title: Characterising the hydrological regime of an ungauged temporary river system: a case study.
abstract: Temporary streams are characterised by specific hydrological regimes, which influence ecosystem processes, groundwater and surface water interactions, sediment regime, nutrient delivery, water quality and ecological status. This paper presents a methodology to characterise and classify the regime of a temporary river in Southern Italy based on hydrological indicators (HIs) computed with long-term daily flow records. By using a principal component analysis (PCA), a set of non-redundant indices were identified describing the main characteristics of the hydrological regime in the study area. The indicators identified were the annual maximum 30- and 90-day mean (DH4 and DH5), the number of zero flow days (DL6), flow permanence (MF) and the 6-month seasonal predictability of dry periods (SD6). A methodology was also tested to estimate selected HIs in ungauged river reaches. Watershed characteristics such as catchment area, gauging station elevation, mean watershed slope, mean annual rainfall, land use, soil hydraulic conductivity and available water content were derived for each site. Selected indicators were then linked to the catchment characteristics using a regression analysis. Finally, MF and SD6 were used to classify the river reaches on the basis of their degree of intermittency. The methodology presented in this paper constitutes a useful tool for ecologists and water resource managers in the Water Framework Directive implementation process, which requires a characterisation of the hydrological regime and a 'river type' classification for all water bodies.
authors.affiliation: Politecnico di Milano, Milan, Italy. ersilia.dambrosio@polimi.it.|Water Research Institute, National Research Council, Bari, Italy. ersilia.dambrosio@polimi.it.
authors.forename: Ersilia
authors.initials: E
authors.lastname: D'Ambrosio
authors.affiliation: Water Research Institute, National Research Council, Bari, Italy.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: De Girolamo
authors.affiliation: Water Research Institute, National Research Council, Bari, Italy.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Barca
authors.affiliation: Water Research Institute, National Research Council, Bari, Italy.|Institute of Atmospheric Sciences and Climate, National Research Council, Lecce, Italy.
authors.forename: Pierina
authors.initials: P
authors.lastname: Ielpo
authors.affiliation: Politecnico di Milano, Milan, Italy.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Rulli
mesh_terms: D062070:Hydrology; D007558:Italy; D045483:Rivers; D014872:Water Movements; D060753:Water Quality
keywords: Flow regime; Hydrological indices; Principal component analysis; Regression analysis; Temporary rivers; Ungauged catchments