2,055 research outputs found
TWINLATIN: Twinning European and Latin-American river basins for research enabling sustainable water resources management. Combined Report D3.1 Hydrological modelling report and D3.2 Evaluation report
Water use has almost tripled over the past 50 years and in some regions the water demand already
exceeds supply (Vorosmarty et al., 2000). The world is facing a “global water crisis”; in many
countries, current levels of water use are unsustainable, with systems vulnerable to collapse from even
small changes in water availability. The need for a scientifically-based assessment of the potential
impacts on water resources of future changes, as a basis for society to adapt to such changes, is strong
for most parts of the world. Although the focus of such assessments has tended to be climate change,
socio-economic changes can have as significant an impact on water availability across the four main
use sectors i.e. domestic, agricultural, industrial (including energy) and environmental. Withdrawal
and consumption of water is expected to continue to grow substantially over the next 20-50 years
(Cosgrove & Rijsberman, 2002), and consequent changes in availability may drastically affect society
and economies.
One of the most needed improvements in Latin American river basin management is a higher level of
detail in hydrological modelling and erosion risk assessment, as a basis for identification and analysis
of mitigation actions, as well as for analysis of global change scenarios. Flow measurements are too
costly to be realised at more than a few locations, which means that modelled data are required for the
rest of the basin. Hence, TWINLATIN Work Package 3 “Hydrological modelling and extremes” was
formulated to provide methods and tools to be used by other WPs, in particular WP6 on “Pollution
pressure and impact analysis” and WP8 on “Change effects and vulnerability assessment”. With an
emphasis on high and low flows and their impacts, WP3 was originally called “Hydrological
modelling, flooding, erosion, water scarcity and water abstraction”. However, at the TWINLATIN
kick-off meeting it was agreed that some of these issues resided more appropriately in WP6 and WP8,
and so WP3 was renamed to focus on hydrological modelling and hydrological extremes.
The specific objectives of WP3 as set out in the Description of Work are
The Glacier Complexes of the Mountain Massifs of the North-West of Inner Asia and their Dynamics
The subject of this paper is
the glaciation of the mountain massifs
Mongun-Taiga, Tavan-Boghd-Ola, Turgeni-
Nuru, and Harhira-Nuru. The glaciation is
represented mostly by small forms that
sometimes form a single complex of domeshaped
peaks. According to the authors,
the modern glaciated area of the mountain
massifs is 21.2 km2 (Tavan-Boghd-Ola),
20.3 km2 (Mongun-Taiga), 42 km2 (Turgeni-
Nuru), and 33.1 km2 (Harhira-Nuru).
The area of the glaciers has been shrinking
since the mid 1960’s. In 1995–2008, the rate
of reduction of the glaciers’ area has grown
considerably: valley glaciers were rapidly
degrading and splitting; accumulation
of morainic material in the lower parts
of the glaciers accelerated. Small glaciers
transformed into snowfields and rock
glaciers. There has been also a degradation
of the highest parts of the glaciers and the
collapse of the glacial complexes with a
single zone of accumulation into isolated
from each other glaciers. Reduced snow
cover area has led to a rise in the firn
line and the disintegration of a common
accumulation area of the glacial complex.
In the of the Mongun-Taiga massif, in 1995–
2008, the firn line rose by 200–300 m. The
reduction of the glaciers significantly lagged
behind the change in the position of the
accumulation area boundary. In the past two
years, there has been a significant recovery
of the glaciers that could eventually lead to
their slower degradation or stabilization of
the glaciers in the study area
Quantifying the role of paleoclimate and Andean Plateau uplift on river incision
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99035/1/jgrf20055-sup-0002-2012JF002533fs02.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99035/2/jgrf20055.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99035/3/jgrf20055-sup-0001-2012JF002533fs01.pd
Latitudinal Variations of Denudation Rates along the Western Andes in South America derived from Cosmogenic Radionuclides
Tectonic, climatic and biotic forces interact and imprint surface processes that shape topographic relief. The combination of chemical weathering and physical erosion on the Earth’s surface is defined as denudation rate. Catchment- averaged denudation rates are one of the main parameters in geological research to quantify surface processes over millennial time scales. The advantage of this method is to identify the characteristics of surface processes previous to human impact. Denudation rates are derived from cosmogenic nuclides which are rare isotopes that are created by cosmic radiation, such as 10Be and 26Al. Cosmogenic nuclides are produced in the atmosphere (meteoric-produced isotopes) or within the mineral structure of different rock material at the surface (in situ-produced isotopes). In situ-produced 10Be is commonly obtained from quartz which is one of the most frequent minerals on the Earth’s surface and, hence, allows a wide range of applications for this method. The identification of dominant natural controls on surface processes in different environmental settings is challenging. With this study, for the first time, this challenge can be solved by including catchment-averaged denudation rates in multivariate statistical-analyses along with tectonic, climatic and biotic catchment parameters. The objective of this thesis is to investigate the dominant natural controls on catchment-averaged denudation rates within different environmental end-members of the Western Andes in South America. The study area covers the environmental end-members reaching from the hyper arid Atacama Desert to the glaciated regions of the Northern Patagonian Ice Fields. The results of this thesis show that local tectonic processes have the highest influence on denudation rates in the arid to hyper arid environments of northern Chile. In between the environmental end-members the effect of vegetation and precipitation on denudation rate varies depending on the initial vegetation-cover amount. In environments with high initial vegetation cover, vegetation is decelerating sediment transportation and is limiting the maximum variation in denudation rates. In the glaciated environment of the Northern Patagonian Ice Field, the latitudinal variation of denudation rates is dependent on the variations in vegetation cover in glaciated and deglaciated catchments
Machine learning based soil maps for a wide range of soil properties for the forested area of Switzerland
Spatial soil information in forests is crucial to assess ecosystem services such as carbon storage, water purification or biodiversity. However, spatially continuous information on soil properties at adequate resolution is rare in forested areas, especially in mountain regions. Therefore, we aimed to build high-resolution soil property maps for pH, soil organic carbon, clay, sand, gravel and soil density for six depth intervals as well as for soil thickness for the entire forested area of Switzerland. We used legacy data from 2071 soil profiles and evaluated six different modelling approaches of digital soil mapping, namely lasso, robust external-drift kriging, geoadditive modelling, quantile regression forest (QRF), cubist and support vector machines. Moreover, we combined the predictions of the individual models by applying a weighted model averaging approach. All models were built from a large set of potential covariates which included e.g. multi-scale terrain attributes and remote sensing data characterizing vegetation cover.
Model performances, evaluated against an independent dataset were similar for all methods. However, QRF achieved the best prediction performance in most cases (18 out of 37 models), while model averaging outperformed the individual models in five cases. For the final soil property maps we therefore used the QRF predictions. Prediction performance showed large differences for the individual soil properties. While for fine earth density the R2 of QRF varied between 0.51 and 0.64 across all depth intervals, soil organic carbon content was more difficult to predict (R2 = 0.19–0.32). Since QRF was used for map prediction, we assessed the 90% prediction intervals from which we derived uncertainty maps. The latter are valuable to better interpret the predictions and provide guidance for future mapping campaigns to improve the soil maps
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