Showing papers by "Fernando Miralles-Wilhelm published in 2014"

The role of recharge and evapotranspiration as hydraulic drivers of ion concentrations in shallow groundwater on Everglades tree islands, Florida (USA)

Abstract: Recently, evapotranspiration has been hypothesized to promote the secondary formation of calcium carbonate year-round on tree islands in the Everglades by influencing groundwater ions concentrations. However, the role of recharge and evapotranspiration as drivers of shallow groundwater ion accumulation has not been investigated. The goal of this study is to develop a hydrologic model that predicts the chloride concentrations of shallow tree island groundwater and to determine the influence of overlying biomass and underlying geologic material on these concentrations. Groundwater and surface water levels and chloride concentrations were monitored on eight constructed tree islands at the Loxahatchee Impoundment Landscape Assessment (LILA) from 2007 to 2010. The tree islands at LILA were constructed predominately of peat, or of peat and limestone, and were planted with saplings of native tree species in 2006 and 2007. The model predicted low shallow groundwater chloride concentrations when inputs of regional groundwater and evapotranspiration-to-recharge rates were elevated, while low evapotranspiration-to-recharge rates resulted in a substantial increase of the chloride concentrations of the shallow groundwater. Modeling results indicated that evapotranspiration typically exceeded recharge on the older tree islands and those with a limestone lithology, which resulted in greater inputs of regional groundwater. A sensitivity analysis indicated the shallow groundwater chloride concentrations were most sensitive to alterations in specific yield during the wet season and hydraulic conductivity in the dry season. In conclusion, the inputs of rainfall, underlying hydrologic properties of tree islands sediments and forest structure may explain the variation in ion concentration seen across Everglades tree islands. Copyright © 2012 John Wiley & Sons, Ltd.

Do groundwater dynamics drive spatial patterns of tree density and diversity in Neotropical savannas

Abstract: Questions What are the temporal and spatial variations of groundwater depth along topographic gradients in Neotropical savannas? Are patterns of tree density and species diversity along topographic gradients in Neotropical savannas controlled by water table depth? Do soil and groundwater nutrient concentrations differ along topographic gradients in Neotropical savannas? Location Fire-protected savannas of central Brazil. Methods Over 16 mo, we monitored temporal and spatial variations in groundwater levels using automated submersible pressure transducers installed in ten wells located along two topographic gradients (five wells per gradient) of 950 m and 1703 m in length, representing elevations of 47 and 37 m a.s.l., respectively. We located the wells according to changes in vegetation physiognomies from woody savannas at high elevations, to open shrubby grasslands at low elevations. Along each topographic gradient we determined soil and groundwater nutrient concentrations as well as richness, density, basal diameter and height of trees within two plots of 14 × 14 m (392 m2) adjacent to each well. Results Along the two gradients, groundwater levels exhibited larger fluctuations at lower than at higher elevations where the water table was deeper. Richness, density and diversity of trees decreased significantly at lower elevations where soils were waterlogged during the wet season. Soil pH and soil concentrations of carbon, nitrogen and manganese decreased significantly as elevation increased along the topographic gradients, but soil nutrient concentrations of phosphorus, aluminium and iron did not change with elevation. Groundwater samples contained only trace amounts of nutrients and were poorly correlated with elevation along the topographic gradients. Conclusions In Neotropical savannas, the minimum distance between the soil surface and water table depth (reached during the wet season) and the relatively large fluctuations in groundwater limit tree density and diversity at low elevations as savanna trees cannot cope with extended waterlogging during the wet season and with low soil water availability during the dry season. Thus, variations of tree density and diversity along topographic gradients are more related to spatial and temporal variations in water table depth than to soil and groundwater nutrient variations in Neotropical savannas.

Hydro-BID: An Integrated System for Modeling Impacts of Climate Change on Water Resources. Part 2

Abstract: As part of its commitment to assist member countries in adapting to climate change, the IDB sponsors work to develop and implement an integrated set of watershed simulation tools known as Hydro-BID. The Hydro-BID Simulation System includes hydrological and climatic analysis modules to estimate the availability (volumes and flows) of fresh water at regional scales, of basins and sub-basins. It also includes economic analyses and decision-making tools to estimate the costs and benefits of adaptation measures and help decision-makers choose between alternative designs of infrastructure projects and water resources management policies.

Geographically weighted spatial modelling of sediment quality in Lake Okeechobee, Florida

Abstract: Lake Okeechobee is a large shallow lake with over 44% (as of 2006) being underlain with phosphorus-enriched mud sediments Wind-induced sediment re-suspension may play a significant role in the nutrient cycling of this lake It is critical to develop optimal models with low uncertainty to map the distribution and changes of total phosphorus (TP) over time Geographically Weighted Regression (GWR) is a powerful spatial regression method that examines the details of relationship between the target variable and independent variables and their changes over space The calibrated GWR models were applied to data sets of organic mud sediment from Lake Okeechobee collected in 1988, 1998 and 2006 Three sets of ancillary data were also used in the models: total iron (Fe), which was strongly and positively correlated to TP (069–072); mud thickness, which was moderately and positively correlated to TP (057–072); and site elevation, which was weakly but negatively correlated to TP (−046- −055) The GWR models we

Climate services: A tool for adaptation to climate change in Latin America and the Caribbean: Action plan and case study applications.

Abstract: A variable and changing climate where uncertainties exist regarding its future extremes requires better quantity, quality and accessible information that support planning and decision-making processes, as well as infrastructure that can take changing conditions into account. New advances in science and technology have provided higher reliability in climate information, more resilient infrastructure and better insights into managing climate risks and opportunities. New practices and tailored climate information and adapted infrastructure-Climate Services-would be able to accelerate and strengthen the process in order to meet the growing demands for useful and usable climate information. In the LAC region, a vision for the development and implementation of climate services has been developed with a vision of integrating climate information into decisionmaking in socioeconomic sectors, through an effective dialogue between providers and users on the range, timing, quality, content and delivery format of climate products and services. Developing and effectively deploying climate information and climate-adapted infrastructure is an important challenge for the water sector in the LAC region. An effective response to this challenge must integrate meeting the needs of the users of such climate services and building capacity in the existing and next-generation of scientists, practitioners, managers and policy makers. With this in mind, this paper focuses on information and infrastructure activities within the overall framework of climate services for the LAC region.

Caso de estudio de Hydro-BID No 1: Modelo de gestión del recurso hídrico en la cuenca del Río Grande en Argentina

Abstract: Este caso de estudio es el primero de la serie “Hydro-BID Aplicaciones” y demuestra las capacidades de la herramienta de modelaje de recursos hidricos “Hydro-BID” en una aplicacion para el Rio Bermejo Superior en el Noroeste de Argentina. Este informe describe los pasos seguidos por un equipo multi-disciplinario del proyecto, trabajando en conjunto con partes interesadas y consultores locales, para evaluar el impacto del cambio climatico en una region que ya sufre de escasez de agua y para evaluar las opciones posibles de adaptacion. El caso de estudio se centra en la Provincia de Jujuy en el noroeste de Argentina, una de las provincias mas remotas y menos desarrolladas del pais. Las caracteristicas claves de la provincia incluyen una region montanosa grande (“altiplano”) en el oeste, con una elevacion de mas de 4.200 m, y el canon llamado Quebrada de Humahuaca que forma la Cuenca del Rio Grande. El rio fluye al sur desde las montanas, a traves de San Salvador de Jujuy, la capital de la provincia (altitud de 1.200 m) y cruza al este para encontrarse con el Rio Lavayan y formar el Rio San Francisco, que eventualmente alcanza el Rio Bermejo.

Hydro-BID Case Study No. 2: Modeling the Impact of Climate Change on Flows of the Rio Piura Using Hydro-BID

Abstract: This is the second case study of the "Hydro-BID Applications" series and demonstrates the capabilities of the water resources modeling tool “Hydro-BID”, used to prepare a hydrologic model of the Rio Piura basin and project stream flows in the basin for the period 2011–2060, under a limited set of climate change scenarios. The project delivered the projected stream flow data to ANA (Peru’s National Water Authority) in a format that can be directly incorporated as input data for its Rio Piura basin WEAP model. ANA is using the data on projected stream flows as inputs to its WEAP model, and to assess the potential impact of climate change on the allocation of available water resources among users and uses in the Rio Piura basin. This work served as a case study to demonstrate the use of Hydro-BID to enhance planning for integrated water resource management.

Hydro-BID: Un sistema integrado para la simulación de impactos del cambio climático sobre los recursos hídricos

Abstract: Como parte de su compromiso de ayudar a los paises miembros en la adaptacion al cambio climatico, el BID patrocina trabajos para desarrollar y aplicar un conjunto integrado de herramientasde simulacion de cuencas conocidas como Hydro-BID. El Sistema de simulacion Hydro-BID incluye modulos de analisis hidrologico y climatico para estimar la disponibilidad (volumenes y caudales) de agua dulce a escalas regional, de cuencas y de sub-cuencas. Incluira tambien los analisis economicos y las herramientas de soporte de decisiones para estimarlos costos y beneficios de las medidas de adaptacion y ayudar a los responsables de tomar decisionesen la escogencia entre disenos alternativos de proyectos de infraestructura asi comoentre politicas de gestion de recursos hidricos.

Base de Datos de Hidrología Analítica para América Latina y el Caribe

Abstract: El sistema Hydro-BID genera salidas de informacion en forma de series de tiempo diarias de los flujos estimados para la localidad y el periodo escogidos. A discrecion del usuario, estas salidas pueden ser resumidas en una serie de tiempo mensual. Con el fin de ilustrar las entradas, la operacion y salidas del sistema Hydro-BID, el equipo de trabajo preparo un caso de estudio para la distribucion de recursos hidricos en la cuenca del Rio Grande en Argentina. La version inicial del Hydro-BID ha recibido una respuesta entusiasta en las presentaciones a usuarios potenciales y miembros del BID asi como de parte de audiencias tecnicas externas via conferencias y talleres. El trabajo realizado durante la Fase 1 se describe en tres Notas Tecnicas. Este documento constituye la Nota Tecnica 1.