River in Upper Egypt. The expected impact of the Grand Ethiopian Renaissance Dam (GERD) on the future availability of the Nile water, together with the significant and rapid water level variations and sedimentation processes, make the Nasser Lake a particularly challenging place to be monitored in the next years. This work describes a preliminary study on the possible usage of the imaging radiometer SLSTR (Sea and Land Surface Temperature Radiometer) onboard Sentinel-3 for estimating water coverage extent in inland water contexts, in synergy with radar altimetry measurements provided by the SRAL (Synthetic aperture Radar ALtimeter) instrument. In particular, this work wants to exploit the simultaneous acquisition offered by SRAL and SLSTR instruments hosted by the Sentinel-3A/B platform. We introduce an alternative technique to the classical calculation of the whole water extent based on high-resolution imagery, essentially intended for the application to wide-swath short-revisit sensors. The proposed approach starts from the hypothesis that a much-reduced subset of pixels may carry enough information for assessing the status of the observed water body by estimating the water coverage percent within each single pixel. Such an assumption can rely only on the radiometric performance of the instrument, SLSTR in this case. The timeseries of water levels by the SRAL instrument were obtained by using the 20 Hz product generated by the SARvatore processor run on the ESA GPOD (Grid Processing On Demand) platform. A timeseries derived from SLSTR measurements has been generated by a simple feature extraction technique, based on the selection of pixels exhibiting the highest variability of the collected radiance. As expected, this subset essentially identifies particular spots on the coastlines of the target, as a consequence of its morphological characteristics. Preliminary results show a promising relationship between the timeseries generated by the two independent measurements and between the available in situ data as well. Under the hypothesis of a time-invariant system (i.e., characterised by no significant morphological changes), once an area-level-volume relationship is identified, volume estimations can be inferred by either altimetric or radiometric measurements per se. Thus, the simultaneous observation by the two instruments represents a relevant opportunity for cross-validating the acquired data. Moreover, the approximation experimented in this work gives the perspective of a very light computational process for expedite water storage estimations in large surface reservoirs, provided that the natural system is fully identified on the basis of groundtruth data.Source: EGU General Assembly 2020, 4-8/5/2020
DOI: 10.5194/egusphere-egu2020-18804

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2020 Contribution to book Open Access OPEN

ICT for Smart Water Systems: Measurements and Data Science
Scozzari A., Mounce S., Han D., Soldovieri F., Solomatine D.
Today, Information and Communication Technologies (ICT) have a pervasive presence in almost every aspect of the management of water. There is no question that the collection of big data from sensing and the insights gained by smart analytics can bring massive benefits. This book focuses on new perspectives for the monitoring, assessment and control of water systems, based on tools and concepts originating from the ICT sector. It presents a portrait of up-to-date sensing techniques for water, and introduces concepts and implications with the analysis of the acquired data. Particular attention is given to the advancements in developing novel devices and data processing approaches. The chapters guide the reader through multiple disciplinary contexts, without aiming to be exhaustive, but with the effort to present relevant topics in such a highly multi-disciplinary framework. This book will be of interest to advanced students, researchers and stakeholders at various levels.DOI: 10.1007/978-3-030-61973-2

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2019 Conference article Open Access OPEN

Sea level trends and variability in the Adriatic Sea and around Venice
Vignudelli S., De Biasio F., Scozzari A., Zecchetto S., Papa A.
A preliminary analysis of sea level (SL) changes around Venice from three tide gauges (TGs) (one off-shore: AAPTF, one at the coast: DSL, and one inside the lagoon: PS) to characterize the variability during 1993-2015 and relative SL trends, is provided. As no global positioning system (GPS) data covering the same period was available to the authors for the three tide gauges, the analysis is restricted to changes relative to the land. Monthly SL means from the European Space Agency (ESA) Sea Level Climate Change Initiative (CCI) altimeter-derived product are also used. A comparison between the monthly mean time series of CCI and AAPTF has been performed using the nearest CCI grid point to the location of AAPTF: the centered Root Mean Square Difference (cRMSD: the root mean square difference of the two series with the respective means removed) resulted 6.33 cm, while the Pearson's linear correlation reached 0.75. Much higher agreement was found, as expected, between the monthly mean records of AAPTF and PS TGs: the cRMSD was 1.03 cm, and the linear correlation 0.99. We obtained 6.65 mm year1 at AAPTF over the Satellite Altimetry (SA) era (1993-2015). A smaller trend has been found here from altimetry (4.25 mm year1). The differences might be explained in terms of Vertical Land Motion (VLM) which was not accounted for in the TGs time series, to the different processing of TGs and altimeter data (in the altimeter signal the Dynamic Atmospheric Correction is removed), and/or uncertainties in this area due to the current CCI product that is based on open ocean altimetry. In general, the altimetry trends derived from CCI are spatially higher in the Adriatic Sea than Global Mean Sea Level (GMSL) in most of the region, with greater values than average in Venice. Reprocessing of along-track altimeter data sets with consistent coastal processing for all missions is expected to enhance SL accuracy and with a better refining of raw trends. The SA era is too short to delineate or discuss an affordable climatology, as decadal SL variations cannot be accounted for by such a short time series, nonetheless the rates calculated in this study are fruitfully compared each other and with those derived by SA.Source: FRM4ALT International Cal/Val Review 2018, pp. 1–10, 22-26 April 2018
DOI: 10.1007/1345_2018_51

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2019 Journal article Open Access OPEN

Effects of climate change on the design of subsurface drainage systems in coastal aquifers in arid/semi-arid regions: case study of the Nile delta
Abd-elaty I., Sallam G. A. H., Straface S., Scozzari A.
The influence of climate change on the availability and quality of both surface- and ground-water resources is well recognized nowadays. In particular, the mitigation of saline water intrusion mechanisms in coastal aquifers is a recurrent environmental issue. In the case of the Nile delta, the presence of sea level rise and the perspective of other human-induced stressors, such as the next operation of the Grand Ethiopian Renaissance Dam, are threats to be taken into account for guaranteeing resilient agricultural practices within the future possible scenarios. Subsurface drainage offers a practical solution to the problem of upward artesian water movement and the simultaneous downward flow of excess irrigation water, to mitigate the salinization in the root zone. Subsurface draining systems can contribute to mitigate the vulnerability to climate change and to the increased anthropic pressure insofar they are able to receive the incremented flow rate due to the foreseen scenarios of sea level rise, recharge and subsidence. This paper introduces a rational design of subsurface drainage systems in coastal aquifers, taking into account the increment of flow in the draining pipes due to future possible conditions of sea level rise, artificial recharge and subsidence within time horizons that are compatible with the expected lifespan of a buried drainage system. The approach proposed in this paper is characterized by the assessment of the incremental flow through the drains as a function of various possible scenarios at different time horizons. Our calculations show that the impact on the discharge into the existing subsurface drainage system under the new foreseen conditions is anything but negligible. Thus, future climate-related scenarios deeply impact the design of such hydraulic structures, and must be taken into account in the frame of the next water management strategies for safeguarding agricultural activities in the Nile delta and in similar coastal contexts.Source: Science of the total environment 672 (2019): 283–295. doi:10.1016/j.scitotenv.2019.03.483
DOI: 10.1016/j.scitotenv.2019.03.483

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2019 Contribution to book Restricted

Water surface elevation in coastal and inland waters using satellite radar altimetry
Vignudelli S., Scozzari A., Abileah R., Gómez-enri J., Benveniste J., Cipollini P.
Changes in water surface elevation are traditionally measured in situ by single instruments at a fixed point, yielding a measurement relative to the land where the instrument is installed. Values are generally taken with frequent sampling (order of minutes or less). Such an instrument is called a tide gauge in the ocean environment and more generically a water gauge in lakes and reservoirs. In rivers, the instrument is usually called a stream gauge, because the water surface elevation is then used to derive discharges. Several types of installations are currently in use in hydrometric practice (Vuglinskiy et al., 2009; WMO, 2010), depending on the kind of water target. Many databases around the world collect and make available water surface elevations. Concerning extreme events, there is a clear requirement for high-frequency (ie, sampling at subhour intervals) information. The GESLA-2 (Global Extreme Sea Level Analysis version 2) database is an updated data set of high-frequency water surface elevations obtained from tide gauges operated by many agencies around the world (Woodworth et al., 2016). Fig. 4.1 shows the geographical distribution of the 1355 stations presently available in GESLA-2.Source: , pp. 87–127, 2019
DOI: 10.1016/b978-0-12-814899-0.00004-3

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2019 Contribution to conference Open Access OPEN

How meteorological and flow timeseries contribute to a modelling exercise: an experience on a carbonate aquifer in Tuscany (Italy)
Vivaldo G., Doveri M., Menichini M., Provenzale A., Scozzari A., Fibbi L., Grifoni D.
The monitoring of a natural resource typically involves the identification of a set of parameters, considered as representative of its underlining mechanisms, in order to extract useful information about the current status and the expected behavior of the natural process. This work is focused on the water resources destined to the drinkable water distribution, by studying possible empirical relationships between meteorological parameters and groundwater quantity indices. This activity is in the wider context of a research for the development of support tools for the management of the resource under specific climate scenarios. For what regards carbonate aquifers, the impact of climate change can be very significant, given the high sensitivity of these reservoirs caused by their karst features. Data used for this study included flowrate at springs of the karst aquifer system of the Apuan Alps (northwestern Tuscany), and meteorological timeseries (both historical and synthetic scenarios) in the relevant hydrological basin. Flowrate measurements were provided by the Tuscan Water Authority (AIT) and GAIA SpA (Integrated Water Service), while synthetic meteorological scenarios were provided by Consorzio LaMMA. This work describes the data-driven approach experimented with the collected time series, essentially based on multi-variate analysis techniques and on a simplified machine learning scheme based on neural networks. In fact, a preliminary test of a data-driven approach based on Multi Layer Perceptron Neural Networks (MLP-NN) is described here. Dedicated techniques for data pre-processing, training and validation have been experimented. In particular, a strong hypothesis of linearity and time-invariance of the system under observation was done, and MLP-NNs were essentially used as non-linear approximators. A further activity regarded the assessment of a performance metric for the evaluation of multiple MLP-NNs with respect to independent test sets, based on either historical or synthetic data. Results are shown in terms of predicted flowrates in a given time window (up to 90 days in our case study), and are organized according to different scenarios of total rainfall quantity.Source: EGU General Assembly 2019, Vienna, 7-12/04/2019

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2019 Contribution to conference Open Access OPEN

Saline intrusion in coastal aquifers: Influence of climate change on the design of subsurface drainage systems in arid/semi-arid regions
Scozzari A., Abd-elaty I., Sallam G., Straface S.
There's a growing awareness today about the effect of climate change on the availability and quality of surfaced ground-water resources. In particular, the mitigation of saline water intrusion mechanisms (SWI) in coastal aquifers is currently a recurrent environmental issue. According to the Intergovernmental Panel on Climate Change (IPCC) (2013), in year 2100 about 95% of the coastal areas in the world will be considerably affected by sea level rise (SLR), hence increasing the risk of inundation in internal land and salt water intrusion (SWI) in coastal aquifers. In the case of the Nile delta, the combination between SLR and other perspective human-induced stressors, such as the next operation of the GERD (Grand Ethiopian Renaissance Dam), represents a threat to be taken into account, in order to guarantee resilient agricultural practices to the next possible scenarios. Subsurface draining systems (SD) can contribute to mitigate the vulnerability to climate change and to the increased anthropic pressure insofar they are capable to receive the incremented flow according to the foreseen scenarios of SLR, subsidence and recharge. In general, subsurface drainage offers a practical solution to the problem of upward artesian water movement and the simultaneous downward flow of excess irrigation water, for mitigating the salinization of the soil in the root zone. Thus, the design objective of the drains is to keep the water table within specified limits, determining a flow of water through the soil to the drains. The drain size and spacing need to be properly calculated to make the drainage system able to discharge the excess of irrigation water as well as the upward groundwater flow. In practice, subsurface drains must be designed to withstand the necessary water flow, which permits to tie the water table to the required depth, for any foreseen working condition that may happen within the lifetime of the hydraulic structure. This work introduces a rational design of SD systems in coastal aquifers, taking into account the increment of flow due to future possible conditions of SLR, recharge and subsidence within a time horizon of about 50 years, which is compatible with the expected lifespan of a buried drainage system. Our proposed approach is characterised by the assessment of the incremental flow through the drains as a function of various possible future scenarios at different times. Our calculations show that the impact of the new foreseen conditions on the discharge into the subsurface drainage system is anything but negligible. Thus, foreseen climate-related scenarios deeply impact the design of such hydraulic structures. This is a fundamental aspect that needs consideration in the frame of the future water management strategies for safeguarding agricultural activities, especially in arid/semi-arid regions. Finally, it must be noted that this necessity has been substantially underestimated until today.Source: EGU General Assembly 2019, Vienna, 7-12/04/2019

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2019 Contribution to conference Open Access OPEN

The Sea Level Rise in the Gulf of Venice observed by Satellite Altimetry and In Situ Observations in the ESA SL_CCI project
De Biasio F., Zecchetto S., Scozzari A., Papa A., Baldin G., Vignudelli S.
Tracking the variability of Sea level rise is an essential step for the safeguard of coastal settlements. In Europe, one of the most important is the city of Venice, threaten by the combined effects of subsidence and eustatism, either antropogenic and natural, which gradually have increased the vulnerability of the historical city to the action of storm surges. Even if the MOSE barrier was designed to defend Venice against such devastating phenomenon, the gradually rising sea levels has long term implications that have not been sufficiently investigated yet. Moreover, the contributions from the various mechanisms responsible of the relative sea level rise have been not clearly isolated and quantified. The European Space Agency (ESA) Climate Change Initiative (CCI) project on "Sea Level" has supplied a revised set of satellite-based sea level products (e.g., monthly mean sea levels and trends) by reprocessing altimeter data over 1993-2015. This study aims to assess the quality of the Sea Level CCI products in the Gulf of Venice, northern Adriatic Sea, comparing them with in-situ measurements of sea level taken by the historical tide gauges of Venezia (Punta della Salute, CNR Acqua Alta Platform) and Trieste (Molo Sartorio). We try also to isolate the contribution of the atmospheric pressure and the subsidence in the relative sea level rise budget. While in Venice, in the period 1993-2015, a relative sea level rise trend of about +6:4 2:1 mm/yr has been determined from in situ data, in Trieste the local tide gauge registered a trend of about +4:5 2:0 mm/yr. At the closest CCI grid points, the SL CCI time series show similar trend: +4:0 1:3 mm/yr in Venice and +3:4 1:2 mm/yr in Trieste. The differences between the in-situ and the altimetry product fitting slope is partly ascribable to vertical land movements and to inverted barometer effect. After removal of the isostatic part of the inverted barometer effect, determined by using time series of atmospheric pressure from in situ measurements and reanalysis products, the fitting slope of the in situ sea level in Venice and Trieste is marginally lowered (+6:2 1:5 mm/yr and +4:21:4 mm/yr respectively), but an effective result is that also the slope standard deviation is reduced. These findings will permit to estimate the importance of vertical land movements and better estimate local processes that might impact on the local sea level rise. During the CCI+ phase (2018-2019) particular efforts will be dedicated to the retrieval of sea level from altimeters in the coastal zone. This work will contribute to identify problems and challenges to extend the sea level climate record to the coastal zone with quality comparable to the open ocean.Source: EGU General Assembly 2019, Vienna, 7-12/04/2019

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2018 Conference article Open Access OPEN

On-line measuring sensors for smart water network monitoring
Di Nardo A. (, ), Baquero Gonzalez D., Baur T., Bernini R., Bodini S., Capasso S., Cascetta F., Castaldo F., Cocco M., Cousin P., D'Acunto M., Di Leo R., Della Ventura B., Di Mauro A. (, Di Natale M., Di Virgilio G., Doveri M., El Mansouri B., Germano R., Giudicianni C., Giunta N., Greco R., Iovino P., Katsou E., Koenig R., Laspidou C. S., Lisbino V., Lupi L., Martínez Díaz E., Musmarra D. (, Montse Mussons O., Paleari O., Raich J., Regan F., Rodriguez-pinzon M. J., Rodriguez-varela J. M., Sanfilippo L., Seelam J. S., Santonastaso G. F. (, Savic D., Scozzari A., Soldovieri F., Tuccinardi F. P., Tzatchkov V. G., Vamvakeridou-lyroudia L. S., Van Rijn M., Velotta R., Venticinque S., Wouters J. W.
Smart cities are getting essential to drive economic growth, increase social prospects and improve high-quality lifestyle for citizens. To meet the goal of smart cities, Information and Communications Technology (ICT) have a key role. The application of smart solutions will allow the cities to use ICT and big data to improve infrastructure and services (i.e. network efficiency, protection from contamination, etc.). In the water sector, the integration of smart meters and sensors coupled with cloud computing and the paradigm of "divide and conquer" introduces a novel and smart management of the water network allowing an efficient online monitoring and transforming the traditional water networks into modern Smart WAter Networks (SWAN). The Ctrl+SWAN (Cloud Technologies & ReaL time monitoring+Smart WAter Network) Action Group (AG) was created within the European Innovation Partnership on Water, in order to promote innovation in the water sector by advancing existing smart solutions. The paper presents an update of a previous work on the state of the art on the best On-line Measuring Sensors (OMS) already available on the market and innovative technologies in the Research and Development (R&D) phases.Source: HIC 2018 - 13th International Conference on Hydroinformatics, pp. 572–581, Palermo, Italy, 1-5 July 2018
DOI: 10.29007/4fcr

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2018 Contribution to conference Open Access OPEN

The role of groundwater modelling for the sustainable management of water resources in a context of climatic change: an experience on a carbonate aquifer in Tuscany (Italy)
Scozzari A., Doveri M., Masetti G., Menichini M., Provenzale A., Raco B., Vivaldo G.
In a growing number of countries, safeguarding drinking water supplies is strictly linked with the sustainable usage of groundwater resources. In the European Union, about 70% of the water destined to the supply network is groundwater, and almost 75% of this source comes from carbonate aquifers. Although groundwater systems can be considered as more resilient to climate change than surface waters, climate change affects them both directly and indirectly. For carbonate aquifers the impact can be very significant, given the high sensitivity of these reservoirs.caused by their karst features. The analysis of hydro-meteorological data over a few decades highlights that also Italy is experiencing a change in the climate regime, with impacts on groundwater yield that are not yet well understood. In this work, we discuss the results of the analysis of data provided by the Tuscan Water Authority (AIT) and GAIA SpA (Integrated Water Service). Data refer to flowrate at springs of the karst aquifer system of the Apuan Alps (northwestern Tuscany). Flowrates trend indicates a slight decline of groundwater yields in this system over the last two decades. A tendency to consume more recharge water through sudden and short flow rate peaks seems also to occur, as a consequence of the increased occurrence of storm events. Data were elaborated in order to study possible empirical relationships between meteorological parameters and groundwater quantity indices, in the wider framework of a research for the development of support tools for the management of the resource under specific climate scenarios. In particular, this work describes the different data-driven approaches experimented with the collected time series, essentially based on multi-variate analysis techniques and on a simplified machine learning scheme based on neural networks. The collected time series were first analyzed by classical statistical and advanced spectral analysis techniques, in order to extract the embedded significant periodicities and trends. Forecasting was thus applied on clean signals only, to reduce the background noise propagation; both empirical models applied to the whole cleaned dataset, and single components projection methodologies were taken into account.Source: EGU General Assembly 2018, Vienna, Austria, 8-13 April 2018

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2018 Contribution to conference Open Access OPEN

Smart water network monitoring using innovative on-line sensors
Di Nardo A. (, ), Di Mauro A. (, Bernini R., Sanfilippo L., Paleari O., Savic D., Santonastaso G. F., Cocco M., Cousin P, Wouters H., Rodriguez-pinzon M., Velotta R., Laspidou C., Doveri M., El Mansouri B., Martínez Díaz E., Rodriguez-varela J. M., Greco R., Scozzari A., Katsou E.
The recent development and dissemination of Information and Communications Technology (ICT) has a key role to drive cities to be smarter. The economic growth needs of cities that become smarter, sustainable, more efficient and liveable. Smart water represents a key core of the smart cities and the application of smart solutions will allow the cities to use ICT and big data to improve infrastructure and services (i.e. network efficiency, protection from contamination, etc.). In the water sector, the integration and implementation of novel technologies for water systems monitoring (drinking, distribution, sea, river water, etc.) as smart meters and sensors together with cloud computing systems introduce an innovative management that transform the traditional water networks into modern Smart WAter Networks (SWAN). The introduction of innovative on-line sensors in the water system can contribute to monitor and control many water quantitative (e.g. flow, pressure, etc.) and quality (e.g. residual chlorine, PH, organic matter, etc.) parameters providing smart water management solutions contributing to prompt Smart Water Network as subsystem of the Smart City, recently recognized by the scientific and technical international community. In fact, the use of innovative on-line sensors allows to overcome the traditional management of water networks and to handle important issues such as reduction of water losses, analysis of big data, improvement of water quality, etc. The Ctrl+SWAN (Cloud Technologies & ReaL time monitoring+Smart WAter Network) Action Group (AG) was created within the European Innovation Partnership on Water, in order to promote innovation in the water sector by advancing existing solutions. The vision of the AG consists of treating water network not as a traditional system with devices trivially added, but as a SWAN featuring new applications to promote optimal management and protection. The paper presents an update of a previous work on the state of the art on the best On-line Measuring Sensors (OMS) already available on the market and innovative technologies in the Research and Development (R&D) phases. Ctrl+SWAN membership bring up to date the list of parameters measured with innovative on-line sensors, the new sensor technologies and their innovative applications.Source: EGU General Assembly 2018, Vienna, Austria, 8-13 April 2018

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2018 Contribution to conference Open Access OPEN

On the use of sentinel-3A SRAL altimeter waveforms at the finest posting rate (80 Hz) for the detection of ships
Gómez-enri J., Mulero R., Vignudelli S., Scozzari A.
The detection of non-ocean scatterers over the sea surface by using pulse-limited satellite altimeters involves a series of challenging targets, such as icebergs, lighthouses and ships, which have been investigated in the literature. In particular, past works focused on the hyperbolic features observed in the thermal noise area of the received waveforms, in order to detect the presence of such non-ocean targets. Following previous analysis made with CryoSat-2 data, in this work we exploit the capabilities of Sentinel-3A SRAL delay- Doppler instrument for the detection and characterisation of ships. In particular, we analyse the shape of the waveforms at two along-track sampling rates: 20 Hz - 80 Hz, in order to investigate the effect of the two resolutions in the discrimination of ships. This analysis might help to investigate the possibility to estimate some geometric features of the detected vessels from the echoes returned by the altimeter. The presented approach offers the opportunity to: i) study the compatibility between the detected target(s) and the known ship traffic, by using the Automatic Identification System (AIS) data; ii) resolve ambiguities among multiple targets, by using two different alongtrack spatial resolutions, due to the different sampling rates. Ship traffic statistics, as introduced by the literature, may take benefit from the method described in this work, providing a contribution to improve the overall precision of such statistics. The Sentinel-3 mission used in this work will provide a constellation with global SAR coverage (S3A and the new S3B) and free accessibility to the data, with a potential enhancement to the estimation of the number and characteristics of the ships with respect to past literature approaches.Source: ESA 11th Coastal Altimetry Workshop, pp. 24–24, ESA - ESRIN (Frascati), 11-15 June 2018

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2018 Contribution to conference Open Access OPEN

An assessment of the quality of the ESA sea level CCI products in the coastal zone of the Northern Adriatic Sea using tide gauge measurements and coastal altimetry products
Vignudelli S., De Biasio F., Scozzari A., Zecchetto S.
Since 1990's, a series of radar altimetry missions accumulated a satellite-based record of sea level that is now long enough to estimate trends. The European Space Agency (ESA) Climate Change Initiative (CCI) project on "Sea Level" has reprocessed these altimeter data over 1993-2015 to provide homogenous sea level for all altimetry missions. The ESA Sea Level CCI products are generated using open ocean altimetry data, and include along track sea level anomalies (SLA) at 1 Hz (around 7 km) and monthly gridded time series of multi-mission merged SLA at a spatial resolution of 0.25° (around 25km) from which some oceanic indicators (e.g., trends) are derived. During the CCI+ phase (2018-2019) the objective is to extend the satellite-based sea level climate record to the coastal zone with quality comparable to the open ocean. This work will report on the initial assessment of the quality of the ESA Sea Level CCI products in the coastal zone of the Adriatic Sea and in particular around the city of Venice. Tide gauges available around Venìce and Trieste will provide an accurate independent source of sea level information to be used as reference of long-term sea level variability at the coast. Coastal altimetry has demonstrated that if standard products are reprocessed with dedicated algorithms reliable data can be obtained up to few kms from the coasts. Therefore, additional along-track data sets (e.g., CTOH, COSTA, etc.) with consistent coastal processing for all missions and derived products dedicated to coastal regimes will be used to evaluate their current capabilities and perspectives for usage in long term sea level research studies.Source: ESA 11th Coastal Altimetry Workshop, pp. 28–28, ESA - ESRIN (Frascati), 12 - 15 June 2018

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2017 Journal article Open Access OPEN

Envisat RA-2 individual echoes: a unique dataset for a better understanding of inland water altimetry potentialities
Abileah R., Scozzari A., Vignudelli S.
The exploitation of synthetic aperture properties in nadir-looking radars is opening new scenarios in the framework of satellite radar altimetry. Both recent and upcoming missions including Cryosat-2, Sentinel-3, Sentinel-6 and SWOT take benefit from the coherent processing of radar data, aimed at improving range measurements in particular contexts, such as ice, open ocean, coastal zone, and even inland waters. This work investigates the possibilities offered by current and future satellite radar altimetry missions for the study of inland water bodies, probing into the peculiarities of the expected radar returns and their potential usage. In this regard, signals collected by the RA-2 instrument (Radar Altimeter 2) onboard the Envisat mission offer an unprecedented possibility, even with a relatively low pulse repetition frequency, to analyze the peculiarities of actual signals for detecting and ranging small water surfaces. In particular, the RA-2 instrument offers a global archive of Individual Echoes (IEs), collected at the native sampling rate of 1795 Hz, in addition to the 18 Hz data obtained by incoherent averaging, which are typically delivered to the users as standard products. RA-2 shares with future radar platforms such as Sentinel-6 a continuous and interleaved working modality, as was recommended by the scientific community in designing next missions' requirements. This is a further reason to consider the usage of RA-2 IEs as particularly attractive. Whilst only available for a small percentage of the earth's surface, sufficient IE data exist to study the height retrieval capability of these echoes, in particular for what concerns small water bodies, where we show that enough coherence is exhibited for focusing relatively narrow surfaces and range them correctly. A peculiar aspect of this work lies in the assumption that most of the returned echoes (in RA-2 IEs) are specular. A theoretical framework is developed according to this assumption, which is validated by investigating real RA-2 data and observing their related specular features. In particular, we discuss how specular echoes are expected to be very common in inland altimetry, and are most often associated with small to medium size lakes and rivers. This paper illustrates the expected electromagnetic behavior of specular water targets by exploiting the classical radar cross-section (RCS) theory for specular surfaces. Results from the model are compared with real IE data in three selected case studies, regarding two rivers of variable width and one flood plain, in order to check different hydrological regimes. The model very closely matches the data in all cases, making the results of this validation activity very promising. In particular, we demonstrate the feasibility of using satellite radar altimetry in rivers much smaller than what was considered possible until nowSource: Remote sensing (Basel) 9 (2017): 605. doi:10.3390/rs9060605
DOI: 10.3390/rs9060605

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2017 Conference article Open Access OPEN

Making use of continuous measurements for change detection purposes: an application to water distribution networks
Scozzari A., Brozzo G.
The monitoring and control of industrial processes often requires the capability to identify particular patterns in a set of acquired measurements. One of the most recurrent applications consists in the detection of changes and the related minimization of false alarms. This requirement is true also when dealing with natural systems. The monitoring of a natural resource usually involves the identification of a set of parameters, which are considered as representative of its underlining processes, in order to extract useful information about its current status and its expected behavior. This work is focused on the water resources destined to the drinkable water distribution, paying attention to two particular aspects: i) the need for a suitable metric to detect anomalous values in the assessment of water quality indicators; ii) the experimentation of a simplified data-driven strategy to estimate natural variations of one or more indicators, in order to mitigate false alarms. This paper proposes a preliminary investigation and a selected case study, in order to exemplify one practical implementation of the proposed approach. The possible application to a context of low-cost distributed sensors is also briefly discussed.Source: I2MTC 2017 - IEEE International Instrumentation and Measurement Technology Conference, Torino, Italy, 22-25 May 2017
DOI: 10.1109/i2mtc.2017.7969738

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