As with most Italian rivers, the Reno River has a long history of human modification, related also to morphological changes of the lower Po River since Roman times, but in the last decades, significant land use changes in the headwaters, dam construction, torrent control works and extensive bed material mining have caused important channel morphology and sediment budget changes. In this paper, two main types of channel adjustment, riverbed incision and channel narrowing, are analysed. Riverbed degradation is discussed by comparing four different longitudinal profiles surveyed in 1928, 1951, 1970 and 1998 in the 120 km long reach upstream of the outlet. The analysis of channel narrowing is carried out by comparing a number of cross-sections surveyed in different years across the same downstream reach. Field sediment transport measurements of seven major floods that occurred between 2003 and 2006 are compared with the bedload transport rates predicted by the most renowned equations. The current low bedload yield is discussed in terms of sediment supply limited conditions due to land use changes, erosion-control works and extensive and out of control bed material mining that have affected the Reno during the last decades

A set of indices was developed in order to classify the vulnerability of agricultural land to water and nitrogen losses (LOS), setting a basis for the integrated water resources management in agricultural systems. To calibrate the indices using multiple regression analysis, the simulation results of GLEAMS model for combinations of different soil properties, topography and climatic conditions of a reference field-crop were used as “observed values”. GLEAMS quantified (i) the annual losses of the percolated water beneath the root zone, (ii) the annual losses of the surface runoff, (iii) the annual losses of the nitrogen leaching beneath the root zone and (iv) the annual losses of nitrogen through the surface runoff, which were used to calibrate the following indices LOSW-P, LOSW-R, LOSN-PN and LOSN-RN, respectively. All the simulations to gain the LOS indices were carried out for the same reference field-crop, the same nitrogen fertilization and the same irrigation practice, in order to obtain the intrinsic vulnerability of agricultural land to water and nitrogen losses. The LOS indices were also combined to derive nitrogen concentrations in the percolated and in the runoff water. Finally, the connection of LOS indices with the groundwater was performed using an additional equation, which determines the minimum transit time of the percolated water to reach the groundwater table

No abstract

Nitrogen fertilizers used in agriculture often cause nitrate leaching towards shallow groundwater, especially in lowland areas where the flat topography minimize the surface run off. In order to introduce good agricultural practices that reduce the amount of nitrate entering the groundwater system, it is important to quantify the kinetic control on nitrate attenuation capacity. With this aim, a series of anaerobic batch experiments, consisting of loamy soils and nitrate-contaminated groundwater, were carried out using acetate and natural dissolved organic matter as electron donors. Acetate was chosen because it is the main intermediate species in many biodegradation pathways of organic compounds, and it is a suitable carbon source for denitrification. Sorption of acetate was also determined, fitting a Langmuir isotherm in both natural and artificially depleted organic matter soils. Experiments were performed in quadruplicate to account for the spatial variability of soil parameters. The geochemical code PHREEQC (version 2) was used to simulate kinetic denitrification using Monod equation, equilibrium Langmuir sorption of acetate, and equilibrium reactions of gas and mineral phases (calcite). The reactive modeling results highlighted a rapid acetate and nitrate mineralization rate, suggesting that the main pathway of nitrate attenuation is through denitrification while calcite acted as a buffer for pH. However, in the absence of acetate, the natural content of organic matter did not allow to complete the denitrification process leading to nitrite accumulation. Reactive modeling is thought to be an efficient and robust tool to quantify the complex biogeochemical reactions which can take place in underground environments.

The aim of this study is to expand the family of LOS indices for the assessment of the intrinsic nitrogen (N) transformation rates of mineralization, nitrification, denitrification, and ammonia volatilization in agricultural lands. The new indices are added to the two existing ones, which concern N losses through percolation and runoff, in order to provide an integrated aspect of the N budget components of each region based on its intrinsic properties by excluding external factors (e.g., agricultural practices, different crops). This provides a common basis for the classification of N processes' dynamics, since they are expressed in units connected to intensity classes, allowing comparisons among different regions. Their calibration is based on non-linear regression analysis using as "observed values" the simulation results of the GLEAMS model from a theoretical reference field crop. Their combination is used for the assessment of the total annual intrinsic rate of N losses and the degree of fertilization failure, which are calculated as secondary indices. The indices can be applied in a GIS environment with easily accessible data and allow the designation of site-specific best management practices (BMPs) to diminish N losses. Finally, a case study in Ferrara Province in Italy is presented in order to highlight the potentiality of these indices to describe the intrinsic N budget components of the agricultural ecosystems and to support BMPs