Costa Rica does not have references on the health quality of Crassostrea gigas growing areas, which can pose a po tential public health risk. This study evaluated the temporal trends of Escherichia coli concentrations in the C. gigas oyster and in the seawater of Punta Cuchillo and Punta Morales growing areas as a basis for the classification and monitoring of bivalve mollusc production sites in the Gulf of Nicoya, Costa Rica. Monthly samples of seawater and C. gigas were collected from each site from July 2011 to June 2012, and their levels of E. coli were determined using the most probable number method. Temperature and salinity were recorded at a one meter depth. Precipitation data was provided by Instituto Meteorológico Nacional (the National Meteorological Institute). Results indicated that the evaluated areas are probably being affected by wastewater discharge. Punta Cuchillo and Punta Morales could be classified as class A or authorized areas for the production of bivalve molluscs. A significant seasonal variability of E. coli concentrations was determined in seawater and oysters from the Gulf of Nicoya, defined primarily by salinity. National legislation should be created to establish controls and implement a monitoring system ensuring the bacteriological quality of the areas used for the cultivation of bivalve molluscs in the country. | Costa Rica no cuenta con referencias sobre la calidad sanitaria de las zonas de cultivo de Crassostrea gigas y esto puede representar un riesgo para la salud pública. Se evaluó la tendencia temporal de las concentraciones de Escherichia coli en la ostra C. gigas y en el agua de mar de las zonas de cultivo de Punta Cuchillo y de Punta Morales como base para la clasificación y la vigilancia de los sitios de producción de moluscos bivalvos en el Golfo de Nicoya, Costa Rica. Muestras mensuales de agua de mar y de C. gigas de cada zona fueron recolectadas de julio de 2011 a junio de 2012 y se les determinó los niveles de E. coli por la técnica del número más probable. La temperatura y la salinidad fueron registradas a un metro de profundidad. Los datos de precipitación fueron suministrados por el Instituto Meteorológico Nacional. Los resultados indicaron que las áreas evaluadas podrían estar siendo afectadas por el vertido de aguas residuales. Punta Cuchillo y Punta Morales podrían clasificarse como zonas autorizadas o tipo A para la producción de moluscos bivalvos. Se determinó una variabilidad estacional significativa de las concentraciones de E. coli en agua de mar y en ostras del Golfo de Nicoya, definida principalmente por la salinidad. Se debe generar una normativa nacional que establezca controles e implemente un sistema de vigilancia que asegure la calidad bacteriológica de las áreas destinadas para el cultivo de moluscos bivalvos en el país. | Universidad Nacional, Costa Rica | Escuela de Ciencias Biológicas

Ramaswamy Sakthivadivel, D. Parker, S. Manor, 'Taller de la Region Sudasi?tica sobre Sistemas de Riego con Aguas Subterr?neas Administrados por los Agricultores y el Manejo Sustentable del Agua Subterr?nea Dhaka, Bangladesh 18-21 de mayo de 1992South Asian Regional Workshop on Groundwater Farmer-Managed Irrigation Systems and Sustainable Groundwater Management, Dhaka, Bangladesh 18-21 May 1992', FMIS Newsletter, 2014

Groundwater flow is an important control on subsurface evaporite (salt) dissolution. Salt dissolution can drive faulting and associated subsidence on the land surface and increase salinity in groundwater. This study aims to understand the groundwater flow system of Gypsum Canyon watershed in the Paradox Basin, Utah, USA, and whether or not groundwater-driven dissolution affects surface deformation. The work characterizes the groundwater flow and solute transport systems of the watershed using a three-dimensional (3D) finite element flow and transport model, SUTRA. Spring samples were analyzed for stable isotopes of water and total dissolved solids. Spring water and hydraulic conductivity data provide constraints for model parameters. Model results indicate that regional groundwater flow is to the northwest towards the Colorado River, and shallow flow systems are influenced by topography. The low permeability obtained from laboratory tests is inconsistent with field observed discharges, supporting the notion that fracture permeability plays a significant role in controlling groundwater flow. Model output implies that groundwater-driven dissolution is small on average, and cannot account for volume changes in the evaporite deposits that could cause surface deformation, but it is speculated that dissolution may be highly localized and/or weaken evaporite deposits, and could lead to surface deformation over time.

Parsimonious groundwater modeling provides insight into hydrogeologic functioning of the Nubian Aquifer System (NAS), the world’s largest non-renewable groundwater system (belonging to Chad, Egypt, Libya, and Sudan). Classical groundwater-resource issues exist (magnitude and lateral extent of drawdown near pumping centers) with joint international management questions regarding transboundary drawdown. Much of NAS is thick, containing a large volume of high-quality groundwater, but receives insignificant recharge, so water-resource availability is time-limited. Informative aquifer data are lacking regarding large-scale response, providing only local-scale information near pumps. Proxy data provide primary underpinning for understanding regional response: Holocene water-table decline from the previous pluvial period, after thousands of years, results in current oasis/sabkha locations where the water table still intersects the ground. Depletion is found to be controlled by two regional parameters, hydraulic diffusivity and vertical anisotropy of permeability. Secondary data that provide insight are drawdowns near pumps and isotope-groundwater ages (million-year-old groundwaters in Egypt). The resultant strong simply structured three-dimensional model representation captures the essence of NAS regional groundwater-flow behavior. Model forecasts inform resource management that transboundary drawdown will likely be minimal—a nonissue—whereas drawdown within pumping centers may become excessive, requiring alternative extraction schemes; correspondingly, significant water-table drawdown may occur in pumping centers co-located with oases, causing oasis loss and environmental impacts.

The Svensk Kärnbränslehantering AB (SKB) has proposed the Forsmark site as a future repository for spent high-level nuclear fuel, involving disposal at about 470 m depth in sparsely fractured crystalline bedrock. An essential part of the completed inter-disciplinary site investigation was to develop an integrated account of the site and its regional setting, including the current state of the geosphere and the biosphere as well as natural processes affecting long-term evolution. First, this report recollects the integrated understanding and some key hydraulic characteristics of the crystalline bedrock at Forsmark along with a description of the flow model set-up and the methodology used for paleoclimatic flow modeling. Second, the protocol used for site-scale groundwater flow and solute transport modeling is demonstrated. In order to conduct a quantitative assessment of groundwater flow paths at Forsmark, the standard guide for groundwater flow modeling was elaborated on, to support both discrete and porous media flow approaches. In total, four independent types of data were used to confirm that the final groundwater flow model for the crystalline bedrock was representative of site conditions.

A fundamental aspect in groundwater heat pump (GWHP) plant design is the correct evaluation of the thermally affected zone that develops around the injection well. This is particularly important to avoid interference with previously existing groundwater uses (wells) and underground structures. Temperature anomalies are detected through numerical methods. Computational fluid dynamic (CFD) models are widely used in this field because they offer the opportunity to calculate the time evolution of the thermal plume produced by a heat pump. The use of neural networks is proposed to determine the time evolution of the groundwater temperature downstream of an installation as a function of the possible utilization profiles of the heat pump. The main advantage of neural network modeling is the possibility of evaluating a large number of scenarios in a very short time, which is very useful for the preliminary analysis of future multiple installations. The neural network is trained using the results from a CFD model (FEFLOW) applied to the installation at Politecnico di Torino (Italy) under several operating conditions. The final results appeared to be reliable and the temperature anomalies around the injection well appeared to be well predicted.

Results of regional-scale geothermal studies are presented, providing new insights into the characteristics of deep groundwater flow systems in the Paleozoic sedimentary basins in the Amazon, Paraná and Parnaíba regions of Brazil. The study makes use mainly of bottom-hole temperature data sets for oil wells, the depths of which vary from 1,000 to 4,000 m. The techniques employed in data analysis have allowed identification of non-linear features in vertical distributions of temperature, produced by deep groundwater flows in the study area. According to the results obtained, vertical velocities of subsurface flows are found to fall in the range 10⁻¹⁰to 10⁻⁹ m/s, while the horizontal velocities are significantly higher, of the order 10⁻⁸ m/s. Identification of large-scale down flows has allowed inferences as to the existence of lateral movements of groundwater. The basins in the Amazon region are found to be characterized by widespread down flow of groundwater, implying the existence of distributed recharge systems operating on regional scales. There is a systematic decrease in horizontal velocities along the direction from west to east. This feature is considered indicative of gravity driven flows induced by episodes of uplift, since Miocene times, in the Andean region.

Effects on groundwater flow of abandoned engineered structures in relation to a potential geological repository for spent high-level nuclear fuel in fractured crystalline rock at the Forsmark site, Sweden, are studied by means of numerical modeling. The effects are analyzed by means of particle tracking, and transport-related performance measures are calculated. The impacts of abandoned, partially open repository tunnels are studied for two situations with different climate conditions: a “temperate” climate case with present-day boundary conditions, and a generic future “glacial” climate case with an ice sheet covering the repository. Then, the impact of abandoned open boreholes drilled through the repository is studied for present-day climate conditions. It is found that open repository tunnels and open boreholes can act as easy pathways from repository level to the ground surface; hence, they can attract a considerable proportion of particles released in the model at deposition hole positions within the repository. The changed flow field and flow paths cause some changes in the studied performance measures, i.e., increased flux at the deposition holes and decreased transport lengths and flow-related transport resistances. However, these effects are small and the transport resistance values are still high.

Saltwater intrusion is generally related to seawater-level rise or induced intrusion due to excessive groundwater extraction in coastal aquifers. However, the hydrogeological heterogeneity of the subsurface plays an important role in (non-)intrusion as well. Local hydrogeological conditions for recharge and saltwater intrusion are studied in a coastal groundwater system in Vietnam where geological formations exhibit highly heterogeneous lithologies. A three-dimensional (3D) hydrostratigraphical solid model of the study area is constructed by way of a recursive classification procedure. The procedure includes a cluster analysis which uses as parameters geological formation, lithological composition, distribution depth and thickness of each lithologically distinctive drilling interval of 47 boreholes, to distinguish and map well-log intervals of similar lithological properties in different geological formations. A 3D hydrostratigraphical fence diagram is then generated from the constructed solid model and is used as a tool to evaluate recharge paths and saltwater intrusion to the groundwater system. Groundwater level and chemistry, and geophysical direct current (DC) resistivity measurements, are used to support the hydrostratigraphical model. Results of this research contribute to the explanation of why the aquifer system of the study area is almost uninfluenced by saltwater intrusion, which is otherwise relatively common in coastal aquifers of Vietnam.