Describe the global hydrological cycle. (8 marks)

ANSWER: The process begins when water evaporates from the oceans and lakes due to the heat energy from the sun. In addition, water can also be evaporated from vegetation, this is called transpiration. Once the water evaporates, the steam condenses and comes back down through precipitation, which can be rain or snow depending on the conditions. The rainwater then returns to the oceans and lakes through streams and rivers. As well as this, water can also infiltrate the soil and the permeable rock and return to the oceans and lakes, this is called groundwater flow.

2. "A drainage basin is an open system with four elements- inputs, storage, transfers and outputs."

     Describe the movement of water within a drainage basin.              (8 marks)

3. " Explain the erosional and depositional features found in a river from its upper to lower course. (10 marks) 

Answer: Some erosional processes includes hydraulic action which is the force of the currents on the banks of the river. Attrition which is the breakdown of seperate materials in the water as they smack together and break up into smaller pieces. Abrasion is when the river uses the load to erode the river banks, most of the erosional processes laterally erode the river channel because this is in the lower course of the river. A Meander is a feature in the lower course and to a lesser extent the middle course. It is a bend in the river, where the river has had to find an easier route towards the sea. The above processes contribute to the creation of this feature. An Oxbow lake Is another eroisional feature found in the lower course of the river and is also formed due to the above processes. The bends of a meander are heavily eroded until the neck dissapears and what is left is a more direct route towards the sea. The old route is eventually redundant because of this. The remains of the old route is left abandoned and eventually dries up which is a shame

4. Explain the formation of an ox-bow lake (10 marks)

Meanders are formed in the lower course of the river. They form when the river's load is used to erode the bed of the river forming deep pools and shallow areas known as riffles. This causes the river to become sinous(winding). The river will begin to erode the sides of its bank (lateral erosion) via the process of hydraulic action and abrasion. The river continues to erode on the outside of the bend because of helicoidal flow as that is where the flow is fastest, deposits are left on the inside of the meander as the flow is too slow carry the material, this is called a river beach or slip off slope. This continues to happen and further erosion causes the neck of the meander to become narrower. During a flood the neck may be breached. Very little water flows through the old meander so it deposits it's load at the entrance sealing off the meander from the main river. This straightens the river's course and forms an ox-bow lake.