thn_dmo.m

%% Theis no-flow boundary interpretation.  
% This is a demo of the interpretation of a pumping test in a confined
% aquifer with an impermeable boundary with the Theis solution. 
%
% MIT License
% Copyright (c) 2017 Philippe Renard - University of Neuchâtel (CHYN)

%% Load the data
% The data set for this example has been typed from: 
% G. de Marsily, Pumping test in Niger.
% 
% Let us load the data and plot them.

[t,s]=ldf('thn_ds1.dat');
diagnostic(t,s)

% The diagnostic plot shows a doubling of the derivative at a time of 1e5
% seconds indicating a possible no-flow boundary effect. We interpret the
% data with the thn model.

%% Model parameter guess
% The parameters allowing to control the Theis no-flow boundary model are the slope
% and intercept of the Jacob straight line that one can observe at
% intermediate time, and the time at which the slope of straight line
% doubles.
% 
% The function thn_gss allows to estimate these numbers, we then check
% with trial if the first guess is acceptable.

p0=thn_gss(t,s);
trial('thn',p0,t,s) 


%%  Model fit and report
% As the first guess was rather good, we proceed with the automatic fit and
% directly report the results of the interpretation.

p=fit('thn',p0,t,s);
q=0.0132;    % Pumping rate in m3/s
r=20;        % radial distance in m
thn_rpt(p,t,s,[q,r],'Theis interpretation of de Marsilly data')

%%
% The estimated transmissivity is 9.8e-4 m2/s, the storativity is
% 3.9e-3, and the distance to the image well is 310 m. These numbers are
% close to the estimation provided by de Marsily.
%
% T  = 1.0e-3 [m2/s]
% S  = 3.7 e-3
% ri = 287 m