scholarly journals Sensitivity of Hydrologic and Geologic Parameters on Recharge Processes in a Highly-Heterogeneous, Semi-Confined Aquifer System

Author(s):  
Stephen R. Maples ◽  
Laura Foglia ◽  
Graham E. Fogg ◽  
Reed M. Maxwell

Abstract. Increasing reliance on groundwater resources has been observed worldwide during the past 50–70 years and has led to unsustainable groundwater abstraction in many regions, especially in semi-arid and arid alluvial groundwater basins. Managed aquifer recharge (MAR) has been promoted to replenish overdrafted groundwater basins and augment surface water supply. However, MAR feasibility in alluvial groundwater basins is complicated by complex geologic architecture that typically includes laterally-continuous, fine-texture confining units that can impede both recharge rates and regional propagation of increases in hydraulic head. Greater feasibility of MAR hinges on identifying locations where rapid, high-volume recharge that provides regional increases in pressure head are possible, but relatively little research has evaluated the factors that control MAR feasibility in alluvial groundwater basins. Here, we combine a transition probability Markov-chain geostatistical model of the subsurface geologic heterogeneity of the east side of the northern Central Valley, California, with the 3D, variably-saturated water flow code, ParFlow, to explore the variability of MAR feasibility in this region. We use a combination of computationally-efficient local and global sensitivity analyses to evaluate the relative importance of factors that contribute to MAR feasibility. A novel proxy parameter approach was used to describe the configuration and proportions of subsurface hydrofacies and water table depth for sensitivity analyses, and results suggest that recharge potential is relatively more sensitive to the variability of this proxy parameter than to the variablity of individual hydrofacies hydraulic properties. Results demonstrate that large variability of MAR feasibility is typical for alluvial aquifer systems and that outsize recharge rates are possible in select locations where interconnected, coarse-texture hydrofacies occur.

2020 ◽  
Vol 24 (5) ◽  
pp. 2437-2456
Author(s):  
Stephen R. Maples ◽  
Laura Foglia ◽  
Graham E. Fogg ◽  
Reed M. Maxwell

Abstract. An increasing reliance on groundwater resources has been observed worldwide during the past 50–70 years and has led to unsustainable groundwater abstraction in many regions, especially in semi-arid and arid alluvial groundwater basins. Managed aquifer recharge (MAR) has been promoted to replenish overdrafted groundwater basins and augment surface water supply. However, MAR feasibility in alluvial groundwater basins is complicated by complex geologic architecture that typically includes laterally continuous, fine-texture confining units that can impede both recharge rates and regional propagation of increases in the hydraulic head. A greater feasibility of MAR hinges on identifying locations where rapid, high-volume recharge that provides regional increases in pressure head are possible, but relatively little research has evaluated the factors that control MAR feasibility in alluvial groundwater basins. Here, we combine a transition probability Markov chain geostatistical model of the subsurface geologic heterogeneity of the eastern side of the northern Central Valley, California, with the three-dimensional, variably saturated water flow code ParFlow to explore the variability of MAR feasibility in this region. We use a combination of computationally efficient local- and global-sensitivity analyses to evaluate the relative importance of factors that contribute to MAR feasibility. A novel proxy parameter approach was used to describe the configuration and proportions of subsurface hydrofacies and the water table depth for sensitivity analyses, and results suggest that recharge potential is relatively more sensitive to the variability of this proxy parameter than to the variability of individual hydrofacies hydraulic properties. Results demonstrate that large variability of MAR feasibility is typical for alluvial aquifer systems and that outsized recharge rates are possible in select locations where interconnected, coarse-texture hydrofacies occur.


2019 ◽  
Vol 27 (8) ◽  
pp. 2869-2888 ◽  
Author(s):  
Stephen R. Maples ◽  
Graham E. Fogg ◽  
Reed M. Maxwell

Abstract Widespread groundwater overdraft in alluvial aquifer systems like the Central Valley (CV) in California, USA, has increased interest in managed aquifer recharge (MAR). Like most clastic sedimentary basins, recharge to the productive semi-confined CV aquifer system remains a challenge due to the presence of nearly ubiquitous, multiple confining units (silt and clay) that limit recharge pathways. Previous studies suggest the presence of interconnected networks of coarse-texture sand and gravel deposits that bypass regional confining units over a small fraction of the CV near the American and Cosumnes rivers. Here, variably saturated infiltration and recharge processes were simulated across a domain that includes high-resolution representation of the heterogeneous alluvial geologic architecture in this area. Results show that recharge potential is highly dependent on subsurface geologic architecture, with a nearly 2 order-of-magnitude range of recharge across the domain. Where interconnected coarse-texture recharge pathways occur, results show that these features can (1) accommodate rapid, high-volume MAR and (2) propagate widespread and rapid pressure responses over multi-kilometer distances in the semi-confined aquifer system. For all MAR simulations, results show that the majority of MAR is accommodated by filling unsaturated-zone (UZ) pore volume. Results also show that coarse-texture UZ facies (where present) accommodate the majority of MAR volume during early time, but fine-texture facies ultimately accommodate the majority of the total MAR volume, even for coarse-dominated sites. These findings highlight the large variability of MAR potential across the landscape and demonstrate the importance of fine-texture facies for accommodating MAR in alluvial aquifer systems.


2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Chiara Sbarbati ◽  
Maurizio Gorla ◽  
Alessandro Lacchini ◽  
Agata Cristaldi ◽  
Davide Lo Monaco ◽  
...  

Groundwater is the main and safest source of water used for drinking purposes in many urban and rural communities worldwide. A deep knowledge of aquifer systems in terms of quality, vulnerability and renewability is fundamental to preserving groundwater resources. Thanks to contributions by different members of Water Alliance in synergy with Sapienza University, during November 2019 a multiisotopic regional scale analysis was carried out on groundwater tapped for drinking purposes in a wide area of the Lombardy Region. The study aimed to improve knowledge of recharge mechanisms, the groundwater’s relative age, and the impact of human activities on groundwater quality. Each Water Alliance supplier selected some wells and springs drawing water from different aquifer groups and distributed from north to south, for a total of 121 samples. Groundwater stable isotope analyses were performed on all the monitoring points, while tritium, nitrogen isotopes (15N and 18O in nitrates), sulphate isotopes (34S and 18O) and 13C isotope in Dissolved Inorganic Carbon (DIC) were analysed in selected monitoring wells based on previous data and major ion concentration results. The results confirm the key role of a multi-isotopic approach in defining aquifer recharge processes, relative groundwater age and the origin of pollutants, offering a useful tool to highlight local issues which could be investigated in depth by each water supplier.


Author(s):  
S.M. Thomas ◽  
D. Bloomer ◽  
R.J. Martin ◽  
A. Horrocks

Applying water efficiently is increasingly important for dairy farmers and other users of surface and groundwater resources to maintain sustainable production. However, irrigation is rarely monitored. We used a questionnaire survey and measurements of five spray irrigation systems working in normal farm conditions to make observations on how efficiently irrigation is being managed. Survey results from 93 dairy farmers showed that, although the farmers believe they know how much water is being applied during irrigation, only 60% make measurements, and about 18% measure irrigation uniformity. Catch-can measurement of irrigation application depth for the different spray systems indicated large variability in application depths during irrigation, and field distribution uniformity ranged greatly between the different systems, decreasing in the order of centre pivots >travelling irrigators> K-line. Changes in irrigation system settings were sometimes made without considering application depths or uniformity. If our five case studies are typical, they may explain the large range of seasonal irrigation amounts recorded in the survey. We recommend that farmers monitor irrigation application depths and uniformity to help manage irrigation water efficiently and to help them estimate the value of irrigation to their enterprise. Keywords: distribution uniformity, water use efficiency, catch cans


Author(s):  
José D. Henao Casas ◽  
Fritz Kalwa ◽  
Marc Walther ◽  
Randolf Rausch

AbstractTo cope with water scarcity in drylands, stormwater is often collected in surface basins and subsequently stored in shallow aquifers via infiltration. These stormwater harvesting systems are often accompanied by high evaporation rates and hygiene problems. This is commonly a consequence of low infiltration rates, which are caused by clogging layers that form on top of the soil profile and the presence of a thick vadose zone. The present study aims to develop a conceptual solution to increase groundwater recharge rates in stormwater harvesting systems. The efficiency of vadose-zone wells and infiltration trenches is tested using analytical equations, numerical models, and sensitivity analyses. Dams built in the channel of ephemeral streams (wadis) are selected as a study case to construct the numerical simulations. The modelling demonstrated that vadose-zone wells and infiltration trenches contribute to effective bypassing of the clogging layer. By implementing these solutions, recharge begins 2250–8100% faster than via infiltration from the bed surface of the wadi reservoir. The sensitivity analysis showed that the recharge rates are especially responsive to well length and trench depth. In terms of recharge quantity, the well had the best performance; it can infiltrate up to 1642% more water than the reservoir, and between 336 and 825% more than the trench. Moreover, the well can yield the highest cumulative recharge per dollar and high recharge rates when there are limitations to the available area. The methods investigated here significantly increased recharge rates, providing practical solutions to enhance aquifer water storage in drylands.


Author(s):  
Florian Brückner ◽  
Rebecca Bahls ◽  
Mohammad Alqadi ◽  
Falk Lindenmaier ◽  
Ibraheem Hamdan ◽  
...  

AbstractIn 2017, a comprehensive review of groundwater resources in Jordan was carried out for the first time since 1995. The change in groundwater levels between 1995 and 2017 was found to be dramatic: large declines have been recorded all over the country, reaching more than 100 m in some areas. The most affected areas are those with large-scale groundwater-irrigated agriculture, but areas that are only used for public water supply are also affected. The decrease of groundwater levels and saturated thickness poses a growing threat for drinking water supply and the demand has to be met from increasingly deeper and more remote sources, causing higher costs for drilling and extraction. Groundwater-level contour lines show that groundwater flow direction has completely reversed in some parts of the main aquifer. Consequently, previously established conceptual models, such as the concept of 12 “groundwater basins” often used in Jordan should be revised or replaced. Additionally, hydraulic conditions are changing from confined to unconfined; this is most likely a major driver for geogenic pollution with heavy metals through leakage from the overlying bituminous aquitard. Three exemplary case studies are presented to illustrate and discuss the main causes for the decline of the water tables (agriculture and population growth) and to show how the results of this assessment can be used on a regional scale.


2021 ◽  
Author(s):  
Hoori Ajami ◽  
Adam Schreiner-McGraw

<p>Mountain System Recharge (MSR) is one of the main components of recharge in many arid and semi-arid aquifers, yet the mechanisms of MSR in high-elevation mountain ranges are poorly understood. The complexity of recharge processes and the lack of groundwater observations in mountain catchments contribute to this problem. MSR consists of two distinct pathways: 1) mountain bedrock aquifer recharge (MAR) consists of snowmelt or rainfall derived infiltration into the mountain bedrock, which either discharges to streams as baseflow or reaches an alluvial aquifer in an adjacent valley via lateral subsurface flow referred to as mountain block recharge (MBR), and 2) Mountain front recharge (MFR) consists of streamflow infiltration at the mountain front. Here, we apply streamflow recession analysis across 11 anthropogenically unaffected catchments in the Sierra Nevada to derive seasonally distinct storage-discharge functions and quantify MAR in response to changes in precipitation. Median annual recharge efficiencies (ratio of annual MAR to precipitation) range from 4 to 28% and can reach up to 60% during the wettest years on record. We implement a global sensitivity analysis to identify parameters that significantly impact MAR rates. Results illustrate that MAR estimates are mostly sensitive to the filter parameters for streamflow data selection used during the recession analysis, and the number of dry days after a rain event where streamflow data are excluded has the greatest impact. Our results demonstrate that storage-discharge functions are useful for quantifying groundwater recharge in mountainous catchments under perennial flow conditions. However, estimated MAR rates are impacted by the uncertainty in streamflow data, filtering of streamflow time series and model structure. Future work will be focused on quantifying uncertainty in MAR estimates caused from various sources.</p><p> </p>


2019 ◽  
Vol 28 (1) ◽  
pp. 175-192
Author(s):  
Phil Hayes ◽  
Chris Nicol ◽  
Andrew D. La Croix ◽  
Julie Pearce ◽  
Sebastian Gonzalez ◽  
...  

AbstractThe Precipice Sandstone is a major Great Artesian Basin aquifer in the Surat Basin, Queensland, Australia, which is used for water supply and production of oil and gas. This report describes use of observed groundwater pressure responses to managed aquifer recharge (MAR) at a regional scale to test recent geological descriptions of Precipice Sandstone extent, and to inform its hydrogeological conceptualisation. Since 2015, two MAR schemes have injected over 20 GL of treated water from coal seam gas production into the Precipice Sandstone, with pressure responses rapidly propagating over 100 km, indicating high aquifer diffusivity. Groundwater modelling of injection and inversion of pressure signals using PEST software shows the spatial variability of aquifer properties, and indicates that basin in-situ stresses and faulting exert control on permeability. Extremely high permeability, up to 200 m/day, occurs in heavily fractured regions with a dual-porosity flow regime. The broader-scale estimates of permeability approach an order of magnitude higher than previous studies, which has implications for the management of water resources in the Precipice Sandstone. Results also show the Precipice Sandstone to have broadly isotropic permeability. The results also support a recent geological interpretation of the Precipice Sandstone as having more limited lateral extent than initially considered. The study shows the effective use of MAR injection data to improve geological and hydrogeological understanding through groundwater model inversion. It also demonstrates the utility of combining hydrogeological and reservoir-engineer datasets in areas explored and developed for both groundwater resources and oil and gas resources.


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