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Identifying sediment sources by applying a fingerprinting mixing model in a Pyrenean drainage catchment
|Authors:||Palazón Tabuenca, Leticia ; Gaspar Ferrer, Leticia ; Latorre Garcés, Borja ; Blake, William H.; Navas Izquierdo, Ana|
|Citation:||Palazón L, Gaspar L, Latorre B, Blake WH, Navas A. Identifying sediment sources by applying a fingerprinting mixing model in a Pyrenean drainage catchment. Journal of Soils and Sediments 15 (10): 2067-2085 (2015)|
Spanish Pyrenean reservoirs are under pressure from high sediment yields in their contributing catchments. Sediment fingerprinting approaches offer the potential to quantify the contribution of different sediment sources, evaluate catchment erosion dynamics and develop management plans to tackle, among other problems, reservoir siltation. Within this context, the objective of this study was to assess catchment source contribution changes both over a longitudinal river reach and to a reservoir delta deposit to improve our understanding of sediment supply dynamics.
Materials and methods
The catchment of the Isábena River (445 km2), located in the central Spanish Pyrenees, is an agroforest catchment supplying sediments, together with the Ésera River, to the Barasona reservoir at an annual rate of ~350 t km2 with implications for reservoir longevity. The ability to discriminate between agricultural, forest, subsoil and scrubland sources based on geochemical, radionuclide and magnetic susceptibility fingerprint properties analysed in the <63-μm sediment fraction was investigated by conducting statistical tests to select an optimum composite fingerprint. The contributions of sediment sources for channel bed and delta sediments were assessed by applying a new data processing methodology which was written in the C programming language and designed to test the entire parameter space, providing a detailed description of the optimal solution by a Monte Carlo method.|
Results and discussion The solution for each sample was characterised by the mean value of the user-defined solutions (n = 100) and the lower goodness of fit value was applied. The solutions from the mixing model had goodness of fit values >82 %. The channel bed sediments in the upper reach were dominated by subsoil sources (>80 %), and the lower reaches had a higher proportion of sediment coming from the agricultural source (>55 %). Contributions for delta sediments were dominated by agricultural, forest and subsoil sources but in varying proportions within the deposit. The switch in the sources of sediment between the headwaters and the catchment outlet was due to differences in the distribution of the land uses/land covers in the contributing areas. Differences between channel bed sediment and delta sediment source contributions were related to local sediment deposition conditions. Conclusions The new unmixing approach is able to provide the optimal solution by a robust and integral Monte Carlo method guaranteeing a broader interpretation of the optimal solution including its dispersion in all unmixing cases. The results support the use of sediment fingerprinting approaches in this Spanish Pyrenees mountain catchment, which will enable us to better understand catchment sediment delivery to an important water supply reservoir.
|Description:||41 Pags.- 5 Tabls.- 6 Figs. The definitive version is available at: http://link.springer.com/journal/11368|
|Publisher version (URL):||http://dx.doi.org/10.1007/s11368-015-1175-6|
|Appears in Collections:||(EEAD) Artículos|
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