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111.
Groundwater extraction is rampant in many developing countries and urban areas whereas the natural recharge is decreasing due to covering of Earth's surface for various developmental activities. This leads to declining levels of groundwater and deterioration in groundwater quality. Artificial recharge with rain water harvesting techniques offers an excellent scope to arrest this degradation. This paper presents a study that analyzes the influence of rain water harvesting (RWH) on groundwater storage and quality. Chennai City, India is selected as study area, as major RWH implementation has taken place during 2002–2003 due to Government legislation. Preliminary analysis of groundwater levels were done spatially and temporally. Groundwater table contours were drawn using the GIS software for pre‐ (1999–2000) and post‐RWH (2009–2010) periods. The groundwater levels follow a decreasing trend before implementation of RWH where as a positive increasing trend takes place after construction of RWH structures. “Groundwater Estimation Committee (GEC)” norms of Government of India were used to estimate the change in storage during pre‐ and post‐RWH periods, which are found to be 1.76 × 106 and 32.77 × 106 m3, respectively. The results show that the implementation of RWH has increased the groundwater storage considerably. Also, the influence of RWH on groundwater quality is found to be encouraging in some parts of the studied area. 相似文献
112.
The effects of timber-cutting on sediment concentrations, soil loss and overland flow in an insigne pine (Pinus radiata) plantation were studied in a mountain watershed of the Cordillera de la Costa, central Chile. Soil formation rates for the lithological conditions of the watershed were estimated. Soil loss measurements on the plantation were taken in 100 m2 plots, equipped with Coshocton samplers, during the years 1991 and 1992. Treatments were: clear-cutting no residues/burned, clear-cutting with residues and undisturbed controls. First-year soil losses were greater from the no residues/burned (2128 kg ha?1) than from the residues (1219 kg ha?1) or undisturbed (48 kg ha?1) plots. During the second post-treatment year, soil loss was greater from the burned plots (1349 kg ha?1) than from the residues (243 kg ha?1) or the undisturbed (72 kg ha?1) plots. Sediment concentrations for the three treatments were 561, 340 and 59 mgl-1 during the first year, and 400, 150 and 83 mgl?1 in the second year. Runoff from the no residues/burned plots was greater than from residues or undisturbed plots during the two post-treatment years. Long-term soil losses were projected to average 240 kg ha?1 yr?1 from areas without residues/burned and 120 kg ha?1 yr?1 in areas with residues treatment, over a 25 year rotation period, whereas control areas were projected to average 60 kg ha?1 yr?1. 相似文献
113.
Anil Kumar Misra Anju Saxena Manish Yaduvanshi Ajai Mishra Yogendra Bhadauriya Alok Thakur 《Environmental Geology》2007,51(8):1361-1376
India is a vast country and is highly diversified in terms of natural resources and socio-economic setup. Moreover, its water
resources are unevenly distributed in space and time. With increasing population and increasing aspiration for improved standard
of living, there is an acute pressure on the demand and availability of water. Though the idea of interlinking of rivers is
not a new concept in India, it had rather persisted long back as much as in other countries of ancient civilization. National
Water Development Agency (NWDA) has given the real shape to the proposal of the interlinking of rivers of the country. In
India the river-linking project in a sensible and scientific manner will not only allow the prevention of the colossal wastage
of a vitally important natural resource, mitigate the flood and inundation by detaining flowing surface water of rainy seasons,
but also ensure availability of water to drier areas; combating both flood and drought simultaneously. Moreover, this project
will generate 34,000 MW of hydropower and irrigation of an additional 35 million hectares (135,135 square miles) of land.
Though linking of rivers may initially appear to be a costly proposition in ecological, geological, hydrological and economical
terms, in the long run the net benefits coming from it will far outweigh these costs or losses. However, in the absence of
any definite international legal framework, Bangladesh has raised objections against the project. This paper aims at looking
at this long-term plan, the project proposal, its involvement and impact not only on the states of India, India as a whole,
but also on its neighbouring nations which are linked with India through the waterways, and share the common climatic conditions
and economic status. 相似文献
114.
Recharge to a saline, unconfined shallow-water-table aquifer is normally considered as an irrecoverable loss of water, but
such thinking could be reviewed empirically. The use of an appropriate groundwater harvesting system does not only provide
an opportunity to recover this lost water, but can also help in catchment salinity management and improvement. Agricultural-based
land-drainage systems such as those that use serial biological concentration (SBC) of salts, provide examples of such harvesting
methods. The impact of groundwater harvesting has been assessed on the hydro-salinity of a saline catchment in southeastern
Australia through modeling. For both the below average rainfall and very wet years, the “do nothing” scenario resulted in
increasing salinization in the catchment. However, after introducing a SBC system, groundwater salinity showed a decreasing
trend while hydraulic heads tended to stabilize around the depth of subsurface collector wells. However, for a successful
groundwater harvesting system, proper understanding of the groundwater flows and salt mobilization associated with a catchment
is necessary. The outcomes of this modelling study have the potential to address similar issues (salinization) and/or needs
(water harvesting) existing elsewhere in the world, particularly in semi-arid regions.
相似文献
Muhammad Nadeem AsgharEmail: |
115.
Uttam Babu Shrestha Sujata Shrestha Shivaraj Ghimire Kamal Nepali Bharat Babu Shrestha 《社会与自然资源》2014,27(12):1242-1256
The Chinese caterpillar fungus is famous for its high market value, unusual life history, and significant medicinal uses. It is harvested by very poor communities and sold for an extraordinarily high price. Most of the studies on this species are focused on therapeutic uses, chemical analyses, ecology, and trade. However, harvesting techniques and intensity of the harvests remain undocumented. We document harvesting techniques, trends of harvest, and perceptions of the Chinese caterpillar fungus harvesters in Dolpa, Nepal, based on surveys, focus-group discussions, and direct observations. Along with increasing market value, intensity of the harvest has been increasing. The Chinese caterpillar fungus harvest has now become the second most important livelihood strategy for the local communities, after agriculture. Reported per-capita harvest based on the first day of collection has declined over the last 4 years, apparently because of the decline in the stock and the increasing number of harvesters. 相似文献
116.
Energy harvesting using piezoelectric materials can be realised by periodic external force. Piezoelectric material directly converts strain energy into electric power to capture a wasted ambient kinetic energy. This recovered energy can be used for operating wireless sensors, such as those found in environmental monitoring, mechanical sensing and structural diagnostic. In our previous work, a flexible piezoelectric device, FPED, was proposed and developed as an energy harvester for generating electric power from flow-induced vibration in ocean and wind environments. In this study a FPED with a painted piezoelectric layer, highly durable in order to withstand extreme bending and weathering caused by waves and currents, is proposed and developed by spray coating for use as an ocean energy harvester. A numerical method is developed to predict electro-fluid–structure interactions and to evaluate electrical performance and mechanical behaviours of the painted FPED. Additionally, validation of the numerical model is provided through several experimental tests. This study also investigates the relationship between the stiffness of the painted FPED and the vibrated frequency, as well as determining their influence on the electrical performance. Finally, the outcomes from a field test, conducted in real ocean space, is presented to provide information on electrical performance, mechanical behaviours and durability of painted FPEDs. The paper shows that a painted FPED is a useful and robust energy harvester for generating electric power from harsh environments. 相似文献
117.