Create the data set. REFLIB.POND contains the raw data for a pond floor and surrounding land. 
data reflib.pond;
   input vdist hdist height;
   datalines;
10    88       0
18    55      -1
24    22.5    -1.67
...more data lines...
64    272.5  -6.25
60    277.5  -6.5
62    277.5  -6.5
;