Abstract

Newly collected morphobathymetric and seismic reflection data from the Valli di Comacchio coastal lagoons, south of the Po River delta (Northeast Italy), combined with historical, remote sensing, and geodetic data highlight a complex geological evolution during the Holocene, strongly affected by anthropic control. All data allowed us to define the present-day depositional environment of the lagoons and reconstruct their recent (late Pleistocene/Holocene) geo-history. We focused on the effects of the anthropic impacts in modifying the pristine environments created by the Holocene transgression along the Adriatic Sea coast, at the mouth of a major river. They include land reclamation works, artificial damming, channel excavations, fluvial diversions, and a recent (last decades) increase in subsidence rate due to gas and water withdrawals. Despite the development of economic activities, which promoted occupation and exploitation of this area in the last millennia, the post-Glacial evolution of the lagoons shows the important role of inherited morphological features, such as sand ridges and barriers. This complex and relatively well-documented evolution makes the Comacchio lagoons a unique example of deep connections between natural processes and long-term human controls, offering insights into the management policies of these important and delicate environments challenged by global changes.

Highlights

  • Introduction iationsAs a consequence of their natural and economic importance, and valuable ecosystem goods and services [1,2], coastal lagoons have been managed historically to exploit their resources

  • The present-day vertical and horizontal deformation pattern of the Valli di Comacchio area can be reconstructed by analyzing the GNSS (Global Navigation Satellite System) permanent station data

  • A grid of topographic data based on a Lidar survey around the Valli di Comacchio lagoons

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Summary

Field Survey

Geophysical data were collected in different periods starting from 2011 and covered the entire accessible water surface of the Valli di Comacchio lagoons, excluding only private areas (Figure 2). Due to the characteristics of the study area, we modified the echosounder to cover shallower sectors of the lagoons: the pulse length was shortened to 200 μs and the bottom-detection/depthestimate section was disabled, obtaining, de facto, a 200 kHz externally triggered ultrasonic pinger. In this way, the shallow-depth limit was reduced to approximately 0.2 m. 5 ms, frequency to 7 and kHzsampling and sampling of kHz. Seismic data were stored in SEGY files in form of instantaneous amplitudes.

Data Processing
Bottom
Differential Bathymetric Models
Geodetic Measurements
Results
Results and Discussion
Recent Sedimentary Evolution
Bathymetric Survey
Normalized reflectivity map map of the of
Topography
11. Lidar-based
Hydrodynamics
Decadal Changes in the Lagoon-Floor Morphology
13. Residualmap bathymetric obtaineddata subtracting collected at about
Morpho-Stratigraphic
Full Text
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