The flows in the hydrological cycle are evapotranspiration, interception, infiltration, and runoff.
In a drainage basin hydrological cycle the stores are on the surface, in rivers, lakes, streams, and in puddles. It is also in the soil, deep below the ground surface as groundwater, and on vegetation after precipitation.
Human activity plays an important role in the hydrological cycle because large amounts of water are needed in every day life. Large reservoirs are constructed so that water can be collected and then pumped to the areas surrounding homes. Reservoir water is collected into a special built area and is therefore a man made store. Whenever people use water, it is treated to remove dangerous materials before being returned to the rivers or sea. However, human activity contaminates the hydrological cycle, causing acid rain and river pollution. Acid rain is created by power stations and other industrial factories pumping waste material into the atmosphere, where it mixes with the moisture in the clouds.
As a result, the surface of the water becomes covered in a thick layer of algae, known as algal bloom.
Farming the land stops vegetation, a store, and rain hitting the bare soil is not intercepted, and there are no plant roots in the soil to bind it together, so the water runs off the surface into the river, carrying a layer of soil with it. So in turn this stops interception, a flow/ transfer, of which vegetation is the most efficient interceptor and evaporator. However this is only the case in short, light precipitation.
In urban areas such as a city, the concrete on the ground stops any type of precipitation escaping back to the rivers, through groundwater flow or throughflow. This happens everywhere even though there are drains to carry the water into the sewers. This is called infiltration as it stops the water being absorbed into the soil. It is also interception as it stops the water, and if the water collects n puddles the rate of evapotranspiration is greater than normal, as some collects, but some returns (even though not through runoff) to the rivers and the cycle starts again. As the concrete is black and heats up quicker than soil, the water evaporates a lot quicker than usual.
If a dam is built over a river stores and flows can be heavily affected. This is because the water is being obstructed and will in turn create a new store. The new store that is created is a lake, which though technically was naturally formed, was actually due to human intervention on the whole river. An example of this is lake Nasser in Eygpt. The effect on the river from the dam is that the river slows down and floods to the sides of the river into the flood plain. Another effect is that as the water in the lake is not moving it is evaporating a lot quicker, and all of the silt from the rest of the river that normally flows out to sea, or in the Niles case forms a delta, is obstructed and is making the lake shallower and shallower by the day.
So to answer the question ‘In what way can the hydrological cycle be regarded as a system and what impact may human activity have on flows and stores?’, the hydrological cycle can be described as a closed system, and there are many human impacts on the flows and stores of the hydrological cycle, the main ones being the diversion of water in dams, and concreted areas.
