Journalartikel

Jahr der Veröffentlichung: 2016

Seiten: 2987-3004

Zeitschrift: Hydrology and Earth System Sciences

Bandnummer: 20

Heftnummer: 7

ISSN: 1027-5606

Open Access Status: Gold

DOI Link: https://doi.org/10.5194/hess-20-2987-2016

Verlag: Copernicus Publications

Abstract: 
This study focuses on the investigation of the mean transit time (MTT) of water and its spatial variability in a tropical high-elevation ecosystem (wet Andean paramo). The study site is the Zhurucay River Ecohydrological Observatory (7.53 km(2)/located in southern Ecuador. A lumped parameter model considering five transit time distribution (TTD) functions was used to estimate MTTs under steady-state conditions (i.e., baseflow MTT). We used a unique data set of the delta O-18 isotopic composition of rainfall and stream-flow water samples collected for 3 years (May 2011 to May 2014) in a nested monitoring system of streams. Linear regression between MTT and landscape (soil and vegetation cover, geology, and topography) and hydrometric (runoff co-efficient and specific discharge rates) variables was used to explore controls on MTT variability, as well as mean electrical conductivity (MEC) as a possible proxy for MTT. Results revealed that the exponential TTD function best describes the hydrology of the site, indicating a relatively simple transition from rainfall water to the streams through the organic horizon of the wet paramo soils. MTT of the streams is relatively short (0.15-0.73 years, 53-264 days). Regression analysis revealed a negative correlation between the catchment's average slope and MTT (R-2 = 0.78, p < 0.05). MTT showed no significant correlation with hydrometric variables, whereas MEC increases with MTT (R-2 = 0.89, p < 0.001). Overall, we conclude that (1) baseflow MTT confirms that the hydrology of the ecosystem is dominated by shallow subsurface flow; (2) the interplay between the high storage capacity of the wet paramo soils and the slope of the catchments provides the ecosystem with high regulation capacity; and (3) MEC is an efficient predictor of MTT variability in this system of catchments with relatively homogeneous geology.

Harvard-Zitierstil: Mosquera, G., Segura, C., Vache, K., Windhorst, D., Breuer, L. and Crespo, P. (2016) Insights into the water mean transit time in a high-elevation tropical ecosystem, Hydrology and Earth System Sciences, 20(7), pp. 2987-3004. https://doi.org/10.5194/hess-20-2987-2016

APA-Zitierstil: Mosquera, G., Segura, C., Vache, K., Windhorst, D., Breuer, L., & Crespo, P. (2016). Insights into the water mean transit time in a high-elevation tropical ecosystem. Hydrology and Earth System Sciences. 20(7), 2987-3004. https://doi.org/10.5194/hess-20-2987-2016