Summary
The catchment of the Rendina reservoir is an area where desertification has not yet shown dramatic negative effects. From this point of view, the area is still pristine.
The geology of the region is characterized by the Pleistocenic marine sediment of the Bradanic through and the volcanic succession of Vulture and Monticchio (see section C). Good quality water springs from several places around the Vulture volcanic apparatus (in the altitude belt between 400 and 600 m asl; the mountain peaks at about 1300 m asl). Many areas are potential sources of good quality overland flow water.
Some of the soil provinces tell of fertile volcanic soils (see section C for a summary soil description). Nevertheless, the basin lowlands are close to semiarid condition, and irrigation is needed for culture to survive the dry summer spell. The situation is worstened by the fact that the Ofanto river (the main water course of the area, of which the Rendina catchment is a tributary) is overexploited and subject to episodes of intense pollution even if the present policy in more respectful of the environment. While many actions have been taken to modify the situation, the importance of the Rendina reservoir seems to grow more and more as the climate continues to change and temperature to rise because Mount Vulture and the Rendina reservoir represent the best water stock of the area and the one that can really mitigate the desertification process in the area itself and in the downstream Ofanto valley.
The Rendina reservoir utilization and management is under the responsibility of the Consorzio di Bonifica del Vulture e Alto Bradano. This Consortium has a Council where farmers and farmer unions sit, so that decisions are ultimately taken by farmers. Data available at the moment tells us of a very high rate of sediment trapped in the reservoir each year, corresponding to 10-13 Mg/hm2/a of specific sediment yield corresponding to a higher erosion rate at plot scale and a unsustainable sedimentation rate in the reservoir (7 Mm^3 stored at present time in the reservoir).
Main problems at watershed scale related to soil degradation and desertification are summarized in the intense soil erosion process (diffuse and concentrated in arable land, vineyards and olive orchards), diffuse mass movement and soil slips , river bank erosion, soil erosion by tillage, lost of natural drainage system , large sediment source areas ( soil erosion evidences until 1cm/year in olive orchards for water and tillage erosion and until 2 cm/year in steep slope arable land), and high connectivity between primary source of sediment and drainage network. Land levelling for new vineyard plantation and periodic reshaping of arable land affected by frequent shallow mass movements. The watershed scale monitoring and analysis will allow assessment of connectivity reduction paradigm for SWC at watershed level.
