Hydrological regime alteration and ecological flow evaluation in mountain rivers

In the Alpine region, the hydropower production has caused alterations in the hydrological regime of most rivers, due to the massive withdrawal of water and to the construction of dams and reservoirs, which modify the natural flow duration curve of the river. These alterations may result in a decrease in hydro-morphological and ecological quality of the river and limitations are considered, usually expressed as an ecological flow that has to be guaranteed. Many types of approaches are suggested in literature to define this flow, taking into account hydrological, physical, chemical and biological factors. Methods based only on hydraulic/hydrological parameters are often preferred, due to simplicity and robustness. More, with methods based only on hydrological parameters is simpler to take into account changes in river regime due to anthropic activities. However, some ecological issues are also important for river quality, such as the lentic-lotic characteristics of flow, but they are difficult to be expressed in crisp numerical values. In the last years more complex methods have been proposed as an alternative to hydrological models. One of them is the method CARAVAGGIO (Core Assessment of River hAbitat VAlue and hydro-morpholoGIcal cOndition). Although this model is able to take into account a great number of different aspects, its application is not always possible due to the difficulties in entering the river in some sites. In this paper a procedure able to merge the ease of use of hydrological methods and the multi-factor approach of CARAVAGGIO is proposed. Ecological flow is estimated from basic hydrological information, using a simple set of coefficients to take into account other quality issues, particularly the lentic-lotic features of flow regime. Application to a case study in the Province of Verbano-Cusio-Ossola, in the north-western part of Piedmont Region in Italy, is presented

Ecosistemi di acque interne e di transizione

In questo contributo la vulnerabilità degli ecosistemi acquatici ai cambiamenti climatici è analizzata in relazione ai meccanismi di organizzazione e mantenimento della biodiversità e dei processi ecosistemici. Dai processi degli ecosistemi derivano funzioni che forniscono una serie di benefici o servizi per il genere umano (Daily et al., 2009). Tali servizi sono in larga misura dipendenti dalle componenti biologiche degli ecosistemi86. Negli ecosistemi acquatici i processi biogeochimici (ad es. denitrificazione batterica e assimilazione da parte della vegetazione acquatica), garantiscono l’abbattimento dei nutrienti, una funzione ecosistemica che produce il servizio di depurazione dell’acqua. Altri servizi sono la laminazione delle piene, la ricarica degli acquiferi, la regolazione del microclima locale, la produzione di risorse alimentari quali pesci, crostacei, ecc. (Jones, 2013). Le alterazioni degli ecosistemi, in particolare la perdita di specie e la diminuzione della biodiversità danneggiano questi servizi, con ricadute anche di tipo economico(si pensi, ad esempio, ai costi della depurazione dell’acqua destinata al consumo umano)

Indici per la valutazione della qualit? ecologica dei laghi

Collection of methods to evaluate lake quality using biological element

The climatic characteristics of extreme precipitations for short-term intervals in the watershed of Lake Maggiore

Alpine and Mediterranean areas are undergoing a profound change in the typology and distribution of rainfall. In particular, there has been an increase in consecutive nonrainy days, and an escalation of extreme rainy events. The climatic characteristic of extreme precipitations over shortterm intervals is an object of study in the watershed of Lake Maggiore, the second largest freshwater basin in Italy (located in the north-west of the country) and an important resource for tourism, fishing and commercial flower growing. The historical extreme rainfall series with high-resolution from 5 to 45 min and above: 1, 2, 3, 6, 12 and 24 h collected at different gauges located at representative sites in the watershed of Lake Maggiore, have been computed to perform regional frequency analysis of annual maxima precipitation based on the Lmoments approach, and to produce growth curves for different return-period rainfall events. Because of different rainfallgenerating mechanisms in the watershed of Lake Maggiore such as elevation, no single parent distribution could be found for the entire study area. This paper concerns an investigation designed to give a first view of the temporal change and evolution of annual maxima precipitation, focusing particularly on both heavy and extreme events recorded at time intervals ranging from few minutes to 24 h and also to create and develop an extreme storm precipitation database, starting from historical sub-daily precipitation series distributed over the territory. There have been two-part changes in extreme rainfall events occurrence in the last 23 years from 1987 to 2009. Little change is observed in 720 min and 24- h precipitations, but the change seen in 5, 10, 15, 20, 30, 45, 60, 120, 180 and 360 min events is significant. In fact, during the 2000s, growth curves have flattened and annual maxima have decreased

Assessment of Trends in Extreme Precipitation Events: A Case Study in Piedmont (North-West Italy)

Intensification of heavy precipitation as discussed in climate change studies has become a public concern, but it has not yet been examined well with observed data, particularly with data at short temporal scale like hourly and sub-hourly data. The original data set was retrieved by using an automated recovery approach. We chose four stations, namely, Vercelli (since 1927), Bra (since 1933), Lombriasco (since 1939) and Pallanza (since 1950) which are located in the northwest of Italy. We assessed trends for durations from 5 min to 12 h in seasonal, annual maxima, and number and magnitude of exceedances of the 95th percentile. Split sample tests have been undertaken to assess differences in quantile estimates derived using a Generalised Pareto distribution fitted to Peaks-Over-Threshold series. The statistical analyses performed include parametric and non-parametric tests. Mostly, we cannot reject the trend stationarity hypothesis. There is no uniform trend on extreme events in the whole area. However, some trends are evident and significant for specific stations and specific indices. Specifically, it is obvious that extreme rainfall events have risen in the last 20 years only for short durations

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To assess if environmental differences other than water quality may affect the outcome of the Benthic Quality Index, a comparison of the application of four different methods (Benthic Quality Index-BQIES, Lake Habitat Modification Score-LHMS, Lake Habitat Quality Assessment-LHQA and Organisation for Economic Co-operation and Development-OECD) used to classify the lake ecological and hydro-morphological status of 10 Italian lakes was performed. Five lakes were natural and five were reservoirs belonging to both Alpine and Mediterranean Ecoregions. The 10 lakes were sampled using the Water Framework Directive compliant standardized national protocol, which includes sampling soft sediment in the littoral, sublittoral and deep layers along transects with a grab of 225 cm(2) during spring and autumn. The application of Generalised Linear Mixed Effect Models both at the lake level and at the single station of each lake highlighted that, at the lake level, no significant correlations existed between any couple of hydro-morphological, ecological and trophic status assessments, with each metric representing a different facet of human impact on the environment. At the single site level, we found significant effects of depth on the metrics of biodiversity. The best approximation of single-site macroinvertebrates diversity among the metrics of overall lake quality was with the LHMS, but not with the BQIES. Our hypotheses that lake macroinvertebrates assemblages depend also on other potential confounding variables of habitat degradation and intrinsic differences between lakes were confirmed, with depth playing a major role. Therefore, the assessment of lakes with different depths may produce different whole-lake BQIES values, only because of the effect of depth gradient and not because of differences in lake quality

Vaginal bacterial and fungal flora in pregnant diabetic and non-diabetic women: a multi center observational case-control study

Objective: We evaluated the prevalence of cervicovaginal Bacteria, group B Streptococcus (GBS), Gardnerella vaginalis (GV), Candida spp., Chlamydia trachomatis (CT), Mycoplasma hominis (MH) and Ureaplasma urealyticum (UU) in pregnant women with and without diabetes mellitus (DM). Materials and method: Cervicovaginal swabs were gathered from 473 pregnant patients divided into 127 diabetic and 346 non-diabetic. The results were correlated to gestational age, parity and glycemic control. Results: A higher prevalence of MH/UU (P=0.012) was found in the diabetic patients. After the 28th weeks of pregnancy the prevalence for all investigated microorganisms appeared similar except for MH/UU (P=0.014). In multigravida were there statistically differences between two groups in testing for Bacteria (P=0.015) and for MH/UU (P=0.037). The diabetic condition correlated to the state of multigravida in cases positive for Candida spp (P=0.049) and in those testing positive for at least one microorganism (P=0.043). Pregnant with a blood glucose > 92 have twice the risk of being positive to a single microbiological test than those with better glycemic control. Conclusions: The higher prevalence of MH/UU after the 28 th weeks can be explained with the physiological reduced insulin tolerance characteristic of this gestational period. Among the diabetic testing positive to Candida spp the statistically significant association was observed only in multigravida condition. These data suggest that diabetic multigravida are at increased risk for Candida spp infection in relation to the improper glycemic control