Author(s): G. Spilotro; I. Argentiero; R. Pellicani; M.D. Fidelibus; A. Parisi

Linked Author(s):

Keywords: River damming; Coastal erosion; Sediment deficit; Basilicata region

Abstract: Water need in semi-arid regions leads to employ all available water resources, in particular surface waters. Rivers dammed for these purposes produce cascading and delayed effects. This paper offers a description of such effects. In the last six millennia, the Mediterranean Sea shorelines have been subjected to natural evolution driven by climate planetary conditions (eustatism) and flooding of estuaries and deltas, as documented by comparing the positions of ancient settlements and recent coastlines. In the last century, positive river sediment balance has been maintained only in less populated areas with no essential modifications of inner basins. Elsewhere, where human activities have modified sediment budget at the basin scale, erosion rate sometimes reaches very high values. The causes of such modifications can be mainly traced back to fluvial equilibrium perturbations due to mining of inert materials and interventions on riverbeds, as well as construction of hydraulic works as dams. Normally, water cost is related to its collection, purification, distribution and aqueduct management, without considering environmental and social costs consequent to water management. Damming the rivers for water storage has several delayed and cascading consequences. It reveals as the most dangerous factor in salt intrusion in coastal aquifers and on coastal dynamics of large sandy beaches. Moreover, damming rivers causes a sedimentary deficit at the physiographic basin scale, as already studied [1,2,3]. As the matter of fact, sediment transport capacity toward the sea dramatically decreases without river flow and deposits remains trapped into the new water reservoir or behind the barrages in the riverbed. These effects will be described for a reference area located in the Basilicata region, southern Italy (Fig. 1). The ionic coastline of the Basilicata region develops about 35 Km of sandy beaches, fed up by five major rivers until 1960s. At the end of ‘70s, 4 dams and 13 minor barrages dammed four rivers of the Basilicata region (Fig. 2). Deficit in sediment budget caused by these anthropogenic activities is the basis of widespread delayed coastal erosion phenomena worldwide.

DOI: https://doi.org/10.3850/978-981-11-2731-1_239-cd

Year: 2018