Field Scale Water Flow And Solute Transport

Author : Jianying Jiao
Publisher :
ISBN 13 :
Total Pages : 186 pages
Book Rating : 4.4/5 (387 download)

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Download or read book A New Direct Inverse Method of Groundwater Flow and Solute Transport written by Jianying Jiao and published by . This book was released on 2022 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Groundwater is the largest accessible source of drinking water and water for irrigation. With increasing population and economic development, the demand for drinking water and water for irrigation is increasing. Therefore, the water table map, groundwater depletion, and solute transport in the shallow groundwater are very significant to humanity and ecosystems. Because observations of the water table and concentrations are rare, the maps of the accurate water table, groundwater depletion, and concentrations are difficult to obtain in the local regions and around the globe. This dissertation addresses how to solve these problems, estimating maps of the water table, groundwater depletion, and concentration in local and continental regions. Because the inverse method is one of the more extensive and effective methods for solving these problems, the inverse method was used in our study. However, the traditional inverse method requires a forward model including boundary and initial conditions. Uncertainty of boundary and initiation conditions leads to large uncertainty of inverted results. According to issues of the traditional inverse method, in the dissertation, we proposed a new direct inverse method that does not require boundary and initial conditions. First, this method was used to estimate maps of the water table and groundwater depletion in the High Plain Aquifer and the continental US. Results show that the water table of the Texas High Plain Aquifer declined 0.5 meters per year from 2000 which is consistent with observations. Expanding from local regions to the continental US, the inverted water table map and standard deviation map in the continental US were presented. Second, we used our inverse method to estimate the groundwater depletion in the continental US and compared our inverted results with data from the Gravity Recovery and Climate Experiment (GRACE) and groundwater withdrawals from USGS. Then, to identify contaminant trajectory and source in a non-uniform flow field, this study proposes a new inverse method by developing local approximate solutions (LAS) of concentration and by conditioning them to measure breakthrough concentrations. The key difference between this new approach and the majority of existing inversion techniques is that standard regression techniques are not employed. Thus, a solute transport forward model does not need to be built and simulated to optimize a model-data mismatch, as a result, non-uniqueness in inversions that is due to an incorrect assumption of transport BC is eliminated. To verify the solute transport inverse method, A series of bromide tracer experiments were performed in an intermediate-scale two-dimensional laboratory soil testbed. The resulting concentration breakthrough measurements, made at increasing monitoring well densities, were used to validate this method that can identify leakage sources and pathways under unknown initial and boundary conditions.