DBPapers

TUNNEL EROSION AFFECTING A SENSITIVE LANDSCAPE

F. Filipov, S. Capsuna, D. Raducu, G. Jitareanu
Thursday 11 October 2018 by Libadmin2018

ABSTRACT

The study was focused on the intensification of sensitive landscape degradation by tunnel erosion (i) to determine the particularity (ii) of this process in the studied area in order to establish regional sustainable management. The studied site is located in the southern part of Jijia Plain, on a complex slope (faces west) from Bogonos Valley. The Tma is 9.5oC and the Pma is 501.7 mm. The dominant soils are Solonetz, Solonchaks, and Regosols formed in salt-bearing clay deposits. The soil characteristics associated with the exposed deposits (consisting of dispersible clay and salts) are the ideal conditions for the initiation and the development of soil erosion. The field observations showed that variable slope gradient increased the deep and the surface erosion and the increased of water flow from torrential rainfall among the cracks formed during the dry hot summers, inducing a linear pattern of deep erosion. The analytical data showed a high content of exchangeable sodium (over 10%) and a high content of dispersible clay (46.8-49.9%) which increased the landscape sensitivity and the susceptibility to sheet linear water erosion and implicitly to tunnelling erosion. The surface erosion together with overgrazing brought to the surface the salic deposit, (which generally appear at 20-30 cm depth, thus in many slope areas thin salt crust ± salt efflorescences formed. In such conditions the plant cover composed by grasses were replaced by very strong halophyte plants as Salicornia herbacea, Aster cinereus, A. punctatus, Atriplex hastata, Cynodon dactylon, Agropyron (Elymus) repens, Arthemisia litoralis, Camphorosma monspeliaca, Puccinelia distans, Festuca pseudovina. The small depth of salt-bearing clay deposits (20-30 cm) associated with high susceptibility to detachment by flow of soil horizons make difficult land melioration. The main cause of land degradation by tunnelling is overgrazing practice which diminishes vegetation cover, allows raindrop splash sheet linear and tunnel erosion, removal of topsoil, and exposing deposit of the dispersible clay, which made the slope impracticable for agriculture and dangerous for animal grazing, with deeply implications in the regional management.

Keywords: erosion, tunnelling, piping, overgrazing, melioration


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