Average precipitation over area

The simplest method is Arithmetic-mean method it is good in flat country, gages are uniformly distributed and the individual gate catches.

The Thiessen method to allow for non-uniform distribution of gages by providing a weighting factor for each gage. The limitation is its inflexibility, not allow for orographic influences)

The most accurate is Isohyetal method. It is suitable map, suit contours providing, permits the use and interpretation of all available data and is well adapted to display and discussion