Browsing by Author "Lazo Jara, Patricio Xavier"

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Combined use of isotopic and hydrometric data to conceptualize ecohydrological processes in a high-elevation tropical ecosystem
(JOHN WILEY AND SONS LTD, 2016-08-15) Mosquera Rojas, Giovanny Mauricio; Célleri Alvear, Rolando Enrique; Crespo Sánchez, Patricio Javier; Lazo Jara, Patricio Xavier
Few high-elevation tropical catchments worldwide are gauged, and even fewer are studied using combined hydrometric and isotopic data. Consequently, we lack information needed to understand processes governing rainfall–runoff dynamics and to predict their influence on downstream ecosystem functioning. To address this need, we present a combination of hydrometric and water stable isotopic observations in the wet Andean páramo ecosystem of the Zhurucay Ecohydrological Observatory (7.53 km2). The catchment is located in the Andes of south Ecuador between 3400 and 3900 m a.s.l. Water samples for stable isotopic analysis were collected during 2 years (May 2011–May 2013), while rainfall and runoff measurements were continuously recorded since late 2010. The isotopic data reveal that andosol soils predominantly situated on hillslopes drain laterally to histosols (Andean páramo wetlands) mainly located at the valley bottom. Histosols, in turn, feed water to creeks and small rivers throughout the year, establishing hydrologic connectivity between wetlands and the drainage network. Runoff is primarily composed of pre-event water stored in the histosols, which is replenished by rainfall that infiltrates through the andosols. Contributions from the mineral horizon and the top of the fractured bedrock are small and only seem to influence discharge in small catchments during low flow generation (non-exceedance flows < Q35). Variations in source contributions are controlled by antecedent soil moisture, rainfall intensity, and duration of rainy periods. Saturated hydraulic conductivity of the soils, higher than the year-round low precipitation intensity, indicates that Hortonian overland flow rarely occurs during high-intensity precipitation events. Deep groundwater contributions to discharge seem to be minimal. These results suggest that, in this high-elevation tropical ecosystem, (1) subsurface flow is a dominant hydrological process and (2) (histosols) wetlands are the major source of stream runoff. Our study highlights that detailed isotopic characterization during short time periods provides valuable information about ecohydrological processes in regions where very few basins are gauged. Copyright © 2016 John Wiley & Sons, Ltd.
Conceptualización de procesos de generación de escorrentía mediante el uso de trazadores ambientales en cuencas de páramo a meso-escala del río Quinuas
(2019-05-21) Plaza Trujillo, Carolina Elizabeth; Crespo Sánchez, Patricio Javier; Lazo Jara, Patricio Xavier
The Andean paramo ecosystem plays a fundamental role in the supply of water resources for the inter-Andean valleys since it covers the demand of the domestic, industrial and energetic sectors. As a result, the water requirement generates negative pressure on the ecosystem, affecting its regeneration rate. Identifying the main sources of runoff within a hydrological system allows to focus efforts and resources for the conservation of these points. In return, it ensures the provision of water. The following study has determined how the precipitation regime and geomorphological characteristics within the Quinuas River basin (91.3 Km2), located in the Cajas National Park, influence its hydrological functioning. The use of conservative tracers allowed the understanding of the hidrogeoecological dynamics of watersheds, and when combined with transfer functions, they estimated mean transit times (MTT) and defined the processes of mixing flow on internal levels. Thus, it was obtained as a result that the precipitation that enters the system is combined with the water stored in the soils and flows into the exit of the basins. Consequently, it was determined that the lagoons are influential in transit time of the water. Finally, the topography that makes up the terrain allows the generation of runoff through the superficial layers of the andosols, defining the dynamics between the external factors (landscape) and internal factors (mixing processes), achieving a real conceptualization for the studied catchment area.
Ecohydrological drivers of neotropical vegetation in montane ecosystems
(2018) Aparecido, Luiza Maria; Mosquera Rojas, Giovanny Mauricio; Lazo Jara, Patricio Xavier; Rodas, Melissa; Lazo, Patricio; Müller, Caroline S.; Moore, Georgianne W.; Oliveira, Rafael S.
Montane ecosystems are known for their high numbers of endemic species, unique climate conditions, and wide variety of ecosystem services such as water supply and carbon storage. Although many ecohydrological and climatic studies of montane environments have been carried out in temperate and boreal regions, few have been done in Neotropical regions. Hence, the objective of this review is to synthesize the existing literature on the main factors (biotic and abiotic) that influence vegetation distribution, functional traits, and ecohydrological processes and feedbacks in tropical montane ecosystems (TME) and to identify key knowledge gaps. Most of the literature used includes work conducted in Neotropical montane rainforests, cloud forests, and grass/scrublands (eg, páramos, punas, and campos de altitude/rupestres). Fog is a major climatic attribute in tropical montane …
Evaluating electrical conductivity as a surrogate tracer to determine the factors controlling event and pre-event water flow partitioning at a tropical montane Andean ecosystem
(Universidad de Cuenca, 2024-09-17) Lazo Jara, Patricio Xavier; Crespo Sánchez, Patricio Javier; Segura, Catalina
The results of this thesis showed that electrical conductivity could be used as an alternative to Oxygen-18 as a tracer for event and pre-event water flow partitioning analyses which highly increases the temporal resolution of tracer concentrations while reducing the uncertainty of the tracer-aided model. The results showed great similarity under a large range of flow conditions, reassuring the consistency of the estimated fractions with 89% of the monitored events showing differences lower than 20% in pre-event water fraction regardless of the antecedent moisture and rainfall conditions. The use of electrical conductivity was possible due to a quasi-conservative behavior related with the presence of organic-rich riparian soils (peat-type) overlying compact bedrock across the catchment. This highlights the potential of electrical conductivity to obtain high temporal frequency data while lowering the costs needed to implement and keep tracer data collection up for long time periods. In addition, results from the comparison of models with different complexities also showed great similarity in their estimations of the event and pre-event water fractions as long as appropriate concentrations of event (Ce) and pre-event (Cp) water for the simpler model are set. In fact, Cp showed to be the most important factor for improving accuracy while Ce had little influence on the results. Hence, the best way to determine Cp was the concentration of a streamflow sample taken before the beginning of each event. These findings will allow to reduce the logistical and economical resources needed to adequately assess hydrograph separation and to carry out quasi-continuous assessments of flow partitioning with high accuracy in high-Andean montane ecosystems. The previous results led to the analysis of several spatial and temporal factors controlling event and pre-event water fractions. This allowed us to obtain tracer and hydrometeorological high-frequency data from a large number of rainfall-runoff events (n=72). The correlations showed that the main temporal controlling factor was rainfall amount with a strong (i.e., r>0.7) and significant (i.e., p<0.05) positive correlation with the event water fraction, whereas, soil type, vegetation cover, and topography were highly correlated when considering the spatial factors. These results suggested an enhanced shallow subsurface hydrological connectivity between hillslopes and riparian wetlands which follow in an increase of event water fraction for events that show higher peak flows while a threshold is exceeded. Overall, our findings suggests that high temporal resolution data is extremely necessary to adequately assess event and pre-event water fraction flow partitioning as it helps to obtain a complete understanding of catchment hydrological behavior at scale event. This improved understanding could aid in the implementation of science-based water management strategies that includes many processes that are often overlooked.
Flow partitioning modelling using high-resolution electrical conductivity data during variable flow conditions in a tropical montane catchment
(2023) Cárdenas Moreno, Irene Lucila; Mosquera Rojas, Giovanny Mauricio; Crespo Sánchez, Patricio Javier; Segura, Catalina; Lazo Jara, Patricio Xavier
Tracer-aided hydrological models (TAHMs) are one of the most powerful tools to identify new (event) and old (pre-event) water fractions contributing to stormflow because they account both for streamflow and tracer mixing dynamics in model calibration. Nevertheless, their representativeness of hydrograph dynamics is often limited due to the unavailability of high-resolution conservative tracer data (e.g., water stable isotopes or chloride). Hence, there is a need to identify alternative tracers yielding similar flow partitioning results than “ideal” ones while requiring fewer financial resources for high-frequency monitoring (e.g., sub-hourly). Here, we compare flow partitioning results of a TAHM calibrated using high-frequency electrical conductivity (EC) and water stable isotope (18O) data collected during 37 rainfall-runoff events monitored during variable hydrometeorological conditions in the Zhurucay Ecohydrological Observatory, a tropical alpine catchment located in southern Ecuador. When the model was calibrated using the sampling resolution of stables isotopes (6-hours to 1-hour), no statistically significant differences of pre-event water fractions (PEWFs) using both tracers for model calibration were found. PEWF differences between both tracers for 89% of the events were < 20% regardless of the events’ antecedent moisture and rainfall conditions. Model transfer functions were also similar suggesting that catchment internal processes inferred using both tracers are comparable. Events presenting larger differences (n = 4; up to 27% PEWF difference) had no samples collected during peak flow. Calibration of the model using EC data collected at sub-hourly intervals (every 5-minutes) showed a significant increase in model performance as compared to the frequency of collection of isotopic data. Similarity in flow partitioning results can be attributed to a quasi-conservative nature of EC due to the presence of organic-rich riparian soils (peat-type) overlying compact bedrock across the catchment. Findings also highlight the importance of capturing rapidly occurring catchment mixing processes though high-temporal frequency monitoring of tracer data. Our study encourages the value of assessing the use of alternative tracers, such as EC, to identify fast occurring rainfall-runoff processes, while lowering the costs needed to implement and sustain tracer data collection for long time periods.
Fraccionamiento y concentración de deuterio (ð2H) y oxígeno- 18 (ð18HO) en diferentes fuentes de agua que aportan a la cuenca del río Zhurucay
(2011) Lazo Jara, Patricio Xavier; Mosquera Rojas, Giovanny Mauricio; Crespo Sánchez, Patricio Javier
How vegetation, soils, and precipitation control passive and dynamic storage change in high–elevation tropical catchments?
(2018-03-14) Lazo Jara, Patricio Xavier; Crespo Sánchez, Patricio Javier; Mosquera Rojas, Giovanny Mauricio
Understanding how tropical montane catchments store and release water is crucial for water resource management at surrounding elevations and downstream populations. Nevertheless, although research in montane tropical ecosystems has focused on streamflow generation, a lack of knowledge regarding catchments’ water storage remains. Consequently, this study focuses on the investigation of catchment storage and the factors controlling its spatial variability in seven páramo catchments (0.20–7.53 km2) located in south Ecuador. We used a hydrometeorological, water stable isotopic, and soils’ hydrophysical properties dataset collected during Nov 2011–October 2014 to estimate catchments’ passive (PasS) and dynamic (DynS) storages. We also investigated relations between these storages and landscape and hydrometric variables using linear regression analysis. The catchments’ PasS and DynS were 313–617 mm and 29–35 mm, respectively. Catchments’ PasS increased as their areal proportion of wetlands (Histosol soils) increased, and their DynS increased as the intensity of precipitation increased. Results also showed that PasS estimations using different methodologies were in agreement. Altogether, results evidence: 1) that only 6–10% of the catchments’ mixing storage (DynS/PasS) is hydrologically active in their water balance, 2) the importance of wetlands for the provisioning of the catchments’ PasS, and 3) the influence of the constant input of low intensity precipitation to sustain the wetlands recharge, and thus, the year–round water supply of páramo catchments. Findings that are crucial towards improvement of soil, vegetation, and water resources management in the páramo and other environments where the presence of peaty–like soils dominates.
Runoff from tropical alpine grasslands increases with areal extent of wetlands
(ELSEVIER, 2015-02-01) Mosquera Rojas, Giovanny Mauricio; Célleri Alvear, Rolando Enrique; Crespo Sánchez, Patricio Javier; Lazo Jara, Patricio Xavier
Tropical alpine grasslands of the northern Andes, commonly known as the páramo, provide abundant high-quality water for downstream populations as well as a variety of other environmental services. Yet, very little is known about the role that landscape characteristics play in the hydrologic functioning of these ecosystems. To help fill this knowledge gap, we investigated the relationships between various landscape attributes and hydrology in a wet páramo ecosystem of southern Ecuador. Using linear regression analysis, we examined the influence of soil type, vegetation cover, catchment area, geology, and topography on runoff coefficient, streamflow rates, and evapotranspiration. Our study site is located at the Zhurucay River experimental catchment, which is composed of seven nested microcatchments ranging in size from 0.20 to 7.53km2 and in elevation from 3200 to 3900ma.s.l. We found that (1) water yield accounts for a high percentage of the water budget; (2) runoff coefficient and specific discharge are strongly correlated with the extent of Andean páramo wetlands (Histosol soils and cushion plants), and also increase with catchment size; (3) conversely, inferred evapotranspiration is the highest in catchments having the greatest percentages of upland terrain (Andosol soils and tussock grasses); and (4) low flows are highly positively correlated with steep slopes. These results suggest that in the high-elevation tropical grasslands of the Andes, runoff coefficient and specific discharge increase with catchment size because as catchment size increases, so does the relative area of permanently near-saturation zones (Andean páramo wetlands); likely because of reduced available storage capacity of the Andean páramo wetlands, and their hydrologic connectivity to the stream network.
The role of vegetation, soils, and precipitation on water storage and hydrological services in Andean Páramo catchments
(2019) Lazo Jara, Patricio Xavier; Mosquera Rojas, Giovanny Mauricio; Mcdonnell, Effrey J.; Crespo Sánchez, Patricio Javier
Understanding how tropical montane catchments store and release water, and the resulting water ecosystem services they provide is crucial for improving water resource management. But while research in high–elevation tropical environments has made progress in defining streamflow generation processes, we still lack fundamental knowledge regarding water storage characteristics of catchments. Here we explore catchment storage and the factors controlling its spatial variability in seven Páramo catchments (0.20–7.53 km 2 ) in southern Ecuador. We applied a field-based approach using hydrometeorological, water stable isotopic, and soils hydrophysical data from a 3 year collection period to estimate the passive (PasS) and dynamic (DynS) storage of the catchments. We also investigated relations between these storages and landscape and hydrometric variables using linear regression analysis. PasS estimates from hydrophysical soil properties and soil water mean transit times were consistent with estimates using streamflow mean transit times. Computed catchment PasS and DynS for the seven watersheds were 313–617 mm and 29–35 mm, respectively. PasS increased directly with the areal proportion of Histosol soils and cushion plant vegetation (wetlands). DynS increased linearly with precipitation intensity. Importantly, only 6–10% of the mixing storage of the catchments (DynS/PasS) was hydrologically active in their water balance. Wetlands internal to the catchments were important for PasS, where constant input of low intensity precipitation sustained wetlands recharge, and thus, the water regulation capacity (i.e., year–round water supply) of Páramo catchments. Our findings provide new insights into the factors controlling the water regulation capacity of Páramo catchments and other peaty soils dominated environments.