MATLAB: How to create contour of water table at 0.2 m intervals

contoursgraphwells

I have some wells that are located by a lake. I have the ground watertable elevation at each well, as well as the elevation at the lake. I created x and y coordinates for these elevations and am now trying to combine it to create contour lines of the water table. How can I do this at 0.2 m intervals?
Not sure what the problem is with using the reshape function here as well.
clc;clear all;close all
% x and y coordinates of well locations and lake points in cm  (3.4cm/km)
w1=[5.9,5.6];  
w8=[8,7.6];
w17=[11.9,2];
w21=[9.7,5.3];
w27=[4.6,4.6];
w56=[5.9,1.7];
w58=[5.9,1];
w59=[6.7,4.1];
lakepoint1=[4,6.55];
lakepoint2=[5.75,6.9];
lakepoint3=[7.7,7.65];
% Combined coordinates into a single matrix 
wells=[w1;w8;w17;w21;w27;w56;w58;w59;lakepoint1;lakepoint2;lakepoint3];
% Converted well locations to metres
scaledwells=wells*0.441176*1000;
%Groundwater table elevations at each well and at 3 points of the lake. (in metres)
gwtablew1=236.07;
gwtablew8=236.65;
gwtablew17=240.37;
gwtablew21=238.13;
gwtablew27=235.96;
gwtablew56=236.66;
gwtablew58=237.70;
gwtablew59=237.90;;
gwtablelake1=234.19;
gwtablelake2=234.19;
gwtablelake3=234.19;
%Combined into single matrix below
gwtable=[gwtablew1;gwtablew8;gwtablew17;gwtablew21;gwtablew27;gwtablew56;gwtablew58;gwtablew59;gwtablelake1;gwtablelake2;gwtablelake3];
%created scatter plot of x and y coordinates of wells and lake points)
scatter(scaledwells(:,1),scaledwells(:,2))
xlabel('m')
ylabel('m')
grid on
%Trying to produce contours
scaledwellsx=scaledwells(:,1)
scaledwellsy=scaledwells(:,2)
nx=length(scaledwellsx);
ny=length(scaledwellsy);
z=reshape(gwtable,ny,nx)
I am receiving the error:
Error using reshape
To RESHAPE the number of elements must not change.
Error in gwass1 (line 45)
z=reshape(gwtable,ny,nx)

Best Answer

You first need to interpolate your data to a grid before plotting contour. Try the following code
clc;clear all;close all
% x and y coordinates of well locations and lake points in cm  (3.4cm/km)
w1=[5.9,5.6];  
w8=[8,7.6];
w17=[11.9,2];
w21=[9.7,5.3];
w27=[4.6,4.6];
w56=[5.9,1.7];
w58=[5.9,1];
w59=[6.7,4.1];
lakepoint1=[4,6.55];
lakepoint2=[5.75,6.9];
lakepoint3=[7.7,7.65];
% Combined coordinates into a single matrix 
wells=[w1;w8;w17;w21;w27;w56;w58;w59;lakepoint1;lakepoint2;lakepoint3];
% Converted well locations to metres
scaledwells=wells*0.441176*1000;
%Groundwater table elevations at each well and at 3 points of the lake. (in metres)
gwtablew1=236.07;
gwtablew8=236.65;
gwtablew17=240.37;
gwtablew21=238.13;
gwtablew27=235.96;
gwtablew56=236.66;
gwtablew58=237.70;
gwtablew59=237.90;;
gwtablelake1=234.19;
gwtablelake2=234.19;
gwtablelake3=234.19;
%Combined into single matrix below
gwtable=[gwtablew1;gwtablew8;gwtablew17;gwtablew21;gwtablew27;gwtablew56;gwtablew58;gwtablew59;gwtablelake1;gwtablelake2;gwtablelake3];
%created scatter plot of x and y coordinates of wells and lake points)
scatter(scaledwells(:,1),scaledwells(:,2))
xlabel('m')
ylabel('m')
grid on
hold on
%Trying to produce contours
scaledwellsx=scaledwells(:,1);
scaledwellsy=scaledwells(:,2);
[X,Y] = meshgrid(sort(scaledwellsx), sort(scaledwellsy));
F = scatteredInterpolant(scaledwellsx,scaledwellsy,gwtable);
Z = F(X,Y);
contour_levels = min(Z,[],'all'):0.2:max(Z,[],'all');
contour(X, Y, Z, contour_levels);
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