Recent progress has been made in quantifying snowmelt in the Himalaya. Although the conditions are favorable for refreezing, little is known about the spatial variability of meltwater refreezing, hindering a complete understanding of seasonal snowmelt dynamics. This study aims to improve our understanding about how refreezing varies in space and time. We simulated refreezing with the seNorge (v2.0) snow model for the Langtang catchment, Nepalese Himalaya, covering a 5-year period. Meteorological forcing data were derived from a unique elaborate network of meteorological stations and high-resolution meteorological simulations. The results show that the annual catchment average refreezing amounts to 122 mm w.e. (21% of the melt), and varies strongly in space depending on elevation and aspect. In addition, there is a seasonal altitudinal variability related to air temperature and snow depth, with most refreezing during the early melt season. Substantial intra-annual variability resulted from fluctuations in snowfall. Daily refreezing simulations decreased by 84% (annual catchment average of 19 mm w.e.) compared to hourly simulations, emphasizing the importance of using sub-daily time steps to capture melt–refreeze cycles. Climate sensitivity experiments revealed that refreezing is highly sensitive to changes in air temperature as a 2°C increase leads to a refreezing decrease of 35%.

The Amundsen Sea embayment is a probable site for the initiation of a future collapse of the West Antarctic Ice Sheet. This paper contributes to a better understanding of the transport pathways of subglacial sediments into this embayment at present and during the last glacial period. It discusses the clay mineral composition of sediment samples taken from the seafloor surface and marine cores in order to decipher spatial and temporal changes in the sediment provenance. The most striking feature in the present-day clay mineral distribution is the high concentration of kaolinite, which is mainly supplied by the Thwaites Glacier system and indicates the presence of hitherto unknown kaolinite-bearing sedimentary strata in the hinterland, probably in the Byrd Subglacial Basin. The main illite input is via the Pine Island Glacier. Smectite originates from the erosion of volcanic rocks in Ellsworth Land and western Marie Byrd Land. The clay mineral assemblages in diamictons deposited during the last glacial period are distinctly different from those in corresponding surface sediments. This relationship indicates that glacial sediment sources were different from modern ones, which could reflect changes in the catchment areas of the glaciers and ice streams.

In this paper, an artificial neural network (ANN) based on hybrid algorithm combiningparticle swarm optimization (PSO) with back-propagation (BP) is proposed to forecast thedaily streamflows in a catchment located in a semi-arid region in Morocco. The PSOalgorithm has a rapid convergence during the initial stages of a global search, while theBP algorithm can achieve faster convergent speed around the global optimum. By combiningthe PSO with the BP, the hybrid algorithm referred to as BP-PSO algorithm is presented inthis paper. To evaluate the performance of the hybrid algorithm, BP neural network is alsoinvolved for a comparison purposes. The results show that the neural network model evolvedby PSO-BP algorithm has a good predictions and better convergence performances

We investigated spatial distribution of lianas, and examined relationships between distribution and topography in a secondary forest on the northern part of the main island of Okinawa, south-west Japan. All lianas with a stem diameter exceeding 2 cm at a point 1.3 m from the root were inventoried, and stem diameter and root position were measured within a small watershed (16.0625 ha). Geographical information systems (GIS) were used to divide the watershed into 257 cells in total, each cell being 25 m × 25 m. Three topographic parameters were measured in each cell: slope angle, slope aspect and relief. In total, 930 stems from 20 species of lianas were recorded. Distribution of all liana stems and 14 of 15 species analysed were biased toward concave sites. Abundance of total lianas was higher in concave sites than in convex sites. Our results suggest that distribution and abundance of lianas are strongly affected by topography, and that lianas tend to be distributed in sites with more water and nutrients, which are formed by relief in the Okinawa forest. Factors affecting stem density differed among species.

Natural flood plains are among the most biologically productive and diverse ecosystems on earth. Globally, riverine flood plains cover > 2 × 106 km2, however, they are among the most threatened ecosystems. Floodplain degradation is closely linked to the rapid decline in freshwater biodiversity; the main reasons for the latter being habitat alteration, flow and flood control, species invasion and pollution. In Europe and North America, up to 90% of flood plains are already ‘cultivated’ and therefore functionally extinct. In the developing world, the remaining natural flood plains are disappearing at an accelerating rate, primarily as a result of changing hydrology. Up to the 2025 time horizon, the future increase of human population will lead to further degradation of riparian areas, intensification of the hydrological cycle, increase in the discharge of pollutants, and further proliferation of species invasions. In the near future, the most threatened flood plains will be those in south-east Asia, Sahelian Africa and North America. There is an urgent need to preserve existing, intact flood plain rivers as strategic global resources and to begin to restore hydrologic dynamics, sediment transport and riparian vegetation to those rivers that retain some level of ecological integrity. Otherwise, dramatic extinctions of aquatic and riparian species and of ecosystem services are faced within the next few decades.