Assessment of stormwater runoff management practices and BMPs under soil sealing: A study case in a peri-urban watershed of the metropolitan area of Rome (Italy).

By 2006, almost 100,000 km2 of EU soil (2.3% of the whole territory) had been sealed, with a per capita quota of 200 m2 of sealed surface for each EU citizen. Italy, in 2016, recorded a soil sealing rate of 2.8% of the entire territory. In this context, the urban expansion which occurred in past decades is considered one of the main causes of the increase in flood frequency and intensity in small catchments, causing both social and financial damage. In the present paper, the positive impact of introducing Best Management Practices (BMPs) at urban scale is assessed, with particular regard to the decreasing of flood prone areas. A suburban watershed of the metropolitan area of Rome has been selected for a study case, as its soil sealing rate can be considered paradigmatic at this scale. Starting from the analysis of rainfall events occurring between 2008 and 2011 which caused millions of euros worth of damage, and using a high resolution data set in a GIS environment, two scenarios, with and without BMP introduction, are evaluated applying a rainfall-runoff model and a bidimensional hydraulic model. From a comparison of the flood maps with and without the introduction of BMPs, it was determined that in 90% of the circumstances the employment of the BMPs would completely remove the hydraulic risk, while in the remaining 10% the BMP would at least reduce the areas subjected to flooding.

Linking phosphorus export and hydrologic modeling: a case study in Central Italy.

Soil erosion is an open topic, not only because soil fertility is lost, but also because nutrients are spilled into water bodies, thereby causing pollution. Research carried out in this field has amply described this process, but the interaction between these factors is complex and experimental research is needed to understand the production of loads of nutrients for different land uses. This paper describes a long-term monitoring case study using high-resolution rainfall data and runoff samples, carried out in the Lake Vico basin (Central Italy) to determine the phosphorus (P) export during erosive rainfall events. State of the art GIS-based basin characterization and advanced rainfall-runoff models are employed in order to describe the relationship between nutrient export and rainfall or runoff time distribution. Results show that the phosphorus export is strongly related to such time distributions, and less to the cumulative amount of rainfall or runoff.

Agricultural nitrate monitoring in a lake basin in Central Italy: a further step ahead towards an integrated nutrient management aimed at controlling water pollution.

Water pollution from point sources has been considerably reduced over the last few decades. Nevertheless, some water quality problems remain, which can be attributed to non-point pollution sources, and in particular to agriculture. In this paper the results of a study intended to assess the consequences, in terms of NO3 water pollution, of growing a crop, whose impact in terms of P pollution is already well known, are presented. The potential consequences, in terms of water pollution from nitrates of a BMP expressly applied to reduce P pollution are also discussed. The study site is the Lake Vico basin, Central Italy, which has suffered a shift in trophic state since the mid 1990s, caused by P compounds used for intensive cultivation of hazelnut trees. The results of the monitoring campaign described in this paper allow to assert that hazelnut tree cropping has probably caused a considerable increase in nitrate concentration in the groundwater, although not in the lake water, because of the specific hydrogeological characteristics of the basin. The main conclusion is that monitoring is essential to single out environmental characteristics peculiar of a specific area, which even the most sophisticated model would not have been able to highlight. This is why monitoring and model simulations should be integrated.