watershed

a line of high land where streams on one side flow into one river, and streams on the other side flow into a different river บริเวณลุ่มน้ำ

Among the measures proposed is a 2.1 billion baht flood prevention plan for the river basins, with a focus on restoring watershed areas, said Royal Irrigation Department chief Chalit Damrongsak.

The demilitarised zone drawn up by the ICJ covers an area of 17.3 square kilometres and reaches deeper into both sides of the watershed line that Thailand viewed as its border with Cambodia.

Many people have no idea the park is a watershed that gives birth to many rivers, not to mention purifying the air they breathe.