Analysis On The Solution To The Unsteady Flow To A Fully Penetrating Well In Leaky Confined Aquifers Assuming Aquitard Storage And Determination Of Its Hydrogeological Parameters

Groundwater, as an essential part of water resources, plays an important role in thedevelopment of national economy. Hydrogeological parameters are the basis of a series ofwork such as groundwater resources evaluation, groundwater numerical simulation,establishing solute transport models, making rational abstraction schemes, and so on. Thispaper took leaky confined aquifers assuming aquitard storage as the research object. Based onthe former research achievements, the methods and accuracy of numerical solution andanalytical solution of unsteady flow to a fully penetrating well in leaky confined aquifersassuming aquitard storage were discussed. To improve the calculation accuracy, this paperpresented an amended analytical solution. The following conclusions are reached.(1) The well function of unsteady flow to a fully penetrating well in leaky confinedaquifers assuming aquitard storage is a generalized integral function. According to theproperty of the integration, the generalized integral function can be transformed into definiteintegral which can be calculated by subsection summation method. The absolute error of thecalculation is below0.0001, and the relative error is within5%.(2) The numerical solution is calculated by appropriate mathematical model andnumerical simulation, which can respond the changes of the water level in the pumping welland can be used for future research.(3) If the parameters of the aquitards above and below the pumping aquifer are the same,the applicable scope of the early time analytical solution can be extended to10times asspecified. The absolute errors of the early time solution in the extended scope are within0.1m, and the relative errors are within3%. The scope of the late time analytical solution can beextended of the early time solution in the extended scope. The absolute errors are within0.01m, and the relative errors are within1%.(4) If the parameters of the aquitards above and below the pumping aquifer are different,whether the early time analytical solution or the late time analytical solution, big errors canbe observed for the time period beyond the time limit of analytical solution. Its relative errormay higher than5%, and its absolute error may bigger than1m. (5) Appropriate correction is made to overcome the shortcomings of the analyticalsolution formula. The calculation accuracy of the corrected formula is obviously improved.The absolute errors of the corrected formula are within0.02m, and the relative errors arewithin5%.(6) When solving hydrogeological parameters through unsteady pumping tests, theappropriate analytical solution formula can be selected by the shape of s~lgt curves. In thisway, the calculation accuracy for the aquifer parameters is above95%and that for theaquitard parameters is generally above90%.The study results are beneficial to promote the advance of hydrogeology and can offerthe theoretical basis for solving the hydrogeological parameters in practical work.