METHOD, DEVICE, AND PROGRAM FOR CALCULATING RIVER BASIN AREA

PROBLEM TO BE SOLVED: To provide a method, a calculating device, and a program for calculating the basin area of a designated river more easily by using two-dimensional vector map data. SOLUTION: The method for calculating a river basin area includes: a step to acquire two-dimensional vector map data within the map frame including the designated river basin area to be calculated from a map database and display the data; a step to receive designation of an object river whose basin area is calculated on the displayed map and to receive designation of a point to be the reference point of the basin area; a step to create and store a contour line relational model by acquiring all the contour line figures in the map frame; a step to calculate, on the basis of the contour line relational model, the ridge lines on the right bank side and on the left bank side of the designated river from the reference point; a step to calculate a continuous ridgeline connecting the ridge lines on the right bank side and the left bank side; and a step to calculate, on the basis of the right bank side ridge line and the left bank side ridge line and the ridgeline, a closed broken line showing the basin area of the designated river and to output the area within the closed broken line as the basin area. COPYRIGHT: (C)2006,JPO&NCIPI