Rolando Célleri

The hydrology of tropical Andean ecosystems: importance, knowledge status, and perspectives.

Abstract This article highlights the economic and ecological value of the water resource systems of Ecuadors páramo and montane forest region and gives a description, based on a survey of recent literature, of the mechanisms controlling the rainfall–runoff process and how changes in land use alter the transformation. The review reveals that available understanding is partial, the result of individual and isolated research efforts, and is hindered by a lack of long-term complete and consistent data sets. Available knowledge does not yet permit up- and downscaling of findings. The article concludes by (1) citing some of the major gaps that impede hydrological understanding of the tropical Andean ecosystems and (2) proposing recommendations to speed up understanding and development of policies and measures to guarantee ecologically safe and sustainable development of the fragile water-based ecosystems of Ecuadors tropical Andean region.

Rainfall in the Andean Páramo: New Insights from High-Resolution Monitoring in Southern Ecuador

AbstractIn mountainous regions, rainfall plays a key role in water supply for millions of people. However, rainfall data for these sites are limited and generally of low quality, making it difficult to evaluate the nature, amount, and timing of rainfall. This is particularly true for the paramo, a high-elevation grassland in the northern Andes that is a primary source of water for large populations in Ecuador, Colombia, and Venezuela. In this study, high-resolution laser disdrometer data and standard tipping-bucket rain gauge data were used to improve knowledge of rainfall in the paramo. For 36 months, rainfall was monitored in a high-elevation (3780 m MSL) headwater catchment in southern Ecuador. Average annual rainfall during this period was 1345 mm. Results indicate that (i) when input from very low–intensity events (drizzle) is taken into account, rainfall is 15% higher than previously thought; (ii) rainfall occurs throughout the year (only approximately 12% of the days are dry); (iii) rainfall occurs...

Evaluation of the Penman-Monteith (FAO 56 PM) Method for Calculating Reference Evapotranspiration Using Limited Data

Reference evapotranspiration (ETo) is often calculated using the Penman-Monteith (FAO 56 PM; Allen et al 1998) method, which requires data on temperature, relative humidity, wind speed, and solar radiation. But in high-mountain environments, such as the Andean páramo, meteorological monitoring is limited and high-quality data are scarce. Therefore, the FAO 56 PM equation can be applied only through the use of an alternative method suggested by the same authors that substitutes estimates for missing data. This study evaluated whether the FAO 56 PM method for estimating missing data can be effectively used for páramo landscapes in the high Andes of southern Ecuador. Our investigation was based on data from 2 automatic weather stations at elevations of 3780 m and 3979 m. We found that using estimated wind speed data has no major effect on calculated ETo but that if solar radiation data are estimated, ETo calculations may be erroneous by as much as 24%; if relative humidity data are estimated, the error may be as high as 14%; and if all data except temperature are estimated, errors higher than 30% may result. Our study demonstrates the importance of using high-quality meteorological data for calculating ETo in the wet páramo landscapes of southern Ecuador.

Analysis of the water balance of small paramo catchments in south ecuador

The paramo is a high altitudinal wetland ecosystem in the upper Andes of Venezuela, Colombia, Ecuador and northern Peru. It is a reliable and constant source of high quality water and as such, the major water provider for the Andean highlands and part of the coastal plains. Water is used for consumption as well as electricity production. However, scientific evidence suggests that the quality and quantity of this water source may be at risk, due to increasing human interference in the wetland ecosystem. The current study analyses the water balance of two microcatchments near Cuenca, Ecuador. One is covered by the typical natural grass vegetation, while the other catchment is heavily interfered and intensive cultivation, cattle grazing and drainage are taking place. Three rain gauges and a V-notch were installed in each catchment, and one meteorological station in a nearby location. Analysis of the precipitation data reveals that seasonal variability in the paramo is extremely low. This property is a major reason for the sustained base flow, which characterises the paramo. However, evapotranspiration, represented by the crop coefficient, is more than twice as high in the cultivated areas (0.95), compared to the natural vegetation (0.42). The increased evapotranspiration may seriously affect the water production of interfered paramo catchments. Finally, based on water balance analysis, the variation in water storage in the paramo is very low, with a yearly variation of about 25 mm. In the interfered catchment, the storage in variation is even lower, about 15 mm, suggesting a deterioration of the regulation capacity.

Rainfall and Cloud Dynamics in the Andes: A Southern Ecuador Case Study

Mountain regions worldwide present a pronounced spatiotemporal precipitation variability, which added to scarce monitoring networks limits our understanding of the generation processes involved. To improve our understanding of clouds and precipitation dynamics and cross-scale generation processes in mountain regions, we analyzed spatiotemporal rainfall patterns using satellite cloud products (SCP) in the Paute basin (900–4200 m a.s.l. and 6481 km2) in the Andes of Ecuador. Precipitation models, using SCP and GIS data, reveal the spatial extension of three regimes: a three-modal (TM) regime present across the basin, a bimodal (BM) regime, along sheltered valleys, and a unimodal (UM) regime at windward slopes of the eastern cordillera. Subsequently, the spatiotemporal analysis using synoptic information shows that the dry season of the BM regime during boreal summer is caused by strong subsidence inhibiting convective clouds formation. Meanwhile, in UM regions, low advective shallow cap clouds mainly cause precipitation, influenced by water vapor from the Amazon and enhanced easterlies during boreal summer. TM regions are transition zones from UM to BM and zones on the windward slopes of the western cordillera. These results highlight the suitability of satellite and GIS data-driven statistical models to study spatiotemporal rainfall seasonality and generation processes in complex terrain, as the Andes.

Dynamic Mapping of Evapotranspiration Using an Energy Balance-Based Model over an Andean Páramo Catchment of Southern Ecuador

Understanding of evapotranspiration (ET) processes over Andean mountain environments is crucial, particularly due to the importance of these regions to deliver water-related ecosystem services. In this context, the detection of spatio-temporal changes in ET remains poorly investigated for specific Andean ecosystems, like the paramo. To overcome this lack of knowledge, we implemented the energy-balance model METRIC with Landsat 7 ETM+ and MODIS-Terra imagery for a paramo catchment. The implementation contemplated adjustments for complex terrain in order to obtain daily, monthly and annual ET maps (between 2013 and 2014). In addition, we compared our results to the global ET product MOD16. Finally, a rigorous validation of the outputs was conducted with residual ET from the water balance. ET retrievals from METRIC (Landsat-based) showed good agreement with the validation-related ET at monthly and annual steps (mean bias error <8 mm·month−1 and annual deviation <17%). However, METRIC (MODIS-based) outputs and the MOD16 product were revealed to be unsuitable for our study due to the low spatial resolution. At last, the plausibility of METRIC to obtain spatial ET retrievals using higher resolution satellite data is demonstrated, which constitutes the first contribution to the understanding of spatially-explicit ET over an alpine catchment in the neo-tropical Andes.

Temporal dynamics in dominant runoff sources and flow paths in the Andean Páramo

Funded by Central Research Office of the Universidad de Cuenca (DIUC) Secretaria de Educacion Superior, Ciencia, Tecnologia e Innovacion (SENESCYT 112–2012) . Grant Number: SENESCYT 112-2012 German Research Foundation (DFG) . Grant Number: BR2238/14-1

RadarNet-Sur First Weather Radar Network in Tropical High Mountains

AbstractWeather radar networks are indispensable tools for forecasting and disaster prevention in industrialized countries. However, they are far less common in the countries of South America, which frequently suffer from an underdeveloped network of meteorological stations. To address this problem in southern Ecuador, this article presents a novel radar network using cost-effective, single-polarization, X-band technology: the RadarNet-Sur. The RadarNet-Sur network is based on three scanning X-band weather radar units that cover approximately 87,000 km2 of southern Ecuador. Several instruments, including five optical disdrometers and two vertically aligned K-band Doppler radar profilers, are used to properly (inter) calibrate the radars. Radar signal processing is a major issue in the high mountains of Ecuador because cost-effective radar technologies typically lack Doppler capabilities. Thus, special procedures were developed for clutter detection and beam blockage correction by integrating ground-based ...

Near-Surface Air Temperature Lapse Rate Over Complex Terrain in the Southern Ecuadorian Andes: Implications for Temperature Mapping

ABSTRACT Near-surface air temperature variation with altitude (Tlr) is important for several applications including hydrology, ecology, climate, and biodiversity. To calculate Tlr accurately, a dense monitoring network over an altitudinal gradient is needed. Typically, meteorological monitoring in mountain regions is scarce and not adequate to calculate Tlr correctly. To overcome this problem in our region, we monitored temperature over a gradient ranging 2600–4200 m a.s.l. during an 18 month period. Using these data, we calculated Tlr for the first time at this altitude in the Andes and tested the impact of using the standard Tlr values instead of the observed ones to map temperature by means of the MTCLIM model. We found that annual lapse rate values (6.9 °C km-1 for Tmean, 5.5 °C km-1 for Tmin, and 8.8 °C km-1 for Tmax) differ significantly from the MTCLIM default values and that temperature maps improved vastly when measured Tlr was entered, especially for Tmax and Tmin. Our results may be representative of the broader area, as Tlr in our study period is not affected by microclimatic conditions generated by differences in topography and land cover between our monitoring sites; moreover, observed temperature during our study period was found to be representative of the longer-term annual climatology of the region.

Quantification of rainfall interception in the high Andean tussock grasslands

El ecosistema de paramo proporciona la mayor parte del agua para las tierras altas andinas tropicales en America del Sur. Aunque la comprension de este entorno ha aumentado ultimamente, sigue habiendo una necesidad urgente de cuantificar los procesos involucrados en el ciclo hidrologico. La perdida de intercepcion (IL) es uno de los procesos menos estudiados en el paramo y, en general, en los pastizales de todo el mundo. El objetivo principal de este estudio fue cuantificar la IL a escala del evento estimandola indirectamente a partir de la precipitacion (P) y la lluvia efectiva (ER). Ademas, se evaluaron las siguientes preguntas: (a) ?Cuanto de la P se convierte en ER? (b) ?Cual es el impacto en los calculos de IL de usar un pluviometro en lugar de un disdrometro? (c) ?Que variables meteorologicas estan relacionadas con el proceso de IL? y (d) ?es posible estimar la IL a partir de variables meteorologicas? Se encontraron altos porcentajes de IL en relacion con P (10–100%). La capacidad de almacenamiento en el dosel de las gramineas es de aproximadamente 2 mm. Las observaciones del disdrometro llevaron a resultados mas precisos que las observaciones del pluviometro porque solo el disdrometro registra precipitacion ligera, precipitacion horizontal y llovizna que aumenta la cantidad de estimaciones de P, ER e IL. Tambien, encontramos que la IL esta mas fuertemente correlacionada con P; e IL se puede estimar con una regresion lineal multiple (R La capacidad de almacenamiento en el dosel de las gramineas es de aproximadamente 2 mm. Las observaciones del disdrometro llevaron a resultados mas precisos que las observaciones del pluviometro porque solo el disdrometro registra precipitacion ligera, precipitacion horizontal y llovizna que aumenta la cantidad de estimaciones de P, ER e IL. Tambien, encontramos que la IL esta mas fuertemente correlacionada con P; e IL se puede estimar con una regresion lineal multiple (R La capacidad de almacenamiento en el dosel de las gramineas es de aproximadamente 2 mm. Las observaciones del disdrometro llevaron a resultados mas precisos que las observaciones del pluviometro porque solo el disdrometro registra precipitacion ligera, precipitacion horizontal y llovizna que aumenta la cantidad de estimaciones de P, ER e IL. Tambien, encontramos que la IL esta mas fuertemente correlacionada con P; e IL se puede estimar con una regresion lineal multiple (R2 = 0.9) de P y humedad relativa para eventos donde 1.7