Modeling the interactions between river morphodynamics and riparian vegetation

The study of river-riparian vegetation interactions is an important and intriguing research field in geophysics. Vegetation is an active element of the ecological dynamics of a floodplain which interacts with the fluvial processes and affects the flow field, sediment transport, and the morphology of the river. In turn, the river provides water, sediments, nutrients, and seeds to the nearby riparian vegetation, depending on the hydrological, hydraulic, and geomorphological characteristic of the stream. In the past, the study of this complex theme was approached in two different ways. On the one hand, the subject was faced from a mainly qualitative point of view by ecologists and biogeographers. Riparian vegetation dynamics and its spatial patterns have been described and demonstrated in detail, and the key role of several fluvial processes has been shown, but no mathematical models have been proposed. On the other hand, the quantitative approach to fluvial processes, which is typical of engineers, has led to the development of several morphodynamic models. However, the biological aspect has usually been neglected, and vegetation has only been considered as a static element. In recent years, different scientific communities (ranging from ecologists to biogeographers and from geomorphologists to hydrologists and fluvial engineers) have begun to collaborate and have proposed both semiquantitative and quantitative models of river-vegetation interconnections. These models demonstrate the importance of linking fluvial morphodynamics and riparian vegetation dynamics to understand the key processes that regulate a riparian environment in order to foresee the impact of anthropogenic actions and to carefully manage and rehabilitate riparian areas. In the first part of this work, we review the main interactions between rivers and riparian vegetation, and their possible modeling. In the second part, we discuss the semiquantitative and quantitative models which have been proposed to date, considering both multi- and single-thread river

Late Pleistocene Lithic Procurement and Geochemical Characterization of the Cerro Kaskio Obsidian Source in South-western Bolivia

Primary questions regarding the foraging behaviour of the first hunter–gatherers who colonized the New World are how they found, procured and utilized high-quality raw materials for manufacturing stone tools. In this paper, we present evidence from the late Pleistocene site of Cueva Bautista in the highlands of south-western Bolivia, which demonstrates that a substantial portion of the recovered stone tool assemblage originated in Cerro Kaskio, a recently discovered obsidian source located 15 km south-west of the site. In addition to describing the geological and geochronological setting, we provide the first geochemical characterization of the Cerro Kaskio source by means of instrumental neutron activation analysis and energy-dispersive X-ray fluorescence. Supported on the technological analysis and archaeometric sourcing of the obsidian lithics found in Cueva Bautista, we discuss the nature of the procurement strategies practised by the earliest mobile hunter–gatherers who explored and colonized the Andean highlands. We conclude that opportunistic lithic resource procurement was probably an important component of the first foraging societies that explored the highland Andes.Fil: Capriles Flores, Jose Mariano. State University of Pennsylvania; Estados UnidosFil: Tripcevich, N.. University of California at Berkeley; Estados UnidosFil: Nielsen, Axel Emil. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; ArgentinaFil: Glascock, Michael D. University of Missouri; Estados UnidosFil: Albarracin Jordan, J.. Universidad Mayor de San Andrés; BoliviaFil: Santoro, C.M.. Universidad de Tarapacá de Arica; Chil