Luisa Liucci

A New Application of Flow Duration Curve (FDC) in Designing Run-of-River Power Plants

The present study evaluates the effects of river run-off regime and hydrological uncertainty on the hydroelectric production of a run-of-river power plant. The mean annual energy from a plant was modeled as a function of run-off regime and design flow, by means of a procedure developed on the mean annual Flow Duration Curves (FDCs) of 15 sample basins in the Umbria Region (Central Italy). Results show that energy output decreases from constant to torrential regimes, following a potential function, and that, the greater the design flow, the greater the rate of decrease. The treatment and validation of these results provided a useful tool for easy identification of optimal design flow, according to the hydrological features of the basin and the target hydroelectric production at the station. Analyses of FDCs with a 20-year return period also showed that the decrease in energy production in dry years and its increase in wet years, compared with the mean annual value, are linearly linked to the design flow. In the present context of possible climate change, this result is presented as the possibility of partially controlling the effects of positive or negative flow rate trends. The results reported here can be applied to any kind of river and hydraulic technology at the power station.

Geomorphodiversity index: Quantifying the diversity of landforms and physical landscape

The physical landscape is the mosaic resulting from a wide spectrum of environmental components. The landforms define the variety, or diversity, of the geomorphological component: the geomorphodiversity. Landforms are usually represented in thematic maps where the scale and the graphic solutions are widely heterogeneous. Since geomorphological maps are not always easy to obtain and standardize, topography might be used as a proxy to infer the morphological signature. To recognize, evaluate, and in some cases promote the geomorphodiversity of an area, a numerical assessment is preferable. Through the use of quantitative approaches, indexes can be defined which quantitatively characterize the physical landscape in a discretized space consisting of continuous and regular cells. In this approach each cell is labelled with an algebraic value, which increases with the diversity degree. In this paper a quantitative index for geomorphodiversity is estimated stressing the topographic variables derived from Digital Elevation Models in a GIS environment. The resulting index is the sum of the variety of each terrain parameter taken into account. The areas characterized by the highest value of geomorphodiversity index show a good correspondence with well-known situations in the region where not always the geological heritage is properly acknowledged. The areas characterized by the lowest value of geodiversity correspond to the center of some intermountain basins of the region. Being the index strictly related to the topographic variety, this result is quite obvious but not easily predictable since in some flat areas the index is higher. Comparing the results with the geomorphological map of the area performs a validation procedure for the method. A positive correlation is found between the index calculated and the presence/absence of landforms. The paper shows that the index is a useful and simple tool for the identification, analysis and promotion of the geological heritage.

The Central Italy Seismic Sequence (2016): Spatial Patterns and Dynamic Fingerprints

The paper investigates spatio–temporal aspects of the seismic sequence that started in Central Italy (Amatrice, Lazio region) in August 2016, causing hundreds of fatalities and producing major damage to settlements. On one hand, scaling properties of the landscape topography are identified and related to geomorphological processes, supporting the identification of preferential spatial directions in tectonic activity and confirming the role of the past tectonic periods and ongoing processes with respect to the driving of the geomorphological evolution of the area. On the other hand, relations between the spatio–temporal evolution of the sequence and the seismogenic fault systems are studied. The dynamic fingerprints of seismicity are established with the help of events thread analysis (ETA), which characterizes anisotropy in spatio–temporal earthquake patterns. ETA confirms the fact that the direction of the seismogenic normal fault-oriented (N)NW–(S)SE is characterized by persistent seismic activity. More importantly, it also highlights the role of the pre-existing compressive structures, Neogenic thrust and transpressive regional fronts, with a trend-oriented (N)NE–(S)SW, in the stress transfer. Both the fractal features of the topographic surface and the dynamic fingerprint of the recent seismic sequence point to the hypothesis of an active interaction between the Quaternary fault systems and the pre-existing compressional structures.