Fluctuations of Lake Orta water levels: preliminary analyses

While the effects of past industrial pollution on the chemistry and biology of Lake Orta have been well documented, annual and seasonal fluctuations of lake levels have not yet been studied. Considering their potential impacts on both the ecosystem and on human safety, fluctuations in lake levels are an important aspect of limnological research. In the enormous catchment of Lake Maggiore, there are many rivers and lakes, and the amount of annual precipitation is both high and concentrated in spring and autumn. This has produced major flood events, most recently in November 2014. Flood events are also frequent on Lake Orta, occurring roughly triennially since 1917. The 1926, 1951, 1976 and 2014 floods were severe, with lake levels raised from 2.30 m to 3.46 m above the hydrometric zero. The most important event occurred in 1976, with a maximum level equal to 292.31 m asl and a return period of 147 years. In 2014 the lake level reached 291.89 m asl and its return period was 54 years. In this study, we defined trends and temporal fluctuations in Lake Orta water levels from 1917 to 2014, focusing on extremes. We report both annual maximum and seasonal variations of the lake water levels over this period. Both Mann-Kendall trend tests and simple linear regression were utilized to detect monotonic trends in annual and seasonal extremes, and logistic regression was used to detect trends in the number of flood events. Lake level decreased during winter and summer seasons, and a small but statistically non-significant positive trend was found in the number of flood events over the period. We provide estimations of return period for lake levels, a metric which could be used in planning lake flood protection measures

Idrologia e clima. Apporti quantitativi a lago: piogge, portate e coefficiente di deflusso

Not availableI dati di precipitazione, per l\u27anno 2013, sono stati raccolti, come di consueto, dalle stazioni pluviometriche dell?Istituto per lo Studio degli Ecosistemi (CNR-ISE), del Servizio Meteorologico Svizzero, dell?Ufficio dei Corsi d?Acqua, Dipartimento del Territorio del Canton Ticino, dell\u27ENEL, dell?Area Previsione e Monitoraggio Ambientale dell?Arpa Piemonte, delle Officine Idroelettriche della Blenio-Maggia, della Societ? Idroelettriche Riunite, dell?Istituto Geofisico Prealpino e del Consorzio del Ticino. Nel 2013 si sono registrati, mediamente all?interno del bacino del Lago Maggiore, 1710 mm, valore in perfetta media pluriennale. I dati riguardanti i deflussi dei principali immissari e dell\u27emissario del Lago Maggiore, sono stati misurati nel 2013, attraverso le reti di rilevamento dell\u27Istituto per lo Studio degli Ecosistemi, dell?Area Previsione e Monitoraggio Ambientale dell?Arpa Piemonte, dell?Ufficio Federale dell?Ambiente di Berna (UFAM) e dei Consorzi del Bardello e del Ticino. L?andamento delle portate nel 2013 ? stato determinato dalla bassa piovosit? dei primi tre mesi dell?anno e dalle consistenti piogge di aprile e maggio che hanno portato la maggior parte dei corsi d?acqua a far registrare i massimi valori di portata proprio nel mese di maggio. La media delle portate annuali ? stata leggermente al di sotto dei valori di riferimento

Indagini sul bacino imbrifero

No abstract availabl

Indagini sul bacino imbrifero

Not availableIndagini sul bacino imbrifero del Lago Maggiore e sulle sue caratteristiche idrologiche: pluviometria e defluss

The hydromorphological state in mountain rivers subject to human impacts: a case study in the North-West of Italy

The aim of this paper is the evaluation of the hydromorphological conditions of mountain rivers subject to extensive human activities. The hydromorphological state of a river depends on a high number of natural and anthropogenic characteristics, such as the presence of weirs, dams, or any other human infrastructure close to the riverbanks. The research focused on the mountain streams in Lake Maggiore catchment, located in the Italian Alps. The analyses were carried out using the method CARAVAGGIO (Core Assessment of River hAbitat VAlue and hydromorpholoGIcal cOndition), which complies with the EC Water Framework Directive. An intensive campaign of field surveys was conducted and a great amount of data was collected to obtain specific synthesis indexes. In particular, the Habitat Quality Assessment (HQA) and the Habitat Modification Score (HMS) were used to determine the diversification of natural characteristics and the level of hydromorphological alteration in the study area. Furthermore, a Lentic-lotic River Descriptor (LRD) was used in support of the information obtained by HQA and HMS. This research shows that the worst hydromorphological conditions can be found in rivers characterised by a high level of human constructions and hydropower plants. Finally, regression analyses were implemented to search a relationship between HQA, HMS and some morphological parameters. LRD was correlated to some hydraulic parameters. The results of this research are characterised by a high stochasticity

Extreme rainfall events: evaluation with different instruments and measurement reliability

With regard to extreme events, it is known that an intensity of about 1 mm/min already represents an extreme intensity. Under alpine conditions, a precipitation event with intensity about 3 mm/min has occurred. Therefore the rain gauges in this region have to be able to measure in this and even in higher intensity ranges. This study deals with basically automated Tipping Bucket Rain (TBR) gauge, and Bulk precipitation samplers, which allows to hold back more than 95% of the cumulative rainfall that are verified within the space of the week without losses during the extreme events and with a minimum evaporation loss. In the last 10 years analysed, for a total of 221 extreme events, in 110 extreme events the Bulk samplers have collected rainfall more than automated TBR. In 17 extreme events an underestimation more than 10% was evaluated. The objective was to single out the counting errors associated with TBR gauge, during extreme events, so as to help the understanding of the measured differences between instruments in the field. We want to prove if the automated precipitation gauge, is or not, a reliable and precise device of measurements precipitation with particular interest regarding heavy and extreme events

Temporal evolution of lake level fluctuations under flood conditions and impacts on the littoral ecosystems

Lake levels fluctuations are conditioned by seasonal variability, water resources management and climate change. Recent studies have shown that global warming potentially affects the risk of flooding and that the decisive factor for flood events is not temperature, but precipitation characteristics and hydrological conditions. Flood events have numerous impacts on social, economic and environmental aspects depending on how humans have altered lands, natural rivers and lake dynamics. Flood protection measures can cause conflicts with conservation measures and with ecosystem services because natural capital is not considered able to control floods and to contribute control floods and that it can contribute to human health and safety. In this paper we analysed the flood events in Lake Maggiore for return time periods of 3 – 5 – 10 – 25 – 50 – 100 – 250 – 500 years, considering the flood frequency in the last ten years using 1868-2021 as a reference period. We discussed the probability distribution of flood peaks, the correlation and linear regression between the lake level fluctuations and macroinvertebrates occurrence. We also presented lake coasts flood hazard mapping. The probability distribution that better describes the annual peak level is the Gumbel function, while for spring and autumn flood events the better distribution is the Log-Pearson type III. One of the historical flood events in terms of magnitude was in 2000, characterized by a return time of about 50 years. The last flood event in 2020, was characterized by a return period of about 10 years. Considering the seasonal frequency of flood, the autumn magnitude was higher than the spring one, and the differences between seasonal flood events progressively increased. The results suggested a high probability of a flood event every three years and also a forecast of a flood of about 197 m asl (3.14 m above the average lake level) every 10 years. Raising the lake level will affect the reed bed area from 193 m asl, and it will be more effective at 194.5 m (up to a 10% reduction). During flood events, the whole reed bed area is submerged. As regard macroinvertebrates composition and abundance, the first results show significant negative relationships between all sampling stations altogether vs the abundance of Cladotanytarsus sp. (Chironominae) and nearly significant positive relationships between water levels at Magadino vs Pscectrocladius sordidellus (Orthocladiinae) abundances. These few results are perhaps due to the current limited data availability

Progetto "Acque pulite"

Abstract not availableLe aree montane, soprattutto in territori ricchi di acqua come quello del Verbano Cusio Ossola e del bacino del Lago Maggiore, sono da sempre oggetto di utilizzo per la produzione di energia elettrica da fonti rinnovabili, principalmente attraverso impianti idroelettrici. Il giusto equilibrio tra il mantenimento della qualit? ecologica degli ecosistemi torrentizi e la produzione di energia elettrica da fonti rinnovabili non ? di facile attuazione, soprattutto in assenza di studi e sperimentazioni dedicate. Lo sfruttamento delle acque a scopo idroelettrico pu? determinare l\u27alterazione e, a volte, la perdita di habitat, causando una riduzione della biodiversit?, con effetti negativi maggiori sui taxa pi? sensibili (ad esempio macroinvertebrati e fauna ittica), causando contestualmente, il degrado della qualit? ecologica di parte o addirittura dell\u27intero corso d\u27acqua a seconda delle tipologie di prelievo/i a cui ? stato sottoposto. Diventa quindi importante, nel contesto locale, ma anche nazionale e internazionale, dove le energie rinnovabili sono un punto focale per la futura produzione di energia, trovare il giusto equilibrio tra la qualit? ecologica degli ecosistemi, e la richiesta di energia pulita e di sviluppo economico. E\u27 proprio in questo contesto che nasce l\u27idea del Progetto "Acque Pulite", che grazie alla disponibilit? e al finanziamento di IDROENERGY S.r.l. ha visto la realizzazione di uno studio pilota sul Torrente San Giovanni. Il Torrente San Giovanni ? uno dei principali immissari del Lago Maggiore e per tale motivo risulta importante conoscere la sua qualit? ecologica e gli effetti su di essa delle diverse attivit? umane che insistono all\u27interno del suo bacino. In particolare, con il Progetto "Acque Pulite" si sono voluti verificare gli effetti della presenza di un\u27opera di presa e di una traversa, costruite per scopo idroelettrico, sulla qualit? idro-morfologica, chimica e biologica dei tratti di torrente a monte e a valle di tali opere

The Relationship Between Working Environment and Employee Performance

A positive working environment is vital in ensuring employee productivity to avoid unnecessary stress to the employees thus affecting their work performances. There are several working environment factors that contributed towards job satisfaction. Hence, this study aimed to investigate the relationship between the working environment and employee performance based on five dimensions of the working environment. The quantitative survey design was utilized in this study and data were collected by using questionnaires. The respondents of this study were administrators from different departments in a local municipality located in Kuching. The data were analysed by using Pearson’s Correlation Analysis to measure the relationship between the variables. The finding shows there is a significant relationship between the working environment and employee performance. Support from supervisor was found to be the dominant variables in ensuring a positive working environment

Water Resource Management through Understanding of the Water Balance Components: A Case Study of a Sub-Alpine Shallow Lake

Water availability is a crucial factor for the hydrological balance of sub-alpine shallow lakes and for their ecosystems. This is the first study on water balance and water management of Lake Candia, a small sub-alpine, shallow morainic lake. The aims of this paper are to better understand the link between surface water and groundwater. The analyses carried out included: (i) evaluation of water balance, (ii) identification of trends for each component of water balance, (iii) detection of the presence of a break point or change in the behavior of each component, and (iv) regression analyses of the terms of hydrological balance and their relative importance. The analyses revealed a high variability mainly regarding the groundwater component, and very good correlation between rainfall and volume variation, between rainfall and the water inflow, and between groundwater source and outflow. Volume variation is linked with rainfall, outflow, groundwater source, and surface water inflow. Despite the fact that the groundwater component does not seem to have a great importance relative to direct rainfall on the lake, it is necessary to study the component with careful resource management policies that point toward the protection of the water resource, sustainable uses, and protection of the Lake Candia ecosystem