A QGIS Plugin for Offshore Wave Hindcasting Based on Geographic Transposition of Wave Gauge Data

Abstract The paper presents a first experimental version of the original QGIS plugin QWaveTransposition that numerically implements the geographic transposition of wave gauge data method proposed by Contini and De Girolamo (1998) for offshore wave hindcasting. The method allows one to transfer wave data measured at a given gauging station to a virtual station located offshore the area of interest, by comparing the effective fetches at both stations. The QWaveTransposition plugin was implemented in Python programming language, including the NumPy package for numerical computations. A graphical user interface was developed to manage the input/output data and model parameters. The fetch geometry at real and virtual stations can be imported by selecting appropriate vector layers from the QGIS map. An application to a sample site in southern Italy is presented for example purposes

Producing a Digital Hydrographic Map Aiming at Renewable Energy Potential Mapping of Lesotho

AbstractSome of the first outcomes of a project aiming at mapping the renewable energy potential in Lesotho are hereby presented. In particular, the present paper deals with the task of the project devoted to produce a digital hydrographic map of Lesotho and an associated geographic database. Different geographical, meteorological and hydrological data were collected in the first steps of the project. The hydrographic network was derived in vector format from a digital elevation model of Lesotho using geoprocessing tools in GIS environment. Results were compared with existing cartography and satellite images. Moreover, a methodology proposed in literature for the assessment of the theoretical maximum hydroelectric producibility at watershed level in Italy was applied to one of the main catchment areas of Lesotho. The activities planned to fulfil the objectives of the project are finally outlined

Assessment of a Simplified Connectivity Index and Specific Sediment Potential in River Basins by Means of Geomorphometric Tools

Sediment connectivity is a major topic in recent research because of its relevance in the characterization of the morphology of river systems and assessing of sediment transport and deposition. Currently, the connectivity indices found in the literature are generally dimensionless and need to be coupled with quantitative soil-loss data for land management and design purposes. In the present work, a simple methodology is proposed to assess two different indices, namely, the simplified connectivity index (SCI) and the specific sediment potential (SSP), based on geomorphometric tools that are commonly available in commercial and open-source geographic information system (GIS) platforms. The proposed metrics allows us to easily assess both the SCI and the SSP as functions of the estimated soil erosion per unit area of the catchment and of the inverse distance of each unit area from the river outlet, this distance being measured along the network path. The proposed indices have been devised to express, respectively, the potential sediment transfer ability and the sediment mass potentially available at a given section of the drainage network. In addition to other parameters used to describe the catchment characteristics potentially affecting the river sediment delivery capacity, the SCI and SSP indices can help to refine theoretical models in order to assess the sediment yield (SY) in ungauged river basins

A Survey near Tambara along the Lower Zambezi River

The paper reports a field investigation on a reach of the lower Zambezi River about 230–240 km downstream of the Cahora Bassa dam in the Republic of Mozambique. In the framework of a wider research program, bathymetric measures of the riverbed were performed on a 10 km stretch of the river using an echo sounder, a GPS receiver, and an integrated navigation-acquisition system. Field observations and measures revealed a general agreement with macro-features of river morphology reported in early literature, dealing with the morphological response of the river to the construction of large dams, in the second half of the 20th century. Results hereby reported are some of the few examples of direct field measures in the lower Zambezi reported in literature, and could be used by researchers and practitioners either as a knowledge base for further surveys or as input data for validation and calibration of mathematical models and remote sensing observations

Investigating the Sediment Yield Predictability in Some Italian Rivers by Means of Hydro-Geomorphometric Variables

In the present work, preliminary results are reported from an ongoing research study aimed at developing an improved prediction model to estimate the sediment yield in Italian ungauged river basins. The statistical correlations between a set of hydro-geomorphometric parameters and suspended sediment yield (SSY) data from 30 Italian rivers were investigated. The main question is whether such variables are helpful to explain the behavior of fluvial systems in the sediment delivery process. To this aim, a broad set of variables, simply derived from digital cartographic sources and available data records, was utilized in order to take into account all the possible features and processes having some influence on sediment production and conveyance. A stepwise regression analysis pointed out that, among all possibilities, the catchment elevation range (Hr), the density of stream hierarchical anomaly (Da), and the stream channel slope ratio (ΔSs) are significantly linked to the SSY. The derived linear regression model equation was proven to be satisfactory (r2-adjusted = 0.72; F-significance = 5.7 × 10−8; ME = 0.61), however, the percentage standard error (40%) implies that the model is still affected by some uncertainties. These can be justified, on one hand, by the wide variance and, on the other hand, by the quality of the observed SSY data. Reducing these uncertainties will be the effort in the follow-up of the research

Relations between Climatic-Geomorphological Parameters and Sediment Yield in a Mediterranean Semi-Arid Area (Sicily, Southern Italy)

In the present work we discuss an on-going research whose primary goal is to test some statistical methods to estimate the average yearly area-specific sediment yield (SSY). Using geomorphological and climatic parameters a series of multiple regression formulae we set up based on a data set containing the SSY information from sixteen catchments of Sicily. Three distinct techniques were adopted to select the parameters to be used in the equations: simple correlation, stepwise regression analysis and a so-called supervised geomorphological-statistical correlation. The comparison of the results showed the effectiveness of the stepwise analysis, which led to a regression equation with a coefficient of determination (r2) of 0.87. Nevertheless, even this methodology showed some elements of uncertainty which have caused , in some cases, appreciable differences between observed and predicted values (mean percentage error equal to 26 %). These differences are likely due either to the hydraulic regime of most of Sicilian watercourses (typical of semi-arid regions ) or to hidden factors (e.g. topography, human impact and concentrated erosion) which can greatly affect the processes of sediment production and transport. The study has pointed out the need to take into account a larger number of observations and to analyse the relations between suitable variables and SSY, at a more detailed time-resolution .JRC.G.3-Econometrics and applied statistic

A Cooperation Project in Lesotho: Renewable Energy Potential Maps Embedded in a WebGIS Tool

In this paper the background, activities undertaken, and main outcomes of the cooperation project “Renewable Energy Potential Maps for Lesotho” are presented. The project was launched in 2018 in fulfilment of the Paris Agreement by the Italian Ministry for the Environment and the Lesotho Ministry of Energy and Meteorology, with the aim to facilitate the local Government in the future planning and development of renewable energy in the country. A user-oriented WebGIS platform was utilised to share and analyse the outcomes of the project: a hydrological map to recognize potential areas for power generation; a wind atlas to identify specific sites with the most potential for wind energy generation; a solar radiation map, defining the different levels of radiation intensity, useful to localise sites for photovoltaic production. Human capacity building and technology transfer were carried out to strengthen the local expertise and ability to manage and plan renewable energy sources exploitation. The implementation of the project was based on a fruitful collaboration between scientists and stakeholders at the same time giving the local authorities a useful dataset and tool for renewable energy growth in Lesotho

Evolution of HIV-1 tropism at quasispecies level after 5 years of combination antiretroviral therapy in patients always suppressed or experiencing episodes of virological failure

Abstract OBJECTIVES: Tropism evolution of HIV-1 quasispecies was analysed by ultra-deep pyrosequencing (UDPS) in patients on first-line combination antiretroviral therapy (cART) always suppressed or experiencing virological failure episodes. METHODS: Among ICONA patients, two groups of 20 patients on cART for 655 years, matched for baseline viraemia and therapy duration, were analysed [Group I, patients always suppressed; and Group II, patients experiencing episode(s) of virological failure]. Viral tropism was assessed by V3 UDPS on plasma RNA before therapy (T0) and on peripheral blood mononuclear cell proviral DNA before-after therapy (T0-T1), using geno2pheno false positive rate (FPR) (threshold for X4: 5.75). For each sample, quasispecies tropism was assigned according to X4 variant frequency: R5, <0.3% X4; minority X4, 0.3%-19.9% X4; and X4, 6520% X4. An R5-X4 switch was defined as a change from R5/minority X4 in plasma/proviral genomes at T0 to X4 in provirus at T1. RESULTS: At baseline, mean FPR and %X4 of viral RNA were positively correlated with those of proviral DNA. After therapy, proviral DNA load significantly decreased in Group I; mean FPR of proviral quasispecies significantly decreased and %X4 increased in Group II. An R5-X4 switch was observed in five patients (two in Group I and three in Group II), all harbouring minority X4 variants at T0. CONCLUSIONS: UDPS analysis reveals that the tropism switch is not an 'on-off' phenomenon, but may result from a profound re-shaping of viral quasispecies, even under suppressive cART. However, episodes of virological failure seem to prevent reduction of proviral DNA and to accelerate viral evolution, as suggested by decreased FPR and increased %X4 at T1 in Group II patients