Browsing by Author "Mosquera Rojas, Giovanny Mauricio"

Now showing 1 - 20 of 27

A field, laboratory, and literature review evaluation of the water retention curve of volcanic ash soils: How well do standard laboratory methods reflect field conditions?
(2021) Jan, Feyen; Marin Molina, Franklin Geovanny; Mosquera Rojas, Giovanny Mauricio; Crespo Sánchez, Patricio Javier; Windhorst, David; Lutz, Breuer; Célleri Alvear, Rolando Enrique
Accurate determination of the water retention curve (WRC) of a soil is essential for the understanding and modelling of the subsurface hydrological, ecological, and biogeochemical processes. Volcanic ash soils with andic properties (Andosols) are recognized as important providers of ecological and hydrological services in mountainous regions worldwide due to their large fraction of small size particles (clay, silt, and organic matter) that gives them an outstanding water holding capacity. Previous comparative analyses of in situ (field) and standard laboratory methods for the determination of the WRC of Andosols showed contrasting results. Based on an extensive analysis of laboratory, experimental, and field measured WRCs of Andosols in combination with data extracted from the published literature we show that standard laboratory methods using small soil sample volumes (?300 cm3) mimic the WRC of these soils only partially. The results obtained by the latter resemble only a small portion of the wet range of the Andosols' WRC (from saturation up to ?5 kPa, or pF 1.7), but overestimate substantially their water content for higher matric potentials. This discrepancy occurs irrespective of site-specific land use and cover, soil properties, and applied method. The disagreement limits our capacity to infer correctly subsurface hydrological behaviour, as illustrated through the analysis of long-term soil moisture and matric potential data from an experimental site in the tropical Andes. These findings imply that results reported in past research should be used with caution and that future research should focus on determining laboratory methods that allow obtaining a correct characterization of the WRC of Andosols. For the latter, a set of recommendations and future directions to solve the identified methodological issues is proposed.
Advancing ecohydrology in the changing tropics: perspectives from early career scientists
(2018) Mosquera Rojas, Giovanny Mauricio
Tropical ecosystems offer a unique setting for understanding ecohydrological processes, but to date, such investigations have been limited. The purpose of this paper is to highlight the importance of studying these processes—specifically, how they are being affected by the transformative changes taking place in the tropics—and to offer an agenda for future research. At present, the ongoing loss of native ecosystems is largely due to agricultural expansion, but parallel processes of afforestation are also taking place, leading to shifts in ecohydrological fluxes. Similarly, shifts in water availability due to climate change will affect both water and carbon fluxes in tropical ecosystems. A number of methods exist that can help us better understand how changes in land use and climate affect ecohydrological processes; these include stable isotopes, remote sensing, and process-based models …
Changes in soil hydro-physical properties and SOM due to pine afforestation and grazing in Andean environments cannot be generalized
(2018) Marín Molina, Franklin Geovanny; Quiroz Dahik, Carlos Alberto; Mosquera Rojas, Giovanny Mauricio; Feyen Null, Jan Null; Cisneros Espinoza, Pedro José Francisco; Crespo Sánchez, Patricio Javier
Andean ecosystems provide important ecosystem services including streamflow regulation and carbon sequestration, services that are controlled by the water retention properties of the soils. Even though these soils have been historically altered by pine afforestation and grazing, little research has been dedicated to the assessment of such impacts at local or regional scales. To partially fill this knowledge gap, we present an evaluation of the impacts of pine plantations and grazing on the soil hydro-physical properties and soil organic matter (SOM) of high montane forests and paramo in southern Ecuador, at elevations varying between 2705 and 3766 m a.s.l. In total, seven study sites were selected and each one was parceled into undisturbed and altered plots with pine plantation and grazing. Soil properties were characterized at two depths, 0–10 and 10–25 cm, and differences in soil parameters between undisturbed and disturbed plots were analyzed versus factors such as ecosystem type, sampling depth, soil type, elevation, and past/present land management. The main soil properties affected by land use change are the saturated hydraulic conductivity (Ksat), the water retention capacity (pF 0 to 2.52), and SOM. The impacts of pine afforestation are dependent on sampling depth, ecosystem type, plantation characteristics, and previous land use, while the impacts of grazing are primarily dependent on sampling depth and land use management (grazing intensity and tilling activities). The site-specific nature of the found relations suggests that extension of findings in response to changes in land use in montane Andean ecosystems is risky; therefore, future evaluations of the impact of land use change on soil parameters should take into consideration that responses are or can be site specific.
Characterization of the stable isotopic composition of precipitation, surface, and subsurface waters in a small Andean catchment in northern Ecuador
(Universidad de Cuenca, 2021-12-16) Lahuatte Imbaquingo, Braulio César; Mosquera Rojas, Giovanny Mauricio
Combining traditional hydrometric data with environmental tracers such as water stable isotopes has proven valuable to improve the understanding of catchment hydrology. Nevertheless, the application of isotopic tracers in headwater catchments of the tropical Andes remains limited. The stable isotopic composition of precipitation, soil water along two experimental hillslopes with different vegetation cover (tussock grass and cushion plants), wetlands, and discharge collected biweekly during one year was used to improve the understanding of the hydrology of a northern Ecuadorian paramo catchment. The analysis of the stable isotopic composition of precipitation indicates that although local precipitation forms under isotopic equilibrium conditions, it is influenced by moisture recycling processes. Regarding catchment hydrological behavior, the spatio-temporal variability of isotopic signals and the analysis of inverse transit time proxies (ITTPs) of surface (discharge) and subsurface (soil water and wetlands) waters suggest that vertical flow paths are dominant across the catchment. Strongly damped isotopic compositions of these waters further suggest a high water storage capacity of the catchment, increasing the transit time or age of water in the hydrological system. Isotopic signals and ITTPs also show the importance of well-mixed subsurface water reservoirs in the hydrology of the system. The hydrological knowledge developed in this study not only increases the understanding of discharge generation and regulation in northern Ecuadorian Paramos, but also can be used to improve the management of water resources in the region. Field restoration activities could be focused on trying to improve the catchment’s components that control its hydrology.
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.
Disentangling water transport and tracer mixing mechanism in mountainous environments influenced by volcanic features
(Universidad de Cuenca, 2020-06-16) Mosquera Rojas, Giovanny Mauricio; Crespo Sánchez, Patricio Javier
Landscape features of volcanic origin influence the transport of water and solutes across high-elevation environments. Nevertheless, knowledge regarding how these features affect subsurface hydrological behavior at different spatial scales (from plot to catchment) is scarce. The effect of the soils originated from volcanic ash, such as Andosols (or Andisols), and the influence of highly fractured geology of volcanic origin on subsurface hydrological behavior and water flow path delineation are poorly understood. To fill this knowledge gap, I took as the main objective in the doctoral project the analysis of how Andosols and fractured volcanic geology influence flow transport and tracer mixing mechanisms. Laboratory, experimental, and field measurements of the water retention curve (WRC) of Andosols in combination with data extracted from the published literature shows that standard laboratory methods resemble well a small portion of the wet range of the WRC, specifically, from saturation to the matric potentials 3 to 5 kPa (pF 1.5-1.7). For higher matric potentials, standard laboratory methods substantially overestimate the water content of the soils in comparison to experimental and field measurements. Further, a unique set of hydrometric, stable isotope, and soil hydraulic properties data were evaluated to investigate how Andosols influence water transport and tracer mixing mechanisms at a steep tropical hillslope. The results from this analysis point to the dominance of vertical flow paths within the soil matrix, despite the formation of a perched water layer below the root zone, which mimics the hydraulic behavior of a wet, layered sloping sponge. Last, I used a tracer-aided hydrological model (TraSPAN) calibrated for the stable isotopes of water and electrical conductivity (or specific conductance) during a rainstorm event for the analysis of the role of the fractured volcanic geology on flow transport and tracer mixing at the catchment scale. The model structure that best simulated the streamflow hydrograph and the tracers concentrations during a rainfall event consisted of two water reservoirs representing the soils with high infiltration capacity and the groundwater system formed in the fractured bedrock. During the monitored event, only 13% of total precipitation was converted into runoff, with a major proportion (75-81%) corresponding to pre-event water stored in the catchment prior to the event. These findings indicate a large water storage capacity of the system in the fractured volcanic geology.
Do mixing models with different input requirement yield similar streamflow source contributions? Case study: a tropical montane catchment
(2021) Timbe Castro, Edison Patricio; Crespo Sánchez, Patricio Javier; Mora Abril, Enmita Lucía; Ramón Flores, Jorge David; Correa Barahona, Alicia Beatriz; Mosquera Rojas, Giovanny Mauricio
Hydrogeochemical based mixing models have been successfully used to investigate the composition and source identification of streamflow. The applicability of these models is limited due to the high costs associated with data collection and the hydrogeochemical analysis of water samples. Fortunately, a variety of mixing models exist, requiting different amount of data as input, and in data scarce regions it is likely that preference will be given to models with the lowest requirement of input data. An unanswered question is if models with high or low input requirement are equally accurate. To this end, the performance of two mixing models with different input requirement, the mixing model analysis (MMA) and the end-member mixing analysis (EMMA), were verified on a tropical montane headwater catchment (21.7 km2) in the Ecuadorian Andes. Nineteen hydrogeochemical tracers were measured on water samples collected weekly during 3 years in streamflow and eight potential water sources or end-members (precipitation, lake water, soil water from different horizons and springs). Results based on 6 conservative tracers, revealed that EMMA (using all tracers) and MMA (using pair-combinations out of the 6 conservative ones), identified the same end-members: rainfall, soil water and spring water., as well as, similar contribution fractions to streamflow from rainfall 21.9% and 21.4%, soil water 52.7% and 52.3%, and spring water 26.1% and 28.7%, respectively. Our findings show that a hydrogeochemical mixing model requiring a few tracers can provide similar outcomes than models demanding more tracers as input data. This underlines the value of a preliminary detailed hydrogeochemical characterization as basis to derive the most cost-efficient monitoring strategy.
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 …
Effect of land cover and hydro-meteorological controls on soil water leachate doc concentrations in a high-elevation tropical environment
(2018-01-08) Pesántez Vallejo, Juan Patricio; Windhorst, David; Mosquera Rojas, Giovanny Mauricio; Crespo Sánchez, Patricio Javier
Páramo soils store high amounts of organic carbon. However, climate change and changes in land cover/use may cause a decrease in their carbon storage capacity. As such, a better understanding of the factors influencing the páramo soils carbon storage and export is urgently needed. To fill this knowledge gap we selected the Quinuas Ecohydrological Observatory (91.3 km²) in south Ecuador, and study the hydro-meteorological conditions controlling the dissolved organic carbon (DOC) content in the soil water for the four main land cover types (tussock grass, natural forest, pine plantations and pasture). Weekly soil water samples for DOC analysis, as well as meteorological variables and soil water content and temperature probes (5-min intervals) from various depth and slope positions were monitored within the soils’ organic and mineral horizons between October 2014 and January 2017. These data was used to generate regression trees and random forest statistical models in order to identify controllers of soil water DOC concentrations. Our results evidenced that land cover is the most important predictor in the models, followed by sampling depth and soil moisture. Natural forest have been identified with the higher DOC concentrations in soil water followed by pasture, tussock grass and pine forest. DOC concentrations also increase with decreasing soil moisture (except when soil moisture is >0.56 m³ m-³ in natural forest). The latter shows that land cover change and factors that affect soil moisture conditions over time, are very likely to lead significant changes in DOC concentrations in soil water and therefore in streams.
Factors controlling the stable isotopic composition of precipitation in the tropical alpine highlands of south Ecuador
(Universidad de Cuenca, 2021-09-08) Zhiña Villa, Darío Xavier; Mosquera Rojas, Giovanny Mauricio
The isotopic composition of precipitation provides valuable information about the factors influencing local precipitation in mountainous areas. This information can help improve the management of water resources in light of changes in global climate. Water Stable Isotopes (WSI) provide information on factors influencing precipitation, such as regional moisture recycling and/or local re-evaporation that affects precipitation at a given study site. The use of Lagrangian transport models can help identify sources of moisture that contribute to local precipitation and provide information on regional climatological factors that might influence the isotopic composition of local precipitation. In the tropical Andes, the understanding of local precipitation and the application of WSI and Lagrangian models that can help fill this knowledge gap remains limited mainly due to the lack of precipitation isotope data sets collected at high temporal frequency (sub-daily to storm-based sampling). Therefore, this study aims to investigate the factors influencing the isotopic composition of precipitation in the tropical alpine highlands (Páramo) of southern Ecuador using a set of WSI data collected at high-temporal frequency during the period October 2017 to October 2018. Results show that there are four main trajectories that the air masses follow (Orinoco plains, Amazon basin, Mato Grosso Massif, and Pacific Ocean) before reaching the study site. Similarly, it was found that regional factors are what largely control the WSI composition of precipitation, although it was also found that convective activity at the study site is a controller of the isotopic composition. The factors found for δ18O signal turned out to explain a large part of the isotopic composition variance, however for D-excess the factors did not explain a high percentage of variance. The results obtained in this study can help to improve climate models using WSI or even help paleoclimate reconstructions in the tropical Andes.
Factors controlling the temporal variability of streamflow transit times in tropical alpine catchments
(Universidad de Cuenca, 2022-06-17) Larco Erazo, Karina Marlene; Mosquera Rojas, Giovanny Mauricio
The mean transit time (MTT) of water is an essential descriptor of streamflow generation and catchment water storage. Research on how MTTs fluctuate over time and the variables influencing such variation is limited. In this study bi-weekly stable isotopic data in precipitation and streamflow are presented, together with daily records of precipitation amount, streamflow, and climatological information. The data were collected over an 8- year period in a nested system of 8 tropical alpine catchments in the Zhurucay Ecohydrological Observatory in southern Ecuador, situated at an elevation of 3400 to 3900 m a.s.l. Isotopic data were used to investigate the temporal variability of streamflow MTTs estimated using yearly periods and a 1-month moving window (i.e., 81 yearly calculated MTTs per catchment). The factors controlling the temporal variability of MTTs were identified using simple and multiple linear regression models between estimated MTTs and hydrometeorological variables. Results reveal that streamflow MTTs at all catchments were short (<1 year) and varied little among catchments (191.30±47.10 days), suggesting that a yearly time span for estimating the temporal variability of MTTs is appropriate. A combination of hydrometeorological variables (i.e., precipitation, streamflow, and runoff coefficient) over antecedent periods up to 1 year was found to control MTT temporal variability among catchments. Overall, these findings point to the prevalence of steady-state conditions in the investigated hydrological system. Our study is key to provide insights into the factors controlling the temporal variability of streamflow MTT in tropical catchments, overcoming data limitations of past investigations. It also provides an increase in the process-based knowledge of the hydrology of high Andean Páramo catchments, with significant implications for improved water supply management
Factors controlling the temporal variability of streamflow transit times in tropical alpine catchments
(2023) Mosquera Rojas, Giovanny Mauricio; Cárdenas Moreno, Irene Lucila; Jacobs, Suzanne R.; Crespo Sánchez, Patricio Javier; Larco Erazo, Karina Marlene
The mean transit time (MTT) of water is an essential descriptor of streamflow generation and catchment water storage. Research on how MTTs fluctuate over time and the variables influencing such variation is limited. In this study, bi-weekly stable isotopic data in precipitation and streamflow were used, together with daily records of hydrometeorological information, to investigate the temporal variability of streamflow MTTs. The data were collected over 8 years in a nested system of 8 tropical alpine catchments in the Zhurucay Ecohydrological Observatory in southern Ecuador (3,450 to 3,900 m a.s.l.). The temporal variability of streamflow MTTs was estimated using yearly periods and a 1-month moving window (i.e., 81 yearly calculated MTTs per catchment). The factors controlling the temporal variability of MTTs were identified using simple and multiple linear regression models with hydrometeorological parameters as explanatory variables. Results reveal that streamflow MTTs in all catchments were short (<1 year) and varied little among catchments (191.30 ± 47.10 days). A combination of hydrometeorological variables (i.e., precipitation, streamflow, and runoff coefficient) over antecedent periods up to 1 year was found to control MTT temporal variability. Overall, these findings point to the prevalence of low temporal variability of hydrological conditions in the investigated catchments. Our study is key to provide insights into the factors controlling the temporal variability of streamflow MTT in tropical catchments, overcoming data limitations of past investigations and with significant implications for improved water supply management.
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.
Flow partitioning modelling using high-resolution isotopic and electrical conductivity data
(2018) Mosquera Rojas, Giovanny Mauricio; Segura, Catalina; Crespo Sánchez, Patricio Javier
Water-stable isotopic (WSI) data are widely used in hydrological modelling investigations. However, the long-term monitoring of these tracers at high-temporal resolution (sub-hourly) remains challenging due to technical and financial limitations. Thus, alternative tracers that allow continuous high-frequency monitoring for identifying fast-occurring hydrological processes via numerical simulations are needed. We used a flexible numerical flow-partitioning model (TraSPAN) that simulates tracer mass balance and water flux response to investigate the relative contributions of event (new) and pre-event (old) water fractions to total runoff. We tested four TraSPAN structures that represent different hydrological functioning to simulate storm flow partitioning for an event in a headwater forested temperate catchment in Western, Oregon, USA using four-hour WSI and 0.25-h electrical conductivity (EC) data. Our results showed strong fits of the water flux and tracer signals and a remarkable level of agreement of flow partitioning proportions and overall process-based hydrological understanding when the model was calibrated using either tracer. In both cases, the best model of the rainstorm event indicated that the proportion of effective precipitation routed as event water varies over time and that water is stored and routed through two reservoir pairs for event and pre-event. Our results provide great promise for the use of sub-hourly monitored EC as an alternative tracer to WSI in hydrological modelling applications that require long-term high-resolution data to investigate non-stationarities in hydrological systems. View Full-Text
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
High-frequency multi-solute calibration using an in situ UV–visible sensor
(2021) Crespo Sánchez, Patricio Javier; Peña Saltos, Pablo Gabriel; Mora Abril, Enmita Lucía; McDowell, William H.; Pesántez Vallejo, Juan Patricio; Birkel, Christian; Mosquera Rojas, Giovanny Mauricio; Arízaga Idrovo, Viviana Cristina
Monitoring the temporal variation of solute concentrations in streams at high temporal frequency can play an important role in understanding the hydrological and biogeochemical behaviour of catchments. UV–visible spectrometry is a relatively inexpensive and easily used tool to infer those concentrations in streams at high temporal resolution. However, it is not yet clear which solutes can be modelled with such an in-situ sensor. Here, we installed a UV–visible spectrometer probe (200–750 nm) in a high-altitude tropical Páramo stream to record the wavelength absorbance at a 5-min temporal resolution. For calibration, we simultaneously sampled stream water at a 4-h frequency from February 2018 to March 2019 for subsequent laboratory analysis. Absorbance spectra and laboratory-determined solute concentrations were used to identify the best calibration method and to determine which solute concentrations can be effectively inferred using in situ spectrometry through the evaluation of six calibration methods of different mathematical complexity. Based on the Nash–Sutcliffe efficiency (NSE) and Akaike information criterion metrics, our results suggest that multivariate methods always outperformed simpler strategies to infer solute concentrations. Eleven out of 21 studied solutes (Al, DOC, Ca, Cu, K, Mg, N, Na, Rb, Si and Sr) were successfully calibrated (NSE >0.50) and could be inferred using UV–visible spectrometry even with a reduced daily sampling frequency. It is worth noting that most calibrated solutes were correlated with wavelengths (WLs) in the low range of the spectra (i.e., UV range) and showed relatively good correlation with DOC. The latter suggests that estimation of metal concentrations could be possible in other streams with a high organic load (e.g., peat dominated catchments). In situ operation of spectrometers to monitor water quality parameters at high temporal frequency (sub-hourly) can enhance the protection of human water supplies and aquatic ecosystems as well as providing information for assessing catchment hydrological functioning.
How do storm characteristics influence concentration-discharge hysteresis in a high-elevation tropical ecosystem?
(2023) Pesántez Alvarado, Juan Martín; Arízaga Idrovo, Viviana Cristina; Mosquera Rojas, Giovanny Mauricio; Crespo Sánchez, Patricio Javier; Jiménez Zamora, Enma Lucrecia; Peña Saltos, Pablo Gabriel
Hydrometeorological characteristics can influence stream chemistry variability and the identification of their dominant drivers provides much needed insight into catchment functioning in the tropics. Particularly, the rainfall-runoff processes that determine catchment capacity to retain and deliver solutes. In this context, concentration-discharge (C-Q) relationships allow assessing solute delivery mechanisms to streams. Here, we used a high-frequency 5-minute multi-solute data set (Al, Cu, DOC, TNb, Ba, Ca, Mg, Na, Sr, K, Si, Rb) to derive hysteresis indicators (direction, magnitude and area) in relation to hydrometeorological variables for a high-elevation tropical experimental catchment. We found geogenic solutes (Na, Sr, K, Si, and Rb) were mostly defined by clockwise hysteresis loops and dilution patterns. Conversely, biogenic solutes influenced by soil processes (Al, Cu, DOC and TNb) resulted in anti-clockwise hysteresis behaviors and mobilization with streamflow. The hysteresis indicators were most strongly influenced by discharge magnitude and the solute concentration itself. As the discharge and the concentration increases (>90th of the flow duration curve) the loop area and the hysteresis index turned to cero showing a direct linear response of the solute to discharge dynamics. Additionally, increasing discharge drives greater dilution or mobilization patterns for the geogenic and biogenic solutes. Higher discharge increases water volume to dilute geogenic solutes and is related to more water passing through shallow soils leaching biogenic solutes. This study contributes to our understanding of how Páramo catchments store and release solutes for a more adequate water resource management
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.
Hydrometeorological factors controlling the stable isotopic composition of precipitation in the highlands of south Ecuador
(2022) Zhiña Villa, Dario Xavier; Mosquera Rojas, Giovanny Mauricio; Esquivel Hernández, Germain; Córdova Mora, Mario Andrés; Sánchez Murillo, Ricardo; Orellana Alvear, Johanna Marlene; Crespo Sánchez, Patricio Javier
Knowledge about precipitation generation remains limited in the tropical Andes due to the lack of water stable isotope (WSI) data. Therefore, we investigated the key factors controlling the isotopic composition of precipitation in the Páramo highlands of southern Ecuador using event-based (high frequency) WSI data collected between November 2017 and October 2018. Our results show that air masses reach the study site preferentially from the eastern flank of the Andes through the Amazon basin (73.2%), the Orinoco plains (11.2%), and the Mato Grosso Massif (2.7%), whereas only a small proportion stems from the Pacific Ocean (12.9%). A combination of local and regional factors influences the δ18O isotopic composition of precipitation. Regional atmospheric features (Atlantic moisture, evapotranspiration over the Amazon Forest, continental rain-out, and altitudinal lapse rates) are what largely control the meteoric δ18O composition. Local precipitation, temperature, and the fraction of precipitation corresponding to moderate to heavy rainfalls are also key features influencing isotopic ratios, highlighting the importance of localized convective precipitation at the study site. Contrary to δ18O, d-excess values showed little temporal variation and could not be statistically linked to regional or local hydrometeorological features. The latter reveals that large amounts of recycled moisture from the Amazon basin contributes to local precipitation regardless of season and predominant trajectories from the east. Our findings will help to improve the isotope-based climatic models and enhance paleoclimate reconstructions in the southern Ecuador highlands. © 2022 American Meteorological Society.
Insight into the stable isotopic composition of glacial lakes in a tropical alpine ecosystem: Chirripó, Costa Rica
(2018) Esquivel Hernández, Germain; Sánchez Murillo, Ricardo; Quesada Román, Adolfo; Mosquera Rojas, Giovanny Mauricio; Birkel, Christian; Boll, Jan
Tropical high-elevation lakes are considered sentinels of global climate change. This work characterizes the hydrological conditions of tropical alpine glacial lakes located in the highlands of Chirripó, Costa Rica, using a unique data set of water stable isotopes (δ2H and δ18O) in precipitation, stream water, and lake water between September 2015 and July 2017. A combined dataset of bathymetric, hydrometric, and isotope data collected between July 2016 and July 2017 on Lake Ditkevi was used to calculate the annual water balance of the lake. Evaporation to inflow ratios from three lake systems was estimated using a linear resistance model, the experimentally estimated local evaporation line of Chirripó, and the first glacial lake water evaporation lines in the region. The temporal isotopic variations (δ18O, d-excess, and lc-excess) confirm variations in the dry and wet season evaporative conditions for the glacial lakes and consistently average annual low evaporation to inflow (E/I) ratios in the range of 2.0 ± 0.8% and 18.1 ± 12.2%. Lake Ditkevi's water balance indicates annual steady-state conditions, with an estimated evaporation loss of 650 mm/year (10.0 ± 5.0% of inflow), a high-water contribution to the catchment (90% of inflow), a residence time of 0.53 ± 0.27 years, and a catchment scale (0.289 km2) water yield or depth equivalent run-off of 278 mm/yr. These results provide novel information about water balance and evaporation losses in tropical alpine glacial lakes, which can serve as baseline information for future isotope-based hydro-climate research in high-elevation regions in the tropics and elsewhere.