Physical and Chemical Processes in the Managed Water Cycle

PHYSICAL PROCESSES:

Evaporation

Evaporation is the physical process whereby the physical state of a liquid is changed into a gaseous or vaporised state. Factors such as solar radiation, thermal energy, air pressure, atmospheric pressure and geographic location all have a profound effect on the land and cycle of water throughout the Earth. An example of Evaporation in the natural water cycle is when the Sun’s solar radiation heats water to transform it into a gaseous substance(water vapour) which is circulated into the atmosphere.

Condensation

Condensation is the physical process whereby gaseous or vaporized substance is changed into a liquid state due to intense air pressure. When the process of Condensation becomes rapid, a solid can be formed. An example of this occurrence is when hail is formed due to the rapid and overactive process of Condensation. Condensation causes the creation of stronger bonds between atoms, creating as liquid substance. This can observed in the natural water cycle when clouds are formed from water vapour. When these clouds become darker in colour and thicker in density, this shows the increase in the process of condensation. The process of Condensation typically occurs in the atmosphere(specifically the stratosphere or troposphere when warm air ascends, decreases in temperature and then loses its capacity to hold water vapor due to its density. Then, as a result of this, excess water is formed to produce cloud droplets.

Precipitation

Precipitation is the process whereby particles(typically of a liquid state) fall or descend from the atmosphere and interacts with the surface of Earth. Precipitation occurs when the density and weight of the condensed vapour in clouds becomes the greater than the density of the cloud itself. This causes the cloud to precipitate this in the form of rain, hail or sleet. The rate of precipitation can vary in different geographic location depending on the air pressure, heat and humidity, or it position in the tropical regions, temperate regions, or Equatorial regions.

Infiltration

Infiltration is the physical process that involves the movement of water through the area whereabouts the atmosphere meets the immediate surface of the Earth. This rate of the process of infiltration is governed by the quality and permeability of the soil. Infiltration depends on the grouping of water on the surface of the Earth, and the force that the raindrops exert when interacting with the soil. Infiltration is also responsible for the storage of water underneath the Earth’s immediate surface. In managed or urban water cycles, the process of infiltration occurs a lot more rarely, due to the lack of grass and soil to guide to water underground. Managed water cycles particularly suffer from the lack of soil fertility and nutrition, due to the lack of the process of Infiltration.

Percolation

Percolation is the process of water moving through the soil, guided by gravity after the process of infiltration. There are two types of water that exists in the soil, vadose water and groundwater. Vadose water exists just near the surface of the earth where air can also penetrate through the soil. This part of the soil is known as the aeration zone, with the air mixing in with the water. Groundwater exists in a zone called the saturation zone where the soil is mainly moist from all the water. The invisible boundary that separates the two zones is called the water table. In industrial terms, the geological formation which transmits water from one location to another in sufficient quantity for economic use is called an aquifer. Finally, the movement of water downhill is entirely based on the water table and the geological boundary conditions of the earth.

Transpiration

Transpiration is a physical process involving the states of matter. This biological process first begins with the absorption of water by plants, as plants utilize the nutrients given by water to cool the leaves exposed to the sun. The sun is the main energy producer in transpiration, fueling the process. Water inside of the leaves in the plant is transferred from the plant to the atmosphere by the energy of the sun, turning it into water vapour. The amount of water released entirely depends on the different plant species. This vapour then continues the evaporation process into the atmosphere whereby the gaseous liquids group, and then form clouds.

Run-off

Run-off is a process concerning the movement of water over the solid surfaces of the earth, as opposed to groundwater or vadose water that travels underground. Runoff is also powered by gravity, by which water travels downhill on a solid surface. Water that eventually reaches soil isn't a part of the runoff process anymore, as it is penetrating the soil and going underground, otherwise known as the infiltration process and soon becomes a part of percolation. The most common form of runoff is the formation of streams. The flow mainly consists of precipitation with water falling directly on the stream, but it also consists of water over the surface of the land and subsurface runoff, which has infiltrated the soil and moves parallel to the flow of the stream, eventually connecting with the main source of water. In the managed water cycle, humans use the concept of catching water and gravity to collect rainwater and guide it towards a large body of water for later use. Products of runoff include piped that transport water from one location to another by the force of gravity. The process of run-off is increased in managed water cycles due to the lack of ability to perform infiltration.

Storage

Storage refers to the storing of water in a particular location. There are three locations where water can be stored, in the atmosphere, on the surface of the Earth, and underground. Water stored in the atmosphere is in the form of vapour and as a result, can freely move from one location to the other with ease. Relating to the storage of water on the surface of the Earth and underground, a reliable storage area will depend on the geologic features of the soil and rocks in the area. In the managed water cycle that we use to process water for human use, the storage of water is essential to keep water safe for later use. Dams are an effective way to store water after collecting water using the runoff concept. These dams can be connected to other pipes that lead towards water appliances in the household that suit our needs.

CHEMICAL PROCESSES:

Chlorination

Chlorinating is an essential process when dealing with the managed water cycle. Chlorination involves the addition of chlorine(Cl) into the water in order to eliminate any external and harmful organisms that may have the potential ability to cause water related diseases. Chlorination occurs typically in the early stages in the processing, which is pumped into the stored water in large quantities to dramatically decrease the amount of harmful organisms and diseases in the water. The Chlorination of water is detrimental to the purity of the water and also the health of people drinking the water. Although, if the process of de-chlorination is not performed, humans that consume this water will unfortunately be dramatically affected due to the chemical chlorine that still remains in the water. In hyrdo-power plants, gas released from the chlorine and then pumped into the uncleansed water.

Chlorination: Cl2+H2O→HOCl+HCl

De-Chlorination

The managed water cycle uses the de-chlorination process of reducing the amount of free chlorine in water. This process essentially removes this harmful chemical from water that all life forms need to survive. Compounds used for de-chlorination are:

Sulfur dioxide
Carbon adsorption
Sodium bisulfite
Sodium metabisulfite

This process has its advantages, knowing that it protects biodiversity from the toxic effects of residual chlorine and it also prevents the formation of harmful compounds when residual chlorine mixes with water-born organic materials. In this process, using sulfur dioxide as the main component in de-chlorination, uses this formula: SO3 -2 + HOCl ÿ SO4 -2 + Cl- + H+, this ultimately removes the free chlorine in the water.

Fluoridation

Fluoridating plays a significant role in the managed water cycle, as it ultimately protects humans from contamination and the harmful organisms in water. This chemical process involves the implementation and addition of fluoride into water when being pumped through pipes in order to prevent tooth decay(Tooth decay: Ca5(PO4)3OH(s) + 4H3O+(aq) → 5Ca2+(aq) + 3HPO42-(aq) + 5H2O(l) and function to stop the growth of cavities in the oral cavity and teeth. An advantage of fluoridating is that it does not vary the taste, appearance and smell of the water. Although, fluoride have a lasting and detrimental impacts on humans through poisoning, as fluoride is a chemical. The chemical equation for the process of fluoridating is:

Fluoridation= Ca5(PO4)3OH(s) + F-(aq) → Ca5(PO4)3F(s) + OH-(aq)

Bleaching

Bleaching is the process that disinfects water. This process is an alternative for boiling water. The managed water cycle uses bleaching products (which can be any household product with chlorine in it), to complete the process. Calcium Hypochloride is the main substance used in order to bleach water and protect humans from water-born diseases.