If your data is in a 2D table (matrix) and you want to locate a column that matches the exact value from another column, then logical indexing is a natural way to go.
Suppose data(:,1) represents the column of subbasin number, and data(:,2) represents the column of area, then to select an area for a given subbasin number
subbasin_no = 12;
area = data((data(:,1)==subbasin_no),2);
"area" contains every value from column 2 where column 1 = subbasin_no.
Note that this is more versatile than VLOOKUP in Excel.
1) The data does not have to be monotonically increasing, as with VLOOKUP
2) You can use logical indexing based on any column (with VLOOKUP, you must perform the look-up based on column 1)
3) It can return multiple values.