Lowering ranges (classified)

The areas designated as sink areas represent flattening at a relative depth of the relief and are fundamentally based on the course of the depth lines.被划定为汇水区（sink areas）的区域，指在地形起伏的相对深度上呈现平坦化的区域，其划分本质上以等深线（depth lines）的走向为依据。