Focused groundwater recharge in a dryland environment: hydrometric and isotopic evidence from central Tanzania

2020 ◽  
Author(s):  
David Seddon ◽  
Japhet J. Kashaigili ◽  
Richard G. Taylor ◽  
Mark O. Cuthbert ◽  
Lucas Mihale ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
Surface Waters ◽  
Poverty Alleviation ◽  
Managed Aquifer Recharge ◽  
Sub Saharan Africa ◽  
Aquifer Recharge ◽  
Ephemeral Stream ◽  
Groundwater Levels ◽  
Sub Saharan ◽  
Semi Arid

<p>Groundwater, and its replenishment via recharge, is critical to livelihoods and poverty alleviation in drylands of sub-Saharan Africa and beyond, yet the processes by which groundwater is replenished remain inadequately observed and resolved. Here, we present three lines of evidence, from an extensively-monitored wellfield in central semi-arid Tanzania, indicating focused groundwater recharge occurring via leakage from episodic, ephemeral stream discharges. First, the duration of ephemeral streamflow observed from daily records from 2007 to 2016 correlates strongly (R<sup>2</sup> = 0.85) with the magnitude of groundwater recharge events observed and estimated from piezometric observations. Second, high-resolution (hourly) monitoring of groundwater levels and stream stage, established in advance of the 2015-16 El Niño, shows the formation and decay of groundwater mounds beneath episodically inundated adjacent streambeds. Third, stable-isotope ratios of O and H of groundwater and precipitation as well as perennial and ephemeral surface waters trace the origin of groundwater to ephemeral stream discharges. The identification and characterisation of focused groundwater recharge have important implications not only, locally, for protecting and potentially augmenting replenishment of a wellfield supplying the capital of Tanzania through Managed Aquifer Recharge but also, more widely, in understanding and modelling groundwater recharge in dryland environments.</p>

scholarly journals Monitoring and modeling infiltration-recharge dynamics of managed aquifer recharge with desalinated seawater

2016 ◽  
Author(s):  
Yonatan Ganot ◽  
Ran Holtzman ◽  
Noam Weisbrod ◽  
Ido Nitzan ◽  
Yoram Katz ◽  
...  
Keyword(s):  
Numerical Model ◽  
Groundwater Recharge ◽  
Multiple Scales ◽  
Pressure Sensors ◽  
Managed Aquifer Recharge ◽  
Analytical Models ◽  
Low Permeability ◽  
Aquifer Recharge ◽  
Groundwater Levels ◽  
Infiltration Rates

Abstract. We study the relation between surface infiltration and groundwater recharge during managed aquifer recharge (MAR) with desalinated seawater in an infiltration pond, at the Menashe site that overlies the northern part of the Israeli Coastal Aquifer. We monitor infiltration dynamics at multiple scales (up to the scale of the entire pond) by measuring the ponding depth, sediment water content and groundwater levels, using pressure sensors, single-ring infiltrometers, soil sensors and observation wells. During a month (January 2015) of continuous intensive MAR (2.45 · 106 m3 discharged to a 10.7 hectare area), groundwater level has risen by 17 m attaining full connection with the pond, while average infiltration rates declined by almost 2 orders of magnitude (from ~ 11 to ~ 0.4 m d−1). This reduction can be explained solely by the lithology of the unsaturated zone that includes relatively low-permeability sediments, whereas clogging processes at pond-surface – abundant in many MAR operations – are negated by the high-quality desalinated seawater or negligible compared to the low-permeability layers. Recharge during infiltration was estimated reasonably well by simple analytical models, whereas a numerical model was used for estimating groundwater recharge after the end of infiltration. It was found that a calibrated numerical model with a one-dimensional representative sediment profile is able to capture MAR dynamics, including temporal reduction of infiltration rates, drainage and groundwater recharge. Measured infiltration rates of an independent MAR event (January 2016) fitted well to those calculated by the calibrated numerical model, showing the model validity. The successful quantification methodologies of the temporal groundwater recharge are useful for MAR practitioners and can serve as an input for groundwater flow models.

scholarly journals Monitoring and modeling infiltration–recharge dynamics of managed aquifer recharge with desalinated seawater

2017 ◽  
Vol 21 (9) ◽  
pp. 4479-4493 ◽  
Author(s):  
Yonatan Ganot ◽  
Ran Holtzman ◽  
Noam Weisbrod ◽  
Ido Nitzan ◽  
Yoram Katz ◽  
...  
Keyword(s):  
Numerical Model ◽  
Groundwater Recharge ◽  
Multiple Scales ◽  
Pressure Sensors ◽  
Managed Aquifer Recharge ◽  
Analytical Models ◽  
Low Permeability ◽  
Aquifer Recharge ◽  
Groundwater Levels ◽  
Infiltration Rates

Abstract. We study the relation between surface infiltration and groundwater recharge during managed aquifer recharge (MAR) with desalinated seawater in an infiltration pond, at the Menashe site that overlies the northern part of the Israeli Coastal Aquifer. We monitor infiltration dynamics at multiple scales (up to the scale of the entire pond) by measuring the ponding depth, sediment water content and groundwater levels, using pressure sensors, single-ring infiltrometers, soil sensors, and observation wells. During a month (January 2015) of continuous intensive MAR (2.45  ×  106 m3 discharged to a 10.7 ha area), groundwater level has risen by 17 m attaining full connection with the pond, while average infiltration rates declined by almost 2 orders of magnitude (from  ∼  11 to  ∼  0.4 m d−1). This reduction can be explained solely by the lithology of the unsaturated zone that includes relatively low-permeability sediments. Clogging processes at the pond-surface – abundant in many MAR operations – are negated by the high-quality desalinated seawater (turbidity  ∼  0.2 NTU, total dissolved solids  ∼  120 mg L−1) or negligible compared to the low-permeability layers. Recharge during infiltration was estimated reasonably well by simple analytical models, whereas a numerical model was used for estimating groundwater recharge after the end of infiltration. It was found that a calibrated numerical model with a one-dimensional representative sediment profile is able to capture MAR dynamics, including temporal reduction of infiltration rates, drainage and groundwater recharge. Measured infiltration rates of an independent MAR event (January 2016) fitted well to those calculated by the calibrated numerical model, showing the model validity. The successful quantification methodologies of the temporal groundwater recharge are useful for MAR practitioners and can serve as an input for groundwater flow models.

scholarly journals Opportunities and challenges for implementing managed aquifer recharge models in drought-prone Barind tract, Bangladesh

2021 ◽  
Vol 11 (12) ◽  
Author(s):  
Md. Iquebal Hossain ◽  
Md. Niamul Bari ◽  
Md. Shafi Uddin Miah
Keyword(s):  
Groundwater Recharge ◽  
Groundwater Resources ◽  
Managed Aquifer Recharge ◽  
Storm Water ◽  
Water Runoff ◽  
Aquifer Recharge ◽  
Groundwater Levels ◽  
Check Dams ◽  
Supplementary Irrigation ◽  
Barind Tract

AbstractThis study focuses on the Barind tract, a drought prone area situated in the north-west region of Bangladesh where inadequate rainfall and limited surface water have created high dependence on groundwater for irrigation and other purposes, leading to significant declines in groundwater level. Managed aquifer recharge (MAR) offers a potential solution to restore groundwater levels. This study sets out to identify the opportunities and challenges for implementing MAR in the Barind tract. To accomplish this aim, different data sets including bore log lithology, rainfall, groundwater levels, information about re-excavated ponds, dighis, kharies, beels, check dams, rubber dams, dug wells and other necessary information were collected from the Barind Multipurpose Development Authority (BMDA) and other sources and analyzed. Major opportunities for MAR are identified for about 2000 km of re-excavated kharies (canals) containing about 750 check dams, more than 3000 re-excavated ponds, a number of beels (comparatively large marshes) and other water bodies which are used to conserve runoff storm water for supplementary irrigation. The conserved water can be used for groundwater recharge and subsequently abstracted for irrigation. Furthermore, roof-top rain water from buildings can also be used for groundwater recharge purposes. In contrast, the major challenges include the high turbidity of storm water runoff leading to clogging of MAR structures, inadequacy of conventional direct surface methods of recharge due to the presence of a 15 m or more thick upper clay layer with limited percolation capacity, and lack of practical knowledge on MAR. Therefore, overcoming the challenges for MAR application is a prerequisite to maximize the opportunities from MAR that can support the sustainable use of groundwater resources.

scholarly journals Shallow groundwater in sub-Saharan Africa: neglected opportunity for sustainable intensification of small-scale agriculture?

2016 ◽  
Author(s):  
John Gowing ◽  
Geoff Parkin ◽  
Nathan Forsythe ◽  
David Walker ◽  
Alemseged Tamiru Haile ◽  
...  
Keyword(s):  
Groundwater Resources ◽  
Climatic Variability ◽  
Shallow Groundwater ◽  
Sustainable Intensification ◽  
Sub Saharan Africa ◽  
Small Scale ◽  
Groundwater Levels ◽  
Sub Saharan ◽  
Small Scale Irrigation

Abstract. There is a need for an evidence-based approach to identify how best to support development of groundwater for small scale irrigation in sub-Saharan Africa (SSA). We argue that it is important to focus this effort on shallow groundwater resources which are most likely to be used by poor rural communities in SSA. However, it is important to consider constraints, since shallow groundwater resources are likely to be vulnerable to over-exploitation and climatic variability. We examine here the opportunities and constraints and draw upon evidence from Ethiopia. We present a methodology for assessing and interpreting available shallow groundwater resources and argue that participatory monitoring of local water resources is desirable and feasible. We consider possib le models for developing distributed small-scale irrigation and assess its technical feasibility. Because of power limits on water lifting and also because of available technology for well construction, groundwater at depths of 50 m or 60 m cannot be regarded as easily accessible for small-scale irrigation. We therefore adopt a working definition of shallow groundwater as < 20 m depth. This detailed case study in the Dangila woreda in Ethiopia explores the feasibility of exploiting shallow groundwater for small-scale irrigation over a range of rainfall conditions. Variability of rainfall over the study period (9 % to 96 % probability of non-exceedance) does not translate into equivalent variability in groundwater levels and river baseflow. Groundwater levels, monitored by local communities, persist into the dry season to at least the end of December in most shallow wells, indicating that groundwater is available for irrigation use after the cessation of the wet season. Arguments historically put forward against the promotion of groundwater use for agriculture in SSA on the basis that aquifers are unproductive and irrigation will have unacceptable impacts on wetlands and other groundwater-dependent ecosystems appear exaggerated. It would be unwise to generalise from this case study to the whole of SSA, but useful insights into the wider issues are revealed by the case study approach. We believe there is a case for arguing that shallow groundwater in sub-Saharan Africa represents a neglected opportunity for sustainable intensification of small-scale agriculture.

scholarly journals A Strategy for Technology Development for Semi-Arid Sub-Saharan Africa

1998 ◽  
Vol 27 (3) ◽  
pp. 157-161
Author(s):  
John H. Sanders ◽  
Barry I. Shapiro ◽  
Sunder Ramaswamy
Keyword(s):  
Development Strategy ◽  
Water Availability ◽  
New Technologies ◽  
Technology Development ◽  
Organic Fertilizer ◽  
Sub Saharan Africa ◽  
Inorganic Fertilizers ◽  
Strategy Evaluation ◽  
Sub Saharan ◽  
Semi Arid

This article proposes a strategy for agricultural technology development for semi-arid West Africa. The strategy evaluation consists of two aspects: a) a review of the successes in the region; and b) analysis with mathematical programming of the potential impacts and constraints to various new technologies tested in the region. The technology development strategy indicates how further productivity gains can be made by responding to the two principal constraints of water availability and soil fertility. These constraints must be simultaneously resolved but the strategy needs to be adapted for different soil characteristics and economic environments. The major emphasis is on the importance of the rapid introduction of inorganic fertilizers combined with techniques to increase water availability; organic and inorganic fertilizers need to be considered complements in the semi-arid regions. Farmers are already introducing labour intensive variations of these techniques in the most degraded regions. The policy concern is to encourage government policymakers to put a high priority on fertilizer and increase the availability of inorganic fertilizer while research efforts continue to develop improved methods for complementary use of organic fertilizer.

scholarly journals Harnessing Poverty Alleviation to Reduce the Stigma of HIV in Sub-Saharan Africa

PLoS Medicine ◽  
2013 ◽  
Vol 10 (11) ◽  
pp. e1001557 ◽  
Author(s):  
Alexander C. Tsai ◽  
David R. Bangsberg ◽  
Sheri D. Weiser
Keyword(s):  
Poverty Alleviation ◽  
Sub Saharan Africa ◽  
Sub Saharan
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