Few Italian rivers today can be considered to be in a natural state. Since humans have colonized ... more Few Italian rivers today can be considered to be in a natural state. Since humans have colonized this region, they have strongly interacted with the rivers and their natural dynamics by shaping their morphology and using the landscape. Exploitation of natural resources has been so extensive that today only small areas of the landscape and of the rivers that flow through it can be considered natural. Italian rivers comprise a diversity of fluvial ecosystems, ranging from Alpine glacier-fed streams to ephemeral Mediterranean streams and from large rivers, such as the Po, to spring-fed brooks and artificial canals. They all flow through densely populated areas. Although Italy is rich in water resources, the distribution is uneven, with the majority occurring in the north (65%), 15% in the centre, 12% in the south, and 8% in the main islands. Because of this variability, this chapter focuses on the Po River, which forms the largest Italian plain and covers ∼24% of Italy. Other Alpine rivers described in the chapter include the Adige, the second longest Italian river, the Tagliamento because of its relatively pristine condition, and the Brenta River because of its historical role in the region and as an example of a river with a mix of natural and regulated reaches.
ABSTRACT Managed aquifer recharge (MAR) design and operation must incorporate the expected long-t... more ABSTRACT Managed aquifer recharge (MAR) design and operation must incorporate the expected long-term performance from a water quantity perspective to sustainably mitigate hydrologic impacts of groundwater overexploitation. Gravity driven infiltration ditches in forested areas are one of many MAR scheme that could augment the available water resources. Research on the longevity of these structures is sparse, leading to concerns about their long-term capability to sustain elevated infiltration capacity. In the present study, an infiltration system consisting of a regular grid of eight ditches divided into 4 sequential plots within a short rotation forested area (AFI) was monitored from its inception to determine its hydrologic performance over time and its possible export to similar areas of the Brenta Megafan (Northern Italy). During the monitored period, the AFI was not significantly affected by clogging since the suspended solids carried by the Brenta River water diversion were extremely low. The main source of clogging was the fallen foliage during the autumn, easily managed via ordinary maintenance. The AFI displayed an almost constant performance to infiltrate the diverted water over the first three years of operation, with a total amount of infiltrated water of approximately 0.8 Mm3/ha/y. The best tracer to reconstruct the downward water movement through this highly permeable vadose zone was temperature, while the groundwater table fluctuation could not be confidently used to infer the effective infiltration, because of its large seasonal variability. The good results suggest that promoting this technique in other areas of the Brenta Megafan that suffer from groundwater resources depletion. This article is protected by copyright. All rights reserved.
Page 1. WFD AND FLEA FLUVIAL ECOSYSTEM ASSESSMENT CIRF discussion paper May 2008 1 THE WATER ... more Page 1. WFD AND FLEA FLUVIAL ECOSYSTEM ASSESSMENT CIRF discussion paper May 2008 1 THE WATER FRAMEWORK DIRECTIVE: A SOAP BUBBLE? AN INTEGRATIVE PROPOSAL: FLEA (FLUVIAL ECOSYSTEM ASSESSMENT) ...
ABSTRACT This study focuses on the short groundwater residence time induced by the development of... more ABSTRACT This study focuses on the short groundwater residence time induced by the development of a dense rooting system in a forested area employed as a buffer zone planned for nitrogen removal. The buffer zone consists of a rectangular area of 0·7 ha sub-irrigated by two ditches and drained by an outflow ditch lying in the centre of the area. The pristine soil (silty clay loam) was characterized by a low hydraulic conductivity, but the agricultural practice first, and then the rooting system increased the permeability of the top soil. This was confirmed by the elevated discharge in the outflow ditch and by the elevated hydraulic conductivity values determined via slug tests. The groundwater residence time was monitored, once the rooting system was completely developed, via Rhodamine-WT injection in the inflow ditch. The breakthrough curves were simulated using a one-dimensional analytical model (CXTFIT) to calculate the residence time. In addition, a three-dimensional flow and transport model (MODFLOW and MT3DMS) was calibrated using piezometric heads, groundwater fluxes and Rhodamine-WT concentrations. The CXTFIT model overestimated the dispersivity and underestimated velocity respect to MT3DMS. This study shows that residence time can decrease respect to the value expected from the hydraulic conductivities of the pristine soils and that one-dimensional analytical models can give a false impression compared with soil parameters respect to three-dimensional flow and transport models. Given the importance of the residence time for biological processes in buffer zones, a greater effort is needed to improve measurement techniques on subsurface flow's heterogeneity.
Few Italian rivers today can be considered to be in a natural state. Since humans have colonized ... more Few Italian rivers today can be considered to be in a natural state. Since humans have colonized this region, they have strongly interacted with the rivers and their natural dynamics by shaping their morphology and using the landscape. Exploitation of natural resources has been so extensive that today only small areas of the landscape and of the rivers that flow through it can be considered natural. Italian rivers comprise a diversity of fluvial ecosystems, ranging from Alpine glacier-fed streams to ephemeral Mediterranean streams and from large rivers, such as the Po, to spring-fed brooks and artificial canals. They all flow through densely populated areas. Although Italy is rich in water resources, the distribution is uneven, with the majority occurring in the north (65%), 15% in the centre, 12% in the south, and 8% in the main islands. Because of this variability, this chapter focuses on the Po River, which forms the largest Italian plain and covers ∼24% of Italy. Other Alpine rivers described in the chapter include the Adige, the second longest Italian river, the Tagliamento because of its relatively pristine condition, and the Brenta River because of its historical role in the region and as an example of a river with a mix of natural and regulated reaches.
ABSTRACT Managed aquifer recharge (MAR) design and operation must incorporate the expected long-t... more ABSTRACT Managed aquifer recharge (MAR) design and operation must incorporate the expected long-term performance from a water quantity perspective to sustainably mitigate hydrologic impacts of groundwater overexploitation. Gravity driven infiltration ditches in forested areas are one of many MAR scheme that could augment the available water resources. Research on the longevity of these structures is sparse, leading to concerns about their long-term capability to sustain elevated infiltration capacity. In the present study, an infiltration system consisting of a regular grid of eight ditches divided into 4 sequential plots within a short rotation forested area (AFI) was monitored from its inception to determine its hydrologic performance over time and its possible export to similar areas of the Brenta Megafan (Northern Italy). During the monitored period, the AFI was not significantly affected by clogging since the suspended solids carried by the Brenta River water diversion were extremely low. The main source of clogging was the fallen foliage during the autumn, easily managed via ordinary maintenance. The AFI displayed an almost constant performance to infiltrate the diverted water over the first three years of operation, with a total amount of infiltrated water of approximately 0.8 Mm3/ha/y. The best tracer to reconstruct the downward water movement through this highly permeable vadose zone was temperature, while the groundwater table fluctuation could not be confidently used to infer the effective infiltration, because of its large seasonal variability. The good results suggest that promoting this technique in other areas of the Brenta Megafan that suffer from groundwater resources depletion. This article is protected by copyright. All rights reserved.
Page 1. WFD AND FLEA FLUVIAL ECOSYSTEM ASSESSMENT CIRF discussion paper May 2008 1 THE WATER ... more Page 1. WFD AND FLEA FLUVIAL ECOSYSTEM ASSESSMENT CIRF discussion paper May 2008 1 THE WATER FRAMEWORK DIRECTIVE: A SOAP BUBBLE? AN INTEGRATIVE PROPOSAL: FLEA (FLUVIAL ECOSYSTEM ASSESSMENT) ...
ABSTRACT This study focuses on the short groundwater residence time induced by the development of... more ABSTRACT This study focuses on the short groundwater residence time induced by the development of a dense rooting system in a forested area employed as a buffer zone planned for nitrogen removal. The buffer zone consists of a rectangular area of 0·7 ha sub-irrigated by two ditches and drained by an outflow ditch lying in the centre of the area. The pristine soil (silty clay loam) was characterized by a low hydraulic conductivity, but the agricultural practice first, and then the rooting system increased the permeability of the top soil. This was confirmed by the elevated discharge in the outflow ditch and by the elevated hydraulic conductivity values determined via slug tests. The groundwater residence time was monitored, once the rooting system was completely developed, via Rhodamine-WT injection in the inflow ditch. The breakthrough curves were simulated using a one-dimensional analytical model (CXTFIT) to calculate the residence time. In addition, a three-dimensional flow and transport model (MODFLOW and MT3DMS) was calibrated using piezometric heads, groundwater fluxes and Rhodamine-WT concentrations. The CXTFIT model overestimated the dispersivity and underestimated velocity respect to MT3DMS. This study shows that residence time can decrease respect to the value expected from the hydraulic conductivities of the pristine soils and that one-dimensional analytical models can give a false impression compared with soil parameters respect to three-dimensional flow and transport models. Given the importance of the residence time for biological processes in buffer zones, a greater effort is needed to improve measurement techniques on subsurface flow's heterogeneity.
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