Implementation of the hydrogen economy for emission reduction will require storage facilities, and underground hydrogen storage (UHS) in porous media offers a readily available large‐scale option. ...Lack of studies on multiphase hydrogen flow in porous media is one of the several barriers for accurate predictions of UHS. This paper reports, for the first time, measurements of hysteresis in hydrogen‐water relative permeability in a sandstone core under shallow storage conditions. We use the steady state technique to measure primary drainage, imbibition and secondary drainage relative permeabilities, and extend laboratory measurements with numerical history matching and capillary pressure measurements to cover the whole mobile saturation range. We observe that gas and water relative permeabilities show strong hysteresis, and nitrogen as substitute for hydrogen in laboratory assessments should be used with care. Our results serve as calibrated input to field scale numerical modeling of hydrogen injection and withdrawal processes during porous media UHS.
Plain Language Summary
Hydrogen storage facilities will need a ramp‐up when the hydrogen share in the future energy mix increase. Large‐scale hydrogen storage can be implemented in empty hydrocarbon fields or ground water reservoirs. Hydrogen storage in such media involve complex interactions with native rocks and fluids, and injection and withdrawal are typically described by flow functions. Relative permeability is one of the key flow functions that describe how easily hydrogen can flow through porous media in the presence of other fluids. In underground storage, hydrogen is cyclically injected and withdrawn multiple times, and its relative permeability may differ between these two processes, described as hysteresis. In this paper, we investigate hydrogen relative permeability in the laboratory and match with results from numerical simulations. We find that hydrogen relative permeability is different for injection and withdrawal and is also different from that of nitrogen. Our results are directly applicable in computer simulators that predict hydrogen storage efficiency.
Key Points
Steady state measurements of hydrogen‐water relative permeability
Numerical history matching needed for extrapolation
Strong hysteresis observed between drainage and imbibition
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Abstract
Radon is a naturally occurring, odorless, colorless, radioactive, tasteless, and noble gas. Radon concentrations have been measured by the usage of alpha spectroscopy (RAD-7). The RAD-7 ...measuring process is based on detecting alpha particles produced from the disintegration of radon and its products using a solid-state alpha detector (usually silicon), and then converting alpha radiation directly to an electrical signal. The radioactivity of radon gas was measured in forty-two samples from reservoir water for different areas north of Baghdad utilizing a RAD7 detector. This study proved that the high value of radon concentrations was less than the permissible limit as recorded by the World Health Organization.
The delineation of favourable areas of water potentials and their management must be based on rigorous scientific studies. Thus, geographic information system (GIS) and remote sensing (RS) techniques ...are extremely important in predicting and mapping favourable groundwater zones. This paper aims to map potential areas of groundwater in Waddai region, eastern Chad. A region which has experienced successive droughts over the last two decades, causing the drying of most of the rivers in the area. This study focuses on combining GIS, RS, and analytical hierarchy process; in addition to the factors controlling the movement and retention of groundwater. Six factors (rainfall, slope, land use/land cover, drainage density, lineament density, and lithology) were used to integrate the spatial analysis of areas likely to hold groundwater. The results indicate that potential groundwater areas are unevenly distributed throughout the study area. For instance, the northwestern part is characterized by a low groundwater potential. This low potential in this part of the study area as well as a small portion of the eastern area is explained by a low density of lineaments and drainage, the presence of moderate precipitations, and a semi-permeable lithology (alternating hard rocks and loose sediments). While every low and moderate area occupy most of the middle of the region, good ground water reservoirs occupy a large part of the region. This distribution is explained by good fracturing, permeability, lineament density, high drainage, gentle slope, and precipitation. Therefore, areas of the northwestern part are highly suitable for groundwater exploration and exploitation. Hence; these results would be a guide for future explorations and will maximizes the economic efficiency of the ground water exploitation processes. Furthermore, this map will be useful as a guide in decision-making and on water policy planning.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Summary
Accounting for water limitation is key to determining vegetation sensitivity to drought. Quantifying water limitation effects on evapotranspiration (ET) is challenged by the heterogeneity of ...vegetation types, climate zones and vertically along the rooting zone.
Here, we train deep neural networks using flux measurements to study ET responses to progressing drought conditions. We determine a water stress factor (fET) that isolates ET reductions from effects of atmospheric aridity and other covarying drivers. We regress fET against the cumulative water deficit, which reveals the control of whole‐column moisture availability.
We find a variety of ET responses to water stress. Responses range from rapid declines of fET to 10% of its water‐unlimited rate at several savannah and grassland sites, to mild fET reductions in most forests, despite substantial water deficits. Most sensitive responses are found at the most arid and warm sites.
A combination of regulation of stomatal and hydraulic conductance and access to belowground water reservoirs, whether in groundwater or deep soil moisture, could explain the different behaviors observed across sites. This variety of responses is not captured by a standard land surface model, likely reflecting simplifications in its representation of belowground water storage.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Abstract
Controlled source audio‐frequency magnetotelluric is frequently used in association with other geophysical methods, especially in complex geological areas to highlight geological structures ...such as water reservoir rock. Although it gives satisfactory results, combining several methods requires time and expense. In addition, despite this combination, several drilling locations proposed after geophysical investigations were inaccurate, resulting in many unsuccessful drillings. The latter occurs due to the difficulty to emphasize the fracture zones properly. To work around this problem, we proposed a novel approach called pseudostratigraphic to reduce the repercussion of unsuccessful drilled boreholes and to demarcate the water reservoir rock. The technique consists to discretize the resistivity of the inverted OCCAM2D model based on the true layer resistivities collected from the borehole log data (observed layers). The discrete resistivity model is known as the new resistivity model. It is used to generate the pseudostratigraphic log at each station by pseudo‐demarcating the thicknesses of the observed layers with a low margin of error. Moreover, the combination of multiple new resistivity models from different survey lines creates a three‐dimensional pseudostratigraphic map useful to emphasize the water reservoir rock. The pseudostratigraphic implementation is carried out in the Xingning area as a real‐world case study. The results show that the intersection of the main fault (
F
1) and the conductive zones (≤100 Ω m) indicates the potential water reservoir rock. Its thickness is estimated around 150–600 with an error equal to ± 7°m. Based on the three‐dimensional pseudostratigraphic map, the water found in the fracture zone located under the reservoir rock is considered much hotter due to the intense geothermal activity along
F
1, thereby making it a better place for hot water exploitation. Finally, the pseudostratigraphic technique could be an innovative and cheap strategy to find groundwater reservoirs in complex geological areas.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The control of taste and odor (T&O) in drinking water reservoirs is the main challenge for water supply. T&O is mainly derived from actinobacteria during non-algal blooms. However, few studies have ...investigated the actinobacterial community in reservoirs, especially the effects of water quality parameters on actinobacteria. This study analyzed the environmental driving force of the actinobacterial community composition and change in time and space through structural equations and network in drinking water reservoirs. The results showed a high abundance of actinobacteria, up to 2.7 × 104 actinobacteria per 1 L, in the hypolimnion of the Lijiahe reservoir in September, which is one order of magnitude greater than that in the Jinpen reservoir. The two drinking water reservoirs had similar dominant genera, mainly Sporichthya sp., and Mycobacterium sp., and difference in the actinobacterial proportions. However, there was a large difference at the dominant species. Rhodococcus fascians (4.02%) was the dominant species in the Lijiahe reservoir, while Mycobacterium chlorophenolicum (6.64%) was the dominant species in the Jinpen reservoir. Network analysis revealed that the structure of the network in the Lijiahe reservoir was more unstable; thus, it was vulnerable to environmental disturbances. In addition, a low abundance of species may play a critical role in the actinobacterial community structure of aquatic ecosystems. Structural equation modeling analysis suggested that water temperature, dissolved oxygen, and nutrition were the dominant factors affecting the abundance and community of actinobacteria. Overall, these findings broaden the understanding of the distribution and co-existence of actinobacterial communities in drinking water reservoirs and provide valuable clues for the biological controls of T&O and reservoir management.
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•Taste and odor are derived from actinobacteria in drinking water reservoirs.•Actinobacterial abundance and community were explored in two reservoirs.•The actinobacteria have positive correlations with nitrogen and phosphorus.•Network shows the co-occurrence patterns among actinobacterial communities.•Structural equation model was built between water quality and actinobacteria.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
California is expected to experience great spatial/temporal variations evaporation. These variations arise from strong north‐south, east‐west gradients in rainfall and vegetation, strong interannual ...variability in rainfall (±30%) and strong seasonal variability in the supply and demand for moisture. We used the Breathing Earth System Simulator to evaluate the rates and sums of evaporation across California, over the 2001–2017 period. Breathing Earth System Simulator is a bottom‐up, biophysical model that couples subroutines that calculate the surface energy balance, photosynthesis, and stomatal conductance. The model is forced with high‐resolution remote sensing data (1 km).The questions we address are as follows: How much water is evaporated across the natural and managed ecosystems of California? How much does evaporation vary during the booms and busts in annual rainfall? and Is evaporation increasing with time due to a warming climate? Mean annual evaporation, averaged over the 2001–2017 period, was relatively steady (393 ± 21 mm/year) given the high interannual variation in precipitation (519 ± 140 mm/year). No significant trend in evaporation at the statewide level was detected over this time period, despite a background of a warming climate. Irrigated agricultural crops and orchards, at 1‐km scale, use less water than inferred estimates for individual fields. This leaves the potential for sharing water, a scarce resource, more equitably among competing stakeholders, for example, farms, fish, people, and ecosystems.
Plain Language Summary
Many stakeholders are contending for the limited water budget that is available to California, the world's fifth largest economy. Yet the amount of water used by natural and managed ecosystems across the state is not well known. We produced a new, process‐oriented estimate of statewide water use by natural and managed ecosystems using a biophysical model forced with satellite remote sensing. Despite the booms and busts in rainfall over the 2001 to 2017 period, we find that statewide water use is conservative, compared to the annual variability in rainfall. Nor do we detect that statewide evaporation is increasing as the climate has warmed over this period. We find that crops use less water than conventional wisdom because a subset of fields across a 1‐km pixel are fallow and are at peak leaf area and maximum evaporation potential for a relatively short period. Forests, on the other hand, use more water than conventional wisdom because they have a long growing season and absorb more energy than crops. Our intent is to provide water managers with new information on water use to better share water among the various stakeholders, for example, agricultural, cities, fish, ground water reservoirs, and water quality.
Key Points
We produced new granular information (1‐km resolution) on evaporation across California using the biophysical model, Breathing Earth System Simulator
Annual variations in evaporation were highly damped (393 mm/year +/− 5%) relative to the booms and busts in rainfall between 2001 and 2017 (+/− 28%)
Statewide evaporation is not increasing with global warming, over 17 years of inspection, because feedbacks dampen the response to a warming climate
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The state of the art for optimal water reservoir operations is rapidly evolving, driven by emerging societal challenges. Changing values for balancing environmental resources, multisectoral human ...system pressures, and more frequent climate extremes are increasing the complexity of operational decision making. Today, reservoir operations benefit from technological advances, including improved monitoring and forecasting systems as well as increasing computational power. Past research in this area has largely focused on improving solution algorithms within the limits of the available computational power, using simplified problem formulations that can misrepresent important systemic complexities and intersectoral interactions. In this study, we review the recent literature focusing on how the operation design problem is formulated, rather than solved, to address existing challenges and take advantage of new opportunities. This paper contributes a comprehensive classification of over 300 studies published over the last years into distinctive categories depending on the adopted problem formulation, which clarifies consolidated methodological approaches and emerging trends. Our analysis also suggests that control policy design methods may benefit from broadening the types of information that is used to condition operational decisions, and from using emulation modeling to identify low‐order, computationally efficient surrogate models capturing realistic representations of river basin systems' complexity in order to isolate key decision‐relevant processes. These advances in reservoir operations hold significant promise for better addressing the challenges of conflicting human pressures and a changing world, which is particularly important, given the renewed interest in dam construction globally.
Key Points
We review the evolution of water reservoir operation studies driven by emerging societal challenges
Simulation‐based control methods facilitate realistic problem formulations that are able to handle system uncertainties
Research opportunities remain to combine policy design with more information sources and emulation modeling
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
•nirS gene abundance ranged from 2.61 to 5.36 × 105 copies/mL in aerobic layers.•Paracoccus sp., Dechloromonas sp. and Thauera sp. were the dominant genera.•Co-interaction of denitrifying bacterial ...communities was explored by network model.•nirS-type denitrifying bacterial compositions were shaped by water quality.
The nirS-type denitrifying bacterial community is the main drivers of the nitrogen loss process in drinking water reservoir ecosystems. The temporal patterns in nirS gene abundance and nirS-type denitrifying bacterial community harbored in aerobic water layers of drinking water reservoirs have not been studied well. In this study, quantitative polymerase chain reaction (qPCR) and Illumina Miseq sequencing were employed to explore the nirS gene abundance and denitrifying bacterial community structure in two drinking water reservoirs. The overall results showed that the water quality parameters in two reservoirs had obvious differences. The qPCR results suggested that nirS gene abundance ranged from (2.61 ± 0.12) × 105 to (3.68 ± 0.16) × 105 copies/mL and (3.01 ± 0.12) × 105 to (5.36 ± 0.31) × 105 copies/mL in Jinpen and Lijiahe reservoirs, respectively. The sequencing results revealed that Paracoccus sp., Azoarcus sp., Dechloromonas sp. and Thauera sp. were the dominant genera observed. At species level, Cupriavidus necator, Dechloromonas sp. R-28400, Paracoccus denitrificans and Pseudomonas stutzeri accounted for more proportions in two reservoirs. More importantly, the co-occurrence network analysis demonstrated that Paracoccus sp. R-24615 and Staphylococcus sp. N23 were the keystone species observed in Jinpen and Lijiahe reservoirs, respectively. Redundancy analysis indicated that water quality (particularly turbidity, water temperature, pH and Chlorophyll a) and sampling time had significant influence on the nirS-type denitrifying bacterial community in both reservoirs. These results will shed new lights on exploring the dynamics of nirS-type denitrifying bacteria in aerobic water layers of drinking water reservoirs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Arid region water reservoirs have different characteristics and solutions from humid regions with the most water shortage in the world socio-economically. This paper outlines possible implementation ...methodologies, procedures and guidance for water storage in natural and artificial reservoirs for better operation and management rules taking into account the impacts of climate change. The literature is full of methodological applications regarding the impact of climate change on the hydro-meteorological records, but the same is not available in reservoirs (surface and underground), which is the scope of this paper. In addition, reservoir structures offer the necessary mitigation and adaptation activities against the effects of climate change to design, construct, maintain, operate or increase their existing capacity. To increase groundwater reservoir capacity in local aquifers, precipitation, associated flooding and flash flooding should be diverted to artificial groundwater recharges through precipitation and surface runoff harvesting activities. Definitions of fully or partially penetrating underground dams are also explained. The real groundwater feeding application is offered from the Kingdom of Saudi Arabia as arid region representative. Finally, a series of recommendations are presented for the future design and management of reservoirs.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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