Evaluating the effects of check dams on channel geometry, bed sediment size and riparian vegetation in Mediterranean mountain torrents

Demetrio Antonio Zema; Giuseppe Bombino; Pietro Denisi; Manuel Esteban Lucas-Borja; Santo Marcello Zimbone

doi:10.1016/j.scitotenv.2018.06.035

Evaluating the effects of check dams on channel geometry, bed sediment size and riparian vegetation in Mediterranean mountain torrents

Sci Total Environ. 2018 Nov 15:642:327-340. doi: 10.1016/j.scitotenv.2018.06.035. Epub 2018 Jun 14.

Authors

Demetrio Antonio Zema¹, Giuseppe Bombino², Pietro Denisi², Manuel Esteban Lucas-Borja³, Santo Marcello Zimbone²

Affiliations

¹ Department "Agraria", University "Mediterranea" of Reggio Calabria, Località Feo di Vito, I-89122 Reggio Calabria, (Italy). Electronic address: dzema@unirc.it.
² Department "Agraria", University "Mediterranea" of Reggio Calabria, Località Feo di Vito, I-89122 Reggio Calabria, (Italy).
³ Departamento de Ciencia y Tecnología Agroforestal y Genética, University of Castilla La Mancha, Campus Universitario s/n, E-02071 Albacete, (Spain).

PMID: 29906724
DOI: 10.1016/j.scitotenv.2018.06.035

Abstract

In mountain streams possible negative impacts of check dams on soil, water and riparian vegetation due to check dam installation can be noticed. In spite of the ample literature on the qualitative effects of engineering works on channel hydrology, morphology, sedimentary effects and riparian vegetation characteristics, quantitative evaluations of the changes induced by check dams on headwater characteristics are rare. In order to fill this gap, this study has evaluated the effects of check dams located in headwaters of Calabria (Southern Italy) on hydrological and geomorphological processes and on the response of riparian vegetation to these actions. The analysis has compared physical and vegetation indicators in transects identified around check dams (upstream and downstream) and far from their direct influence (control transects). Check dams were found to influence significantly unit discharge, surface and subsurface sediments (both upstream and downstream), channel shape and transverse distribution of riparian vegetation (upstream) as well as cover and structure of riparian complexes (downstream). The actions of the structures on torrent longitudinal slope and biodiversity of vegetation were less significant. The differences on bed profile slope were significant only between upstream and downstream transects. The results of the Agglomerative Hierarchical Cluster analysis confirmed the substantial similarity between upstream and control transects, thus highlighting that the construction of check dams, needed to mitigate the hydro-geological risks, has not strongly influenced the torrent functioning and ecology before check dam construction. Moreover, simple and quantitative linkages between torrent hydraulics, geomorphology and vegetation characteristics exist in the analysed headwaters; these relationships among physical adjustments of channels and most of the resulting characteristics of the riparian vegetation are specific for the transect locations with respect of check dams. Conversely, the biodiversity of the riparian vegetation basically eludes any quantitative relations with the physical and other vegetal characteristics of the torrent transects.

Keywords: Bed profile; Channel morphology; Headwater; Torrent hydraulics; Transects; Vegetation biodiversity.