DSpace Repository :: Browsing by Author "Rivera, Diego"

Browsing by Author "Rivera, Diego"

Now showing 1 - 20 of 23

A satellite-based ex post analysis of water management in a blueberry orchard
(2020) Holzapfel, Eduardo; Lillo-Saavedra, Mario; Rivera, Diego; Gavilán, Viviana; García-Pedrero, Angel; Gonzalo-Martín, Consuelo
In the scenario of current water scarcity caused by climate change and increasing water demand for food production, farmers must adapt their water management practices by shifting from supply-driven water management to demand-driven water management, considering trade-offs among quality, quantity and costs. Thus, agricultural practices must take full advantage of technology, research and development and adapt to local requirements. Nowadays, remote sensing is a useful tool for estimating crop water demand (evapotranspiration) as well as mapping their spatial and temporal variability. In this work, we present a new methodology that allows the user to audit (ex post) the irrigation strategies of a blueberry field in central Chile using a decision support system for irrigation decision called AquaSat® as the main tool. This tool combines satellite information with field data and provides spatially distributed information on crop water use for managing irrigation at a farm scale. The main contribution of this work is to detail a new approach for irrigation management through the comparison of volume of applied water, against evapotranspiration and potential demand. This procedure allows the user to audit current irrigation management and to determine the impacts on productivity. From our results, we can conclude that the applied water levels used at the farm during both seasons throughout of the irrigation sector were insufficient to reach the potential blueberries yield.
Calidad de vida urbana: una evaluación de las condiciones de habitabilidad derivados de la hiper densificación vertical en Estación Central
(Universidad del Desarrollo. Facultad de Ingeniería, 2022) Retamales Retamales, Luciana Rayen; Castro , Javier; Rivera, Diego
Este trabajo presenta un estudio de la calidad de vida urbana de los habitantes de construcciones verticales hiper densificadas a través del análisis de condiciones de habitabilidad y equipamiento del entorno y que influyen en el bienestar social y personal. Este se aplica en la comuna de Estación Central como caso de estudio, que en los últimos años se ha vuelto una comuna sobrepoblada por este tipo de construcciones. El objetivo de esta investigación es evaluar las condiciones de habitabilidad y equipamiento de entorno derivadas de la hiper densificación vertical para la identificación de variables claves que permitan una calidad vida urbana sostenible. Para lograrlo, se propone una aproximación cualitativa a las opiniones de 21 habitantes de este tipo de construcciones, que estén a cargo de menores de 10 años y que viven en el territorio desde hace 6 meses o más, seleccionados por conveniencia y basado en entrevistas semi estructuradas con opiniones contrastadas para la determinación de variables y parámetros claves que explican la relación entre la vivienda adecuada y la calidad de vida urbana. Los datos muestran que a pesar de que el acceso a la vivienda determina una mejora en la calidad de vida de las personas, las condiciones básicas de vivienda adecuada están alteradas por factores internos y externos cuando se construye con una densificación desequilibrada, que puede traer consecuencias en torno a la vivienda y barrio. Se concluye que la calidad de vida urbana, desde la perspectiva de vivienda, se ve alternada tanto por las condiciones de la vivienda, como también los espacios comunes. En cuanto al barrio, a pesar de la accesibilidad que se da en los equipamientos y espacios públicos cercanos a las viviendas, existe una sobredemanda de ellos y una escasa oferta que pueda cubrirla.
Comparing Methods for the Regionalization of Intensity−Duration−Frequency (IDF) Curve Parameters in Sparsely-Gauged and Ungauged Areas of Central Chile
(2023) Sangüesa, Claudia; Pizarro, Roberto; Ingram, Ben; Ibáñez, Alfredo; Rivera, Diego; García-Chevesich, Pablo; Pino, Juan; Pérez, Felipe; Balocchi, Francisco; Peña, Francisco
Estimating intensity−duration−frequency (IDF) curves requires local historical information of precipitation intensity. When such information is unavailable, as in areas without rain gauges, it is necessary to consider other methods to estimate curve parameters. In this study, three methods were explored to estimate IDF curves in ungauged areas: Kriging (KG), Inverse Distance Weighting (IDW), and Storm Index (SI). To test the viability of these methods, historical data collected from 31 rain gauges distributed in central Chile, 35° S to 38° S, are used. As a result of the reduced number of rain gauges to evaluate the performance of each method, we used LOOCV (Leaving One Out Cross Validation). The results indicate that KG was limited due to the sparse distribution of rain gauges in central Chile. SI (a linear scaling method) showed the smallest prediction error in all of the ungauged locations, and outperformed both KG and IDW. However, the SI method does not provide estimates of uncertainty, as is possible with KG. The simplicity of SI renders it a viable method for extrapolating IDF curves to locations without data in the central zone of Chile
Comparison of Three Daily Rainfall-Runoff Hydrological Models Using Four Evapotranspiration Models in Four Small Forested Watersheds with Different Land Cover in South-Central Chile
(2021) Flores, Neftali; Rodríguez, Rolando; Yépez, Santiago; Osores, Víctor; Rau, Pedro; Rivera, Diego; Balocchi, Francisco
We used the lumped rainfall–runoff hydrologic models Génie Rural à 4, 5, 6 paramètres Journalier (GR4J, GR5J and GR6J) to evaluate the most robust model for simulating discharge on four forested small catchments (<40 ha) in south-central Chile. Different evapotranspiration methods were evaluated: Oudin, Hargreaves–Samani and Priestley–Taylor. Oudin’s model allows the achievement of the highest efficiencies in the flow simulation. The more sensitive parameters for each model were identified through a Generalized Probability Uncertainty Estimation (GLUE) model. Our results demonstrate that the three hydrological models were capable of efficiently simulating flow in the four study catchments. However, the GR6J model obtained the most satisfactory results in terms of simulated to measured streamflow closeness. In general, the three models tended to underestimate peak flow, as well as underestimate and overestimate flow events in most of the in situ observations, according to the probability of non-exceedance. We also evaluated the models’ performance in a simulation of summer discharge due to the importance of downstream water supply in the months of greatest scarcity. Again, we found that GR6J obtained the most efficient simulations
Desperdicios de alimentos en hogares en Chile: estudio piloto de cuantificación y composición mediante diario de cocina en hogares de la Región Metropolitana
(Universidad del Desarrollo. Facultad de Ingeniería, 2022) Sáez Aguilera, Jessica Camila; Rivera, Diego
Este trabajo presenta una revisión acerca de la problemática de los desperdicios de alimentos en los hogares, tomando de referencia estudios internacionales. Se realizó un piloto de cuantificación y composición de residuos para estimar la generación y composición de los desperdicios de alimentos en los hogares de Chile. La propuesta metodológica considera un instrumento ampliamente utilizado, llamado Diario de Cocina, durante una semana en 14 hogares de la Región Metropolitana reclutados para participar de forma voluntaria. La investigación demuestra que el método de diario es útil como instrumento para comenzar a levantar información necesaria para el cumplimiento del ODS 12.3. La muestra levantada indica que los hogares en la Región Metropolitana generan entre 72,4 kg/per cápita/año y 94,8 kg per cápita/año. Este estudio concluye que Chile no cuenta con información actualizada y confiable aún para generar las acciones que ayuden a reducir a la mitad el desperdicio de alimentos per cápita mundial al año 2030. Además, el método del diario de cocina es un instrumento aplicable.
Earthquake-induced landslides coupled to fluvial incision in Andean Patagonia: inferring their effects on landscape at geological time scales
(2022) Morales, Bastian; Lizama, Elizabet; Somos-Valenzuela, Marcelo; Rivera, Diego; Ningshen, Chen
Earthquakes can deeply erode the mountainous landscape through co-seismic landslides, generating large amounts of sediment and debris that are then transported and distributed by rivers, controlling the landscape evolution. We can observe this influence in the Liqui˜ne Ofqui Fault System (LOFS), an active intra-arc fault system extending hundreds of kilometers through the Andes in Chilean Patagonia. For example, on April 21, 2007, a 6.2 Mw earthquake in the Ays´en Fjord triggered over 500 landslides with volumes reaching 12-20 Mm3. Although there is a well-defined seismic cycle, no study has focused on the effects of co-seismic landslides and sedimentary dynamics on the evolution of this mountainous landscape. In this research, we seek to improve the long-term understanding of the interaction between landslides and fluvial incisions in this segment of the Andes. For this reason, we implemented the Landlab-HyLands landscape evolution model (LEM), a hybrid landscape evolution model that allows modeling landslide activity coupled to fluvial incision. We consider the landslides that occurred during the 2007 earthquake as a precedent and simulate nine scenarios of ten seismic cycles over 21,000 years based on the 2100-year seismic cycle of the Holocene documented in this region. We further used multiple uplift rates, sediment erodibility, and m/n constant ratios associated with the current power law to assess this parameterization’s impact on the landscape. According to our results, landslides are a fundamental mechanism in the landscape’s evolution in this region. Deposits derived from landslides can create transitory landscape forms that can intervene in fluvial dynamics. According to our simulations, a significant part of the landslide sediment can remain on the slopes for thousands of years. We identified that parameterization considerably impacts the evolutionary response of the landscape in the evaluated time scale. Low m/n ratios can generate a different evolutionary response than other scenarios because the slopes are constantly driven towards their threshold angle, intensifying the interaction between landslides and fluvial incisions. Based on our analysis and considering the historical record of the Aysen Fjord, we can explain a critical primary control of the LOFS on landscape erosion and sediment production because of the surface seismic cycle. In our study, we demonstrate how the implementation of hybrid LEM can help to infer the contribution of sediments associated with large earthquakes and to improve the understanding of the role of landslides in the evolutionary history of Andean Patagonia. However, we stress that it is essential to advance in capturing erodibility and incision parameters of the current power law in the Andes and local geomechanical information. Finally, we believe the LEM can help to deepen the knowledge of these processes in other Andean basins exposed to these geomorphological processes.
Effects of the number of drip laterals on yield and quality of apples grown in two soil types
(2021) Lecaros-Arellano, F.; Holzapfel, Eduardo; Fereres, E.; Rivera, Diego; Muñoz, N.; Jara, J.
The effects of water distribution patterns in drip irrigation on fruit production and fruit quality were evaluated during two seasons in two commercial orchards of Gala Brookfield apple trees, grafted on M.9 dwarf rootstock. Research was conducted at El Manzano farm, with a clay-loam soil irrigated three times per week, and in Santa Mercedes farm, with a stony loam soil irrigated daily. Both farms are located in the Central Valley of Chile. The farm irrigation system was modified to establish three treatments which differed in the number of drip laterals per row (one, two and four), with 4.0, 2.0, and 1.0 L h−1 emitters spaced at 50 cm in both farms, respectively. All treatments received the same amount of water per week in each farm, based on the technical criteria of the farm advisor. Applied water in each farm was compared against the water use estimated by the AQUASAT platform. In the clay-loam soil, the volume of applied water was similar to the AQUASAT estimate. However, in the stony loam soil applied water was less than that estimated by AQUASAT. The results showed significant differences in production among treatments which varied only in the volume of wetted soil. The best results pooled over the two years were obtained with one lateral per row (T1) in the clay-loam soil (yield of 59.3 t ha−1), and with four laterals per row (T3) in the stony loam soil which yielded 50.8 t ha−1. Higher yields were associated with a tendency of greater fruit numbers per tree in both farms. Fruit quality requirements for export (equatorial diameter > 60 mm, weight > 90 g) were achieved but not the firmness in the second season at the stony loam soil, due to an irrigation deficit. Our results in apple emphasize the need to wet sufficient soil volume under drip irrigation, regardless of irrigation amounts, in light textured soils in particular
Estimation of Yield Response Factor for Each Growth Stage under Local Conditions Using AquaCrop-OS
(2020) Kuschel-Otárola, Mathias; Schütze, Niels; Holzapfel, Eduardo; Godoy Faúndez, Alex; Mialyk, Oleksandr; Rivera, Diego
We propose a methodology to estimate the yield response factor (i.e., the slope of the water-yield function) under local conditions for a given crop, weather, sowing date, and management at each growth stage using AquaCrop-OS. The methodology was applied to three crops (maize, sugar beet, and wheat) and four soil types (clay loam, loam, silty clay loam, and silty loam), considering three levels of bulk density: low, medium, and high. Yields are estimated for different weather and management scenarios using a problem-specific algorithm for optimal irrigation scheduling with limited water supply (GET-OPTIS). Our results show a good agreement between benchmarking (mathematical approach) and benchmark (estimated by AquaCrop-OS) using the Normalised Root Mean Square Error (NRMSE), allowing us to estimate reliable yield response factors ( Ky ) under local conditions and to dispose of the typical simple mathematical approach, which estimates the yield reduction as a result of water scarcity at each growth stage.
Ex Post Analysis of Water Supply Demand in an Agricultural Basin by Multi-Source Data Integration
(2021) Lillo-Saavedra, Mario; Gavilán, Viviana; García-Pedrero, Angel; Gonzalo-Martín, Consuelo; Hoz, Felipe de la; Somos-Valenzuela, Marcelo; Rivera, Diego
In this work, we present a new methodology integrating data from multiple sources, such as observations from the Landsat-8 (L8) and Sentinel-2 (S2) satellites, with information gathered in field campaigns and information derived from different public databases, in order to characterize the water demand of crops (potential and estimated) in a spatially and temporally distributed manner. This methodology is applied to a case study corresponding to the basin of the Longaví River, located in south-central Chile. Potential and estimated demands, aggregated at different spatio-temporal scales, are compared to the streamflow of the Longaví River, as well as extractions from the groundwater system. The results obtained allow us to conclude that the availability of spatio-temporal information on the water availability and demand pairing allows us to close the water gap—i.e., the difference between supply and demand—allowing for better management of water resources in a watershed
Exploring soil databases: a self-organizing map approach
(2015) Rivera, Diego; Sandoval, Marcos; Godoy Faúndez, Alex
A soil quality database (SQDB) is a collection of soil samples described by a given set of parameters, allowing farmers, scientists and other stakeholders to make informed decisions about practices, processes and policies for soil use and management. If each parameter is considered as a dimension of the space spanned by the SQDB, extracting information becomes a difficult task when the number of parameters is >3. A widely used approach to explore multidimensional data sets is the self-organizing map (SOM) method, which is suitable for clustering, visualization and extraction of information from multidimensional data. We applied the SOM method as an exploratory technique to an unlabelled SQDB to extract knowledge - data patterns and data associations - from the data set (the time and location of each sample were unknown). The SQDB used in this study is a set of 1240 unlabelled samples within the Central Valley of Chile, covering ca 7500km(2). The predominant soils are Andisols with a large organic matter content (7-12%), small bulk densities (0.6-1.0g/cm(3)) and large water-holding capacity. We identified three patterns: (i) isolated region within the map with close neurons (smooth transitions), (ii) two or more regions with predominantly large or small values and (iii) homogeneous map with small values with an isolated region of large values. These patterns show that the data set represented more than two groups that were not necessarily related. For pH, no important associations with other investigated parameters were observed. Previous studies carried out by the local agricultural research station showed that pH values below 5.5 constrain nutrient uptake. Thus, locations presenting pH<5,5 should be subject to seasonal monitoring to assess management practices that mitigate soil acidity. The component plane for organic matter indicates that ca. 50% of the soil samples had contents <8% related to soil series characteristics and management practices. As the k-means is initialized by random partitions, the two-step approach (clustering the map representing the input data) is less sensitive to variations in the input data (subsamples) than is the direct application of k-means to the input data, but it also reduces the computational cost. The ability of SOMs to visualize multidimensional data sets helps gain an understanding of the data in the exploratory phase, such as the association and integration of physical, chemical and biological parameters.
Force Measurement with a Strain Gauge Subjected to Pure Bending in the Fluid–Wall Interaction of Open Water Channels
(2022) Santana, Luis; Rivera, Diego; Forcael, Eric
An experimental method to measure forces of small magnitude with a strain gauge as a force sensor in the fluid–wall interaction of open water channels is presented. Six uniaxial strain gauges were employed for this purpose, which were embedded across the entire sensing area and subjected to pure bending, employing two-point bending tests. Sixteen two-point bending tests were performed to determine the existence of a direct relationship between the load and the instrument signal. Furthermore, a regression analysis was used to estimate the parameters of the model. A data acquisition system was developed to register the behavior of the strain gauge relative to the lateral displacement induced by the loading nose of the universal testing machine. The results showed a significant linear relationship between the load and the instrumental signal, provided that the strain gauge was embedded between 30% and 45% of the central axis in the sensing area of the sensor (R2 > 0.99). Thus, the proposed sensor can be employed to measure forces of small magnitude. Additionally, the linear relationship between the load and the instrumental signal can be used as a calibration equation, provided that the strain gauge is embedded close to the central axis of the sensing area.
Generation of soil maps permeability. Case study in two cantons of Loja province, Ecuador
(2023) Espinosa Marín, Jorge Andrés; Rivera, Diego; Haro Prado, Renato
The generation of permeability maps is based on the analysis and interpretation of geology, environmental morphology, land use, and slope, which enables the selection of sampling areas with similar characteristics. The method represents the integration of the physical characteristics of the study area and then determines the infiltration capacity differences in the most representative geopedologic units. In determining the basic data, minidisc infiltrometers were used to perform seventy-two infiltration tests in different types of soils with varying organic matter content, texture, soil structure, and vegetation cover, which showed the spatial variability that exists in two cantons of Loja province, Ecuador. In addition, it was observed that the infiltration rate depended mainly on the content of the organic matter in the soil and is consistent with information collected on permeability worldwide. In this study, generated pedotransfer function (FTP) coefficient of determination R. 0.78, the determination of the coefficient indicates a satisfactory estimate of the permeability with the variables that were analyzed; in addition, the methodology for assessing the permeability was suitable for the conditions of this investigation. For this reason, the method described here should be tested in other areas of the country with a greater number of field trials and with more variable contents of organic matter and soil textural classes.
Global patterns of nitrate isotope composition in rivers and adjacent aquifers reveal reactive nitrogen cascading
(2021) Matiatos, Ioannis; Wassenaar, Leonard; Monteiro, Lucilena R.; Venkiteswaran, Jason J.; Gooddy, Daren C.; Boeckx, Pascal; Sacchi, Elisa; Yue, Fu-Jun; Michalski, Greg; Alonso-Hernández, Carlos; Biasi, Christina; Bouchaou, Lhoussaine; Edirisinghe, Nandana V.; Fadhullah, Widad; Fianko, Joseph R.; García-Moya, Alejandro; Kazakis, Nerantzis; Li, Si-Liang; Luu, Minh T. N.; Priyadarshanee, Sakhila; Re, Viviana; Rivera, Diego; Romanelli, Asunción; Sanyal, Prasanta; Tamooh, Fredrick; Trinh, Duc A.; Walters, Wendell; Welti, Nina
Remediation of nitrate pollution of Earth’s rivers and aquifers is hampered by cumulative biogeochemical processes and nitrogen sources. Isotopes (δ15N, δ18O) help unravel spatiotemporal nitrogen(N)-cycling of aquatic nitrate (NO3−). We synthesized nitrate isotope data (n = ~5200) for global rivers and shallow aquifers for common patterns and processes. Rivers had lower median NO3− (0.3 ± 0.2 mg L−1, n = 2902) compared to aquifers (5.5 ± 5.1 mg L−1, n = 2291) and slightly lower δ15N values (+7.1 ± 3.8‰, n = 2902 vs +7.7 ± 4.5‰, n = 2291), but were indistinguishable in δ18O (+2.3 ± 6.2‰, n = 2790 vs +2.3 ± 5.4‰, n = 2235). The isotope composition of NO3− was correlated with water temperature revealing enhanced N-cascading in warmer climates. Seasonal analyses revealed higher δ15N and δ18O values in wintertime, suggesting waste-related N-source signals are better preserved in the cold seasons. Isotopic assays of nitrate biogeochemical transformations are key to understanding nitrate pollution and to inform beneficial agricultural and land management strategies
Legal disputes as a proxy for regional conflicts over water rights in Chile
(2016) Rivera, Diego; Godoy Faúndez, Alex; Lillo, Mario; Alvez, Amaya; Delgado, Verónica; Gonzalo-Martín, Consuelo; Menasalvas, Ernestina; Costumero, Roberto; García-Pedrero, Angel
Water demand and climate variability increases competition and tension between water users agricultural, industrial, mining, hydropower- and local communities. Since 1981, the Water Code has regulated water allocation through private individual property rights, fostering markets as the distribution mechanism among users. When legal conflicts occur between parties, it is the responsibility of the courts to settle the conflict. The aim of this research is twofold: first, to apply a geographical approach by mapping water conflicts using legal disputes reaching the higher courts as a proxy for conflict intensity and second, to explain the diversity of water disputes and how they vary regionally. We built a representative database with a sample of 1000 legal records corresponding to decisions issued by the Supreme Court and 17 courts of appeal throughout the country from 1981 to 2014. For geo-tagging, all records were transformed to plain text and analyzed to find words matching the entries of a geographical thesaurus, allowing records to be linked to geographical locations. The geo-tagging algorithm is capable of automatically populating a searchable database. Several maps were constructed using a color scale to visualize conflict intensity. Legal disputes represent different types of conflicts among water users, such as competition between agriculture and hydropower. Processed data allowed the identification of the regional variation of conflicts. The spatial pattern for the intensity of conflicts related to specific sections of the Water Code is explained in terms of the main geographical, climatic and productive characteristics of Chile. Geo-tagging legal records shows a strong potential to understand and define regional variation of water conflicts. However, data availability would become a barrier if measures to improve data management were not taken. Regarding the institutional framework, the same regulations for water management rules are applied throughout the highly diverse ecosystems of the country, impeding the resolution of conflicts that are strongly related to the local geographical context. This leads to a collision of interests and visions around water resources of both a public and private, extractive and non-extractive uses, national, and international nature of individuals, aboriginal communities, and corporations, especially mining industries. (C) 2016 Elsevier B.V. All rights reserved.
Multiperiod Optimisation of Irrigated Crops under Different Conditions of Water Availability
(01/10/2018) Kuschel-Otarola, Mathias; Rivera, Diego; Holzapfel, Eduardo; Palma, Cristian D.; Godoy Faúndez, Alex
We propose a nonlinear optimisation model which maximises profits by resource allocation on a monthly time scale, considering a monthly crop yield model. The proposed model was applied to six management scenarios (two seasonal and four monthly), nine conditions of water availability, and two situations of resource availability under Chilean conditions. These situations provided the same seasonal amount of resources, but different distributions over time. The model included improvements in water resource management such as water storage and water transactions, being the latter a monthly decision variable that can increase farmers’ profits. According to our results, monthly scenarios gave high profits, even better with appropriate resource distribution. When water costs are high, water transactions allow loss reduction of up to 50%. Regarding labour, the lack of availability is more critical than the wages
Neutral Sugar Content and Composition as a Sensitive Indicator of Fire Severity in the Andisols of an Araucaria–Nothofagus Forest in Southern Chile
(2021) Rivas, Yessica; Retamal-Salgado, Jorge; Knicker, Heike; Matus, Francisco; Rivera, Diego
Wildfire induces soil alterations that have a long-term impact on soil organic matter (SOM) quality. We postulated that after different fire severities, the neutral sugars in soils can be used as an indicator of soil organic matter quality after fire. The aim of this study was to determine the contribution of neutral sugar, bulk and occluded particulate organic matter (oPOM) affected by wildfire, at different soil depths in an Araucaria–Nothofagus Forest, four years post-after fire. The concentration and composition of the neutral sugars in the soils clearly comprised the major fraction in the unburned soil. Medium- and high-severity fires caused a drastic reduction in soil sugars in the bulk soil as well as in the oPOM fractions. The 13C-CPMAS NMR spectroscopy analysis revealed a high contribution of recalcitrant carbon to the decomposition such as aryl–C and aryl–O derived from charred material, whereas the abundance of O–alkyl C and alkyl C functional groups were decreased. The neutral sugars (Galactose+Mannose/Xilose+Arabinose) revealed a major microbial origin in fire affected areas as the ratio was >2. Therefore. Therefore, we suggest that the neutral sugar content of soil should be used for monitoring both short- and long-term changes in SOM altered by fires
Simulación hidrológica del caudal del estero Batuco en la microcuenca agroforestal Batuco (Ránquil, Región del Ñuble, Chile) bajo condiciones climáticas presentes y futuras
(2021) Hormazábal, Víctor; Vargas Rojas, Victor; Abarca del Río, Rodrigo; Little Cárdenas, Christian; Rivera, Diego; Carrasco, Noelia; Villalobos Volpi, Enrique
Se estima el comportamiento del caudal del estero Batuco, principal afluente de la microcuenca agroforestal Batuco en la Comuna de Ránquil, entre enero de 1975 y diciembre de 2064, en el escenario del cambio climático RCP8.5. Para tal efecto se simuló hidrológicamente la microcuenca Batuco, usando el modelo y software en versión gratuita WEAP. La información de entrada del modelo para estimar el caudal simulado provino de distintas bases de datos, tanto in situ como de reanálisis cercano a la zona de estudio, así como de datos aproximados del consumo (habitantes y cultivos). Se crearon series temporales para la precipitación y temperatura con los datos in situ, para posteriormente usarse como base para aplicar una corrección de sesgo a los datos de reanálisis Arclim. Los resultados son una primera aproximación que podrá ser mejorada cuando se pueda calibrar in situ con datos de caudal observado, los cuales actualmente no existen para la zona de estudio. No obstante, evidencian tendencias claras a la reducción sostenida de los caudales. Se determinó que el caudal simulado del estero Batuco marca una pendiente negativa en el periodo de estudio (1975-2064) de ≈−6,3 L/s por década, que se manifiesta también para todas las temporadas del año. Las anomalías estandarizadas de los promedios por cada 10 años, muestran en el periodo de 1980 un valor ≈ 1,2 desviaciones estándar con respecto a la media de la serie, mientras que en el periodo del 2060 se alcanza un valor ≈ -1,5. Las anomalías estandarizadas de las pendientes por cada 10 años sugieren un comportamiento cíclico, donde su amplitud disminuye con el tiempo para toda la serie y las diferentes temporadas del año
Simulation of Water-Use Efficiency of Crops under Different Irrigation Strategies
(2020) Kuschel-Otárola, Mathias; Rivera, Diego; Holzapfel, Eduardo; Schütze, Niels; Neumann, Patricio; Godoy Faúndez, Alex
Irrigation management is a key factor in attaining optimal yields, as different irrigation strategies lead to different yields even when using the same amount of water or under the same weather conditions. Our research aimed to simulate the water-use efficiency (WUE) of crops considering different irrigation strategies in the Central Valley of Chile. By means of AquaCrop-OS, we simulated expected yields for combinations of crops (maize, sugar beet, wheat), soil (clay loam, loam, silty clay loam, and silty loam), and bulk density. Thus, we tested four watering strategies: rainfed, soil moisture-based irrigation, irrigation with a fixed interval every 1, 3, 5, and 7 days, and an algorithm for optimal irrigation scheduling under water supply constraints (GET-OPTIS). The results showed that an efficient irrigation strategy must account for soil and crop characteristics. Among the tested strategies, GET-OPTIS led to the best performance for crop yield, water use, water-use efficiency, and profit, followed by the soil moisture-based strategy. Thus, soil type has an important influence on the yield and performance of different irrigation strategies, as it provides a significant storage and buffer for plants, making it possible to produce “more crop per drop”. This work can serve as a methodological guide for simulating the water-use efficiency of crops and can be used alongside evidence from the field
Uncertainty in a monthly water balance model using the generalized likelihood uncertainty estimation methodology
(2015) Rivera, Diego; Rivas, Yessica; Godoy Faúndez, Alex
Hydrological models are simplified representations of natural processes and subject to errors. Uncertainty bounds are a commonly used way to assess the impact of an input or model architecture uncertainty in model outputs. Different sets of parameters could have equally robust goodness-of-fit indicators, which is known as Equifinality. We assessed the outputs from a lumped conceptual hydrological model to an agricultural watershed in central Chile under strong interannual variability (coefficient of variability of 25%) by using the Equifinality concept and uncertainty bounds. The simulation period ran from January 1999 to December 2006. Equifinality and uncertainty bounds from GLUE methodology (Generalized Likelihood Uncertainty Estimation) were used to identify parameter sets as potential representations of the system. The aim of this paper is to exploit the use of uncertainty bounds to differentiate behavioural parameter sets in a simple hydrological model. Then, we analyze the presence of equifinality in order to improve the identification of relevant hydrological processes. The water balance model for Chillan River exhibits, at a first stage, equifinality. However, it was possible to narrow the range for the parameters and eventually identify a set of parameters representing the behaviour of the watershed (a behavioural model) in agreement with observational and soft data (calculation of areal precipitation over the watershed using an isohyetal map). The mean width of the uncertainty bound around the predicted runoff for the simulation period decreased from 50 to 20 m3s(-1) after fixing the parameter controlling the areal precipitation over the watershed. This decrement is equivalent to decreasing the ratio between simulated and observed discharge from 5.2 to 2.5. Despite the criticisms against the GLUE methodology, such as the lack of statistical formality, it is identified as a useful tool assisting the modeller with the identification of critical parameters.
Understanding Water Disputes in Chile by Text and Data Mining tools.
(Taylor & Francis, 2019) Herrera, Mauricio; Candia, Cristián; Rivera, Diego; Aitken, Douglas; Brieba, Daniel; Boettiger Philipps, Camila; Guillermo, Donoso; Godoy Faúndez, Alex
This paper provides a multidimensional study based on data and text mining of prosecuted disputes on water rights in Chile, and an analysis of the state’s capacity, particularly of the institutions related to water regulation. This study shows not only a substantial increase of legal disputes regarding water rights over the years (1981- 2014), but also clear patterns in the geographic location of these conflicts, as well as in the types of legal actions, arguments and strategies used in their pursuit. Through a topic analysis, we find a growing diversification over time of the subjects contained in the legal claims, suggesting an increase in structure and complexity.

Browsing by Author "Rivera, Diego"

Results Per Page

Sort Options