H031-0015
Hybrid Model for Estimation of Steady-State Plume Length in 3D Scenarios
Tuesday, 8 December 2020
Poster
Sandhya Birla, Indian Institute of Technology Delhi, New Delhi, India, Jyotiranjan Barik, Indian Institute of Technology Delhi, India, Department of Civil Engineering, New Delhi, India, Prabhas Kumar Yadav, Technische Universität Dresden, Germany, Institute of Groundwater Management, Dresden, Germany, Rudolf Liedl, Techn. Univ. Dresden, Dresden, Germany and Bhagu Ram Chahar, Indian Institute of Technology Delhi, Civil Engineering, New Delhi, India
Abstract:
Knowing the plume extension is the most critical aspect in the field of groundwater contamination management. Frequently, this assessment is based on analytical models, which do not have components for external stresses, like groundwater recharge, on plume extension. Reactive numerical transport models can overcome this difficulty in principle but require advanced knowledge. The maximum longitudinal extension of plume or steady-state plume length (
Lmax) is a critical variable for the risk assessment. Several analytical solutions are available to assess the
Lmax. However, the analytical solution works under simplifying assumptions, thus deviating highly from the observed plume lengths. This research extends the applicability of the analytical models as these are an excellent tool for pre-assessment of the contaminant site strategies.
A realistic numerical model is set up with the assumptions of an existing 3D analytical solution. Once the numerical model is confirmed with the analytical solution, the numerical simulations are run with different source dimensions and varying recharge rates. The study also studies the influence of the aspect ratio of rectangular source-geometry. The results indicate that the dilution effect leads to a lateral and longitudinal decrease in plume length, and the recharge entering the aquifer top causes the plume to tilt downwards from the source zone. Scenarios have been developed with A/P-ratio as an influencing factor. However, the source area (A) dominates over the source perimeter (P). A hybrid analytical-empirical solution (hybrid model) has also been proposed to calculate the Lmax by introducing an empirical correction factor superimposed with an analytical model. This factor is a function of the recharge rate, source area, and source perimeter. The impact of the recharge rate is also studied for varying domain length and flow velocity. Future works are needed to verify and refine the developed model further.
