oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Predicting the Aquifer Characteristic in the Headquarters of Ndokwa Land
J.O. Oseji,M.O. Ofomola
Online Journal of Earth Sciences , 2012, DOI: 10.3923/ojesci.2010.35.37
Abstract: The aquifer characteristics within the local government headquarters of Ndokwa land (Obiaruku, Kwale and Aboh) was achieved by obtaining the geoelectric section of the area. The data was used to determine areas with confined and unconfined aquifer and also the area having the highest water basin in the headquarters of Ndokwa land, the research also enabled one to recommend the depth at which boreholes could be to drilled for appreciable quantity of groundwater exploitation.
Assessing impacts of climate change, sea level rise, and drainage canals on saltwater intrusion to coastal aquifer
P. Rasmussen,T. O. Sonnenborg,G. Goncear,K. Hinsby
Hydrology and Earth System Sciences Discussions , 2012, DOI: 10.5194/hessd-9-7969-2012
Abstract: Groundwater abstraction from coastal aquifers is vulnerable to climate change and sea level rise because both may potentially impact saltwater intrusion and hence groundwater quality depending on the hydrogeological setting. In the present study the impacts of sea level rise and changes in groundwater recharge are quantified for an island located in the Western Baltic Sea. Agricultural land dominates the western and central parts of the island, which geologically are developed as push moraine hills and a former lagoon (later wetland area) behind barrier islands to the east. The low-lying central area of the island was extensively drained and reclaimed during the second half of the 19th century. Summer cottages along the beach on the former barrier islands dominate the eastern part of the island. The main water abstraction is for holiday cottages during the summer period (June–August). The water is abstracted from 11 wells drilled to a depth of around 20 m in the upper 5–10 m of a confined chalk aquifer. Increasing chloride concentrations have been observed in several abstraction wells and in some cases the WHO drinking water standard has been exceeded. Using the modeling package MODFLOW/MT3D/SEAWAT the historical, present and future freshwater–sea water distribution is simulated. The model is calibrated against hydraulic head observations and validated against geochemical and geophysical data from new investigation wells, including borehole logs, and from an airborne transient electromagnetic survey. The impact of climate changes on saltwater intrusion is found to be sensitive to the boundary conditions of the investigated system. For the flux-controlled aquifer to the west of the drained area only changes in groundwater recharge impacts the freshwater–sea water interface whereas sea level rise do not result in increasing sea water intrusion. However, on the barrier islands to the east of the reclaimed area below which the sea is hydraulically connected to the drainage canal, and the boundary of the flow system therefore controlled, the projected changes in sea level, groundwater recharge and stage of the drainage canal all have significant impacts on saltwater intrusion and hence the chloride concentrations found in the abstraction wells.
Land Use Change and Global Adaptations to Climate Change  [PDF]
Roxana Juliá,Faye Duchin
Sustainability , 2013, DOI: 10.3390/su5125442
Abstract: This paper uses the World Trade Model with Climate Sensitive Land (WTMCL) to evaluate possible future land-use changes associated with adaptations to climate change in a globalized world. In this approach, changes in regional agricultural production, which are based on comparative advantage, define patterns of land use change in agriculture in all regions of the world. We evaluate four scenarios that combine assumptions about future increases in food demand and future changes in land endowments of different productivities associated with climatic conditions: each scenario generates distinct patterns of regional specialization in the production of agricultural commodities and associated land-use change. The analysis also projects future food availability under the simulated conditions and the direction of likely changes in prices of the major agricultural commodity groups.
Determination of Agriculture Land Use and Land Cover Change Using Remote Sensing and GIS in TROIA National Park  [PDF]
L. Genc,Y. B. Bostanci
Journal of Tekirdag Agricultural Faculty , 2007,
Abstract: The area selected for land use land cover (LULC) dynamics, TROIA national park, is located in the city of anakkale, TURKEY. The national park covers an area of about 13600 ha. Remote sensing studies especially multi-temporal analysis of changes provides sufficient information about the dynamics of historic landscape. Tasseled Cap Indexes and Normalized Difference Vegetation Index (NDVI) were used to create the new images from Landsat TM 1987 and Landsat TM 2006 images for classification. Supervised classification was applied with ground truth data and auxiliary data collected from different sources such as air photo, cadastral information and others.Four classes of changed and unchanged multi-temporal raster were discriminated from created new images as followed: Active Agriculture, Grassland, Forestry, and Water. Classification accuracy was determined for 1987 image and 2006 image as 81% and 87% respectively. It was found that LULC change was dynamic between classes because of the land consolidation in the region. Grassland was changed to active agriculture area by 75% and to forestry class by 5%. Forested area also converted to active agriculture by 46% and to grassland by 9%. It was concluded that land consolidation project in the study area was the main force to change land cover.
Behavior and mechanism of the adsorption/desorption of tectonically deformed coals
YiWen Ju,Bo Jiang,QuanLin Hou,YongJie Tan,GuiLiang Wang,WenJiao Xiao
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-008-0412-4
Abstract: The physical and chemical texture of tectonically deformed coals produced by various formational mechanisms are different from those of primary coals, thus resulting in major differences among the physical properties of the reservoirs of these coals. We have studied the adsorption/desorption behavior of tectonically deformed coals by the use of isothermal adsorption/desorption experiments under equilibrium moisture condition. Experiments of isothermal adsorption/desorption of methane or multi-component gases have indicated that, the adsorption curves of coals with a low degree of tectonic deformation conform to the type of isothermal adsorption curve described by the Langmuir equation; the methane adsorption curves of coals with strong tectonic deformation cannot be described by the Langmuir equation. The adsorption/desorption process of methane and multi-component gases in the deformed coals is not consistent with primary coals, which form an effect of hysteresis in different kinds of tectonically deformed coals. With the change of pore structure of tectonically deformed coals at reservoir condition, the added adsorbed CH4 in the experiments is desorbed on the pore surface of coals during the pressure reduction process. Thus, the result shows that the adsorption volume in the process of desorbing is greater than that in adsorbing. Because of the deformation, structural change, and transformation of the adsorption potential field of coals, it is essential to form a new kind of isothermal adsorption curve and the hysteresis effect of the desorption process.
Impacts of soil-aquifer heat and water fluxes on simulated global climate
N. Y. Krakauer,M. J. Puma,B. I. Cook
Hydrology and Earth System Sciences Discussions , 2013, DOI: 10.5194/hessd-10-1185-2013
Abstract: Climate models have traditionally only represented heat and water fluxes within relatively shallow soil layers, but there is increasing interest in the possible role of heat and water exchanges with the deeper subsurface. Here, we integrate an idealized 50 m deep aquifer into the land surface module of the GISS ModelE general circulation model to test the influence of aquifer-soil moisture and heat exchanges on climate variables. We evaluate the impact on the modeled climate of aquifer-soil heat and water fluxes separately, as well as in combination. The addition of the aquifer to ModelE has limited impact on annual-mean climate, with little change in global mean land temperature, precipitation, or evaporation. The seasonal amplitude of deep soil temperature is strongly damped by the soil-aquifer heat flux. This not only improves the model representation of permafrost area but propagates to the surface, resulting in an increase in the seasonal amplitude of surface air temperature of >1 K in the Arctic. The soil-aquifer water and heat fluxes both slightly decrease interannual variability in soil moisture and land-surface temperature, and decrease the soil moisture memory of the land surface on annual timescales. The results of this experiment suggest that deepening the modeled land surface, compared to modeling only a shallower soil column with a no-flux bottom boundary condition, has limited impact on mean climate but does affect seasonality and interannual persistence.
Delayed drainage of aquitard in response to sudden change in groundwater level in adjacent confined aquifer: Analytical and experimental studies
ZhiFang Zhou,QiaoNa Guo,Zhi Dou
Chinese Science Bulletin , 2013, DOI: 10.1007/s11434-013-5730-5
Abstract: The problem of the groundwater dynamics and water balance of a confined aquifer in the aquifer system has been solved in previous studies, whereas that in the aquitard adjacent to the confined aquifer has seldom been considered. In reality, the groundwater dynamics of the aquitard are closely related to the exploitation of groundwater resources, groundwater contamination, underground storage utilization and land subsidence. In this paper, an analytical solution is derived to describe the drawdown variation in the aquitard when the head in the adjacent confined aquifer declines by a constant value. The characteristics of groundwater dynamics and water balance of the aquitard are analyzed using a dimensionless analytical solution. There is obvious delayed behavior in the response of groundwater dynamics in the aquitard, which is characterized by the delay index τ0. The delayed behavior in the response of groundwater dynamics is not only dependent on the properties of the aquitard, but also proportional to the square of the thickness of the aquitard. The law of the delayed release of water is described in terms of the ratio of the delayed release of water. A water balance equation for the aquitard is established. Three stages of the water balance and the corresponding characteristics are presented with the water balance curves of the aquitard. The analytical solution is given to analyze the flux per unit horizontal area of the aquitard. The hydrogeological parameters of the aquitard, namely the hydraulic conductivity, specific storativity and hydraulic diffusivity, are estimated according to type-curve fitting between the analytical solution and observed flux. The parameters are identified and validated in an experiment.
Land use change suppresses precipitation
W. Junkermann,J. Hacker,T. Lyons,U. Nair
Atmospheric Chemistry and Physics Discussions , 2009,
Abstract: A feedback loop between regional scale deforestation and climate change was investigated in an experiment using novel, small size airborne platforms and instrument setups. Experiments were performed in a worldwide unique natural laboratory in Western Australia, characterized by two adjacent homogeneous observation areas with distinctly different land use characteristics. Conversion of several ten thousand square km of forests into agricultural land began more than a century ago. Changes in albedo and surface roughness and the water budget of soil and the planetary boundary layer evolved over decades. Besides different meteorology we found a significant up to now overseen source of aerosol over the agriculture. The enhanced number of cloud condensation nuclei is coupled through the hydrological groundwater cycle with deforestation. Modification of surface properties and aerosol number concentrations are key factors for the observed reduction of precipitation. The results document the importance of aerosol indirect effects on climate due to nanometer size biogenic aerosol and human impact on aerosol sources.
Land use change suppresses precipitation  [PDF]
W. Junkermann,J. Hacker,T. Lyons,U. Nair
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2009,
Abstract: A feedback loop between regional scale deforestation and climate change was investigated in an experiment using novel, small size airborne platforms and instrument setups. Experiments were performed in a worldwide unique natural laboratory in Western Australia, characterized by two adjacent homogeneous observation areas with distinctly different land use characteristics. Conversion of several ten thousand square km of forests into agricultural land began more than a century ago. Changes in albedo, surface roughness, the soil water budget and the planetary boundary layer evolved over decades. Besides different meteorology, we found a significant up to now overlooked source of aerosol over the agriculture area. The enhanced number of cloud condensation nuclei is coupled through the hydrological groundwater cycle with deforestation. Modification of surface properties and aerosol number concentrations are key factors for the observed reduction of precipitation. The results document the importance of aerosol indirect effects on climate due to nanometer size biogenic aerosol and human impact on aerosol sources.
Trend in Land Use/Land Cover Change Detection by RS and GIS Application
N. Nagarajan,S. Poongothai
International Journal of Engineering and Technology , 2011,
Abstract: The study aims to effects of Land Use / Land Cover Changes (LU/LCC) is the quantitative method, to expound the impact of land use/land cover changes in Manimuktha sub-watershed of Vellar basin, Tamilnadu, India. The relationship between Land Use Changes and its trend is analysed using IRS IC LISS III and PAN merged data. Further, the preparation of LU/LC map using Survey of India (SOI)Toposheet for the year 1972 has come in handy to know the past land use pattern. Similarly, the Land Use/Land Cover (LU/LC) map of various years, namely, 1996, 2003 and 2007, which was obtained from Institute of Remote Sensing, Anna University (IRS) and digitized, using Arc GIS 9.1 software. About 52.89 per cent of land is devoted to agricultural practices under agriculture and cropland has a major impact over the hydrological processes of the basin. Hence, the information obtained from change detection of LU/LC aids in providing optimal solutions for the selection, planning, implementation and monitoring of development schemes to meet the increasing demands of human needs has lead to land management.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.