Tracing water paths through small catchments under a tropical montane rain forest in south Ecuador by an oxygen isotope approach

Goller, Rainer; Wilcke, Wolfgang; Leng, Melanie J.; Tobschall, H. J.; Wagner, Kevin; Valarezo, Carlos; Zech, Wolfgang

doi:10.1016/j.jhydrol.2004.10.022

Cited by 107 publications

(118 citation statements)

References 23 publications

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“…Monthly sampling resolution and monthly data are still frequently used in stable water isotope studies when either the effort or the costs are too high to realize a higher sampling frequency (e.g., Goller et al, 2005;Rodgers et al, 2005;Viville et al, 2006;Liu et al, 2007;Rock and Mayer, 2007;Chen et al, 2012), which goes in line with a large share of observation points of the Global Network of Isotopes in Precipitation and Rivers (GNIP) of the I.A.E.A.-W.M.O.…”

Section: Discussionmentioning

confidence: 99%

Sampling frequency trade-offs in the assessment of mean transit times of tropical montane catchment waters under semi-steady-state conditions

Timbe

Windhorst²,

Célleri

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract. Precipitation event samples and weekly based water samples from streams and soils were collected in a tropical montane cloud forest catchment for 2 years and analyzed for stable water isotopes in order to understand the effect of sampling frequency in the performance of three lumped-parameter distribution functions (exponential-piston flow, linear-piston flow and gamma) which were used to estimate mean transit times of waters. Precipitation data, used as input function for the models, were aggregated to daily, weekly, bi-weekly, monthly and bi-monthly sampling resolutions, while analyzed frequencies for outflows went from weekly to bi-monthly. By using different scenarios involving diverse sampling frequencies, this study reveals that the effect of lowering the sampling frequency depends on the water type. For soil waters, with transit times on the order of few weeks, there was a clear trend of over predictions. In contrast, the trend for stream waters, which have a more damped isotopic signal and mean transit times on the order of 2 to 4 years, was less clear and showed a dependence on the type of model used. The trade-off to coarse data resolutions could potentially lead to misleading conclusions on how water actually moves through the catchment, notwithstanding that these predictions could reach better fitting efficiencies, fewer uncertainties, errors and biases. For both water types an optimal sampling frequency seems to be 1 or at most 2 weeks. The results of our analyses provide information for the planning of future fieldwork in similar Andean or other catchments.

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Section: Discussionmentioning

confidence: 99%

Sampling frequency trade-offs in the assessment of mean transit times of tropical montane catchment waters under semi-steady-state conditions

Timbe

Windhorst²,

Célleri

et al. 2015

Hydrol. Earth Syst. Sci.

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“…DRY than in WET. Furthermore, lateral flow in the organic layer following water saturation of the soil is important at our study site (Goller et al 2005;Boy et al 2008b), which is likely to have occurred in WET. Lateral flow might have flushed NH 4 + quickly to the stream and consequently reduced its availability.…”

Section: Seasonal Variability Of N Transformationsmentioning

confidence: 97%

Stable N isotope composition of nitrate reflects N transformations during the passage of water through a montane rain forest in Ecuador

2010

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“…Forest" (Bruijnzeel and Hamilton, 2000), underlain by a Humic Dystrudept (Goller et al, 2005) with a silt content of about 60% in all horizons (Schrumpf et al, 2001). …”

Section: Site Selectionmentioning

confidence: 99%

“…This assumption of organic layer flow was originally made by Goller et al (2005), who also worked in this catchment. They postulated a switch to rapid water flow in the highly permeable organic layer parallel to the mineral soil surface during storm events.…”

Section: Flowpaths In the South Ecuadorian Montane Rainforestmentioning

confidence: 99%

“…Hence, this event ranks among the most intense rain events of our study area. Since soil moisture status was very high before and during the event studied by Goller et al (2005), saturation excess overland flow might have caused the assumed flow on top of or in the near-surface mineral soil. During the majority of events, however, the prevailing vertical flowpaths likely persist to the subsoil below 20 cm soil depth.…”

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Spatial and temporal variability of soil saturated hydraulic conductivity in gradients of disturbance

Zimmermann

Elsenbeer

2008

Journal of Hydrology

126

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Elektronisch veröffentlicht auf dem Publikationsserver der Universität Potsdam: http://opus.kobv. de/ubp/volltexte/2008/1640/ urn:nbn:de:kobv:517-opus-16402 [http://nbn-resolving.de/urn:nbn:de:kobv:517-opus16402] SummaryAs land-cover conversion continues to expand into ever more remote areas in the humid tropics, montane rainforests are increasingly threatened. In addition to the loss of biodiversity, land-use change potentially deteriorates regional water cycles, which may have undesirable effects for local populations such as decreased water supply during dry seasons, enhanced flooding in the rainy season, or deterioration of drinking water quality.Montane rainforests in the south Ecuadorian Andes are not only subject to man-made disturbances but also to naturally occurring landslides. I was interested in the impact of this ecosystem dynamics on a key parameter of the hydrologic cycle, the soil saturated hydraulic conductivity (synonym: permeability; Ks from here on), because it is a sensitive indicator for soil disturbances. Depending on the rainfall regime, the potential disturbance-induced decrease of Ks may become relevant for regional watersheds.My general objective was to quantify the effects of the regional natural and human disturbances on the saturated hydraulic conductivity and to describe the resulting spatialtemporal patterns. The main hypotheses were: 1) disturbances cause an apparent displacement of the less permeable soil layer towards the surface, either due to a loss of the permeable surface soil after land-sliding, or as a consequence of the surface soil compaction under cattle pastures; 2) 'recovery' from disturbance, either because of landslide re-vegetation or because of secondary succession after pasture abandonment, involves an apparent displacement of the less permeable layer back towards the original depth an 3) disturbances cause a simplification of the Ks spatial structure, i.e. the spatially dependent random variation diminishes; the subsequent recovery entails the re-establishment of the original structure.In my first study, I developed a synthesis of recent geostatistical research regarding its applicability to soil hydraulic data, including exploratory data analysis and variogram estimation techniques; I subsequently evaluated the results in terms of spatial prediction uncertainty. Concerning the exploratory data analysis, my main results were: 1) Gaussian uniand bivariate distributions of the log-transformed data; 2) the existence of significant local trends; 3) no need for robust estimation; 4) no anisotropic variation. I found partly considerable differences in covariance parameters resulting from different variogram estimation techniques, which, in the framework of spatial prediction, were mainly reflected in the spatial connectivity of the Ks-field. Ignoring the trend component and an arbitrary use of robust estimators, however, would have the most severe consequences in this respect.Regarding variogram modeling, I encouraged restricted maximum likelihood estimation becau...

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Tracing water paths through small catchments under a tropical montane rain forest in south Ecuador by an oxygen isotope approach

Cited by 107 publications

References 23 publications

Sampling frequency trade-offs in the assessment of mean transit times of tropical montane catchment waters under semi-steady-state conditions

Sampling frequency trade-offs in the assessment of mean transit times of tropical montane catchment waters under semi-steady-state conditions

Stable N isotope composition of nitrate reflects N transformations during the passage of water through a montane rain forest in Ecuador

Spatial and temporal variability of soil saturated hydraulic conductivity in gradients of disturbance

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