Автор(ы): Ulloa-Cedamanos F., Probst A., dos Santos V., Camboulive T., Granouillac F., Probst J.-L.
Редактор(ы):
Год: 2021
Название: Stream Hydrochemical Response to Flood Events in a Multi-Lithological Karstic Catchment from the Pyrenees Mountains (SW France)
Источник: Water
Место публикации: .
Том: 13
Выпуск: 1818
Страницы: 1-23
Web/Url:
№ полки:
Добавлено: Turner
Ключевые слова: carbonate dissolution, chemical weathering, streamflow components, chemostatic and hysteretic behavior, rainstorm events, hydrochemical survey, high frequency monitoring, discrete monitoring, karstic critical zone, karst water, hydrograph separation
Источник:
Реферат: Hydrological variations hold a significant influence over the water chemistry in the karstic
critical zone. In this context, the karstic Baget Catchment (BC) has been monitored at a high resolution
over two years at the outlet in order to set up a typology of the flood events. The objective was to
assess the multiple streamwater physico-chemical patterns in response to hydrological variations,
streamflow component (quick-response, subsurface, and baseflow) and lithological contributions,
and biogeochemical processes. The karstic catchment exhibited an impulsive response to flood
events in relation to the typical structural and morphological characteristics of the karst. In addition,
this response was constrained by the magnitude of the rainfall and the preceding hydroclimatic
conditions. The variability of the dissolved load in streamflow was closely associated with the
characteristics of the weathered rocks and the hydrological conditions throughout the year. Two
simple indicators allow to characterize the concentration–discharge relationships with different
hysteresis patterns on a set of floods with various intensities and shapes of the hydrograph and under
different hydrological conditions before the flood. Almost all elements exhibited either clockwise
loops or more complex behaviors, suggesting a higher overall concentration when the major water
contribution comes from the quick-response flow (karst and surface runoff fraction). Besides, the
epikarst flushing under dry conditions led counterclockwise hysteresis patterns for calcium (Ca2+)
and bicarbonate (HCO 3−) which revealed an overall chemostatic behavior as a result of carbonate
dissolution in the karst. On the contrary, sulfate (SO4 2−) exhibited the widest relative variation
during flooding and showed a significant sensitivity to the dilution process with increasing discharge.
For medium flood episodes (Qmax 8.3 m3·s−1) occurring after several rain events, a dilution pattern was
noted for all elements originating from rock weathering. Finally, high-frequency sampling during
storm events improved the understanding of the factors controlling the hydrochemical dynamic in
karstic catchments.