1,720,982 research outputs found
1D thermodynamic modelling of Lake Maggiore for thermal structure evolution predictions under climate change
No full textThe deep subalpine lakes have been characterised during the last decades by an oligomictic behaviour, full overturns being achieved only at the end of cold and windy winters. Since vertical mixing is essential for the chemical and biological dynamics, the study of how such behaviour will evolve with future climate change is strongly relevant. In order to investigate that on Lake Maggiore, we built a 1D thermodynamic model of the basin using the General Lake Model (GLM) (Hipsey et al., 2014). Calibration was performed reproducing the thermal evolution in the period 1998-2014, feeding the model with meteorological data measured at the Pallanza and Locarno-Monti weather stations and comparing the results against monthly temperature observations along the deepest water column at the Ghiffa limnological site. The availability of extended data series, spanning years with very different meteorological and hydrological features, allowed to obtain calibration coefficients that are less specific and suitable for predictions. Two versions of the model were initially developed, one with a closed and fixed-level lake approximation and another reproducing the complete hydrological and thermal balances, including inflows, outflow, and direct rainfall contributions. Daily discharges for the major tributaries and the emissary in the calibration period were available, while the daily temperatures of the inflows were computed from daily air temperatures using the air2stream model (Toffolon & Piccolroaz, 2015), calibrated using monthly available observations. We studied the effects of an evolving climate scenario, with a linear increase of air temperature of 4?C from 2014 to 2081, as predicted by the International Panel for Climate Change (IPCC). A weather generator was used to estimate the corresponding variations of the other meteorological and hydrological parameters in response to the temperature rise, producing multiple series of input data for the thermodynamic simulations, whose results were statistically analysed. This allowed to evaluate the possible evolution of the thermal structure of the lake, especially considering the hypolimnion heating, the trend in the vertical mixing frequency and the influence of the "climatic memory" of the present state over future conditions
Modelling physical and ecological processes in medium-to-large deep European perialpine lakes: directions of past research and issues to address for the future
No full textDeep intrusions of tributaries are suppressed for increasing winter residual stratification in deep oligomictic perialpine lakes south of the Alps
No full textModelling physical and ecological processes in medium-to-large deep European perialpine lakes: A review
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The climatic characteristics of extreme precipitations for short-term intervals in the watershed of Lake Maggiore
No full textAlpine 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
Using ecohydrological regionalisation to estimate long term series of total nutrient loads flowing into Lake Como from institutional discrete monitoring data
No full textTwo decades of limnological investigation on Lake Como: field data analysis and ecosystem modeling
No full textPossible effects of climate change on the mixing regime of Lake Maggiore and implications for its water quality
No full textCentenary (1930–2023) climate, and snow cover changes in the Western Alps of Italy. The Ossola valley
Full text linkIn this paper, we study centennial trends of climate and snow cover within the Ossola valley, in the Western Italian Alps. We pursue different tests (Mann Kendall MK, bulk, and sequential/progressive MKprog, Linear Regression, also with change point detection, and moving window average MW) on two datasets, namely (i) dataset1, daily temperature, precipitation, snow depth for 9 stations in the area, during 1930-2018, and (ii) dataset2, snow depth and density, measured twice a month (from February 1(st) to June 1(st)) for 47 stations during 2007-2023. We also verify correlation with glacier retreat nearby. In dataset1, we highlight a positive trend for minimum temperature with MK, and Linear Regression. Using MKprog/MW, a negative change of snow cover depth, and duration starting from the late 1980s is found. In dataset2, despite the annual variability in snow cover and 2022-2023 winter drought, we assess the maximum snow water equivalent (SWE) to be delayed with respect to maximum snow depth at high altitude (over a month above 2.700 m a.s.l.), highlighting the effect of settling in decreasing snow depth during spring. We also present a formula linking through Linear Regression the Day of the Year of SWE peak to altitude, relevant to assess the onset of thaw season. Due to the high altitude of the stations, and the paradigmatic nature of the Ossola Valley, hosting Toce River, a main contributor to the Lake Maggiore of Italy, our results are of interest, and can be used as a benchmark for the Italian Alps
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