Hydro-gravimetry in West-Africa: First results from the Djougou (Benin) superconducting gravimeter

Hector, Basile; Hinderer, J.; Séguis, Luc; Boy, Jean‐Paul; Calvo, Marta; Descloîtres, Marc; Rosat, Séverine; Galle, Sylvie; Riccardi, Umberto

doi:10.1016/j.jog.2014.04.003

Cited by 36 publications

(57 citation statements)

References 64 publications

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“…Gravity Monitoring at the Base Station A superconducting gravimeter, the SG-060, was installed as part of the Gravity and Hydrology in Africa (GHYRAF) project [Hinderer et al, 2009] and recorded gravity changes with a high accuracy (%0.1 lGal) since July 2010. In addition, absolute gravity has been measured using a FG5 at a 3 month sampling rate since July 2008 [Hinderer et al, 2009Hector et al, 2013;Hinderer et al, 2014a;Hector et al, 2014]. Instrument locations are shown in Figure 1d.…”

Section: Hybrid Gravimetrymentioning

confidence: 99%

“…Instrument locations are shown in Figure 1d. A detailed description of data processing, sensitivity analysis, and the footprint area of the gravimeters can be found in Hector et al [2014]. The main results are summarized herein and gravity residuals (after corrections of tides, ocean loading, polar motion, and atmospheric effects) are shown in Figure 3.…”

Section: Hybrid Gravimetrymentioning

confidence: 99%

“…Before interpreting these residuals in terms of local hydrology, a sensitivity analysis was undertaken to explore other potential local effects on gravity, including temporal effects such as vertical motion (displacement of the gravimeter in the earth gravity field), erosion (mass removal), and vegetation (seasonal mass variations), or static effects such as topography, shelter masking, or station construction [Van Camp et al, 2006;Kroner and Jahr, 2006;Hasan et al, 2006;Meurers et al, 2007;Creutzfeldt et al, 2008;Masson et al, 2012;Deville et al, 2012;Hector et al, 2014]. For the SG and FG5 base station, one may refer to studies conducted by Hector et al [2013Hector et al [ , 2014. Concerning the microgravity network, a thorough sensitivity analysis can be found in Appendix B, the main results of which are summarized hereafter:…”

Section: 1002/2014wr015773mentioning

confidence: 99%

“…When using gravimeters to measure shallow water storage changes, the footprint (the area where 90% of the signal originates) typically ranges from a few dozen meters around the instrument up to kilometers in areas with marked topography [Meurers et al, 2007;Creutzfeldt et al, 2008;Masson et al, 2012;Hector et al, 2014]. This is comparable to footprints of instruments devoted to evapotranspiration, an important component of the water budget, such as Eddy-covariance stations or large-aperture scintillometers [e.g., Guyot et al, 2009].…”

Section: Introductionmentioning

confidence: 99%

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Water storage changes as a marker for base flow generation processes in a tropical humid basement catchment (Benin): Insights from hybrid gravimetry

Hector

Séguis

Hinderer

et al. 2015

Water Resources Research

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In basement catchments of subhumid West Africa, base flow is the main component of annual streamflow. However, the important heterogeneity of lithology hinders the understanding of base flow generation processes. Since these processes are linked with water storage changes (WSCs) across the catchment, we propose the use of hybrid gravity data in addition to neutron probe-derived water content and water levels to monitor spatiotemporal WSC of a typical crystalline basement headwater catchment (16 ha) in Benin. WSC behaviors are shown to provide insights into hydrological processes in terms of water redistribution toward the catchment outlet. Hybrid gravimetry produces gravity change observations from time-lapse microgravity surveys coupled with gravity changes monitored at a base station using a superconducting gravimeter and/or an absolute gravimeter. A dense microgravity campaign (70 surveys of 14 stations) covering three contrasted years was set up with a rigorous protocol, leading to low uncertainties (<2.5 lGal) on station gravity determinations (with respect to the network reference station). Empirical orthogonal function analyses of both gravity changes and WSCs from neutron probe data show similar spatial patterns in the seasonal signal. Areas where storage and water table show a capping behavior (when data reach a plateau during the wet season), suggesting threshold-governed fast subsurface redistribution, are identified. This observed storage dynamics, together with geological structures investigated by electrical resistivity tomography and drill log analysis, make it possible to derive a conceptual model for the catchment hydrology.

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Section: Hybrid Gravimetrymentioning

confidence: 99%

Section: Hybrid Gravimetrymentioning

confidence: 99%

Section: 1002/2014wr015773mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Water storage changes as a marker for base flow generation processes in a tropical humid basement catchment (Benin): Insights from hybrid gravimetry

Hector

Séguis

Hinderer

et al. 2015

Water Resources Research

Self Cite

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“…2, the conical shape of influence (footprint) is due to the fact that the lateral extension of a layer has to increase with depth to produce the same surface gravity effect (Hector et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Monitoring of a geothermal reservoir by hybrid gravimetry; feasibility study applied to the Soultz-sous-Forêts and Rittershoffen sites in the Rhine graben

et al. 2015

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The study is devoted to the monitoring of a geothermal reservoir by hybrid gravimetry combining different types of instruments (permanent superconducting gravimeter, absolute ballistic gravimeter, and micro-gravimeters) and different techniques of measurements (both time-discrete and recording data collection). Using a micro-gravimetric repetition network around a reference station, which is regularly measured, leads to the knowledge of the time and space changes in surface gravity. Such changes can be linked to the natural or anthropic activities of the reservoir. A feasibility study using this methodology is applied to two geothermal sites in the Alsace region (France) of the Rhine graben. We show the results in terms of gravity double differences from weekly repetitions of a network of 11 stations around the geothermal reservoir of Soultz-sous-Forêts, separated into 5 loops during July-August 2013 and 2014 as well as preliminary results from 2 stations near Rittershoffen (ECOGI). We point out the importance of a precise leveling of the gravity points for the control of the vertical deformation. A first modeling of surface gravity changes induced by realistic geothermal density perturbations (Newtonian attraction) is computed in the frame of the existing geological model and leads to gravity changes below the μGal level being hence undetectable. However, and for the same case, borehole gravity modeling showed a significant anomaly with depth that can be used as a complementary monitoring method. We show that in the limit of our uncertainties (SD~5 μGal), we do not detect any significant gravity change on the geothermal site of Soultz in agreement with the fact that there was indeed no geothermal activity during our analysis period. On the contrary, the measurements near Rittershoffen show a signal above the noise level which correlates in time with a production test but cannot be explained in terms of Newtonian attraction effects according to our basic numerical simulation.

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Emerging methods for noninvasive sensing of soil moisture dynamics from field to catchment scale: a review

et al. 2015

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Soil moisture is an important state variable in the terrestrial system because it controls the exchange of water and energy between the land surface and the atmosphere. In this paper, we review recent advances in non-invasive techniques that allow continuous non-invasive and contactless measurements of soil moisture dynamics at the field to basin scale. In particular, we report on 1) cosmic-ray neutron probes, 2) GNSS reflectrometry, 3) ground-based microwave radiometry, 4) gamma-ray monitoring, 5) terrestrial gravimetry and 6) low-frequency electromagnetic surface waves. Each method is described in terms of its basic principle, measurement scales, calibration issues, measurement accuracy, and applications. We hope that this review will further stimulate the community to invest in the continued development of novel soil moisture sensing methods that

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Hydro-gravimetry in West-Africa: First results from the Djougou (Benin) superconducting gravimeter

Cited by 36 publications

References 64 publications

Water storage changes as a marker for base flow generation processes in a tropical humid basement catchment (Benin): Insights from hybrid gravimetry

Water storage changes as a marker for base flow generation processes in a tropical humid basement catchment (Benin): Insights from hybrid gravimetry

Monitoring of a geothermal reservoir by hybrid gravimetry; feasibility study applied to the Soultz-sous-Forêts and Rittershoffen sites in the Rhine graben

Emerging methods for noninvasive sensing of soil moisture dynamics from field to catchment scale: a review

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