Using Groundwater Responses to Infer Recharge - Part 5

1998 ◽  
Author(s):  
D Armstrong ◽  
K Narayan
Keyword(s):  
Time Lag ◽  
Worked Examples ◽  
Unconfined Aquifer ◽  
Confined Aquifer ◽  
Case Histories ◽  
Cross Sectional ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Unconfined Aquifers ◽  
Event Basis

Analytical methods of assessing the response of groundwater levels to a range of factors, including elastic (barometric and tidal) influences in confined aquifers and recharge to unconfined aquifers due to infiltration of rain and other surface water, are presented. Responses in a confined aquifer to distant recharge events and the associated time lag is discussed. Also covered are responses to changes in storage volume resulting from direct recharge at the outcrop of an unconfined aquifer system both seasonally and on a single recharge event basis. Worked examples and case histories are used to illustrate methods of estimating the amount of recharge at different sites within a catchment. The application of vertical cross-sectional flow nets to the estimation of recharge is presented in the context of recharge/discharge profiles.

Using groundwater levels and Specific Yield to Estimate the Recharge, South of Erbil, Kurdistan Region, Iraq

2018 ◽  
Vol 7 (4) ◽  
pp. 191
Author(s):  
Sherwan Sh. Qurtas
Keyword(s):  
Unconfined Aquifer ◽  
Middle Part ◽  
Water Levels ◽  
Specific Yield ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Water Table Fluctuation Method ◽  
Recharge Estimation ◽  
Fluctuation Method

Recharge estimation accurately is crucial to proper groundwater resource management, for the groundwater is dynamic and replenished natural resource. Usually recharge estimation depends on the; the water balance, water levels, and precipitation. This paper is studying the south-middle part of Erbil basin, with the majority of Quaternary sediments, the unconfined aquifer system is dominant, and the unsaturated zone is ranging from 15 to 50 meters, which groundwater levels response is moderate. The purpose of this study is quantification the natural recharge from precipitation. The water table fluctuation method is applied; using groundwater levels data of selected monitoring wells, neighboring meteorological station of the wells, and the specific yield of the aquifers. This method is widely used for its simplicity, scientific, realistic, and direct measurement. The accuracy depends on the how much the determination of specific yield is accurate, accuracy of the data, and the extrapolations of recession of groundwater levels curves of no rain periods. The normal annual precipitation there is 420 mm, the average recharge is 89 mm, and the average specific yield is around 0.03. The data of one water year of 2009 and 2010 has taken for some technical and accuracy reasons.

scholarly journals POTENSI AIR TANAH DI DAERAH CIKARANG DAN SEKITARNYA, KABUPATEN BEKASI BERDASARKAN ANALISIS PENGUKURAN GEOLISTRIK

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Heru Sri Naryanto
Keyword(s):  
Land Surface ◽  
Depth Distribution ◽  
Unconfined Aquifer ◽  
Confined Aquifer ◽  
Population Changes ◽  
Unconfined Aquifers ◽  
Bottom Depth ◽  
Groundwater Quantity ◽  
Effects Of Land Use ◽  
Basin System

Groundwater is one of the most important for human activities. The effects of land use and population changes in Bekasi area cause the degradation of groundwater quantity and quality. The aquifers potential in Cikarang and its surrounding as a study area are studied using geoelectric method. Geoelectric analysis can be measured the geometry of subsurface aquifer (thickness, depth, distribution, and structural geology). The aquifers in the study area are included of Bekasi Groundwater Basin System. The aquifers contain confined aquifer and unconfined aquifer. The thickness of unconfined aquifers less than 30 m, as lenses and bottom depth less than 40 m below of land surface. The thickness of confined aquifers is variation with maximum 80 m and the bottom depth 20-160 m below of land surface. The degradation of groundwater in Cikarang and its surrounding needs better groundwater management for sustainable development.          Katakunci : potensi airtanah, akuifer, geolistrik, Cikarang

scholarly journals Groundwater recharge to the confined aquifer system in the Terai plain of Nawalparasi district, western Nepal: a hydrochemical approach

1998 ◽  
Vol 17 ◽  
Author(s):  
Dinesh Pathak ◽  
G. Krishna Rao
Keyword(s):  
Water Resources ◽  
Groundwater Recharge ◽  
River Water ◽  
Chemical Constituents ◽  
Confined Aquifer ◽  
Aquifer System ◽  
Unconfined Aquifers ◽  
Groundwater Samples ◽  
Tube Wells ◽  
Major Chemical

Groundwater recharge estimate is an essential part of the management of the water resources. The Terai plain of Nepal with multi-aquifer system and a number of river systems need thorough understanding on their interconnection. Groundwater samples from the dugwells, shallow tube wells, deep tube wells, and river water were analysed for major chemical constituents. The chemistry of confined aquifer system is found to be different from the unconfined aquifers. The groundwater recharge to the confined aquifers is therefore believed to be not by vertical infiltration from the shallow aquifers but directly from the palaeo and present river beds. Estimation of groundwater recharge in parts of the Terai plain by rainfall factor warrants rethinking.

scholarly journals Aquifer heterogeneity and response time: the challenge for groundwater management

2013 ◽  
Vol 64 (12) ◽  
pp. 1141 ◽  
Author(s):  
B. F. J. Kelly ◽  
W. A. Timms ◽  
M. S. Andersen ◽  
A. M. McCallum ◽  
R. S. Blakers ◽  
...  
Keyword(s):  
Surface Water ◽  
Groundwater Management ◽  
Time Lag ◽  
High Volume ◽  
Irrigated Agriculture ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Murray Darling Basin ◽  
Hydraulic Gradients ◽  
The Impact

Groundwater is an important contributor to irrigation water supplies. The time lag between withdrawal and the subsequent impacts on the river corridor presents a challenge for water management. We highlight aspects of this challenge by examining trends in the groundwater levels and changes in groundwater management goals for the Namoi Catchment, which is within the Murray–Darling Basin, Australia. The first high-volume irrigation bore was installed in the cotton-growing districts in the Namoi Catchment in 1966. The development of high-yielding bores made accessible a vast new water supply, enabling cotton growers to buffer the droughts. Prior to the development of a groundwater resource it is difficult to accurately predict how the water at the point of withdrawal is hydraulically connected to recharge zones and nearby surface-water features. This is due to the heterogeneity of the sediments from which the water is withdrawn. It can take years or decades for the impact of groundwater withdrawal to be transmitted kilometres through the aquifer system. We present the analysis of both historical and new groundwater level and streamflow data to quantify the impacts of extensive groundwater withdrawals on the watertable, hydraulic gradients within the semi-confined aquifers, and the movement of water between rivers and aquifers. The results highlight the need to monitor the impacts of irrigated agriculture at both the regional and local scales, and the need for additional research on how to optimise the conjunctive use of both surface-water and groundwater to sustain irrigated agriculture while minimising the impact on groundwater-dependent ecosystems.

scholarly journals Groundwater fluctuations in heterogeneous coastal leaky aquifer systems

2010 ◽  
Vol 7 (4) ◽  
pp. 4473-4499 ◽  
Author(s):  
M.-H. Chuang ◽  
C.-S. Huang ◽  
G.-H. Li ◽  
H.-D. Yeh
Keyword(s):  
Unconfined Aquifer ◽  
Confined Aquifer ◽  
Aquifer System ◽  
Heterogeneous Aquifer ◽  
The Past ◽  
Depositional Processes ◽  
Aquifer Systems ◽  
Infinite Extent ◽  
Leaky Aquifer ◽  
Finite Extent

Abstract. In the past, the coastal leaky aquifer system, including an unconfined aquifer on the top, a confined aquifer at the bottom, and an aquitard in between, was commonly assumed to be homogeneous and of an infinite extent in the horizontal direction. The leaky aquifer system may however be nonhomogeneous and of a finite extent due to variations in depositional and post depositional processes. Thus, in the paper, the leaky aquifer system is divided into several horizontal regions for simulating the heterogeneity involved in both the confined aquifer and aquitard. A one-dimensional analytical model is developed for describing the head fluctuation in such a heterogeneous leaky aquifer system. The head of the upper unconfined aquifer is assumed to remain constant. It is found that both the length and location of the discontinuous aquitards presented in the coastal area have significant effects on the amplitude and phase shift of the head fluctuation in the confined aquifer. In addition, the influences of both the heterogeneous aquifer and aquitard on the spatial head distribution are investigated.

scholarly journals Responses of Groundwater Lowering Systems: Empirical Equations Via Field Records

2019 ◽  
Vol 9 (2) ◽  
pp. 1527-1535
Keyword(s):  
Pumping Test ◽  
Unconfined Aquifer ◽  
Groundwater Table ◽  
Empirical Equations ◽  
Nile Valley ◽  
Confined Aquifer ◽  
Unconfined Aquifers ◽  
Confined Aquifers ◽  
Correlation Factors ◽  
Good Agreement

This study aims to evaluate the accuracy of analytical equations which are mostly used in the design of dewatering systems using deepwells. This is accomplished by analyzing the data obtained from dewatering systems executed in twenty different sites within the Egyptian Nile Valley and Delta. The studied cases included gravity flow (unconfined aquifer), artesian flow (confined aquifer) and mixed flow (semi-confined aquifer) cases. For each of the considered sites, the actual discharge from pumping drilled wells and the actual drawdown of the groundwater table were measured. Besides, a pumping test was performed at each of these sites. The field data was then analyzed by adopting the empirical analytical equations to assess the responses of groundwater to the implemented lowering systems. The obtained results showed that the actual monitored drawdown values were not in good agreement with the analytical results. Therefore, practical correlation factors, based on data from the investigated sites and a comprehensive parametric study, were derived to enhance the results of the analytical equations. Hence, by implementing such cumulative drawdown correlation factors in the empirical equations, a more accurate assessment of the expected drawdown values can be attained. For aquifers within the Nile valley and Delta, average cumulative drawdown correlation factors of 0.7, 0.65 and 0.8 were found to be satisfactory for unconfined aquifers, confined aquifers, and semi-confined aquifers, respectively.

Cross-Lagged Relationships Between Self-Esteem, Self-Construal, and Happiness in a Three-Wave Longitudinal Study

2019 ◽  
Vol 40 (3) ◽  
pp. 177-185
Author(s):  
Daniela Moza ◽  
Laurențiu Maricuțoiu ◽  
Alin Gavreliuc
Keyword(s):  
Structural Equation ◽  
Time Lag ◽  
Self Esteem ◽  
Equation Modeling ◽  
Future Research ◽  
Cross Sectional ◽  
Self Construal ◽  
Self Worth ◽  
Practical Implications ◽  
Independent Person

Abstract. Previous research established that an independent construal of the self is associated with higher self-esteem, which, in turn, is associated with increased happiness. Regarding the directionality of these relationships, theoretical arguments have suggested that self-construal precedes self-esteem and that self-esteem precedes happiness. However, most research in this area is cross-sectional, thus limiting any conclusions about directionality. The present study tested these relationships in 101 Romanian undergraduates using a 3-wave cross-lagged design with a 6-month time lag between every two waves. Structural equation modeling analyses revealed that self-esteem is an antecedent of both happiness and dimensions of independent self-construal (i.e., consistency vs. variability and self-expression vs. harmony). In other words, one’s positive evaluation of self-worth precedes one’s self-perception as being a happy and independent person. The findings are discussed with respect to the theoretical and practical implications, along with limitations and suggestions for future research.

The Distribution of Volatile Organics in a Leachate Plume, Gloucester, Ontario

1987 ◽  
Vol 22 (1) ◽  
pp. 49-64 ◽  
Author(s):  
J.F. Devlin ◽  
W.A. Gorman
Keyword(s):  
Organic Contaminants ◽  
Source Area ◽  
Unconfined Aquifer ◽  
High Concentration ◽  
Organic Contamination ◽  
Aquifer System ◽  
Aquifer Systems ◽  
Volatile Organic ◽  
Volatile Organic Contaminants ◽  
Aquifer Sediments

Abstract The Gloucester Landfill is located near Ottawa, Ontario, on a northeast trending ridge of Quaternary age. The ridge comprises outwash sediments which make up two aquifer systems. A confined system exists next to bedrock, and is overlain by a silty-clayey stratum (the confining layer) which is, in turn, overlain by an unconfined aquifer system. Two independent volatile organic plumes have previously been identified at the landfill: the southeast plume, which has penetrated the confined aquifer system, and the northeast plume which is migrating in the unconfined aquifer. The distribution of volatile organic contaminants at the northeast plume site appears to be a function of two factors: (1) heterogeneities in the aquifer sediments are causing the channeling of contaminants through a narrow path; (2) the low fraction of organic carbon in the unconfined aquifer sediments at the northeast site is resulting in little retardation of the contaminants there, relative to those at the southeast site. Acetate was the only volatile fatty acid detected in the leachate. It was measurable only in areas where the volatile organic contamination was significant. Although methane was detected in the contaminated sediments, suggesting that microbial activity was present, the high concentration of acetate (>1000 ppm) which was detected down-gradient from the source area indicates that any biodegradation which is occurring is proceeding at a very slow rate.

scholarly journals Depletion of groundwater resources under rapid urbanisation in Africa: recent and future trends in the Nairobi Aquifer System, Kenya

2020 ◽  
Vol 28 (8) ◽  
pp. 2635-2656
Author(s):  
Samson Oiro ◽  
Jean-Christophe Comte ◽  
Chris Soulsby ◽  
Alan MacDonald ◽  
Canute Mwakamba
Keyword(s):  
Negative Impact ◽  
Groundwater Resources ◽  
Climatic Data ◽  
Groundwater Abstraction ◽  
Management Scenarios ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Future Evolution ◽  
Level Data ◽  
Groundwater Assessment

AbstractThe Nairobi volcano-sedimentary regional aquifer system (NAS) of Kenya hosts >6 M people, including 4.7 M people in the city of Nairobi. This work combines analysis of multi-decadal in-situ water-level data with numerical groundwater modelling to provide an assessment of the past and likely future evolution of Nairobi’s groundwater resources. Since the mid-1970s, groundwater abstraction has increased 10-fold at a rate similar to urban population growth, groundwater levels have declined at a median rate of 6 m/decade underneath Nairobi since 1950, whilst built-up areas have increased by 70% since 2000. Despite the absence of significant trends in climatic data since the 1970s, more recently, drought conditions have resulted in increased applications for borehole licences. Based on a new conceptual understanding of the NAS (including insights from geophysics and stable isotopes), numerical simulations provide further quantitative estimates of the accelerating negative impact of abstraction and capture the historical groundwater levels quite well. Analysis suggests a groundwater-level decline of 4 m on average over the entire aquifer area and up to 46 m below Nairobi, net groundwater storage loss of 1.5 billion m3 and 9% river baseflow reduction since 1950. Given current practices and trajectories, these figures are predicted to increase six-fold by 2120. Modelled future management scenarios suggest that future groundwater abstraction required to meet Nairobi projected water demand is unsustainable and that the regional anthropogenically-driven depletion trend can be partially mitigated through conjunctive water use. The presented approach can inform groundwater assessment for other major African cities undergoing similar rapid groundwater development.

Sign in / Sign up

Export Citation Format

Share Document