Hydrologic vulnerability to climate change of the Mandrone glacier (Adamello-Presanella group, Italian Alps)

In order to assess the annual mass balance of the Mandrone glacier in the Central Alps an energy-balance model was applied, supported by snowpack, meteorological and glaciological observations, together with satellite measurements of snow covered areas and albedo. The Physically based Distributed Snow Land and Ice Model (PDSLIM), a distributed multi-layer model for temperate glaciers, which was previously tested on both basin and point scales, was applied. Verification was performed with a network of ablation stakes over two summer periods. Satellite images processed within the Global Land Ice Measurements from Space (GLIMS) project were used to estimate the ice albedo and to verify the position of the simulated transient snowline on specific dates. The energy balance was estimated for the Mandrone and Presena glaciers in the Central Italian Alps. Their modeled balances (−1439 and −1503 mm w.e. year−1, respectively), estimated over a 15 year period, are in good agreement with those obtained with the glaciological method for the Caresèr glacier, a WGMS (World Glacier Monitoring Service) reference located in the nearby Ortles-Cevedale group. Projections according to the regional climate model COSMO-CLM (standing for COnsortium for Small-scale MOdeling model in CLimate Mode) indicate that the Mandrone glacier might not survive the current century and might be halved in size by 2050

Data reconstruction and homogenization for reducing uncertainties in high-resolution climate analysis in Alpine regions

Analysis of climatic series needs pre-processing to attain spatial- and time-consistent homogeneity. The latter, in high-resolution investigations, can rely on the strong correlations among series, which in turn requires a strict fulfilment of the quality standard in terms of completeness. Fifty-nine daily precipitation and temperature series of 50 years from Trentino, northern Italy, were pre-processed for climatic analysis. This study describes: (1) the preliminary gap-filling protocol for daily series, based on geostatistical correlations on both horizontal and vertical domains; (2) an algorithm to reduce inhomogeneity owing to the systematic snowfall underestimation of rain gauges; and (3) the processing protocol to take into account any source of undocumented inhomogeneity in series. This was performed by application of the t test and F-test of R code RHtestV2. This pre-processing shows straightforward results; correction of snowfall measurements re-evaluates attribution of patterns of altitudinal trends in time trends; homogenization increases the strength of the climatic signal and reduces the scattering of time trends, assessed over a few decades, of a factor of 2

Hydrological aspects of the Mesoscale Alpine Programme: finding from field experiments and simulations

Proc. International Conference on Alpine Metorology, Zagreb 23-27 Ma

Potential climate change effects on the meteorological forcing and the design efficiency of urban drainage systems

Urban drainage systems design and management are strictly connected to meteorological forcing. For design purposes synthetic forms (e.g. depth duration frequency curves) are usually adopted to represent the meteorological solicitation, while a stochastic representation could be more promptly used to investigate the effects of potential climate change both on the design and on the efficiency of urban drainage devices. A simplified semi-probabilistic approach, relying on simple models of the stochastic rainfall process and of the rainfall-runoff (hydrological) transformation, is expected to be a sound tool. Since the rainfall process is described through the definition of three random variables and their probability distribution, the main advantage is the possibility of changing one, two or more characteristics of the rainfall model at a time. The effect of the change can then be easily evaluated through the application of the hydrological model. The semi-probabilistic approach is applied to study some aspects of the drainage system design for locations in the Italian territory. Potential effects of climate change on fictitious urban basins are evaluated through a rainfall stochastic model calibrated on the basis of long series observations recorded at site. Precipitation climate change scenarios were defined on the basis of both international climate studies report and local meteorological observation analysis. The effects on the urban drainage system are evaluated with respect to specific urban drainage devices and the efficiency of the design procedure in the hypothesis of climate change is finally discussed

Multivariate statistical analysis of flood variables by copulas: two italian case studies

Multivariate statistics are important to determine the flood hydrograph for the design of hydraulic structures and for the hydraulic risk assessment. In the last decade, the copula approach has been investigated in hydrological practice to assess the design flood hydrograph in terms of flood peak, volume and duration. In this paper, the copula approach is exploited to perform pair analyses of these three random variables for two Italian watersheds, in the Apennine and the Alps respectively. The criterion to separate continuous flow series into independent events is discussed along with its implications on the dependence structure. The goodness-of-fits of the proposed copulas are then assessed by non-parametric tests. Marginal distributions to derive joint distributions are briefly suggested. The possibility of generating flood events according to the proposed model and potential applications to hydraulic structure design and flood management are finally examined

HYDROLOGICAL ASPECTS OF THE MESOSCALE ALPINE PROGRAMME: FINDINGS FROM FIELD EXPERIMENTS AND SIMULATIONS

Results of the Mesoscale Alpine Programme provide some answers to basic scientific questions of hydrological relevance posed in its scientific plan i.e: 1. verify the forecasting capabilities of a hydrological flood model, forced by the special measurements or coupled with advanced mesoscale atmospheric prediction models; 2. assess the role of the water storage in reservoirs on the runoff generation during floods in mountainous regions; 3. study the influence of soil moisture conditions prior to flood events in determining the production of runoff and investigate the capabilities and limitations of some soil moisture monitoring techniques over rugged terrain. Summary results from investigations in some areas in the southern (Toce, Ticino, Verzasca and Maggia watersheds) and northern (Ammer watershed) side of the Alps during the Mesoscale Alpine Programme and the 1999 Special Observing Period experiment are presented

Estimate of turbulent fluxes with eddy-covariance technique in a complex topography: A case study in the Italian Alps

A sensitivity analysis to different eddy—covariance data processing algorithms is presented for a dataset collected in an Alpine environment with complex topography. In Summer 2012 a micrometeorological station was installed at Cividate Camuno (274 m a.s.l., Oglio river basin, Central Italian Alps), in a flat and rectangular grass-covered lawn. The grass was 0.6 m tall during most of the field campaign. The station is equipped with traditional devices, four multiplexed TDR probes, and an eddy--covariance apparatus sampling at 20 Hz (Gill WindMaster Sonic Anemometer and Licor Li7500 Gas Analyzer), at about 3 m above the ground. The local winds regime is strongly affected by the morphology of the valley, and the topography is complex also due to the heterogeneity of the surrounding-areas land—cover. Using EddyPro software, the sensitivity of the turbulent fluxes estimate was assessed addressing three major issues of the data processing procedure, i.e. the choice of the computational averaging period, of the axis rotation method and of the data detrending criterion. Once identified three test periods of consecutive days without rainfall, the fluxes of momentum, sensible heat and latent heat were computed at the averaging period of 30, 60 and 120 min respectively. At each averaging period, both the triple rotation method, the double rotation method and the planar fit method were applied. Particularly the latter was applied both fitting a unique plane for all the wind directions and fitting multiple planes, one for each sector of the wind rose. Regarding the detrending criteria, data were processed with a block average and a linear detrend, the latter with time constant of 5, 30, 60 and 120 min respectively. Therefore, for each test period about 50 estimates of the fluxes were provided. As a result the obtained fluxes were compared. Even if with different flux quality, their pattern is quite stable with regard to the applied estimate procedures, but with sensitively different average values

Failure Probability Analysis of Levees Affected by Mammal Bioerosion

Mammal bioerosion is an emergent threat to the functionality of levees. In the present paper, the problem of assessing the failure probability of levees affected by mammal bioerosion is addressed. A fully bivariate description of peak flow discharge and flood duration is combined with a deterministic unsteady seepage flow model to obtain a suitable model of variably disturbed levee response to the observed natural variability of floods. Monte Carlo analysis is also implemented to evaluate the epistemic uncertainty connected to the description of the river system. The obtained model is tested with respect to a real-world levee located along the Secchia River in northern Italy, which underwent a disastrous failure caused by mammal bioerosion in 2014. The convex linear combination of two Archimedean copulas is found to fit the empirical dependence structure between peak flow discharge and flood duration. The reliability of the unsteady seepage flow model is tested against detailed numerical simulations of the seepage occurring through the levee body. A limit state function is obtained by comparing the maximum extent of the seepage front to the distance between the den end and the riverside levee slope, and the corresponding levee safety and failure regions are delimited. Results obtained from the developed model reveal a significant impact of mammal dens located near the levee crest in terms of failure probability and related return period. This impact is consistent with failures observed in the study area