SIGPAC y series multitemporales LANSAT 15 TM como estrategia híbrida de clasificación de usos de suelo para aplicaciones hidrológicas

El objetivo de este trabajo consiste en la obtención de un mapa de usos y coberturas de suelo para su integración en un modelo hidrológico de balance de agua a lo largo de 2009. Los resultados de dicha aplicación (evapotranspiración, humedad de suelo, necesidades de riego) se obtienen a escala de parcela, con escala temporal diaria y contemplando los usos y coberturas más frecuentes en la zona. La herramienta diseñada para aplicar el modelo (HidroMORE, Modelo Hidrológico de Estimación de Recarga y Evapotranspiración) proporciona los resultados en forma de mapa imagen. Con este fin, se presenta una alternativa híbrida de clasificación consistente en la combinación de la base de datos vectorial del Sistema de Información Geográfica de Parcelas Agrícolas (SIGPAC), junto con una serie multitemporal de imágenes Landsat 5 TM (Thematic Mapper) del año 2009. El primero aporta la definición parcelaria, mientras que la segunda provee la información suficiente para resolver clases poco definidas en el SIGPAC, especialmente la categoría ‘tierra arable’. Se utilizaron metodologías de teledetección como la clasificación, la segmentación multitemporal y el NDVI (Normalized Difference Vegetation Index), junto con herramientas SIG. El método propuesto supuso una mejora global de la precisión respecto a un método de clasificación supervisada convencional del 20% para la zona de estudio en 2009, y con un coste operacional muy bajo.The aim of this work consists on retrieving a land use-land cover map in order to integrate it in a water balance model along 2009. The results of this application, i.e., evapotranspiration, soil moisture, irrigation rates, are obtained at field scale, in a daily basis, and over the most representative agricultural uses. The model is implemented in a computerized tool, HidroMORE, which provides image maps of the results. A hybrid alternative of classification is presented for such hydrological application. It consisted in a combination of the vectorial database from the Spanish Geographic Information System for Agricultural Plots (SIGPAC) and a Landsat 5 TM multitemporal series of images for the year of study. The SIGPAC affords the spatial shape of the plots, whereas the images allow the segmentation of some ambiguous categories, i.e., ‘agricultural plots’. Remote sensing techniques (classification, segmentation, and NDVI, Normalized Difference Vegetation Index) were used, as well as GIS tools. The proposed method improved by 20% the global accuracy comparing to a typical supervised classification in the study area along 2009, while the computational cost is low

Evaporación en suelo desnudo en condiciones de alta demanda atmosférica

Ponencia presentada en: II Congreso de la Asociación Española de Climatología “El tiempo del clima”, celebrado en Valencia del 7 al 9 de junio de 2001[ES]La evaporación desde suelo desnudo tiene una gran importancia por la gran cantidad de superficie que se encuentra en esta condición a lo largo del tiempo en regiones semiáridas. En este trabajo se analiza la evaporación del suelo desnudo en sus dos fases. Para ello se utilizan datos obtenidos en una experiencia en campo, en condiciones de alta demanda evaporativa atmosférica y con diferentes contenidos de humedad del suelo. Se ha procedido a la determinación de la duración de la primera fase por varios métodos. Destaca, entre ellos, el cambio de la reflectividad del suelo durante el secado gradual. Los resultados muestran que la duración de la primera fase es inferior o cercana a un día, dependiendo del agua aportada. El análisis de la evaporación en la segunda fase muestra una fuerte dependencia del contenido en agua del suelo.[EN]Evaporation from bare soil is of great importance due to the extensive land surfaces subject to this condition in semiarid regions. In this paper evaporation from bare soil is analysed in its two stages. For this purpose, data has been obtained from fieldwork carried out in areas where high atmospheric evaporative conditions and different soil moisture contents were present. The length of the first stage of evaporation has then been determined using several methods, the most important being the change in reflectivity during a gradual drying out process. The results show that the length of the first stage is less than or nearly a day, depending on the irrigation water. Analysis of the second stage of evaporation shows a high dependence on soil water content

Interest group perceptions on water policy reforms: insight from a water-stressed basin

[EN] Water policies have been implemented worldwide to face water stress. However, the existence of water users' groups with opposite interests and different political power results in the plain failure or low effectiveness of water policy reforms. A better understanding of users' perceptions regarding policy outcomes is important to avoid the failure of water policies and the intensification of water conflicts. This paper empirically examines the divergent perception of interest groups on the implementation of different policies dealing with water scarcity and their proactive involvement with water agencies. We have conducted a survey in the Jucar River Basin (a water-stressed basin in southeastern Spain) to analyze interest group opinions regarding water policy effectiveness and water institutions' performance in water management. Questionnaires were sent to the main irrigation districts and urban water utilities within the basin. The collected information gives a general picture of the behavior of opposite water interest groups in this basin. The analysis of the perceptions on water policy reform between the groups highlights the existence of significant differences between preferred measures to address water scarcity and lobbying capacity. These differences depend on the size of the group, the specific basin location, and other group characteristics.Esteban, E.; Dinar, A.; Albiac-Murillo, J.; Calera, A.; García Molla, M.; Avella Reus, LF. (2018). Interest group perceptions on water policy reforms: insight from a water-stressed basin. Water Policy. 20(4):794-810. https://doi.org/10.2166/wp.2018.114S794810204Böhmelt, T., Bernauer, T., Buhaug, H., Gleditsch, N. P., Tribaldos, T., & Wischnath, G. (2014). Demand, supply, and restraint: Determinants of domestic water conflict and cooperation. Global Environmental Change, 29, 337-348. doi:10.1016/j.gloenvcha.2013.11.018Devlin, C., & Hendrix, C. S. (2014). Trends and triggers redux: Climate change, rainfall, and interstate conflict. Political Geography, 43, 27-39. doi:10.1016/j.polgeo.2014.07.001Estrela T. , (2004). Jucar Pilot River Basin: Provisional Article 5 Report. Oficina de Planificación Hidrográfica. Confederación Hidrográfica del Júcar. Ministerio de Medio Ambiente, Valencia, Spain.Gandure, S., Walker, S., & Botha, J. J. (2013). Farmers’ perceptions of adaptation to climate change and water stress in a South African rural community. Environmental Development, 5, 39-53. doi:10.1016/j.envdev.2012.11.004Gizelis, T.-I., & Wooden, A. E. (2010). Water resources, institutions, & intrastate conflict. Political Geography, 29(8), 444-453. doi:10.1016/j.polgeo.2010.10.005Greiner, R., & Gregg, D. (2011). Farmers’ intrinsic motivations, barriers to the adoption of conservation practices and effectiveness of policy instruments: Empirical evidence from northern Australia. Land Use Policy, 28(1), 257-265. doi:10.1016/j.landusepol.2010.06.006Greiner, R., Patterson, L., & Miller, O. (2009). Motivations, risk perceptions and adoption of conservation practices by farmers. Agricultural Systems, 99(2-3), 86-104. doi:10.1016/j.agsy.2008.10.003Hendrix, C. S., & Glaser, S. M. (2007). Trends and triggers: Climate, climate change and civil conflict in Sub-Saharan Africa. Political Geography, 26(6), 695-715. doi:10.1016/j.polgeo.2007.06.006Kahil, M. T., Ward, F. A., Albiac, J., Eggleston, J., & Sanz, D. (2016). Hydro-economic modeling with aquifer–river interactions to guide sustainable basin management. Journal of Hydrology, 539, 510-524. doi:10.1016/j.jhydrol.2016.05.057Mekonnen, M. M., & Hoekstra, A. Y. (2016). Four billion people facing severe water scarcity. Science Advances, 2(2), e1500323. doi:10.1126/sciadv.1500323Mertz, O., Mbow, C., Reenberg, A., & Diouf, A. (2008). Farmers’ Perceptions of Climate Change and Agricultural Adaptation Strategies in Rural Sahel. Environmental Management, 43(5), 804-816. doi:10.1007/s00267-008-9197-0Ortega-Reig, M., Palau-Salvador, G., Cascant i Sempere, M. J., Benitez-Buelga, J., Badiella, D., & Trawick, P. (2014). The integrated use of surface, ground and recycled waste water in adapting to drought in the traditional irrigation system of Valencia. Agricultural Water Management, 133, 55-64. doi:10.1016/j.agwat.2013.11.004Pérez-Martín, M. A., Estrela, T., Andreu, J., & Ferrer, J. (2014). Modeling Water Resources and River-Aquifer Interaction in the Júcar River Basin, Spain. Water Resources Management, 28(12), 4337-4358. doi:10.1007/s11269-014-0755-3Raleigh, C., & Urdal, H. (2007). Climate change, environmental degradation and armed conflict. Political Geography, 26(6), 674-694. doi:10.1016/j.polgeo.2007.06.005Sanz, D., Gómez-Alday, J. J., Castaño, S., Moratalla, A., De las Heras, J., & Martínez-Alfaro, P. E. (2009). Hydrostratigraphic framework and hydrogeological behaviour of the Mancha Oriental System (SE Spain). Hydrogeology Journal, 17(6), 1375-1391. doi:10.1007/s10040-009-0446-yUrquijo, J., & De Stefano, L. (2015). Perception of Drought and Local Responses by Farmers: A Perspective from the Jucar River Basin, Spain. Water Resources Management, 30(2), 577-591. doi:10.1007/s11269-015-1178-5Van Oel, P. R., Krol, M. S., & Hoekstra, A. Y. (2009). A river basin as a common‐pool resource: A case study for the Jaguaribe basin in the semi‐arid Northeast of Brazil. International Journal of River Basin Management, 7(4), 345-353. doi:10.1080/15715124.2009.9635393Ward, F. A., & Pulido-Velazquez, M. (2008). Water conservation in irrigation can increase water use. Proceedings of the National Academy of Sciences, 105(47), 18215-18220. doi:10.1073/pnas.080555410

Necesidades de agua de riego en una explotación comercial de almendro mediante teledetección

La superficie dedicada al cultivo del almendro (Prunus dulcis) en regadío se ha duplicado en España en los últimos 5 años. La alta respuesta del rendimiento de este cultivo a la cantidad de agua aplicada junto con su elevada rentabilidad ha propiciado que actualmente el cultivo del almendro se convierta en una alternativa al cultivo de cereales y otros leñosos en muchas zonas del territorio nacional. No obstante, la expansión del cultivo en zonas con escasez de agua hace necesario el desarrollo y la aplicación de herramientas que permitan conocer sus necesidades de agua con la suficiente precisión, resolución espacial y temporal, con el objetivo de optimizar los recursos hídricos, realizar una gestión más rentable y sostenible con el entorno. De esta manera, las series temporales de imágenes de NDVI de satélite surgen como una herramienta valiosa que permiten caracterizar la evolución espacial y temporal de la cubierta vegetal y estimar con precisión la evolución del coeficiente de cultivo a lo largo del ciclo de crecimiento siguiendo las relaciones establecidas en la literatura científica. El objetivo del presente estudio es determinar la evapotranspiración del cultivo del almendro y sus necesidades de agua de riego a través de la implementación del modelo de balance diario de agua en el suelo explorado por las raíces descrito en el manual de FAO 56 y asistido por teledetección. La metodología propuesta integra el coeficiente basal de cultivo (Kcb) derivado de la serie temporal de imágenes de satélite en el balance de agua. Dicha metodología está bien documentada en la literatura científica para otros cultivos, aunque permanece casi inexplorada y con escasa experiencia previa para el cultivo del almendro. El estudio se ha realizado en una explotación de almendro con riego localizado situada en el término municipal de Abarán (provincia de Murcia) durante la campaña 2019. Las necesidades de agua de riego estimadas con el modelo propuesto son evaluadas frente a datos reales de riego aplicados por el agricultor. Los resultados obtenidos revelan el desempeño de la metodología propuesta para estimar con precisión las necesidades de agua de riego del cultivo del almendro a lo largo de la campaña de estudio, capturando diferencias en los requerimientos de agua del cultivo entre las parcelas analizadas. La aplicación de la metodología en situaciones reales permite al agricultor ajustar el suministro de agua a las demandas del cultivo, y ampliar su conocimiento sobre el uso del agua realizado en la explotación. Esta información resulta de gran utilidad para la toma de decisiones orientadas a la mejora de la planificación de riegos, elaboración de estrategias de riego deficitario controlado (RDC) y a una optimización de la gestión y uso de los recursos hídricos

The Political Economy of Water Policy Design and Implementation in the Jucar Basin, Spain

Water scarcity has intensified conflicts between regions and interest groups for the use of water resources. Water policies have been implemented worldwide to face with water stress; however, existence of opposite interest between water users together with differences in their political power hinder the effectiveness of the water policy reform. A better understanding of users’ behavior is necessary to avoid the failure of water policies and the intensification of water scarcity problems and water conflicts. This paper empirically examines the perception of interest group about the implementation of different water policies to deal with water scarcity, and also their proactive involvement, or lobbying, with water organizations. We have conducted a survey in a water stressed basin in Southeastern Spain (Jucar River Basin) to analyze interest group opinions regarding water institutions’ performance and management; and the cost and benefits from group influence or lobbying on policy makers. The results highlight the existence of notably differences between the preferred measure to face with water scarcity together with sizable divergences in the active lobbying capacity of the interest groups depending on the size of the group, the specific basin location (upstream or downstream), and group characteristics.This Project was possible because the support of the project INIA RTA2014-00050-00-00. Ariel Dinar would like to acknowledge support by the Multistate Hatch Project W3190- Management and Policy Challenges in a Water-Scarce WorldPublishe

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

Monitoring 10-m LST from the Combination MODIS/Sentinel-2, Validation in a High Contrast Semi-Arid Agroecosystem

Downscaling techniques offer a solution to the lack of high-resolution satellite Thermal InfraRed (TIR) data and can bridge the gap until operational TIR missions accomplishing spatio-temporal requirements are available. These techniques are generally based on the Visible Near InfraRed (VNIR)-TIR variable relations at a coarse spatial resolution, and the assumption that the relationship between spectral bands is independent of the spatial resolution. In this work, we adopted a previous downscaling method and introduced some adjustments to the original formulation to improve the model performance. Maps of Land Surface Temperature (LST) with 10-m spatial resolution were obtained as output from the combination of MODIS/Sentinel-2 images. An experiment was conducted in an agricultural area located in the Barrax test site, Spain (39°03′35″ N, 2°06′ W), for the summer of 2018. Ground measurements of LST transects collocated with the MODIS overpasses were used for a robust local validation of the downscaling approach. Data from 6 different dates were available, covering a variety of croplands and surface conditions, with LST values ranging 300-325 K. Differences within ±4.0 K were observed between measured and modeled temperatures, with an average estimation error of ±2.2 K and a systematic deviation of 0.2 K for the full ground dataset. A further cross-validation of the disaggregated 10-m LST products was conducted using an additional set of Landsat-7/ETM+ images. A similar uncertainty of ±2.0 K was obtained as an average. These results are encouraging for the adaptation of this methodology to the tandem Sentinel-3/Sentinel-2, and are promising since the 10-m pixel size, together with the 3-5 days revisit frequency of Sentinel-2 satellites can fulfill the LST input requirements of the surface energy balance methods for a variety of hydrological, climatological or agricultural applications. However, certain limitations to capture the variability of extreme LST, or in recently sprinkler irrigated fields, claim the necessity to explore the implementation of soil moisture or vegetation indices sensitive to soil water content as inputs in the downscaling approach. The ground LST dataset introduced in this paper will be of great value for further refinements and assessments

A One-Layer Satellite Surface Energy Balance for Estimating Evapotranspiration Rates and Crop Water Stress Indexes

Daily evapotranspiration fluxes over the semi-arid Catania Plain area (Eastern Sicily, Italy) were evaluated using remotely sensed data from Landsat Thematic Mapper TM5 images. A one-source parameterization of the surface sensible heat flux exchange using satellite surface temperature has been used. The transfer of sensible and latent heat is described by aerodynamic resistance and surface resistance. Required model inputs are brightness, temperature, fractional vegetation cover or leaf area index, albedo, crop height, roughness lengths, net radiation, air temperature, air humidity and wind speed. The aerodynamic resistance (rah) is formulated on the basis of the Monin-Obukhov surface layer similarity theory and the surface resistance (rs) is evaluated from the energy balance equation. The instantaneous surface flux values were converted into evaporative fraction (EF) over the heterogeneous land surface to derive daily evapotranspiration values. Remote sensing-based assessments of crop water stress (CWSI) were also made in order to identify local irrigation requirements. Evapotranspiration data and crop coefficient values obtained from the approach were compared with: (i) data from the semi-empirical approach “Kc reflectance-based”, which integrates satellite data in the visible and NIR regions of the electromagnetic spectrum with ground-based measurements and (ii) surface energy flux measurements collected from a micrometeorological tower located in the experiment area. The expected variability associated with ET flux measurements suggests that the approach-derived surface fluxes were in acceptable agreement with the observations

Anchorage of VEGF to the extracellular matrix conveys differential signaling responses to endothelial cells

Matrix-bound VEGF elicits more distinct vascular effects than soluble VEGF, including prolonged VEGFR2 activation with altered patterns of tyrosine activation and downstream enhancement of the p38/MAPK pathway