Concept of drainage basins and catchments

Correct answer: A. An antecedent river maintains its course while the land is uplifted, whereas a superimposed river retains a course inherited from an upper rock cover onto the rocks beneath

Explanation: A is correct. An antecedent river existed before uplift and maintains its general course by cutting down as the land rises. A superimposed river first develops on an upper rock cover; after erosion removes that cover, its inherited course continues across the underlying rocks. Neither type is limited to deltas, and superimposed drainage is not necessarily underground or karstic.

Correct answer: A. Because it shows where water comes from and where it flows

Explanation: A drainage basin is the area from which precipitation collects and flows toward a common outlet, such as a river channel, lake, or sea. Studying it reveals the relationships among rainfall, infiltration, groundwater recharge, surface runoff, stream flow, evaporation, and storage. This makes the basin a practical planning unit: managers can estimate available water, identify flood-prone areas, protect recharge zones, schedule irrigation, and control pollution upstream before it spreads downstream. Option A is correct because it describes the basin’s source-to-outlet flow system. The other options concern astronomy, marine biology, or seismology and do not explain water management.

Correct answer: A. Because water input, flow, storage and outlet can be studied together within it.

Explanation: A drainage basin is the area from which precipitation and surface or subsurface flow drain toward a common river channel, lake or outlet. Its boundary is usually defined by surrounding higher ridges, so managers can examine rainfall input, interception, infiltration, groundwater storage, runoff, erosion, water use and downstream discharge within one connected unit. This makes it practical for planning reservoirs, irrigation, flood control, pollution reduction and conservation, while recognising that groundwater boundaries may sometimes cross the surface divide. Option A gives the central reason. B, C and D are plainly incorrect because a basin is not only ocean, does receive rainfall and is not a cloud.