Multiscale Hydrogeomorphometric Analysis for Fluvial Risk Management. Application in the Carrión River, Spain

The sustainable management of fluvial systems requires reliable knowledge of the mechanisms that control the basins and their drainages, which in turn must be prioritized for the application of measures for flood-risk reduction. Thus, given the need to develop methodological frameworks capable of integrating remote sensing technologies at different scales, as well as traditional metrics and anthropic variables, in this study, a multiscale method is proposed for the characterization and prioritization of river stretches for fluvial risk management. This methodology involves the study of drivers at the watershed level, and a detailed morphometric and hydrogeomorphological analysis of the main channel for fluvial landscape classification, segmentation, and aggregation into units, considering also anthropic variables. Therefore, it includes the use of LiDAR data and exploration GIS tools, whose results are corroborated through fieldwork, where ephemeral and topographic evidence of fluvial dynamics are collected. The procedure is validated in the Carrión river basin, Palencia, Spain, where a high degree of maturity and geomorphological development are determined. Hence, the main channel can be classified into eight geomorphic units and divided into homogeneous segments, which, according to categorical elements such as urban interventions, are prioritized, obtaining, as a result, six stretches of main interest for river risk management.

Quaternary formations mapping in the region of Volta Grande do Rio Uruguai (Brazil)

Quaternary formations (detrital and weathered materials) are an important natural resource for different areas of scientific investigation, from understanding their relation to erosive processes and morphodynamic processes that create landforms or to understanding the history of the first human settlements (geoarcheology). Quaternary coverings can be formed in situ or be transported by external geologic agents. Regarding soils, Quaternary formations are related to landscape topography and are transformed according to the characteristics of this topography. Hence, classifying and mapping these soils is not always easy. The present article aims to map the Quaternary formations along a stretch of the Uruguay River basin known as Volta Grande (SC/RS-Brazil), by using topographic attributes derived from the SRTM GL1-Up Sampled digital elevation model, soil particle-size analysis, and a generated Multiresolution Index of Valley Bottom Flatness (MRVBF) index . The results of the analysis show that: (i) colluvium is the predominant Quaternary formation in the study area; (ii) there is a predominance of clay, corroborating previous studies of the region; (iii) the spatial distribution of the study area’s Quaternary formations reflect local slope dynamics based on morphology and topographic position; and, (iv) the existence of colluvium-alluvium on the Uruguay River’s banks indicates that slope attributes contributed to the pedogeomorphological dynamics of the study area and not only fluvial dynamics. Based on the results, the methodology applied in this study might be useful for pedogeomorphological studies, notably in the analysis and mapping of Quaternary formations, despite some of its limitations.

Eunotia Ehrenberg (Eunotiaceae, Bacillariophyta) in a subtropical floodplain: a new species and taxonomic contributions

The Upper Paraná River floodplain is one of the few remaining non-dammed stretches in Brazil. It has a typical fluvial dynamics represented by the flood pulse and a highly complex habitat, which allows the existence and maintenance of a great biodiversity, including diatom species. As it happens in tropical lowland environments, also in this floodplain, the genus Eunotia is one of the most diverse and abundant diatom groups. Therefore, this study addresses morphologic and morphometric details of a new species and the most abundant Eunotia species in sediment cores from two wetland lakes. The morphological characteristics from each species were obtained through microscopy documentation of cell walls, and compared with other related species.

Spatial planning and flood risk: The case of the Buna River, Shkoder, Albania

<p>In the last years, Albania underwent a rapid development, which resulted in an uncontrolled building boom and general land degradation. For these reasons, an ever-greater portion of the Albanian population is exposed to natural risks, whose major threats are represented by floods and earthquakes. Spatial planning and hydraulic risk management are a worldwide necessity which is best achieved when natural and artificial elements located closely to watercourses are known in detail. A geodatabase is a practical tool to store and manage such information. Land use and land cover changes have negative consequences on watershed management in Buna River Basin. They increase impervious ground surfaces, decrease infiltration rate and increase runoff rate, hence causing flood during the dry seasons. This study was undertaken to achieve the natural and artificial elements connected to hydraulic risk and fluvial dynamics in Buna River. Through a GIS overlay and GPS measurements where mapped elements include buildings, hydraulic works, weirs, drainage outlets, riverbanks, structural damages, fluvial bars and eroding banks. Consequently, a GIS geo database was built to visualize the spatial distribution of the mapped elements and to store a series of technical data, including the present preservation condition for man-made objects. GPS data was integrated in GIS to examine the extent of land use and cover change in the sub catchment of Buna River. Both quantitative and qualitative data were used for this study.  The geo database provides an overview of the territories connected with the fluvial dynamics, highlighting that in the studied territory; the more is urbanized, the more it is exposed to hydraulic risk.</p><p><strong>Key word;</strong> spatial planning, natural hazards, relief drill, Buna river, Shkoder.</p>