HR: 13:40h
AN: H23I-01 INVITED    [Abstracts]
TI: Some Transient Analytical Groundwater Responses for Basis Spline Pulse Inputs
AU: * Knight, J H
EM: John.Knight@csiro.au
AF: CSIRO Land and Water, 120 Meiers Rd, Indooroopilly, QLD 4083, Australia
AB: The linearised Boussinesq equation describes the transient movement of a groundwater free surface in unconfined flow. The classical solutions of the heat or diffusion equation provide many transient analytical solutions for the interaction between groundwater and surface water. The classic Glover and Balmer solution gives the depletion of a stream when groundwater is pumped from a nearby well. I will present generalisations of this for the flow of groundwater recharge into a stream, and for more complicated aquifer and stream geometries. The most commonly used transient analytical solutions are for either a delta function pulse input in the time domain, or else its integral the unit step input. Traditionally the response for an arbitrary input in the time domain is calculated as a finite difference approximation to a convolution integral, which is equivalent to finding the output corresponding to a row of delta function inputs. I will describe recent work in which the input time series is described as a sum of cubic basis spline functions, which is a smooth approximation to the original input function. In many cases of interest the output for each basis spline input pulse can be found analytically. This means that the input can be expressed as a sum of basis splines and the output can immediately be expressed as a sum of the appropriate response functions with the same coefficients. This principle is quite general, and examples will be given from various interactions between streams and groundwater.
DE: 1829 Groundwater hydrology
DE: 1830 Groundwater/surface water interaction
DE: 1832 Groundwater transport
DE: 1842 Irrigation
SC: Hydrology [H]
MN: 2007 Fall Meeting