Download or read book Tidal fluctuations and ground water dynamics in atoll island aquifers written by Marc E. Herman and published by . This book was released on 1984 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geohydrology of Enewetak Atoll Islands and Reefs written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Extensive tidal studies in island wells and the lagoon at Enewetak Atoll have shown that island ground water dynamics are controlled by a layered aquifer system. The surface aquifer of unconsolidated Holocene material extends to a depth of approximately 15 m, and has a hydraulic conductivity K = 60 m/day. From 15 to 60 m (approximate lagoon depth) the reef structure consists of successive layers of altered Pleistocene materials, with bulk permeability substantially higher than that of the surface aquifer. Because of wave set-up over the windward reef and the limited pass area for outflow at the south end of the atoll, lagoon tides rise in phase with the ocean tides but fall later than the ocean water level. This results in a net lagoon-to-ocean head which can act as the driving force for outflow through the permeable Pleistocene aquifer. This model suggests that fresh water, nutrients or radioactive contaminants found in island ground water or reef interstitial water may be discharged primarily into the ocean rather than the lagoon. Atoll island fresh water resources are controlled by recharge, seawater dilution due to vertical tidal mixing between the surface and deeper aquifers, and by loss due to entrainment by the outflowing water in the deeper aquifers. Estimated lagoon-ot-ocean transit times through the deep aquifer are on the order of a few years, which corresponds well to the freshwater residence time estimates based on inventory and recharge. Islands in close proximity to reef channels have more fresh ground water than others, which is consistent with a locally reduced hydraulic gradient and slower flow through the Pleistocene aquifers.
Download or read book Ground water resources of the Laura area Majuro Atoll Marshall Islands written by Scott N. Hamlin and published by . This book was released on 1987 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Barrier Island Groundwater Dynamics written by Rachel Mary Housego and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nearly 1.5 million people inhabit barrier islands along the U.S. Atlantic and Gulf Coasts and coastal groundwater dynamics influence the availability of freshwater, ecosystem health, pollutant transport, and flooding in these densely populated communities. However, groundwater dynamics, including the aquifer head distribution and subsurface salinity structure, in coastal aquifers are affected by multiple environmental forcings, such as waves, tides, storm surges, and precipitation that act on a variety of spatial and temporal scales, making coastal groundwater dynamics complex and difficult to predict. Here, measurements of groundwater heads, salinities, and temperatures collected for 3 years across a 550-m-wide barrier island are used in conjunction with observations of ocean tides, surge, waves, sound level, and rainfall to characterize the dynamics of the surface aquifer. Infiltration from surge, tides, and waves during storms caused up to 2 m increases in the groundwater level under the dune. The head gradients owing to these storm-induced groundwater bulges suggest flows become inland directed on the ocean-side of the island during storms. An upper saline plume (20-30 PSU) was observed above fresher (10 PSU) water up to 30 m inland of the dune face, which was the maximum wave runup location. Differences in inland propagation between tidal- and storm-induced groundwater head fluctuations are explained using analytical theories for intermediate depth aquifers. Additionally, a separate analytical water-table evolution model driven with estimated ocean shoreline water levels (based on the 36-hr-averaged offshore tide, surge, and wave height) and measured precipitation is validated by citizen-science flood reports and predicts the maximum water-table height within 0.1 m of the observed levels across the barrier island.
Download or read book Hydrogeology and Ground water Resources of Ngatik Island Sapwuahfik Atoll State of Pohnpei Federated States of Micronesia written by Stephen S. Anthony and published by . This book was released on 1996 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ground Water on Tropical Pacific Islands written by Gordon W. Tribble and published by Geological Survey. This book was released on 2008 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Groundwater Flow and Development Alternatives written by John E. Griggs and published by . This book was released on 1989 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Groundwater Resources and Salt Water Intrusion in a Changing Environment written by Maurizio Polemio and published by MDPI. This book was released on 2019-11-13 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Special Issue presents the work of 30 scientists from 11 countries. It confirms that the impacts of global change, resulting from both climate change and increasing anthropogenic pressure, are huge on worldwide coastal areas (and critically so on some islands in the Pacific Ocean), with highly negative effects on coastal groundwater resources, which are widely affected by seawater intrusion. Some improved research methods are proposed in the contributions: using innovative hydrogeological, geophysical, and geochemical monitoring; assessing impacts of the changing environment on the coastal groundwater resources in terms of quantity and quality; and using modelling, especially to improve management approaches. The scientific research needed to face these challenges must continue to be deployed by different approaches based on the monitoring, modelling and management of groundwater resources. Novel and more efficient methods must be developed to keep up with the accelerating pace of global change.
Download or read book Groundwater Models for Resources Analysis and Management written by Aly I. El-Kadi and published by CRC Press. This book was released on 2017-11-22 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by renowned experts in the field, this book assesses the status of groundwater models and defines models and modeling needs in the 21st century. It reviews the state of the art in model development and application in regional groundwater management, unsaturated flow/multiphase flow and transport, island modeling, biological and virus transport, and fracture flow. Both deterministic and stochastic aspects of unsaturated flow and transport are covered. The book also introduces a unique assessment of models as analysis and management tools for groundwater resources. Topics covered include model vs. data uncertainty, accuracy of the dispersion/convection equation, protocols for model testing and validation, post-audit studies, and applying models to karst aquifers.
Download or read book Groundwater surface Water Interactions in the Tidally dominated Coastal Region of the Bengal Basin written by Christopher Milos Tasich and published by . This book was released on 2013 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wave Tidal and Seasonal Dynamics of Groundwater Flow Saltwater freshwater Mixing and Reactive Transport in Beach Aquifers written by James W. Heiss and published by . This book was released on 2017 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nutrient, metal, and carbon fluxes in submarine groundwater discharge can adversely impact the chemistry of nearshore marine ecosystems. These solutes can undergo biogeochemical transformations in saltwater-freshwater mixing zones that form when fresh groundwater flowing toward the sea meets with saline groundwater of marine origin in sandy beaches. This dissertation focuses on the driving mechanisms of flow, the time scales of mixing, and biogeochemical processes that are key in altering the fate and fluxes of nutrients prior to discharge to the sea. ☐ A field and numerical modeling study investigated intertidal salinity dynamics in a sandy tidally-influenced beach aquifer across a wide range of temporal scales and hydrologic forcings. Seasonal variations in the terrestrial freshwater gradient were primarily responsible for controlling the shape and size of the intertidal saltwaterfreshwater mixing zone, followed by spring-neap variability in tidal amplitude, and tidal stage. Intertidal salinities decreased as the seasonal freshwater hydraulic gradient increased in spring and winter, and increased as freshwater forcing decreased in summer. The effects of Hurricane Sandy and seasonal sea level anomalies on the subsurface salinity distribution were minor compared to seasonal freshwater forcing. ☐ Coupled surface and subsurface measurements reveal for the first time the motion and areal extent of infiltration, recharge, and discharge zones at swash and tidal time scales under and across the beachface. Infiltration was controlled by the location of wave runup and occurred across a part of the beach widely accepted in literature to be a zone of groundwater discharge, while recharge occurred at both swash and tidal time scales. The results demonstrate that identification of infiltration, recharge, and discharge zones can be achieved only through coupled measurements of the swash location and water content conditions in the beach. A more accurate conceptual model of groundwater-surface water interactions in the intertidal zone is developed that will require that sediment transport models be reevaluated to properly represent zones of groundwater-surface water exchange. ☐ A variable-density groundwater flow and reactive solute transport model of a beach aquifer was used to investigate the influence of 5 physical factors, including tidal amplitude, freshwater flux, hydraulic conductivity, beach slope, and dispersivity on the biogeochemical reactivity of the intertidal zone for mixing-dependent and mixing-independent reactions, modeled as denitrification and sulfate reduction, respectively. A sensitivity analysis of nitrate and sulfate removal efficiencies demonstrates that tidal forcing promotes denitrification along the boundary of the intertidal saltwater circulation cell between 1 and 10 ppt. Denitrification increases with the size of the mixing zone, while sulfate supply is the main factor controlling sulfate reduction. The results reveal the type of beaches that are most chemically active and have the largest role in moderating chemical fluxes to the sea. ☐ These studies demonstrate that hydrologic and biogeochemical processes interact across time and space, and that these interactions moderate chemical fluxes to the sea. Thus, the findings have important implications for managing marine ecosystems, and the recreational and economic resources they provide.
Download or read book Coastal Watershed Management written by A. Fares and published by WIT Press. This book was released on 2008-05-23 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coastal watersheds differ from others by their unique features, including proximity to the ocean, weather and rainfall patterns, subsurface features, and land covers. Land use changes and competing needs for valuable water and land resources are especially more distinctive to such watersheds. This book covers recent research relevant to coastal watersheds. It addresses the impact of a stream’s chemical, biological, and sediment pollutants on the quality of the receiving waters, such as estuaries, bays, and near-shore waters. The contents of the book can be divided into three sections; a) overview of hydrological modelling, b) water quality assessment, and c) watershed management. This book differs from other hydrology books by dealing with coastal watersheds which are characterized by their unique features: including weather and rainfall patterns, subsurface characteristics, and land use and cover. In addition to academia, the book should be of interest to organizations concerned with watershed management, such as local and federal governments and environmental groups. Overall, the book is expected to satisfy a great need toward understanding and managing critical areas in many parts of the world.
Download or read book Ground Water Resources of the Laura Area Majuro Atoll Marshall Islands written by Scott N. Hamlin, Stephen S. Anthony and published by . This book was released on 1987 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Coastal Hazards Related to Storm Surge written by Rick Luettich and published by MDPI. This book was released on 2018-03-13 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Coastal Hazards Related to Storm Surge" that was published in JMSE
Download or read book Hydrology in the Humid Tropic Environment written by Arnold Ivan Johnson and published by IAHS Press. This book was released on 1998 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ground water Resources and Simulation of Flow in Aquifers Containing Freshwater and Seawater Island County Washington written by and published by . This book was released on 1989 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geology and hydrogeology of carbonate islands written by Leonard H.L. Vacher and published by Elsevier. This book was released on 2004-04-13 with total page 967 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book on geology and hydrogeology of carbonate islands is volume 54 in the Developments in Sedimentology series.
