39 research outputs found

    Sustainable groundwater development for improved livelihoods in Sub-Saharan Africa

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    At least 400 million people in Sub-Saharan Africa source their domestic water supply from groundwater. Yet this often abundant resource only accounts for around 20% of total irrigation. More widespread irrigation could help reduce rural poverty, improve food security, and counter droughts. Why is groundwater so under-tapped

    Comment letters to the National Commission on Commission on Fraudulent Financial Reporting, 1987 (Treadway Commission) Vol. 2

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    https://egrove.olemiss.edu/aicpa_sop/1662/thumbnail.jp

    Water for world development : proceedings of the VIth IWRA World Congress on Water Resources, May 29 - June 3, 1988, Ottawa, Canada; volume 1, summary, special sessions, training and education

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    Meeting: IWRA World Congress on Water Resources, 6th, 29 May-3 June, 1988, Ottawa, CanadaSome text in French and Spanis

    Water for world development : proceedings of the VIth IWRA World Congress on Water Resources, May 29 - June 3, 1988, Ottawa, Canada; volume 3, agriculture, irrigation, and drainage; environment

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    Meeting: IWRA World Congress on Water Resources, 6th, 29 May-3 June, 1988, Ottawa, CanadaSome text in Frenc

    VIe congrès mondial des ressources en eau de l'aire, Ottawa, Canada du 29 mai au 3 juin, 1988

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    Meeting: IWRA World Congress on Water Resources, 6th, 29 May-3 June, 1988, Ottawa, CanadaSome text in French and Spanis

    Gestion durable des ressources en eau dans les régions arides : Moyen Orient et Nord de l'Afrique

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    Project number related to IDRC support could not be determine

    Aquifer Monitoring Using Ambient Seismic Noise Recorded With Distributed Acoustic Sensing (DAS) Deployed on Dark Fiber

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    Groundwater is a critical resource for human activities worldwide, and a vital component of many natural ecosystems. However, the state and dynamics of water-bearing aquifers remain uncertain, mostly due to the paucity of subsurface data at high spatial and temporal resolution. Here, we show that analysis of infrastructure-generated ambient seismic noise acquired on distributed acoustic sensing (DAS) arrays has potential as a tool to track variations in seismic velocities (dv/v) caused by groundwater level fluctuations. We analyze 5 months of ambient noise acquired along an unused, 23 km-long telecommunication fiber-optic cable in the Sacramento Valley, CA, a so-called “dark fiber." Three array subsections, ∼6 km apart, are processed and the stretching technique is applied to retrieve daily dv/v beneath each location. Near the Sacramento river, dv/v variations in the order of 2%–3% correlate with precipitation events and fluctuations in river stage of ∼1.5 m. In contrast, regions away (2.5 km) from the river do not experience large dv/v variations. These observations reveal short-scale spatial variability in aquifer dynamics captured by this approach. Dispersion analysis and surface wave inversion of noise gathers reveal that seismic velocity perturbations occur at depths of 10–30 m. Rock physics modeling confirms that observed dv/v are linked to pore pressure changes at these depths, caused by groundwater table fluctuations. Our results suggest that DAS combined with ambient noise interferometry provides a means of tracking aquifer dynamics at high spatial and temporal resolutions at local to regional scales, relevant for effective groundwater resource management
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