Q.Is complete reduction of relief of a high land mass possible?

Think of a river as a courier service that has to deliver a fixed number of parcels every day. If the courier is given more parcels than it can carry, it drops some along the way. If it is given fewer, it starts picking up extra parcels from the roadside to keep itself busy. A river does exactly this, but with sediment — the sand, silt, gravel, and mud that it carries downstream.

Now, the river's "parcels" come from two places. First, the land around it: rain washes soil into the channel, and tributaries dump their own loads. Second, the river itself: as it flows, it scrapes its own bed and banks, adding more material. The river's "capacity" is its ability to transport all this — a fast, deep, powerful river can carry far more than a sluggish, shallow one. So the equilibrium is simply this: a river is in equilibrium when the amount of sediment it receives exactly equals the amount it can carry away. Nothing builds up, and nothing gets scoured out.

But here is the subtle part. The river is not a passive pipe. It actively adjusts itself to reach this balance. If you suddenly dump a huge load of sediment into it — say, from a landslide or heavy deforestation upstream — the river cannot carry it all. So it drops the excess on its bed. That raises the riverbed, which makes the water shallower and slower, which reduces its capacity further. The river is now "out of equilibrium," and it will keep depositing until the slope and flow adjust to a new balance. Conversely, if you take sediment away — say, by building a dam that traps the load upstream — the water downstream suddenly has spare capacity. It starts eroding its own bed and banks to pick up more material, deepening and widening the channel. That is why rivers downstream of dams often cut down dramatically.

What matters for you is that this equilibrium is dynamic, not static. It is a moving target. The river is always chasing a balance, but the balance itself keeps shifting because rainfall changes, seasons change, and human activity changes the landscape. A river in equilibrium is not a calm, unchanging thing — it is a system that has adjusted its slope, width, depth, and speed so that it neither silts up nor erodes aggressively. Geographers call this a "graded stream," and it is the closest a river gets to a steady state.

Why does this matter beyond the textbook? Because it explains almost every river-related problem you will read about. Flooding often happens when a river loses its equilibrium — it cannot carry the load, so it deposits sediment in its own channel, raising the bed and reducing its capacity to hold floodwater. Soil erosion on farmland is a river being given more sediment than it can handle, so it drops it and then, when the load reduces, it erodes the banks instead. And when engineers straighten a river or line its banks with concrete, they are changing its capacity without changing its load — so the river responds by eroding somewhere else, often downstream, in ways nobody planned.

A few things to hold onto:

• Load is what the river is given; capacity is what it can carry. Equilibrium is load = capacity.
• The river adjusts its own slope, width, and depth to reach this balance — it is not a fixed pipe.
• Deposition happens when load > capacity; erosion happens when capacity > load.
• The equilibrium is dynamic — it shifts with seasons, climate, and human activity.
• A river in equilibrium is called graded — it has adjusted its profile to its load and flow.

The practical takeaway: whenever you see a river depositing sediment or eroding its banks, ask what changed the balance. Was the load increased (deforestation, farming, mining)? Or was the capacity reduced (damming, water extraction, channel straightening)? The answer to that question explains the river's behaviour — and often the human story behind it.