MATHEMATICAL RAINFALL MODEL FOR HYDROGRAPHIC DEMARCATION OF MANABI (ECUADOR)

To determine the average annual rainfall at a specific site in a basin, it is necessary to count with rainfall information in the study area and topographic information. Counting with base information, is comes to the filling of them data missing with the help of any of them methods statistical existing for the effect. Thiessen polygons are built. Based on this procedure, may be elaborated isohyet or curves of equal rainfall, that are an input that can help also to estimate of precipitation in a specific geographical site. Here is a methodology that allows creating with the help of geographic information systems (GIS), a mathematical model to estimate very accurately the values of rainfall based only on the geographical coordinates. To achieve this objective, the basins of the Hydrographic Demarcation of Manabi have been chosen to develop the indicated mathematical model, which can be applied to other basins in the world. Keywords: multiple regression; mathematical model; GIS; Hydrology; rainfall.