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SPATIAL VARIABILITY OF GROUNDWATER ARSENIC IN BANGLADESH: AN EVALUATION OF GEOLOGIC AND PHYSICAL CONTROLS

KARTHIK, BHAMIDIMARRI B.K.
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1005673192

Abstract Details

2001, MS, University of Cincinnati, Engineering : Environmental Engineering.
The widespread arsenic contamination of groundwater in Bangladesh has been recognized as posing a serious health problem to millions of people in the region. Understanding of the complex lateral and vertical variability in its countrywide distribution is an important step towards better spatial estimation and also improved understanding of the controlling physical processes. A geostatistical characterization of arsenic followed by classical and indicator variogram analysis was performed in an attempt to study the partitioning of variability across scales and thereby identify the dominant physical process controls on arsenic. The results suggest that 'large-scale' (greater than tens of km approx.) geological and physical features control a significant fraction of the spatial variability in shallow wells (55%) as well as in the deeper wells (88%). The indicator variogram analysis also suggested the possibility of deeper aquifers acting as potential safe water sources in the country. The usefulness of countrywide spatial contamination maps is brought into question. The residual, small-scale variability appears to be unrelated to the widespread application of groundwater towards irrigation in the country. Experiments on the sampling pattern of wells in the arsenic datasets revealed that the variability in the arsenic distribution is proportional to the degree of spatial clustering of sampled tube wells. The result suggests that the nugget value in the variograms is not governed by purely random variability and instead, is controlled by distinct 'small-scale' processes. It is proposed that the prevalence of higher arsenic concentrations of arsenic in shallow wells is because of these 'small-scale' processes (less than tens of km approx.) exerting a greater degree of control at shallower depths in the sediments. A possibility of the right-skewedness of arsenic distribution leading to completely random variations in the arsenic concentrations yielding an increased number of higher arsenic magnitudes, is also explored briefly.
Dr. Shafiqul Islam (Advisor)
54 p.
Engineering, Environmental
geostatistics; groundwater arsenic; Bangladesh; spatial variability

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Citations

  • KARTHIK, B. B.K. (2001). SPATIAL VARIABILITY OF GROUNDWATER ARSENIC IN BANGLADESH: AN EVALUATION OF GEOLOGIC AND PHYSICAL CONTROLS [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1005673192

    APA Style (7th edition)

  • KARTHIK, BHAMIDIMARRI. SPATIAL VARIABILITY OF GROUNDWATER ARSENIC IN BANGLADESH: AN EVALUATION OF GEOLOGIC AND PHYSICAL CONTROLS. 2001. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1005673192.

    MLA Style (8th edition)

  • KARTHIK, BHAMIDIMARRI. "SPATIAL VARIABILITY OF GROUNDWATER ARSENIC IN BANGLADESH: AN EVALUATION OF GEOLOGIC AND PHYSICAL CONTROLS." Master's thesis, University of Cincinnati, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1005673192

    Chicago Manual of Style (17th edition)

ucin1005673192
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© 2001, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.
Release 3.2.12