Effects of anthropogenic land-subsidence on inundation dynamics: the case study of Ravenna, Italy

Abstract

Abstract. Can differential land-subsidence significantly alter river flooding dynamics, and thus flood risk in flood prone areas? Many studies show how the lowering of the coastal areas is closely related to an increase in the flood-hazard due to more important tidal flooding and see level rise. The literature on the relationship between differential land-subsidence and possible alterations to riverine flood-hazard of inland areas is still sparse, although several geographical areas characterized by significant land-subsidence rates during the last 50 years experienced intensification in both inundation magnitude and frequency. We investigate the possible impact of a significant differential ground lowering on flood hazard over a 77 km 2 area around the city of Ravenna, in Italy. The rate of land-subsidence in the study area, naturally in the order of a few mm year −1 , dramatically increased up to 110 mm year −1 after World War II, primarily due to groundwater pumping and gas production platforms. The result was a cumulative drop that locally exceeds 1.5 m. Using a recent digital elevation model (res. 5 m) and literature data on land-subsidence, we constructed a ground elevation model over the study area in 1897 and we characterized either the current and the historical DEM with or without road embankments and land-reclamation channels in their current configuration. We then considered these four different topographic models and a twodimensional hydrodynamic model to simulate and compare the inundation dynamics associated with a levee failure scenario along embankment system of the river Montone, which flows eastward in the southern portion of the study area. For each topographic model, we quantified the flood hazard in terms of maximum water depth (h) and we compared the actual effects on flood-hazard dynamics of differential land-subsidence relative to those associated with other man-made topographic alterations, which resulted to be much more significant.

Floods, landscape modifications and population dynamics in anthropogenic coastal lowlands: The Polesine (northern Italy) case study

“…Anthropogenic impacts on surface water management have been the subject of several studies, focusing on the effects of climate and land-use changes on frequency and magnitude of floods (Bronstert et al, 2002;Camorani et al, 2005;Ferrier and Jenkins, 2009;Fohrer et al, 2001;Hall et al, 2014;Huang et al, 2017;Kundzewicz et al, 2014;Li et al, 2009;Tomer and Schilling, 2009;Whitfield, 2012;Wooldridge et al, 2001;Zhang et al, 2018;Zope et al, 2016Zope et al, , 2017, on the impacts of engineering works aimed at flood control and navigation (Gai et al, 2017;Mitkova et al, 2005;Pattison and Lane, 2012;Spinewine and Zech, 2008;Surian and Rinaldi, 2003), and on coastal and estuarine dynamics as well (Nicholls and Hoozemans, 1996;Silvestri et al, 2018;Simeoni and Corbau, 2009). Less attention has been paid to the effect of anthropogenic landscape modifications on flooding dynamics, i.e., on the evolution and features of the flooding process, as it is affected by the interaction with the landscape (Carisi et al, 2016;Onishi et al, 2014).…”

Land use and land cover dynamics in Leiria City: relation between peri-urbanization processes and hydro-geomorphologic disasters

“…In recent years, some studies have analysed the relationship between the occurrence of LULC and landslides (Glade 2003;Alcántara-Ayala et al 2006;Papathoma-Köhle and Glade 2013;Reichenbach et al 2014;Persichillo et al 2017;Guerra et al 2017;Gariano et al 2018;Vitagliano et al 2020) and floods (Li et al 2009;Onishi et al 2014;Carisi et al 2016;Zhang et al 2018) some of them addressing linkages to climate change. With regard to landslides, several studies point to the importance of LULC of anthropic origin in slope instability, leading to the activation or reactivation of landslides (Meusburger and Alewell 2008;Van den Eeckhaut et al 2009;Ravetz et al 2013;Bruschi et al 2013;Reichenbach et al 2014).…”