Marcello Niedda

• dott.
• Professor (Associate) at University of Sassari

Evaluating the lateral saturated hydraulic conductivity, Ks,l, of soil horizons is crucial for understanding and modelling the subsurface flow dynamics in many shallow hill soils. A Ks,l measurement method should be able to catch the effects of soil heterogeneities governing hydrological processes at the scale of interest, in order to yield Ks,l re...

The lateral saturated hydraulic conductivity, Ks,l, is the soil property that mostly governs subsurface flow in hillslopes. Determinations of Ks,l at the hillslope scale are expected to yield valuable information for interpreting and modeling hydrological processes since soil heterogeneities are functionally averaged in this case. However, these da...

La conducibilità idraulica laterale del suolo saturo, Ks,l, è un parametro fondamentale in quanto controlla i meccanismi di formazione dei deflussi sottosuperficiali nei versanti. Tuttavia, stime di Ks,l ottenute mediante esperimenti condotti alla scala puntuale, come ad esempio tecniche infiltrometriche, potrebbero risultare inappropriate ai fini...

Lakes are sensitive to changes in climate and human activities. Over the last few decades, Mediterranean lakes have experienced various problems due to the current climate change (drought, flood, warming, salt accumulation, water quality changes, etc.), often amplified by water use, intensification of land use activities, and pollution. The overall...

Conversion of Mediterranean maquis and/or natural forest into agropastoral lands is a cause of soil degradation in many Mediterranean areas. Indicators of soil physical quality (SPQ) quantitatively linked to soil hydraulic properties are a valuable tool to assess the effect of land use changes. In this investigation, the Beerkan Estimation of Soil...

Biochar represents a soil conditioner that can change the physical and hydraulic properties of the soil. To date, little information is available about the biochar-induced changes on physical and hydraulic properties of fine textured soils. Therefore, an evaluation of its effects before the field use is advisable. The main objective of this investiga...

In Mediterranean environments, evaporation is a key component of lake water budgets. This applies to Lake Baratz in Sardinia, Italy, a closed lake that almost dried up in 2008 after a succession of years with low seasonal rainfall. We used the energy budget method and Penman’s equation to estimate evaporation over Lake Baratz. We measured, using a...

Sommario La piena improvvisa verificatasi il 18 Novembre 2013 in Sardegna è esaminata come prototipo degli eventi alluvionali del Mediterraneo occidentale per la caratterizzazione del rischio di piena alla scala di piccolo e medio bacino idrografico. La disponibilità di stime di precipitazione ad alta risoluzione spazio-temporale, ottenute da osser...

In Mediterranean environments, evaporation is a key component of lake water budgets. This applies to Lake Baratz in Sardinia, Italy, a closed lake that almost dried up in 2008 after a succession of years with low seasonal rainfall. We used the energy budget method and Penman's equation to estimate evaporation over Lake Baratz. We measured, using a...

Many hillslopes covered with maquis in the semi-arid Mediterranean environment have been cleared in recent decades. There is little information on what effect this has on the hydrology of the soil. We compared the hydraulic properties of the soil and the subsurface hydrological dynamics on two adjacent sites on a hillslope. One site was covered wit...

In the semi-arid Mediterranean environment, the rainfall–runoff relationships are complex because of the markedly irregular patterns in rainfall, the seasonal mismatch between evaporation and rainfall, and the spatial heterogeneity in landscape properties. Watersheds often display considerable non-linear threshold behavior, which still make runoff...

On November 18, 2013, the North-Eastern part of Sardinia was impacted by extreme flash flooding, which killed 19 people and caused up to 1 billion Euro damage. The flooding was associated with an extratropical cyclone in the western Mediterranean Basin, named Cyclone Cleopatra which developed slow-moving embedded thunderstorm complexes, as cold air...

Sommario La conducibilità idraulica alla saturazione, KS, è un parametro fondamentale per la simulazione del flusso idrico nel suolo. La memoria illustra un approccio sperimentale per la stima della KS laterale alla scala di versante. La metodologia proposta è stata applicata in due aree contigue ricoperte, rispettivamente, da macchia mediterranea...

Although crop residue management is known to affect near-surface soil physical quality, little is known about the temporal variability of these indicators over short time intervals. This study evaluates the temporal changes of nine indicators of soil physical quality. These are organic carbon content, structural stability index, bulk density, macro...

Lake water levels are sensitive sentinels of changes in the climate and landscape of the broader lake catchment. This means that lakes can be useful for quantifying the effects of these changes on the water yield of a catchment. This study presents a water balance model of a closed catchment-lake system in the semi-arid Mediterranean climate over t...

Biochar has been reported to improve soil physical properties, such as bulk density, water retention, porosity and penetration resistance. However, compared to these properties, little is known about the impact of biochar addition on soil hydraulic conductivity, especially for fine-textured soils. In this study we evaluated the impact of biochar am...

Data collected in 4 years of field observations were used in conjunction with continuous simulation models to study, at the small‐basin scale, the water balance of a closed catchment‐lake system in a semi‐arid Mediterranean environment. The open water evaporation was computed with the Penman equation, using the data set collected in the middle of t...

No-tillage (NT) is an alternative way of reducing costs and lessening the burden of working the land, but in essence it is a method of sustainable land use in dryland cropping systems. The physical quality of the soil is the fundamental factor that defines the sustainability of agro-ecosystems, and its evaluation can be obtained using both capaciti...

In recent decades the hydrological community has increasingly improved its understanding of the runoff generation in river basins. Since Horton (1933), numerous studies have investigated these mechanisms at the plot, hillslope and catchment scale (e.g.: Betson, 1964; Dunne and Black, 1970; Pilgrim et al ., 1978; Kirkby, 1978; Mosley, 1979; Beven, 1...

This experimental research compares the physical and hydraulic properties of two adjacent soils, one covered with a native forest of Mediterranean maquis, and the other with spontaneous grass. The latter replaced the previous natural forest. The aim is to quantify the significant differences in the soil properties caused by the removal of the natur...

Many of the hydrological and ecological functions of alluvial flood plains within watersheds depend on the water flow exchanges between the vadoze soil zone and the shallow groundwater. The water balance of the soil in the flood plain is investigated, in order to evaluate the main hydrological processes that underlie the temporal dynamics of soil m...

Root reinforcement is considered in many situations an important effect of vegetation for slope stability. In the past 20 years many studies analyzed root reinforcement in laboratory and field experiments, as well as through modeling frameworks. Nearby the important contribution of roots to shear strength, roots are recognized to impart stabilizati...

Environmental monitoring was carried out in order to investigate the role of topsoil, rock matrix and fractures in controlling the water flow in unsaturated zone of calcareous rocks and in determining the timing and the magnitude of groundwater recharge. A comprehensive dataset of climate data, soil moisture and rock pressure heads was used to eval...

In land use planning along river paths it may be useful to consider the statistics of the flooding process of the river. The set of rules regulating land use planning in Italy results in the return period required being very long and, as a result, there are very high river discharge peaks which are taken into consideration and not much possibility...

Environmental monitoring and hydrodynamic studies were carried out to understand the forcing mechanisms that are responsible for the circulation patterns of the several small coastal lagoons of Sardinia, in the center of the Mediterranean Sea, Italy. The water level observed in the Calich lagoon showed a free-surface oscillation with a semidiurnal...

The effects of topography resolution on upscaling point-scale processes and parameters on watershed hydrology numerical routing are investigated. Parsimonious continuous simulation was applied to two forested catchments with shallow and sloping soils, one medium (123 km2) and one small-sized (4.5 km2), where saturation-excess runoff prevails. The c...

A coupled ground-water/channel flow distributed model has been developed for continuous simulation in a 123-km(2) basin. The aim was to analyze the streamflow generation processes in natural vegetated environments. Finite-difference schemes have been used to solve conservation equations of the 2D saturated subsurface flow and the 1D kinematic surfa...

Dealing with significantly large design problems for water-resource systems a mixed optimization procedure based on network linear programming and the subgradient method will be described. Using a linear problem formulation, the procedure uses network linear programming as a subproblem that assumes the knowledge of design variables. Since inside it...

The research concerns the potential applications of data extracted from topographic maps with GIS for the study of the main physical relations between channel network structures and the runoff generation at the basin scale. It deals with the methodology set up for the automatic channel network extraction, according to the link-based approach, using...