Contribución de la fotogrametría y de la modelización numérica a la gestión conjunta agua superficial/subterránea. Aplicación a cuencas de la provincia de Cádiz.

Para la correcta gestión de los recursos hídricos, de vital importancia para el desarrollo humano, es necesario un conocimiento profundo y exhaustivo del funcionamiento del ciclo hidrológico y de los diferentes elementos que lo constituyen, así como de los componentes físicos que intervienen en el almacenamiento y distribución del recurso. La investigación desarrollada en esta Tesis Doctoral, se centra en dos líneas de investigación principales: i) ajuste de modelos de balance apoyados en técnicas fotogramétricas no convencionales y, ii) implementación de modelos numéricos de optimización para la definición de estrategias de gestión en el uso conjunto de agua superficial/subterránea. Respecto a la primera línea de investigación, se plantea el uso de técnicas basadas en el procesamiento y explotación de imágenes fotográficas, tales como fotogrametría terrestre de bajo coste y fotogrametría basada en algoritmos SfM (Structure from Motion). En el primer caso se ha hecho uso de cámaras time‐lapse y en el segundo caso, las imágenes han sido obtenidas desde vehículos aéreos no tripulados (UAS). Paralelamente y como segunda línea de investigación, se ha explorado el empleo de los Sistemas de Soporte a la Decisión (SSD), en concreto AQUATOOL‐SIMGES, para identificar las singularidades en la gestión de una cuenca y para definir y simular estrategias de gestión encaminadas a la optimización de recursos hídricos. Para la aplicación de las metodologías propuestas se han seleccionado casos de estudio idóneos para su implementación, calibración y puesta a punto. El uso de fotogrametría terrestre de bajo coste, se ha desarrollado en el embalse de Montejaque (Cuenca del río Guadares, España). El empleo de técnicas fotogramétricas desde vehículos aéreos no tripulados (UAS) se ha aplicado en la laguna de La Vega, en el Parque Metropolitano de los Toruños (Cádiz, España). Finalmente, la modelización numérica se ha llevado a cabo en la cuenca del río Barbate (Cádiz, España). El objetivo principal de los estudios desarrollados ha sido poner en práctica metodologías novedosas, de bajo coste y de fácil aplicación para la mejora del conocimiento y la gestión de recursos hídricos y que puedan ser aplicables a distintas cuencas o subsistemas hidrológicos, bajo contextos ambientales semejantes. Estas metodologías han permitido, cuantificar infiltraciones en embalses, relacionar los caudales infiltrados con los niveles de almacenamiento, obtener datos para el completado de hidrogramas históricos, definir cartografías 3D de alta resolución, establecer relaciones humedal/río‐acuífero, identificar las características singulares de una cuenca en relación a la gestión y a la disponibilidad de recursos hídricos, estimar valores de evaporación y además, definir y simular diferentes estrategias de gestión centradas en la optimización de recursos hídricos.204 página

Towards a Sustainable and Adaptive Groundwater Management: Lessons from the Benalup Aquifer (Southern Spain)

Reversing the chemical and quantitative impacts derived from human activity on aquifers demands a multidisciplinary approach. This requires, firstly, to update the hydrogeological knowledge of the groundwater systems, which is pivotal for the sustainable use of this resource, and secondly, to integrate the social, economic and administrative reality of the region. The present work focuses on the Benalup aquifer, whose exploitation plays a major role in the economy of the area, based mainly on irrigated agriculture. This activity has had negative consequences for the aquifer in quantitative and chemical terms, leading to its declaration as in poor condition. The study presented here shows the results obtained from the application of hydrogeological techniques, remote sensing and citizen participation tools, which have allowed us to deepen and improve the current knowledge of the system's hydrogeological, geometric, administrative and social aspects. Additionally, the lessons learned from this case study are analyzed. The deficiencies detected are discussed, and alternatives aimed at the sustainable use of groundwater are proposed, such as the possibility of a joint use of surface and groundwater resources, the creation of a Water User Association responsible for the management of groundwater and the need for greater efforts aimed at educating and raising awareness of water conservation among citizens

New design parameters for biparabolic beach profiles (SW Cadiz, Spain)

165 profiles of seventy-one beaches along the Gulf of Cadiz (SW, Spain) were studied to improve the formulation of the beach profile in tidal seas. Maritime climate, degree of energy exposure and size of the sand grains were taken into account to study the two sections of the biparabolic profile. The objective of the study was the determination of more accurate formulations of the design parameters for the equilibrium profile that involves tidal seas. These formulations were modelled and validated based on existing profiles to quantify the error existing between the real profile and the modelling. This comparative analysis was extended by considering the formulations proposed by other authors. The best results were obtained with the proposal presented herein

A Design Parameter for Reef Beach Profiles—A Methodology Applied to Cadiz, Spain

The southwestern coast of Spain is in a tidal zone (mesotidal) which causes the equilibrium profile to be developed in two different sections: the breakage section and the swash section. These two sections give rise to the typical bi-parabolic profile existing in tidal seas. The existence of areas with reefs/rocks which interrupt the normal development of the typical bi-parabolic profile causes different types of beach profiles. The objective of this article is designing an easy methodology for determining new formulations for the design parameters of the equilibrium profile of beaches with reefs in tidal seas. These formulations are applied on 16 profiles to quantify the error between the real profile data and the modelling results. A comparative analysis is extended to the formulations proposed by other authors, from which it is found that better results are obtained with the new formulations

Modeling River Runoff Temporal Behavior through a Hybrid Causal-Hydrological (HCH) Method

The uncertainty in traditional hydrological modeling is a challenge that has not yet been overcome. This research aimed to provide a new method called the hybrid causal-hydrological (HCH) method, which consists of the combination of traditional rainfall-runoff models with novel hydrological approaches based on artificial intelligence, called Bayesian causal modeling (BCM). This was implemented by building nine causal models for three sub-basins of the Barbate River Basin (SW Spain). The models were populated by gauging (observing) short runoff series and from long and short hydrological runoff series obtained from the Temez rainfall-runoff model (T-RRM). To enrich the data, all series were synthetically replicated using an ARMA model. Regarding the results, on the one hand differences in the dependence intensities between the long and short series were displayed in the dependence mitigation graphs (DMGs), which were attributable to the insufficient amount of data available from the hydrological records and to climate change processes. The similarities in the temporal dependence propagation (basin memory) and in the symmetry of DMGs validate the reliability of the hybrid methodology, as well as the results generated in this study. Consequently, water planning and management can be substantially improved with this approach

Applications of Unmanned Aerial Systems (UASs) in Hydrology: A Review

In less than two decades, UASs (unmanned aerial systems) have revolutionized the field of hydrology, bridging the gap between traditional satellite observations and ground-based measurements and allowing the limitations of manned aircraft to be overcome. With unparalleled spatial and temporal resolutions and product-tailoring possibilities, UAS are contributing to the acquisition of large volumes of data on water bodies, submerged parameters and their interactions in different hydrological contexts and in inaccessible or hazardous locations. This paper provides a comprehensive review of 122 works on the applications of UASs in surface water and groundwater research with a purpose-oriented approach. Concretely, the review addresses: (i) the current applications of UAS in surface and groundwater studies, (ii) the type of platforms and sensors mainly used in these tasks, (iii) types of products generated from UAS-borne data, (iv) the associated advantages and limitations, and (v) knowledge gaps and future prospects of UASs application in hydrology. The first aim of this review is to serve as a reference or introductory document for all researchers and water managers who are interested in embracing this novel technology. The second aim is to unify in a single document all the possibilities, potential approaches and results obtained by different authors through the implementation of UASs

Precipitation Variability and Drought Assessment Using the SPI: Application to Long-Term Series in the Strait of Gibraltar Area

The standardized precipitation index (SPI) provides reliable estimations about the intensity, magnitude and spatial extent of droughts in a variety of time scales based on long-term precipitation series. In this work, we assess the evolution of monthly precipitation in the Barbate River basin (S. Iberian Peninsula) between 1910/11 and 2017/18 through the generation of a representative precipitation series for the 108-year period and the subsequent application of the SPI. This extensive series was obtained after processing all the precipitation data (67 stations) available within and nearby the basin and subsequent complex gap-filling stages. The SPI identified 26 periods of drought, 12 of them severe and 6 extreme, with return periods of 9 and 18 years, respectively. Complementary analysis evidenced changes in precipitation cyclicity, with periodicities of 5 and 7-8 years during the first and second half of the study period, respectively. Additionally, the amplitude of pluviometric oscillations increased during the second half of the period, and extreme events were more frequent. While the decade 1940-1950 was very dry, with precipitation 11% below the basin's average, 1960-1970 was very humid, with precipitation 23% above average. Contrary to the results of climate change projections specific to this area, a clear downward trend in precipitation is not detected

Evolving spectrum but persistent high mortality of COVID-19 among patients on kidney replacement therapy in the vaccine era: the Spanish COVID-19 KRT Registry

COVID-19; Kidney transplant; DialysisCOVID-19; Trasplantament de ronyó; DiàlisiCOVID-19; Trasplante de riñón; DiálisisBackground Kidney replacement therapy (KRT) conferred a high risk for coronavirus disease 2019 (COVID-19) related mortality early in the pandemic. We evaluate the presentation, treatment and outcomes of COVID-19 in patients on KRT over time during the pandemic. Methods This registry-based study involved 6080 dialysis and kidney transplant (KT) patients with COVID-19, representing roughly 10% of total Spanish KRT patients. Epidemiology, comorbidity, infection, vaccine status and treatment data were recorded, and predictors of hospital admission, intensive care unit (ICU) admission and mortality were evaluated. Results Vaccine introduction decreased the number of COVID-19 cases from 1747 to 280 per wave. Of 3856 (64%) COVID-19 KRT patients admitted to the hospital, 1481/3856 (38%) were admitted during the first of six waves. Independent predictors for admission included KT and the first wave. During follow-up, 1207 patients (21%) died, 500/1207 (41%) during the first wave. Among vaccinated patients, mortality was 19%, mostly affecting KT recipients. Overall, independent predictors for mortality were older age, disease severity (lymphopaenia, pneumonia) and ICU rejection. Among patient factors, older age, male sex, diabetes, KT and no angiotensin receptor blockers (ARB) were independent predictors of death. In KT recipients, individual immunosuppressants were independent predictors of death. Over time, patient characteristics evolved and in later pandemic waves, COVID-19 was mainly diagnosed in vaccinated KT recipients; in the few unvaccinated dialysis patients, ICU admissions increased and mortality decreased (28% for the first wave and 16–22% thereafter). Conclusions The clinical presentation and outcomes of COVID-19 during the first wave no longer represent COVID-19 in KRT patients, as the pandemic has become centred around vaccinated KT recipients. Vaccines lowered the incidence of diagnosed COVID-19 and mortality. However, mortality remains high despite increased access to ICU care.We want to thank all the implicated Spanish centres for their altruist collaboration. A.O. research is supported by FIS/Fondos FEDER [PI18/01366, PI19/00588, PI19/00815, DTS18/00032, ERA-PerMed-JTC2018 (KIDNEY ATTACK AC18/00064 and PERSTIGAN AC18/00071, ISCIII-RETIC REDinREN RD016/0009)], Sociedad Española de Nefrología, FRIAT, Comunidad de Madrid en Biomedicina B2017/BMD-3686 CIFRA2-CM. Instituto de Salud Carlos III (ISCIII) RICORS program to RICORS2040 (RD21/0005/0001), FEDER funds

Learning from hydrological and hydrogeological problems in civil engineering. Study of reservoirs in Andalusia, Spain

This study presents a novel review of seven case histories of Andalusian reservoirs (Southern Spain) affected by different hydrological and hydrogeological problems that have led to severe malfunctions. The failures reported are related to (i) water quality degradation due to salinization and acid mine drainage, (ii) leakage in karstified terrains, (iii) environmental and hydrogeological impacts associated with an inadequate water planning and (iv) large evaporative losses from the reservoir. Detailed information on the geological context, hydrological/hydrogeological origin of the problem, repercussions on infrastructure functioning and remedial measures applied or proposed has been gathered for each case. Results of on-site research carried out by the authors in some of the locations studied and a comparative analysis of similar case histories at international level are also included. The purpose of this work is to emphasize the need of learning from past mistakes and provide guidance for future dam construction works, especially in the Mediterranean region. It also highlights the role of geological and hydrogeological research in dam sitting and the consequences of inadequate terrain characterisation, biased hydrological planning and data misinterpretation or undervaluation. This review evidences the need of conducting comprehensive studies that do not only focus on the infrastructure itself, but also on non-constructive aspects (monitoring of geological features and hydrological variables) and relevant processes (e.g. leakage, salinization and contamination) that might compromise the efficient functioning of the infrastructur

Beach Leveling Using a Remotely Piloted Aircraft System (RPAS): Problems and Solutions

The size and great dynamism of coastal systems require faster and more automated mapping methods like the use of a remotely piloted aircraft system (RPAS) or unmanned aerial vehicle (UAV). This method allows for shorter intervals between surveys. The main problem for surveying using low-altitude digital photogrammetry in beach areas is their visual homogeneity. Obviously, the fewer the homologous points defined by the program, the lower the accuracy. Moreover, some factors influence the error performed in photogrammetric techniques, such as flight height, flight time, percentage of frame overlap (side and forward), and the number of ground control points (GCPs). A total of 72 different cases were conducted varying these factors, and the results were analyzed. Among the conclusions, it should be highlighted that the error for noon flights is almost double that for the early morning flights. Secondly, there is no appreciable difference regarding the side overlap. But, on the other side, RMSE increased to three times (from 0.05 to 0.15 m) when forward overlap decreased from 85% to 70%. Moreover, relative accuracy is 0.05% of the flying height which means a significant increase in error (66%) between flights performed at 60 and 100 m height). Furthermore, the median of the error for noon flights (0.12 m) is almost double that for the early morning flights (0.07 m) because of the higher percentage of grids with data for early flights. Therefore, beach levelings must never be performed at noon when carried out by RPAS. Eventually, a new parameter has been considered: the relationship between the number of GCPs and the surface to be monitored. A minimum value of 7 GCP/Ha should be taken into account when designing a beach leveling campaign using RPAS.Fundacion Campus Tecnologico de Algeciras; Coastal Engineering Research group (University of Cadiz