Page 529 - AWSAR 2.0

In the last decade, a lot of analytical solutions have been developed to estimate the Lmax. However, very less is known about the limitations or applicability and usefulnessofthesemodelsinfieldconditions. Furthermore, the longevity of the contaminant source in the subsurface requires that, in addition to the standard conditions, the effect of hydrogeological
stresses (e.g., flood, drought)
should be included to quantify
contamination precisely.
Unfortunately, only a few
scientific works have made
any attempt to address
the complex interplay of
contaminant transport and hydrogeological stresses.
Both contaminant sources
and plumes are influenced by
these stresses (called external
stresses hereafter). Therefore,
my research attempts to study
the impact of external stresses
on plume growth. With the
inclusion of external stresses
as a factor, the efficiency of
these analytical models can be
improved.
In my research, numerical modeling (MODFLOW and
MT3D) and analytical solutions are used together to understand the contaminant plume extension resulting from different external stresses. Realistic numerical models are set up with homogeneous, saturated, uniform flow field, and parameters as assumed by the analytical solution. Once the numerical model is able to reproduce the same results
as analytical models, several scenarios are generated with varying stresses. The inclusion of these stresses makes the system closer to field conditions. The analysis gives insights on the results, observed changes in Lmax on the application of external stresses, and also the behavior of numerical plume length under varying environments. A correction factor is suggested for the analytical solution, which improves the estimation significantly. Results are also validated with field data from various contamination sites. The improved solution provides a closer match to field plume lengths.
The research is of particular importance, as preventive and
Ms. Sandhya Birla || 505
Fig.: Schematic sketch illustrating the maximum plume length (Lmax).
The research is of particular importance, as preventive and curative measures in areas of groundwater contamination have been a low priority in India for years, and the trend continues. Also, the investigation and remediation techniques are not economically viable in the Indian context. Hence, developments in the analytical solution
can be beneficial in Indian scenarios. The study primarily focuses on the development of mathematical models and the improvement in analytical solutions, which have the potential of emerging as efficient groundwater management tools.