Global change and long-term gully sediment production dynamics in Basilicata, southern Italy.

The Fossa Bradanica in Basilicata (S Italy) is affected by almost 15% permanent Pleistocene and Holocene gullies. In the past decades climate versus land use management have dramatically increase both the soil loss rate and the muddy-flooding frequency. In this paper the impact of global change on soil production rates and erosion/deposition dynamics at medium-time scale (1949-2000) for two permanent gullies (Fosso Lavandaio and Fosso San Teodoro) has been studied. Pluviometric regime, land use changes and multi-temporal (1949, 1986 and 2000) subtraction method of digital elevation models have been conducted. From 1949 to 1986 the sediment production rate was estimated in 1,988.43 Mg ha year at Fosso Lavandaio and in 808.5 Mg ha year at Fosso San Teodoro, with deposition prevailing over erosion processes. From 1986 to 2000 the sediment production rate was estimated in 2,487.92 Mg ha year at Fosso Lavandaio and in 2,883.9 Mg ha year at Fosso San Teodoro, with higher values of net erosion. The data confirm that the increase in sedimentation would be due to human activities, in particular the levelling of gully heads for the production of cereals and orchards. Differently, the increase of the erosion processes depends on the recent changes of the pluviometric regime characterized by the extension of dry horizon and the concentration of high magnitude precipitation in macro-events of three to four consecutive days. [ABSTRACT FROM AUTHOR]