Effects of Surface Heterogeneity Due to Drip Irrigation on Scintillometer Estimates of Sensible, Latent Heat Fluxes and Evapotranspiration over Vineyards

Accurate estimates of sensible (H) and latent (LE) heat fluxes and actual evapotranspiration (ET) are required for monitoring vegetation growth and improved agricultural water management. A large aperture scintillometer (LAS) was used to provide these estimates with the objective of quantifying the effects of surface heterogeneity due to soil moisture and vegetation growth variability. The study was conducted over drip-irrigated vineyards located in a semi-arid region in Albacete, Spain during summer 2007. Surface heterogeneity was characterized by integrating eddy covariance (EC) observations of H, LE and ET; land surface temperature (LST) and normalized difference vegetation index (NDVI) data from Landsat and MODIS sensors; LST from an infrared thermometer (IRT); a data fusion model; and a two-source surface energy balance model. The EC observations showed 16% lack of closure during unstable atmospheric conditions and was corrected using the residual method. The comparison between the LAS and EC measurements of H, LE, and ET showed root mean square difference (RMSD) of 25 W m−2, 19 W m−2, and 0.41 mm day−1, respectively. LAS overestimated H and underestimated both LE and ET by 24 W m−2, 34 W m−2, and 0.36 mm day−1, respectively. The effects of soil moisture on LAS measurement of H was evaluated using the Bowen ratio, β. Discrepancies between HLAS and HEC were higher at β ≤ 0.5 but improved at 1 ≥ β \u3e 0.5 and β \u3e 1.0 with R2 of 0.76, 0.78, and 0.82, respectively. Variable vineyard growth affected LAS performance as its footprints saw lower NDVILAS compared to that of the EC (NDVIEC) by ~0.022. Surface heterogeneity increased during wetter periods, as characterized by the LST–NDVI space and temperature vegetation dryness index (TVDI). As TVDI increased (decreased) during drier (wetter) conditions, the discrepancies between HLAS and HEC, as well as LELAS and LEEC Re decreased (increased). Thresholds of TVDI of 0.3, 0.25, and 0.5 were identified, above which better agreements between LAS and EC estimates of H, LE, and ET, respectively, were obtained. These findings highlight the effectiveness and ability of LAS in monitoring vegetation growth over heterogonous areas with variable soil moisture, its potential use in supporting irrigation scheduling and agricultural water management over large regions

Estimating Evapotranspiration of an Apple Orchard Using a Remote Sensing-Based Soil Water Balance

The main goal of this research was to estimate the actual evapotranspiration (ETc) of a drip-irrigated apple orchard located in the semi-arid region of Talca Valley (Chile) using a remote sensing-based soil water balance model. The methodology to estimate ETc is a modified version of the Food and Agriculture Organization of the United Nations (FAO) dual crop coefficient approach, in which the basal crop coefficient (Kcb) was derived from the soil adjusted vegetation index (SAVI) calculated from satellite images and incorporated into a daily soil water balance in the root zone. A linear relationship between the Kcb and SAVI was developed for the apple orchard Kcb = 1.82 SAVI 0.07 (R2 = 0.95). The methodology was applied during two growing seasons (2010–2011 and 2012–2013), and ETc was evaluated using latent heat fluxes (LE) from an eddy covariance system. The results indicate that the remote sensing-based soil water balance estimated ETc reasonably well over two growing seasons. The root mean square error (RMSE) between the measured and simulated ETc values during 2010–2011 and 2012–2013 were, respectively, 0.78 and 0.74 mm day1, which mean a relative error of 25%. The index of agreement (d) values were, respectively, 0.73 and 0.90. In addition, the weekly ETc showed better agreement. The proposed methodology could be considered as a useful tool for scheduling irrigation and driving the estimation of water requirements over large areas for apple orchards

Propuestas de diseño de estrategias y herramientas de control de gestión para la caja de compensación y de asignación familiar Los Héroes

Tesis para optar al grado de Magíster en Control de GestiónAutor no autoriza el acceso a texto completo de su tesis en el Portal de Tesis Electrónicas de la U. de Chile.A través de este proyecto de grado se ha buscado entender en primer lugar qué es una Caja de Compensación y cuál es su función, comprender cómo nacieron y la complejidad de su industria. De lo anterior se pudo desprender que el génesis de estas organizaciones fue aumentar el bienestar social a los afiliados que pertenecían a este tipo de instituciones mediante la financiación del estado. El bienestar social en palabras simples, se refiere a beneficiar a sus afiliados mediante compensaciones en dinero, préstamos, pago de licencias u cualquier otro mecanismo que ayude al afiliado a satisfacer sus necesidades, proyectos personales, momentos importantes (ej: matrimonio, nacimiento de un hijo, etc) y situaciones de crisis (financiar deuda). Con el pasar del tiempo el Estado dejó en manos de privados la administración de estas corporaciones, debiendo ellas buscar la forma de financiar sus actividades. Esto generó la primera problemática comentada en este proyecto, respecto al marcado énfasis financiero en desmedro de la función Social, considerando que las cajas de compensación son organizaciones sin fines de lucro, pero que necesitan generar utilidades para poder mantener su funcionamiento y/o sostenibilidad. Ya detectado este problema se comenzó a generar el análisis de la industria y a conocer más detalladamente el funcionamiento de Los Héroes, para comenzar a desarrollar la planificación estratégica. Se observó que la competencia entre Cajas de Compensación es bastante fuerte y que es muy complejo diferenciar una de otra, ya que los productos ofrecidos por ellas son muy similares entre sí. A su vez de todas las aristas analizadas en el enfoque externo, se destaca el factor normativo y de regulación, ya que en esta industria en particular, se genera gran cantidad de leyes, circulares y oficios que impactan fuertemente el funcionamiento de la empresa, que incluso han contraído los ingresos generados por éstas, y que también han cuestionado su gestión y forma de operar, lo que la ha obligado a adaptarse rápidamente a los cambios exigidos. Adicionalmente el consumidor en el último tiempo tiene más conocimientos de sus derechos y más leyes e organismos fiscalizadores que los resguardan, debiendo la organización preocuparse de cumplir con los estándares exigidos y de generar planes de acción que le permitan responder los reclamos de los clientes en tiempo y forma para no dañar su imagen, la que en el último tiempo para las Cajas de Compensación en general han estado en tela de juicio por la sociedad. Los mayores puntos a destacar a nivel interno, es la necesidad constante de financiamiento para solventar sus operaciones. Al analizar los estados financieros se pueden observar que los ratios de liquidez que posee son débiles ya que no recibe ningún tipo de aporte, los únicos ingresos que percibe es por el cobro de intereses por los créditos otorgados y remuneración por servicios prestados (mundo transaccional y otros productos financieros). Al mismo tiempo, se observó que la empresa cuenta con una gran cobertura de sucursales, lo que le genera un alto costo operativo y de mantenimiento de la infraestructura. Finalmente, respecto al capital humano, en este tipo de industria requiere de personal que no es fácil de reclutar, que debe tener ciertos conocimientos específicos que le permitan entender el negocio y el funcionamiento operacional. A lo descrito se agrega el alto nivel de rotación que poseen y que incrementa el problema de contar con personal capacitado para atender y operar. Del mismo modo, se analizó e hizo un inventario de las herramientas estratégicas que posee la organización para luego establecer mejoras en el modelo de control de forma de modificar algunas existentes e incorporar alguna otra que permitiera dar claridad antes de desarrollar y proponer la estrategia. Se determinó para Los Héroes que aunque ha desarrollado una misión, visión y valores, no entregan claridad a sus colaboradores y afiliados, de cuál es su razón de ser y los objetivos que la mueven. Esto nos ratifica lo primordial que es tener claridad de lo que se busca lograr como organización, ya que esto es la piedra angular para desarrollar una estrategia efectiva a fin de que todos los integrantes de la organización saben el camino a seguir. Como no existe claridad de lo que se buscaba lograr, se pudo observar que las herramientas estratégicas que tiene incorporada la organización no conversan entre sí, no tienen identificado cual es la propuesta de valor que le ofrecen al cliente, existen tableros de control pero al no tener desarrollado un mapa estratégico es complejo establecer si los indicadores generados o los planes de acción asociados contribuyen al cumplimiento de la estrategia. A nivel de control de gestión, existe una matriz de desempeño e indicadores asociados, pero no existe una matriz de incentivos clara que permita conocer las recompensas que se obtiene por el cumplimiento de ellos, esto produce el efecto contrario que se quiere lograr, ya que en lugar de que los colaboradores realicen un mayor esfuerzo en el cumplimiento de estos objetivos al no tener conocimiento de las recompensas no se motivan a desarrollar un mayor esfuerzo. Adicionalmente pese a haber cumplidos la matriz de desempeño con sus objetivos e indicadores asociados no necesariamente se gatillan las recompensas lo que le quita credibilidad al mecanismo de incentivos. Sobre los indicadores en su mayoría son más operacionales que estratégicos y a su vez son demasiados lo que no permite visualizar cuales son los realmente importante que se cumplan. Como propuesta se realizó en primera instancia con toda la información recopilada una nueva misión, visión y valores, sobre ellas se comenzó a generar la planificación estratégica. Luego para identificar los factores claves para el éxito se utilizó la estrategia de los océanos azules, comparando a Los Héroes con su competencia, obteniendo que criterios potenciar y cuales disminuir. Se identificaron los factores críticos de éxito, los cuales se determinó que son: La diferenciación mediante la innovación y creación de nuevos productos complementados con una atención de calidad, el mejor uso de los recursos y la retención de talentos. En base a la información obtenida se creó la propuesta de valor y se determinó sus relaciones causa efecto para poder determinar los ejes estratégicos. Se propuso un mapa de empatía para ver como compatibilizaban las sensaciones de los clientes con la propuesta de valor y esto permitió desarrollar el modelo de negocios que nos entregó las aristas a abarcar en el mapa estratégico. Ya con el mapa, se generaron los indicadores claves para cada iniciativa y se generaron dos niveles que fueron los corporativos que afectan directamente a la unidad de negocios y los gerenciales que apalancan a los corporativos. Con la información recopilada se generó el cuadro de mando integral. Finalmente teniendo los focos estratégicos claros se generó un esquema de incentivos que permitiera incentivar al cumplimiento de lo planificad

Estimating Evapotranspiration of an Apple Orchard Using a Remote Sensing-Based Soil Water Balance

The main goal of this research was to estimate the actual evapotranspiration (ETc) of a drip-irrigated apple orchard located in the semi-arid region of Talca Valley (Chile) using a remote sensing-based soil water balance model. The methodology to estimate ETc is a modified version of the Food and Agriculture Organization of the United Nations (FAO) dual crop coefficient approach, in which the basal crop coefficient (Kcb) was derived from the soil adjusted vegetation index (SAVI) calculated from satellite images and incorporated into a daily soil water balance in the root zone. A linear relationship between the Kcb and SAVI was developed for the apple orchard Kcb = 1.82 SAVI 0.07 (R2 = 0.95). The methodology was applied during two growing seasons (2010–2011 and 2012–2013), and ETc was evaluated using latent heat fluxes (LE) from an eddy covariance system. The results indicate that the remote sensing-based soil water balance estimated ETc reasonably well over two growing seasons. The root mean square error (RMSE) between the measured and simulated ETc values during 2010–2011 and 2012–2013 were, respectively, 0.78 and 0.74 mm day1, which mean a relative error of 25%. The index of agreement (d) values were, respectively, 0.73 and 0.90. In addition, the weekly ETc showed better agreement. The proposed methodology could be considered as a useful tool for scheduling irrigation and driving the estimation of water requirements over large areas for apple orchards

Effects of Surface Heterogeneity Due to Drip Irrigation on Scintillometer Estimates of Sensible, Latent Heat Fluxes and Evapotranspiration over Vineyards

Accurate estimates of sensible (H) and latent (LE) heat fluxes and actual evapotranspiration (ET) are required for monitoring vegetation growth and improved agricultural water management. A large aperture scintillometer (LAS) was used to provide these estimates with the objective of quantifying the effects of surface heterogeneity due to soil moisture and vegetation growth variability. The study was conducted over drip-irrigated vineyards located in a semi-arid region in Albacete, Spain during summer 2007. Surface heterogeneity was characterized by integrating eddy covariance (EC) observations of H, LE and ET; land surface temperature (LST) and normalized difference vegetation index (NDVI) data from Landsat and MODIS sensors; LST from an infrared thermometer (IRT); a data fusion model; and a two-source surface energy balance model. The EC observations showed 16% lack of closure during unstable atmospheric conditions and was corrected using the residual method. The comparison between the LAS and EC measurements of H, LE, and ET showed root mean square difference (RMSD) of 25 W m−2, 19 W m−2, and 0.41 mm day−1, respectively. LAS overestimated H and underestimated both LE and ET by 24 W m−2, 34 W m−2, and 0.36 mm day−1, respectively. The effects of soil moisture on LAS measurement of H was evaluated using the Bowen ratio, β. Discrepancies between HLAS and HEC were higher at β ≤ 0.5 but improved at 1 ≥ β \u3e 0.5 and β \u3e 1.0 with R2 of 0.76, 0.78, and 0.82, respectively. Variable vineyard growth affected LAS performance as its footprints saw lower NDVILAS compared to that of the EC (NDVIEC) by ~0.022. Surface heterogeneity increased during wetter periods, as characterized by the LST–NDVI space and temperature vegetation dryness index (TVDI). As TVDI increased (decreased) during drier (wetter) conditions, the discrepancies between HLAS and HEC, as well as LELAS and LEEC Re decreased (increased). Thresholds of TVDI of 0.3, 0.25, and 0.5 were identified, above which better agreements between LAS and EC estimates of H, LE, and ET, respectively, were obtained. These findings highlight the effectiveness and ability of LAS in monitoring vegetation growth over heterogonous areas with variable soil moisture, its potential use in supporting irrigation scheduling and agricultural water management over large regions

Irrigation Performance Assessment in Table Grape Using the Reflectance-Based Crop Coefficient

In this paper, we present the results of our study on the operational application of the reflectance-based crop coefficient for assessing table grape irrigation requirements. The methodology was applied to provide irrigation advice and to assess the irrigation performance. The net irrigation water requirements (NIWR) simulated using the reflectance-based basal crop coefficient were provided to the farmer during the growing season and compared with the actual irrigation volumes applied. Two treatments were implemented in the field, increasing and reducing the irrigation doses by 25%, respectively, compared to the regular management. The experiment was carried out in a commercial orchard during three consecutive growing seasons in Northern Chile. The NIWR based on the model was approximately 900 mm per season for the orchard at tree maturity. The experimental results demonstrate that the regular irrigation applied covered only 76% of the NIWR for the whole season, and the analysis of monthly and weekly accumulated values indicates several periods of water shortage. The regular management system tended to underestimate the water requirements from October to January and overestimate the water requirements after harvest from February to April. The level of the deficit of water was quantified using such plant physiological parameters as stem water potential, vegetative development (coverage), and fruit productivity. The estimated NIWR was roughly covered in the treatment where the irrigation dose was increased, and the analyses of the crop production and fruit quality point to the relative advantage of this treatment. Finally, we conclude that the proposed approach allows the analysis of irrigation performance on the scale of commercial fields. These analytic capabilities are based on the well-demonstrated relationship of the crop evapotranspiration with the information provided by satellite images, and provide valuable information for irrigation management by identifying periods of water shortage and over-irrigation

Assessing satellite-based basal crop coefficients for irrigated grapes (Vitis vinifera L.)

A combined methodology of basal crop coefficient (Kcb) derived from vegetation indices (VI) obtained from satellite images and a daily soil water balance in the root zone of the crop was proposed to accurately estimate the daily grape crop coefficient and actual evapotranspiration. The modeled values were compared with field measurements of crop evapotranspiration (ET) using an energy balance eddy-covariance flux tower and adjusted for closure using the measured Bowen ratio. A linear relation between Kcb and VI for vineyard was obtained, Kcb = 1.44 x NDVI-0.10 and Kcb = 1.79 x SAVI-0.08. The correlation of the measured crop coefficient (Kc) and modeled (Kcrf) exhibits a linear tendency, Kc = 0.96Kcrf, r2 = 0.67. Other derived parameters such as weekly Kc and daily and weekly ET show good consistency with measurements and higher coefficients of determination. The study of the soil water balance suggests the importance of soil water storage in grapes within the La Mancha region. These results validate the use of remote sensing as a tool for the estimation of evapotranspiration of irrigated wine grapes planted on trellis systems.Evapotranspiration of grapes Vegetation indices Remote sensing Canopy reflectance Crop coefficients

Effect of Shading Nets on Yield, Leaf Biomass and Petiole Nutrients of a Muscat of Alexandria Vineyard Growing under Hyper-Arid Conditions

Background: Currently, viticulture is exposed to extreme weather fluctuations and global warming, thus the implementation of short-term adaptation strategies to mitigate climate change impacts will be of a wide importance for the sustainability and competitiveness of wine industry. This research aimed to study the effect of shading nets on the viticultural performance of a Muscat of Alexandria vineyard growing under hyper-arid conditions. Methods: Three treatments were randomly arranged in the vineyard: (i) a control (without shading), (ii) a white shading net (25% of shading), and (iii) a black shading net (40% of shading). Subsequently, yield, vine vigor, berry composition, leaf biomass and petiole nutrient content were assessed. Results: Both shading nets decreased the incidence of solar radiation in vines. The application of white shading nets induced a high bunch weight and a higher number of berries per bunch than the black shading nets. Black shading nets increased pruning weight, decreased Ravaz index and induced a considerably accumulation of soluble solids in grapes. This treatment also decreased bunch weight and the number of berries per bunch, and increased rachis length compared to control. Black shading nets decreased Mg petiole content, leaf dry weight and leaf biomass at flowering compared to uncovered vines. Conclusions: Shading considerably affected the viticultural performance of Muscat of Alexandria vines growing under hyper-arid conditions, modifying yield, leaf biomass and petiole nutrients

Effects of Surface Heterogeneity Due to Drip Irrigation on Scintillometer Estimates of Sensible, Latent Heat Fluxes and Evapotranspiration over Vineyards

Accurate estimates of sensible (H) and latent (LE) heat fluxes and actual evapotranspiration (ET) are required for monitoring vegetation growth and improved agricultural water management. A large aperture scintillometer (LAS) was used to provide these estimates with the objective of quantifying the effects of surface heterogeneity due to soil moisture and vegetation growth variability. The study was conducted over drip-irrigated vineyards located in a semi-arid region in Albacete, Spain during summer 2007. Surface heterogeneity was characterized by integrating eddy covariance (EC) observations of H, LE and ET; land surface temperature (LST) and normalized difference vegetation index (NDVI) data from Landsat and MODIS sensors; LST from an infrared thermometer (IRT); a data fusion model; and a two-source surface energy balance model. The EC observations showed 16% lack of closure during unstable atmospheric conditions and was corrected using the residual method. The comparison between the LAS and EC measurements of H, LE, and ET showed root mean square difference (RMSD) of 25 W m−2, 19 W m−2, and 0.41 mm day−1, respectively. LAS overestimated H and underestimated both LE and ET by 24 W m−2, 34 W m−2, and 0.36 mm day−1, respectively. The effects of soil moisture on LAS measurement of H was evaluated using the Bowen ratio, β. Discrepancies between HLAS and HEC were higher at β ≤ 0.5 but improved at 1 ≥ β > 0.5 and β > 1.0 with R2 of 0.76, 0.78, and 0.82, respectively. Variable vineyard growth affected LAS performance as its footprints saw lower NDVILAS compared to that of the EC (NDVIEC) by ~0.022. Surface heterogeneity increased during wetter periods, as characterized by the LST–NDVI space and temperature vegetation dryness index (TVDI). As TVDI increased (decreased) during drier (wetter) conditions, the discrepancies between HLAS and HEC, as well as LELAS and LEEC Re decreased (increased). Thresholds of TVDI of 0.3, 0.25, and 0.5 were identified, above which better agreements between LAS and EC estimates of H, LE, and ET, respectively, were obtained. These findings highlight the effectiveness and ability of LAS in monitoring vegetation growth over heterogonous areas with variable soil moisture, its potential use in supporting irrigation scheduling and agricultural water management over large regions