Numerical Simulation Study On The Seepage Field Of Percolating Water Abstraction From Beneath Riverbed And The Reliability Analysis Of Water Quality

The technique of percolating water abstraction from beneath the riverbed directly extracts clean water from a riverbed by means of engineering approach to make the riverbed itself as filtering bed purifying heavy turbidity and slightly polluted river water. This dissertation is intended to establish the theoretical system of the technique, on the basis of Baisha Waterwork in Chongqing City, in combination with a large amount of research , including field investigation and numerical simulation. The main accomplishments as follows:(1) Having been formed through the endless geological process, the grit layer with certain thickness existed at the bottom of washland characterizes non-homogeneous granularity and favorable permeability. The efficiency of riverbed filter exceeds greatly the man-made filtering beds such as percolating pool and quick filter chamber because the grit layer commonly posses multiplayer structure and the top layer of riverbed generally grows biological mud membrane in case of corresponding hydrodynamic force is available.(2) In combination with the Baisha project, a systematical study on the characters of seepage field was conducted by numerical simulation. It can be concluded that the seepage field has typical three-dimensional flow. From then, a hydrologic model for calculating hydrograph and determining amount of water abstraction is established.(3) The reliability of water quality from Baisha project was analyzed by means of reliability theory and selecting reasonable reliability analysis method.