Stefano Ferraris

Università degli Studi di Torino | UNITO · Dipartimento Interateneo di Scienze, Progetto e Politiche Del Territorio

Variations in the extent and duration of snow cover impinge on surface albedo and snowmelt rate, influencing the energy and water budgets. Monitoring snow coverage is therefore crucial for both optimising the supply of snowpack-derived water and understanding how climate change could impact on this source, vital for sustaining human activities and...

The young water fraction (Fyw), defined as the fraction of catchment outflow with transit times of less than about 2–3 months, is increasingly used in hydrological studies, replacing the widely used Mean Transit Time (MTT), which is subject to aggregation error. The use of this new metric in catchment intercomparison studies is helpful to understan...

The Poisson-stopped sum of the Hurwitz–Lerch zeta distribution is proposed as a model for interarrival times and rainfall depths. Theoretical properties and characterizations are investigated in comparison with other two models implemented to perform the same task: the Hurwitz–Lerch zeta distribution and the one inflated Hurwitz–Lerch zeta distribu...

Evapotranspiration is a key variable of the hydrological cycle but poorly studied in Alpine ecosystems. The current study aimed to characterise the impact of topography and temporal variability on actual evapotranspiration (ETa) and its environmental drivers at an Alpine abandoned grassland encroached by shrubs on a steep slope. Eddy covariance, me...

Ecosystems in the Alps are considered hotspots of climate and land use change. In addition, alpine regions are usually characterized by complex morphologies, which make measurement (especially in the long term) of states and fluxes of water, energy and matter particularly challenging. Therefore, there is a limited availability of information and mo...

Climate change increases the occurrence and severity of droughts due to increasing temperatures, altered circulation patterns, and reduced snow occurrence. While Europe has suffered from drought events in the last decade unlike ever seen since the beginning of weather recordings, harmonized long-term datasets across the continent are needed to moni...

The spatial and temporal variability of air temperature, precipitation, actual evapotranspiration (AET) and their related water balance components, as well as their responses to anthropogenic climate change, provide fundamental information for an effective management of water resources and for a proactive involvement of users and stakeholders, in o...

The spatial and temporal variability of temperature, precipitation, actual evapotranspiration and of the related water balance components, as well as their responses to anthropogenic climate change, provide fundamental information for an effective management of water resources. In this study we evaluated the past, present and future quantity of gro...

A peat deposit (Zennare basin, Venice coastland ‐ Italy) was monitored in previous field studies to investigate the hydrological response of organic soil to meteorological dynamics. Field tests and modelling predictions highlighted the risk of the complete loss of this peat layer during the next 50 years, due to oxidation enhanced by the increased...

Soil erosion is affected by rainfall temporal patterns and intensity variability. In vineyards, machine traffic is implemented with particular intensity from late spring to harvest, and it is responsible for soil compaction, which likely affects soil hydraulic properties, runoff, and soil erosion. Additionally, the hydraulic and physical properties...

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, p...

The international debate on resilience has grown around the ability of a community to prepare for and adapt to natural disasters, with a growing interest in holistically understanding complex systems. Although the concept of resilience has been investigated from different perspectives, the lack of understanding of its conceptual comprehensive aspec...

The discrete 3-parameter Lerch distribution is used to analyse the frequency distribution of interarrival times derived from 26 daily precipitation time-series, collected by stations located throughout a 28000 km2 area in NW Italy (altitudes ranging from 113 m to 2170 m a.s.l.). The precipitation regime of these Alpine regions is very different (la...

Studies about turbulent exchanges, momentum and mass transfer and energy balance on mountain slopes allow a better comprehension of the interactions between soil and atmosphere in complex orography. In addition, if long periods of observations are considered, the evolution of energy and mass fluxes can be derived. This is useful for model delicate...

Soil moisture measurement is essential to validate hydrological models and satellite data. In this work we provide an overview of different local and plot scale soil moisture measurement techniques applied in three different conditions in terms of altitude, land use, and soil type, namely a plain, a mountain meadow and a hilly vineyard. The main go...

In this study, we explored the effects of microbial activity on the evaporation of water from cores of a sandy soil under laboratory conditions. We applied treatments to stimulate microbial activity by adding different amounts of synthetic analogue root exudates. For comparison, we used soil samples without synthetic root exudates as control and sa...

Soil management in vineyard inter-rows has a great influence on soil hydraulic conductivity and bulk density, and, consequently, on runoff and soil erosion processes at the field scale. The maintenance of bare soil in vineyard inter-rows with tillage, as well as the tractor traffic, are known to expose the soil to compaction, reduction of soil wate...

In recent years, our understanding of snow gliding and glide-snow avalanches has improved; however, the contributing factors are still poorly understood and difficult to measure. In particular, the role of soil properties has not been considered as much as other environmental parameters (e.g. air temperature). Focusing on soil properties we establi...

The partitioning of crop canopy water may affect soil water distribution and this may in turn affect sprinkler irrigation application efficiency. The aim of this work was to develop a methodology to evaluate spatial and temporal soil water content distribution in the case of sprinkler irrigation application efficiency considering stemflow. Time dom...

Root exudates of both living and artificial origins are known to affect various rhizosphere microbial and micro-faunal activities. However, information on effects on root exudates on soil hydraulic properties responsible for water transmission and distribution in the vadose zone is inadequate, especially in dry soils. To study the effect of artific...

Long-term runoff and soil erosion data have been collected from differently managed field-scale vineyard plots within the "Tenuta Cannona Experimental Vine and Wine Center of Regione Piemonte", located in the Alto Monferrato vine production area (NW Italy). The primary intent of the program was to evaluate the effects of agricultural management pra...

We adopted electromagnetic induction (EMI) and self-potential measurements along irrigation canal bank in order to detect groundwater seepage. The EMI methods is sensitive to the electrical conductivity of the subsoil, that is affected by the salt and clay content and water content. The depth of investigation depends on the soil electrical conducti...

Runoff and soil losses caused by natural rainfall events were monitored over a 12-year period in an experimental vineyard located in Alto Monferrato, a vine-growing area of Piedmont (NW Italy). The measurements were carried out on three plots, each of which was managed with a different inter-row soil management practice: conventional tillage (CT),...

Within scenarios of water scarcity, the irrigation efficiency plays an increasingly strategic role. In this paper, a method that uses an advance-infiltration model based on four field measurements and the soil particle size distribution is proposed to estimate border-irrigation efficiencies. This method was applied to fifteen irrigation events and...

Geophysical surveys can provide useful, albeit indirect, information on vadose zone processes. However, the ability to provide a quantitative description of the subsurface hydrological phenomena requires to fully integrate geophysical data into hydrological modeling. Here, we describe a controlled infiltration experiment that was monitored using bo...

The modeling of unsaturated groundwater flow is affected by a high degree of uncertainty related to both measurement and model errors. Geophysical methods such as Electrical Resistivity Tomography (ERT) can provide useful indirect information on the hydrological processes occurring in the vadose zone. In this paper, we propose and test an iterated...

Erosion and landslides have been identified as two of the major threats that affect European soils. In Italy vineyards cultivated on hill and mountain slopes are frequently affected by intense soil erosion processes and landslides, especially during extreme rainfall events. The management practices adopted in vine cultivation are strictly related w...

Agricultural management influences the rainfall-runoff processes and has relevant effect on soil erosion, especially on hillslope vineyards. Mechanization in the inter-row is particularly important in this issues. Vegetation cover, soil structure modification and crust formation dramatically influence the overland flow. In this work ponded infiltra...

Climate models predict a general future increase in air temperatures and, therefore, an augmentation of water requirements for agricultural purposes. However, without an appropriate management of the water resource, the competition between agriculture and other sectors risk to worsen the water scarcity crisis. Reducing the losses from irrigation ca...

Understanding and characterizing the soil moisture spatial variability and its relevant physical controls is a main challenge in hydrological sciences. In this work we examine the spatial variability characteristics of soil moisture data at 0-30 cm depth collected over three years (2006-2008) on a plot (about 200 m2) in Grugliasco (Po Plain, Northe...

Within the hydrological cycle, actual evaporation represents the second most important process in terms of volumes of water transported, second only to the precipitation phenomena. Several methods for the estimation of the Ea were proposed by researchers in scientific literature, but the estimation of the Ea from potential evapotranspiration often...

Soil moisture is widely recognized as a state variable governing the mass and energy balance between the land surface and the atmosphere. For that, its knowledge is of upmost importance for many applications including flood and landslide prediction. In alpine catchments, soil moisture estimation is a very difficult task, because of complex topograp...

Within the hydrological cycle, actual evaporation represents the second most important process in terms of volumes of water transported, second only to the precipitation phenomena. Several methods for the estimation of the Ea were proposed by researchers in scientific literature, but the estimation of the Ea from potential evapotranspiration often...

Understanding space-time soil moisture variability at various scales is a key issue in hydrological research. At the plot scale soil moisture variability is expected to be explained by physical factors such as soil hydraulic properties, local topography and vegetation cover. This study aims to: i) characterize the spatial and temporal variability o...

Ground-penetrating radar (GPR) and Electrical Resistivity Tomography (ERT) can provide useful indirect information on the dynamic processes occurring in the vadose zone. However, to achieve a quantitative description of soil moisture dynamics, the information content of geophysical observations has to be exploited in a hydrological modeling framewo...

In this work a set of time-series of inter-arrival times of rainfall events, at daily scale, was analysed, with the aim to verify the issue of increasing duration of dry periods. The set consists of 12 time-series recorded at rain gauges in 1926-2005, six of them belong to an Italian Sub-Alpine area (Piedmont) and six to a Mediterranean one (Sicily...

This paper describes how in a clay soil, consolidation and then shear deformation at a constant porosity affect the hydraulic conductivity of the saturated soil. We used a Bishop and Wesley triaxial cell to consolidate the soil along the normal consolidation line and then to shear-deform the soil at a constant porosity to the point where the critic...

The determination of permittivity of sand and clay soil over a wide frequency band can be useful in several applications. Fringing Capacitive sensors can be used to measure the real and imaginary part of the permittivity of materials in the RF and microwave frequency bands. In this paper the use of a commercial capacitive sensor has been exploited...

The objective of the work is to analyse the mass and energy fluxes after a snowfall in a alpine hillslope. It has water sources with water flowing all the year. Also, it faces south-east, therefore it has very fast snowmelt and heating dynamics. Latent and sensible heat fluxes have been measured with a closed path Eddy Covariance station. Photos ha...

We test the ability of three box models (Milly, 1993; Kim et al., 1996; Laio et al., 2001b) to describe soil moisture dynamics in a regularly monitored experimental site in northwestern Italy. The models include increasingly complex representations of leakage and evapotranspiration processes. We force the models with the local rainfall, and we dete...

We propose a finite volume method for the numerical resolution of two-dimensional steady diffusion problems with possibly discontinuous coefficients on unstructured polygonal meshes. Our numerical method is cellcentered, secondorder accurate on smooth solutions and based on a special numerical treatment of the diffusion/dispersion coefficients that...

We evaluate the reliability of the joint use of Ground Penetrating Radar (GPR) and Time Domain Reflectometry (TDR) to map dry snow depth, layering, and density where the snowpack thickness is highly irregular and the use of classical survey methods (i.e., hand probes and snow sampling) is unsustainable.We choose a test site characterised by irregul...

An important method to estimate the permittivity of dielectric materials is based on the measurement of the scat-tering parameters of a TEM (Transverse Electro-Magnetic) waveguide filled by the dielectric to be characterized and on the inversion of the scattering response for the unknown permittivity. This approach is exploited in many applications...

Groundwater flow in variably saturated soils is described by the nonlinear Richards' equation. The mass-conservative finite volume discretization recently proposed in (Adv. Water Resour. 2004; 27:1199–1215) produces a nonlinear algebraic problem, whose resolution demands for the application of an appropriate iterative strategy, such as the Picard o...

The influence of the measurement set-up on the estimation of dielectric permittivity spectra from time-domain reflectometry responses is investigated. The analysis is based on a simplified model of the time-domain reflectometry measurement set-up, where an ideal voltage step is applied to an ideal transmission line that models the probe. The main r...

The influence of the measurement setup on the estimation of dielectric permittivity spectra from time-domain reflectometry (TDR) responses is investigated. The analysis is based on a simplified model of the TDR measurement setup, where an ideal voltage step is applied to an ideal transmission line that models the probe. The main result of this anal...

TDR response properties and their use in the estimation of soil permittivity

Micro-basins are slope management structures built out of earth and stones on hillslopes around cultivated trees (e.g., olive trees) for the harvesting of rainfall and runoff water, and for the rehabilitation of land degraded by water erosion.In this study, the results of an experimental survey for the comparison of soil water content for both insi...

Il progetto " SnowRKnown " , finanziato dalla Fondazione CRT ha avuto lo scopo di investigare il volume idrico equivalente di un manto nevoso di copertura (Snow Water Equivalent-SWE) a scala di bacino con l'utilizzo di metodologie innovative. La stima dello SWE, prodotto tra l'altezza del manto nevoso ed il rapporto fra le densità della neve e quel...

The knowledge of moisture content changes in shallow soil layers has important environmental implications and is fundamental in fields of application such as soil science. In fact, the exchange of energy and water with the atmosphere, the mechanisms of flood generation as well as the infiltration of water and contaminant into the subsurface are pri...

Knowledge of water content is important for water resources management and risk prevention. For areas covered with forest, the presence of decomposed or undecomposed forest litter poses a real problem for the monitoring of volumetric water content. Traditional methods such as time domain reflectometry ( TDR) are difficult to apply, as the inconsist...

The Piedmont plain in the provinces of Turin and Cuneo is characterised by surface irrigation systems. Maize is the most spread crop. The increasing frequency of dry springs and summers has enhanced the scarcity of water for such irrigation systems. The aim of this work is to evaluate the efficiency of surface irrigation in three representative far...

Soil formation is often a very slow process that requires thousands and even millions of years. Human influence, occasionally on a par with the function of climate or geological forces, can accelerate the process and can be viewed as a distinct soil forming factor. This paper describes a soil, Haplic Regosol, in which anthrosolization dominates the...

Soil moisture has a key role for the internal dynamics of ecohydrological systems and for their relationships with the climate system. At continental midlatitudes, soil moisture was recognized as a key variable in determining the strength of summer droughts (Ferranti and Viterbo, 2006). Lack of observations of soil moisture (and evapotranspiration)...

The first results of the "SnowRKnown" project (supported by Fondazione CRT), which investigates the Snow Water Equivalent (SWE) at the basin scale with innovative devices, are presented. The estimation of the SWE, the product between the height of the snow cover and the ratio between snow and water densities, is usually based on punctual measures w...

The purpose of this paper is to test the hypothesis that gradual rather than abrupt increases in strength lead to increased root penetration of strong layers. This was tested experimentally in a model system with multi-layered wax discs with a total thickness of up to 6mm that either increased in strength with depth, or decreased in strength with d...

Knowledge of the soil water retention function is fundamental to quantifying the flow of water and dissolved contaminants in the vadose zone. This function is usually determined by fitting a particular model (see, for example, van Genuchten (1980) or Brooks-Corey (1964)) to observed retention points. Independent of the model chosen, interpretation...

Time Domain Reflectometry (TDR) is widely used to determine the dielectric properties of soils and other materials. This measurement technique is capable of detecting permittivity information on large frequency bandwidth and it is very effective, being cheap, fast and suitable for outdoor applications. Over the last 20 years, a great amount of work...

Peatlands respond to natural hydrologic cycles of precipitation and evapotranspiration with reversible deformations due to variations of water content in both the unsaturated and saturated zone. This phenomenon results in short-term vertical displacements of the soil surface that superimpose to the irreversible long-term subsidence naturally occurr...

Peatlands respond to natural hydrologic cycles of precipitation and evapotranspiration with reversible deformations due to variations of water content in both the unsaturated and saturated zone. This phenomenon results in short-term vertical displacements of the soil surface that superimpose to the irreversible long-term subsidence naturally occurr...

The southernmost part of the Venice Lagoon catchment was progressively reclaimed from marshland starting from the end of the 19th century and finishing in the late 1930s (Figure 1). As a major result, the area was turned into a fertile farmland. At present, the area is kept dry by a distributed drainage system that collects the water from a capilla...

The flow condition in the vadose zone was monitored by taking measurements of the electromagnetic properties of the subsoil (electrical conductivity and permittivity) to estimate the spatial distribution of the volumetric water content. A controlled experiment of 4x1 m2 of pond infiltration was designed and done in a sandy soil; the time-lapse elec...

The solution to the 2-D time-dependent unsaturated flow equation is numerically approximated by a second-order accurate cell-centered finite-volume discretization on unstructured grids. The approximation method is based on a vertex-centered Least Squares linear reconstruction of the solution gradients at mesh edges.A Taylor series development in ti...

The transient and the steady-state single-test tension infiltrometer methods are expected to provide poor hydraulic conductivity K0 estimates in soils situated in the lateral capillarity domain. To evaluate the best strategy for conducting a single-test experiment in these soils, infiltration experiments were numerically simulated for a sandy loam...

The water content of a porous matrix in equilibrium with the soil can be used to calculate the matric potential, provided that moisture retention characteristic of the porous matrix is known (e.g. Or and Wraith 1999; Whalley et al. 2001). However, the development of the sensors raises the question of the sensor response time. In this paper we use a...

A new model for the multidimensional simulation of root growth is presented. It is based on the geometrical description of root activity proposed by Coelho and Or (1996) using normal and log-normal relationships. At each time step the algorithm adds a new small portion of roots using another multidimensional gaussian law constrained on the water av...

The Zennare Basin is part of the southern catchment of the Lagoon of Venice, Italy, reclaimed during the 1930s for agricultural purposes. It is an area that lies almost completely below sea level and is characterized by the presence of peat deposits. Histosol drainage for agricultural practices has enhanced the loss of mass due to oxidation of orga...