Study site description: Rendina, Italy

Table of Contents

1. Responsible IP partner
2. General information
   1. Site selection
   2. Local partners
   3. Photographs of study site
3. Bio-physical description
4. Land use management and degradation processes
5. Socio-economic description
6. Institutional and political setting
7. Relevant end-users / stakeholder groups (at all levels)
8. Past and on-going projects
9. References
10. Annex: Soil characteristics of the Rendina Basin

Site selection

The main reasons for selecting this site/region are that the chosen area presents a series of characteristics that makes it different from all the other sites (this will be made clear later in the text). First of all the reasons why it was proposed are:

1. climate conditions in the Rendina catchment are moving from the prevailing humid to subhumid conditions towards subhumid / semiarid conditions;
2. the surrounding area is (subhumid)-semiarid at present and is moving towards semiarid-arid, even arid conditions;
3. the Rendina is the one place where a good amount of good quality water can be collected for drinking and irrigation purposes now and in the near in the future if the catchment is well managed.

Consequently, the Rendina catchment is a strategic catchment because of the essential role it will play in mitigating the effect of global warming and desertification in the surrounding areas, under the condition that it is well managed and its functions conserved and improved. Hence the present situation in the Rendina basin is not one of desertification but of degradation, mainly due to excessive sediment production and agricultural mismanagement. The catchment of the Rendina reservoir is an area where desertification has not yet shown dramatic negative effects, also because irrigation and water storage in the reservoir mitigate it. At the same time, saving water quality in the whole catchment requires a catchment approach, which may be complemented by a field-size approach if needed. The former is necessary and the latter is probably advisable but not strictly needed.

Good quality water springs from several places around the Vulture volcanic complex in the altitude belt between 400 and 600 m asl; the mountain peaks are about 1300 m asl. Many areas are potential sources of good quality overland flow water.

Some of the soil provinces display fertile volcanic soils (see section C.1 for a summary soil description). However, the basin lowlands are close to semiarid conditions, and irrigation is needed for crops to survive the dry summer spell. The situation is worsened 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 is 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 in which farmers and farmer unions participate, 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/km²/yr of sediment yield corresponding to a higher erosion rate at plot scale and a unsustainable sedimentation rate in the reservoir (7 M m³ presently stored in the reservoir).

The situation will further worsen in the near future if a further increase in temperature is taken for granted. The area where volcanic soils with andic properties are present lies along the Vulture slopes. The main towns and most populated areas are at the bottom of the slopes. Hence there is a potentially very risky situation if forest starts degrading. Some trees such as birch and conifer plantations are at the limit of their respective habitats and 2 degrees of temperature increase will push their roots into the sky. Chestnuts will have to be helped climbing the mountain while oaks or other drought-resistant species will have to be used to replace lower altitude chestnuts. There is at present a particular combination of factors that produce oscillations of the temperature (minimum of solar activity and North Atlantic Oscillation (NAO) towards low temperatures), bringing the global warming to a momentary stop locally. When NAO will starts rising again the temperature rise will be unprecedented. If this combines with the incapacity of local people to understand the consequences of global warming, forests will be at stake and Mount Vulture will become a source of sediment (water erosion) and surface mass movements with fast mud and debris flows. Apart from obvious human and social consequences (including deaths), the capacity of the system to keep present refilling rates to the water tables nourishing the springs around Mt. Vulture will decline, thus increasing the severity of desertification processes in the surrounding areas.