ADCP velocity profiles analisys in the Castellammare gulf

Velocity profiles have been collected in three points within the Castellammare gulf at around 1500 m far from the coastline. This area is characterized by the presence of an aquaculture farm that positioned 5 floating cages in this zone. The impact of this activity on the environment strictly depends on the currents and water exchange. The general aim of this research is the characterization of the circulation characteristics of this area. The analysis of the free surface oscillations shows the typical behaviour of tide forcing, with high minima and maxima during the night, due to the higher moon attraction during these hours compared with the morning hours. A prevalent current direction from South-West to North-East has been recorded at each depth. This direction is almost parallel to the coastline. This behaviour is probably determined by morphology of the area and the general circulation of the Castellammare gulf

Floodability: A New Paradigm for Designing Urban Drainage and Achieving Sustainable Urban Growth

For a large part of human history, urbanization was focused on two main objectives: defence and resource harvesting. The first objective was always achieved in a broad sense, i.e., defending the population from other humans and from natural events. Focusing on human activities, this defensive approach was also applied to urban drainage, which resulted in a systematic underestimation of the impacts of urbanization on natural systems. Environmental sustainability was introduced in an attempt to mitigate these impacts, as they had the potential to endanger future developments; thus, the possibility that urban floods may be the lesser evil was accepted. Resilience was then introduced to improve not only defence of urban areas but also their ability to recover from negative events, even though physical resilience is not always accompanied by social resilience. This paper attempts to address the philosophy of urban drainage design, introducing the new concept of floodability as an evolution of flood resilience by identifying its requirements and drivers and by using real examples to present the new concept

Soil moisture limiting olive orchard evapotranspiration

Two years of field data concerning soil moisture dynamics and water vapor fluxes over a rainfed olive orchard in Sicily are presented here in order to understand how climate, seasonality, water availability and farming practices drive evapotranspiration in such a peculiar Mediterranean vegetation. Soil moisture has been measured in two different points characterized by a uniformly sandy soil and at multiple depths up to 1.2 m. The observed dynamics are driven by rainfall inputs, which are frequent during the winter season and rare during the growing season, and by vegetation uptakes, which deplete the water stored in the soil. The top layers soil moisture status is much more time dependent and variable than deeper layers, which instead show a smoother signal. Water vapor fluxes have been measured with the eddy covariance method using a sonic anemometer and a gas analyzer set above the canopy. The measured fluxes show a seasonal behavior justified by the vegetation growing activities, which start approximately in April. High evaporative demand is satisfied when soil moisture is not a limiting factor: that happens at the beginning of the growing season and in fall when olive trees are still active and the late summer rainfalls have replenished the soil. Moving through the growing season, when soil water is depleted day by day, the evaporative demand is no more satisfied because of a soil moisture limit. Plants have difficulty in extracting water from the soil, and then reduce their activity by closing the stomata with a consequent reduction of the evapotranspirative fluxes. Fluxes have been found to be also dependent on tillage operations, which remove grass from the soil thus eliminating a cause of water depletion. In this work, soil moisture data and the ratio between actual and potential evapotranspiration has been related in order to depict a single stepwise relation linking water availability in the soil and vegetation evapotranspirative activity

Soil water content assessment: Critical issues concerning the operational application of the triangle method

Knowledge of soil water content plays a key role in water management efforts to improve irrigation efficiency. Among the indirect estimation methods of soil water content via Earth Observation data is the triangle method, used to analyze optical and thermal features because these are primarily controlled by water content within the near-surface evaporation layer and root zone in bare and vegetated soils. Although the soil-vegetation-atmosphere transfer theory describes the ongoing processes, theoretical models reveal limits for operational use. When applying simplified empirical formulations, meteorological forcing could be replaced with alternative variables when the above-canopy temperature is unknown, to mitigate the effects of calibration inaccuracies or to account for the temporal admittance of the soil. However, if applied over a limited area, a characterization of both dry and wet edges could not be properly achieved; thus, a multi-temporal analysis can be exploited to include outer extremes in soil water content. A diachronic empirical approach introduces the need to assume a constancy of other meteorological forcing variables that control thermal features. Airborne images were acquired on a Sicilian vineyard during most of an entire irrigation period (fruit-set to ripening stages, vintage 2008), during which in situ soil water content was measured to set up the triangle method. Within this framework, we tested the triangle method by employing alternative thermal forcing. The results were inaccurate when air temperature at airborne acquisition was employed. Sonic and aerodynamic air temperatures confirmed and partially explained the limits of simultaneous meteorological forcing, and the use of proxy variables improved model accuracy. The analysis indicates that high spatial resolution does not necessarily imply higher accuracies

Modelling flows duration curves in Mediterranean river basins through an ecohydrological approach

The flow duration curve, representing the relationship between magnitude and frequency of streamflows in a basin, provides an important synthesis of the relevant hydrological processes occurring at the basin scale. It is typically obtained from field observations and, since most of the geographical areas of the world still lack suitable streamflow observations, its reconstruction in ungauged river basins is certainly an open and relevant issue in the hydrological literature. Different theoretical approaches have been developed in recent years, and in particular, a novel ecohydrological framework has provided considerable results. The aim of this study is to test with field data, a recent analytical model for the probabilistic characterization of base flows in river basins using few climatic, ecohydrologic and geomorphologic parameters. The base flow is the slow, subsurface contribution to runoff that in many circumstances, such as in the case of relatively flat, vegetated catchments, represents the major runoff component in terms of discharged volumes. The model, coupling soil moisture balances with a simplified scheme of the hydrological response of the basin, provides the probability distribution function of the daily streamflows and the corresponding flow duration curves. The temporal dynamic of the soil water content is seen as the result of deterministic, state dependent loss processes (e.g., evapotranspiration, leakage) and stochastic increments driven by intermittent rainfall forcings. The episodical exceedence of a certain critical level, comprised between the field capacity and complete soil saturation, for the catchment-averaged soil moisture is seen as the triggering mechanism for water release from soil toward the catchment outlet. According to this approach the derived probability density function of slow component of runoff is well described by a Gamma distribution. In this work the original approach, that was structured in a spatially lumped framework by assuming average properties, is considered and opportunely modified to adapt it to the peculiarities of some Mediterranean regions, where catchments are often relatively small and characterized by significant periods with absence of water discharge, especially during the summer. The model is tested using long daily streamflows series recorded in a small catchment located in southern Italy. A sensitivity analysis of the model to the most relevant parameters is also carried out. After performing a procedure to determinate appropriate model parameters, the flow duration curve predicted by the model is compared to the empirical one. Important implications arising from this comparison are here presented and discussed

EHSM: a new conceptual model for daily streamflow simulation under ecohydrological framework

A parsimonious conceptual lumped model is presented here with the aim of simulating daily streamflow in semi-arid areas. The model is able to reproduce surface and sub-surface runoff, soil moisture dynamics and evapotranspirative fluxes, averaged over a basin starting from daily time series of rainfall and temperature and from the initial value of soil. The rainfall is partioned in two components: the first, which interests a totally impermeable area, is routed directly on a superficial linear reservoir, while the second passes through permeable soil. If the rainfall input exceeds the soil storage capacity, which is a function of soil moisture at that specific time, this saturation excess is routed on the superficial reservoir as well. When soil moisture is higher than the field capacity, the model simulates the leakage component, which is described as an instantaneous pulse from the soil bucket to a second deep linear reservoir. The two reservoirs work in parallel with different time of response: the superficial reservoir has a time lag of about 1-2 days, while the deep reservoir is characterized by a lag time of weeks. Soil moisture dynamics, which are crucial in determining how much water could be keep or released as streamflow or leakage, are simulated with a simple bucket model feed by rainfall and depleted by evapotranspiration. The latter component is calculated as a stepwise function of soil moisture. When there is no limitation given by water availability in the soil, basin vegetation evapo-transpires at maximum level, which is a function of daily temperature and crop characteristics. When soil moisture decreases under a critical value (similar to a stomata closure point), evapotranspiration linearly decreases to zero. The model has been calibrated using Montecarlo simulations on 23 Sicilian basins with very different hydrological behavior. This calibration method has allowed to adapt the conceptual model framework to the basin characteristics and at the same time to obtain the set of parameters with the higher efficiency in reproducing historical streamflow. Performances have been compared with the ones obtained with the IHACRES model, which is one of the most used models for daily streamflow simulation in semi-arid catchments. EHSM is able to obtain, on the analyzed basins, performances similar or better than IHACRES using a lower number of parameters. At the same time, the proposed model gives reliable estimate of soil moisture traces and evapotranspiration fluxes, variables very useful in support flood alert models or irrigation models

Errata: Mapping soil water content under sparse vegetation and changeable sky conditions: comparison of two thermal inertia approaches

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Water and Energy Saving in Urban Water Systems: The ALADIN Project

The ALADIN project was aimed at contributing to environmental and energy sustainability of the urban water system by means of a decision support tool able to allow an evaluation of the energy impact related to each different macro-sectors of urban water cycle highlighting the main energy flows and to assess the system energy balance and identify the possible energy-efficient solutions. Moreover the tool suggests the most efficient actions in reducing water losses. In the present paper the main features of the developed tool are presented. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

Multicriteria performance analysis of an integrated urban wastewater system for energy management

The optimization and management of an integrated urban wastewater system is a complex problem involving many processes and variables. The possible control options are defined by several management strategies that may differently impact the economic, operational or environmental performance of the system. The present paper aims to contribute to the environmental and energy sustainability of urban wastewater systems by means of a multicriteria performance analysis. The paper begins with a complete analysis of the system performance in several fields of interest (energy, environment, quality of service, operation, economy and financial resources), and it highlights the management strengths and weaknesses in each subsystem. The analysis was carried out by means of a prototype, developed during the ALADIN project, which enables understanding the system, planning effective improvement actions and assessing their possible effects in each part of the urban water cycle. To demonstrate the potential of such an approach, it was tested on an actual integrated urban wastewater system in Sicily

USING HIGH RESOLUTION RAINGAUGE DATA FOR STORM TRACKING ANALYSIS IN THE URBAN AREA OF PALERMO, ITALY

This paper presents a comparative analysis between rain-gauge storm tracking techniques in order to achieve a better knowledge of the rainfall dynamics over an urbanized area. The temporal and spatial distribution and kinematics of short term rainfall are recognized as one of the most important reasons in error production in rainfall-runoff on urban catchments. The uncertainty due to rainfall variability can greatly affect urban drainage modeling performance and reliability thus reducing the confidence of operators in their results. Modeling representations of urban catchments and drainage systems are commonly adopted for surface flooding forecasting and management and an adequate knowledge of rainfall spatial and temporal variability should be considered as a fundamental step for a robust interpretation of the physical processes that take part in urban areas during intense rainfall events. The starting basis of such studies is usually given by a network of high resolution raingauges disseminated inside and around the examined urban area. One of the raingauge techniques used is based on simulating the storm motion by visualizing the sequence of the rainfall patterns obtained using rain-gauge data and on spatial correlation. The storm speed and direction are obtained using the rain-gauge method by tracking the advance of the maximum rainfall intensity in time and space. A second method is based on the identification, for each gauge, of the time of occurrence of some significant features such the time of onset of a storm or the time of peak. A third method is based on the classical idea of spacetime autocorrelation function; This function describes the way in which the correspondence between the rainfall patterns at two points in space-time reduces as the distance between two points is increased. The analysis has been carried out on the basis given by high resolution rainfall data collected over Palermo urban area (Italy). The urban area has a surface of around 30 km2 and it is mainly distributed on North West – South East direction. The monitoring network is made of 10 tipping bucket raingauges. Bucket volume is equivalent to 0.1 mm rainfall. Raingauges have been uniformly distributed over the urban areas allocating them mainly over public buildings and school in order to allow for easy access. The network has been put in place in January 2006 and it is still working. Data is monthly collected by the operator that also provide for clock synchronization and ordinary maintenance and cleaning. An accurate analysis of the results of this comparison between the techniques has been carried out and, since the city of Palermo is not covered by any meteorological radar, the analysis of storm dynamics will allow to create a system monitoring hydrometeorological conditions which operates on time basis using the information coming from the raingauge network as forecast triggers