you are given the map in figure f1 below. note the red line that demarcates the center of the rio grande in 1936 and that the blue channel is the river's position in 1992. because this section of the river is a nearly level plain and average annual flow varies widely, the river migrates across the floodplain. since the center of the river is the international boundary, any such movement impacts this densely populated bi-national floodplain. study the map to evaluate which of the following statements is not true.