Assessment of the impact of climate variability and human activities on the runoff in five catchments of the Adriatic Coast of south-central Italy

Study region: South-central Italy. Study focus: A detailed analysis is carried out in five catchments in the Adriatic Coast where a complex system of artificial lakes, forced conducts and hydropower stations has modified the river regime. This together with the decrease of the annual rainfall in central Italy, make quantifying the relative contributions of human activities and climatic variability to streamflow change a challenging task. Statistically significant trends in annual rainfall and streamflow and change points in runoff have been investigated. Potential changes in precipitation-runoff relationship have been examined and a quantitative evaluation of the effect of climate variability and human activities on runoff has been assessed separately. New hydrological insights for the region: Significant negative trends in runoff have been found in all the catchments, except the Feltrino river. Precipitation also exhibits negative trend, except the Pescara basin. Significant change points in runoff were detected in all the basins and the study period was divided in a pre-change and a post-change period. By climate elasticity method the climatic variability seems to be the main driving factor of the runoff decrease. Only for the Pescara river human activities were dominant factors of the runoff reduction, as expected from the absence of any significant trend in the annual precipitation. The hydrological model confirms this result, although the assessment of two contributions is affected by some uncertainties.