Los cuerpos de agua superficial (CAS) permanentes o efímeros (pozas, tinajas, escurrimientos, etc.) que se encuentran en depresiones del terreno, como arroyos y cañadas, son soporte fundamental para el ecosistema en zonas áridas. Mediante el uso de cámaras-trampa, en este estudio se identifican especies de vertebrados terrestres silvestres presentes en 4 sitios con agua superficial, en el extremo sur de la sierra El Mechudo, Baja California Sur, y se analiza el uso de los CAS por las especies en los periodos de actividad. En cada sitio se caracterizó el hábitat (topografía, vegetación y agua). Los 4 sitios mostraron diferencias en sus características ambientales. Se identificaron 41 especies de vertebrados terrestres (3 reptiles, 31 aves y 7 mamíferos). Se encontraron también varias especies de murciélagos que no fueron identificadas. La riqueza de especies y frecuencia de visita fue diferente en cada sitio. Con excepción de 3 especies de mamíferos, el horario de actividad fue similar en los 4 sitios. La presente investigación aporta información sobre la importancia de los CAS en zonas semiáridas, describiendo el hábitat, las especies y su comportamiento, elementos básicos para la conservación y manejo de los recursos naturales.<br>Permanent or ephemeral water ponds (puddles, catchments, drains, and so on) located on ground depressions, such as streams and creeks, are a fundamental support for ecosystems in dry areas. This study identified the species of native terrestrial vertebrates in 4 sites in the southernmost part of the Sierra El Mechudo, B.C.S., including how such species use these bodies of water based on the periods of species activity. Habitats were characterized in 4 sites (topography, vegetation, and water sources); camera-traps were placed around water ponds from March to October 2007. The 4 sites differed in their environmental characteristics. Overall, there were 41 species of terrestrial vertebrates (3 reptiles, 31 birds, and 7 mammals), with several unidentified species of bats that were also found. Specific richness and visit (record) frequency were also different at each site. Species activity schedule was similar in the 4 sites with the exception of 3 species of mammals. This study provides important information of superficial water in semiarid areas, including description of habitat, species, and their behavior, which are basic elements for conservation and management of natural resources.

Temporal and spatial changes of the hydrological cycle are the consequences of climate variations. In addition to changes in surface runoff with possible floods and droughts, climate variations may affect groundwater through alteration of groundwater recharge with consequences for future water management. This study investigates the impact of climate change, according to the Special Report on Emission Scenarios (SRES) A1B, A2 and B1, on groundwater recharge in the catchment area of a fissured aquifer in the Black Forest, Germany, which has sparse groundwater data. The study uses a water-balance model considering a conceptual approach for groundwater-surface water exchange. River discharge data are used for model calibration and validation. The results show temporal and spatial changes in groundwater recharge. Groundwater recharge is progressively reduced for summer during the twenty-first century. The annual sum of groundwater recharge is affected negatively for scenarios A1B and A2. On average, groundwater recharge during the twenty-first century is reduced mainly for the lower parts of the valley and increased for the upper parts of the valley and the crests. The reduced storage of water as snow during winter due to projected higher air temperatures causes an important relative increase in rainfall and, therefore, higher groundwater recharge and river discharge.

Unpublished

Previous geoetic studies cooducted with migratory fish populatioos from dowostream of the Três Marias dam io the São Fraocisco River Basio (Brazil) have documeoted the occurreoce of populatioo structuriog, as reported for Brycon orthotaenia aod Prochilodus argenteus, two commercially importaot species io this basio. We revisited the geoetic structure of these species usiog microsatellites. B. orthotaenia was sampled duriog the spawoiog seasoo aod was aoalyzed usiog five heterologous microsatellites. P. argenteus was collected io the ooo-reproductive seasoo aod geoetic aoalysis was cooducted usiog teo species-specific microsatellites. For both species, geoetic diversity betweeo collectioo sites was similar. Coosideriog B. orthotaenia, F ST aod R ST estimates aod the Bayesiao aoalysis demoostrated sigoificaot differeoces betweeo sites. Two well-defioed populatioos were ideotified io the study area, iodicatiog populatioo structuriog for this species. No sigoificaot differeoces were fouod for P. argenteus. These data provide ioformatioo for koowledge regardiog geoetic structure of migratory fish species, which may cootribute toward the cooservatioo besides the uoderstaodiog the biology aod ecology of these importaot fishery resources.<br>Estudios geoéticos aoteriores realizados coo poblaciooes de peces migratorios de aguas abajo de la represa de las Tres Marías eo la cueoca del río Sao Fraocisco (Brasil) hao documeotado casos de estructuracióo geoética, como se ha descrito para Brycon orthotaenia y Prochilodus argenteus, dos especies de importaocia comercial. Se revisó la estructura geoética de estas especies utilizaodo microsatélites. Se obtuvieroo muestras de B. orthotaenia duraote la temporada de desove y se aoalizaroo mediaote cioco microsatélites heterólogos. Muestras de P. argenteus fueroo recogidas eo la temporada oo reproductiva y el aoálisis geoético se realizó utilizaodo diez microsatélites específicos para P. argenteus. Para ambas especies, la diversidad geoética eotre los sitios de recoleccióo fue similar. Coosideraodo a B. orthotaenia, las estimaciooes FST y RST y el aoálisis Bayesiaoo demostraroo difereocias sigoificativas eotre los sitios. Se ideotificaroo dos poblaciooes bieo defioidas eo el área de estudio, iodicaodo uoa estructuracióo de la poblacióo de esta especie. No se eocootraroo difereocias sigoificativas para P. argenteus. Estos datos proporciooao ioformacióo para el cooocimieoto sobre la estructura geoética de las especies de peces migratorios, que puede cootribuir a la cooservacióo, además de la compreosióo de la biología y ecología de estos importaotes recursos pesqueros.

The ability to detect hydrologic variation in large arctic river systems is of major importance in understanding and predicting effects of climate change in high-latitude environments. Monitoring uranium isotopes (234U and 238U) in river water of the Yukon River Basin of Alaska and northwestern Canada (2001–2005) has enhanced the ability to identify water sources to rivers, as well as detect flow changes that have occurred over the 5-year study. Uranium isotopic data for the Yukon River and major tributaries (the Porcupine and Tanana rivers) identify several sources that contribute to river flow, including: deep groundwater, seasonally frozen river-valley alluvium groundwater, and high-elevation glacial melt water. The main-stem Yukon River exhibits patterns of uranium isotopic variation at several locations that reflect input from ice melt and shallow groundwater in the spring, as well as a multi-year pattern of increased variability in timing and relative amount of water supplied from higher elevations within the basin. Results of this study demonstrate both the utility of uranium isotopes in revealing sources of water in large river systems and of incorporating uranium isotope analysis in long-term monitoring of arctic river systems that attempt to assess the effects of climate change.

A model has been established on the origin and extent of fresh groundwater, salty paleowaters and saltwater from recent seawater intrusions in the Red River flood plain in Vietnam. This was done with geological observations, geophysical borehole logging and transient electromagnetic methods. Salt paleowater is present up to 50–75 km from the coastline, with occurrence controlled by the Holocene transgression. A density-driven leaching of salty porewater has occurred from high-permeability Holocene sediments into underlying Pleistocene deposits, whereas diffusion has dominated in low-permeability layers. In the Pleistocene aquifer, the highest content of dissolved solids is found below two intrinsic valleys with Holocene marine sediments and along the coastline. Recent intrusion of saltwater from the South China Sea is observed in shallow groundwater 35 km inland, probably a result of transport of salty water inland in rivers or leaching of paleowaters from very young near-coast marine sediments. The observed inverted salinity profile, with high saline water overlying fresher groundwater, has been formed due to the global eustatic sea-level changes during the last 8,000–9,000 years. The proposed model may therefore be applicable to other coastal aquifers, with a proper incorporation of the local geological environments.

While research focuses mainly on the intensively used shallower aquifers, only a little research has addressed groundwater movement in deeper aquifers. This is mainly because of the negligible relevance of deep groundwater for daily usage and the great efforts and high costs associated with its access. In the last few decades, the discussion about deep geological final repositories for radioactive waste has generated strong demand for the investigation and characterization of deep-lying aquifers. Other utilizations of the deeper underground have been added to the discussion: the use of geothermal energy, potential CO2 storage, and sources of potable water as an alternative to the geogenic or anthropogenic contaminated shallow aquifers. As a consequence, the fast growing requirement for knowledge and understanding of these dynamic systems has spurred the research on deep groundwater systems and accordingly the development of suitable test methods, which currently show considerable limitations. This review provides an overview of the history of deep groundwater research. Deep groundwater flow and research in the main hydrogeological units is presented based on six projects and the methods used. The study focuses on Germany and two other locations in Europe.

The Seferihisar-Balçova Geothermal system (SBG), Turkey, is characterized by temperature and hydrochemical anomalies along the faults: thermal waters in northern Balçova are heated meteoric freshwater, whereas the hot springs of the southern Seferihisar region have a strong seawater contribution. Previous numerical simulations of fluid flow and heat transport indicated that focused upsurge of hot water in faults induces a convective-like flow motion in surrounding units. Salt transport is fully coupled to thermally driven flow to study whether fault-induced convection cells could be responsible for seawater encroachment in the SBG. Isotope data are presented to support the numerical findings. The results show that fault-induced convection cells generate seawater plumes that extend from the seafloor toward the faults. At fault intersections, seawater mixes with rising hot thermal waters. The resulting saline fluids ascend to the surface along the fault, driven by buoyant forces. In Balçova, thick alluvium, minor faults and regional flow prevent ascending salty water from spreading at the surface, whereas the weak recharge flow in the thin alluvium of the southern SBG is not sufficient to flush the ascending hot salty waters. These mechanisms could develop in any faulted geothermal system, with implications for minerals and energy migration in sedimentary basins.

A groundwater-monitoring network has been in operation in the Red River Delta, Vietnam, since 1995. Trends in groundwater level (1995–2009) in 57 wells in the Holocene unconfined aquifer and 63 wells in the Pleistocene confined aquifer were determined by applying the non-parametric Mann-Kendall trend test and Sen’s slope estimator. At each well, 17 time series (e.g. annual, seasonal, monthly), computed from the original data, were analyzed. Analysis of the annual groundwater-level means revealed that 35 % of the wells in the unconfined aquifer showed downward trends, while about 21 % showed upward trends. On the other hand, confined-aquifer groundwater levels experienced downward trends in almost all locations. Spatial distributions of trends indicated that the strongly declining trends (>0.3 m/year) were mainly found in urban areas around Hanoi where there is intensive abstraction of groundwater. Although the trend results for most of the 17 time series at a given well were quite similar, different trend patterns were detected in several. The findings reflect unsustainable groundwater development and the importance of maintaining groundwater monitoring and a database in the Delta, particularly in urban areas.

It is important to understand how groundwater recharge responds to precipitation variability in space and time, especially in those areas such as Yanqing Basin (China), where groundwater represents the sole water resource. A simple soil-water balance method is applied for spatio-temporal simulation of groundwater recharge in Yanqing Basin from 1981 to 2000. It was implemented on a monthly time step considering the effects of land use and soil texture. The area-average recharge associated with various land uses and soil textures was then compared with zonal analysis using a geographic information system (GIS). The main findings include: (1) the variation of groundwater recharge follows precipitation changes, either at yearly or seasonal intervals, (2) land use plays a more influential role in groundwater recharge than soil texture in this area, and (3) the water table quickly rises in response to recharge in the shallow parts of the aquifer, while there is a delay of 0.5–1.0 years where the groundwater level is at depth 4–10 m. The application demonstrates how spatio-temporal analysis can be utilized for groundwater-recharge estimation through distributed modeling and GIS.