3.2) Water

Question 1

• What are the IMPACTS of an increasing global population on water supplies? (case studies)

Answer 1

• Nevada and Ghana are examples of why water management schemes are needed in a developed and developing country as both rely on water supply from mountain snow melt.

1. Nevada relies on the Rocky Mountain snow melt to create the Colorado River and Ghana relies on mountains to the north to supply the Pra River 🏔️
   ➞ This leads to an unpredictable basin flow of water as it depends on how quickly the snow melts and temperatures of the area where the river flows 🌊
   ↳ If the temperature is too high, evaporation could occur if the river is still. Both of these rivers are depended on to fit the demands of domestic, agricultural, and industrial water needs.
2. The seven states which the Colorado River runs through along with Ghana have experienced a large surge in population causing more water to be needed for the Colorado and Pra Rivers 👨‍👩‍👧‍👦
   ➞ Therefore, more water is needed for domestic purposes, including in households (i.e. baths, toilets, air conditioning, cleaning, and preparing food) 🏡
   ↳ Water is also needed to water golf courses and ponds to make the area more attractive. Also, agricultural needs such as to hydrate animals kept on the land and to water crops allowing them to grow to meet the demands of a growing population 🚜
3. There are both wet and dry seasons for both of these rivers, meaning there is a need for flood control during wet seasons as the river breaking its banks could result in a loss of homes 🏚️
   ➞ Water storage is needed to secure a supply during drought. There also needs to be a large enough flow to ensure the rivers reach the sea.
   ↳ High temperatures around the basin lead to high evaporation rates, resulting in a loss of water 💧🚫
4. The ability to create water management schemes allows for populations to grow in previously uninhabitable areas (such as the Nevada desert).
   ➞ However, this strain on the water supply means that a sustainable relationship with water must be created 🤝
5. In Ghana, water is needed for drinking, washing dishes, irrigation and transportation, but may not always be useable as the water can be polluted with sewage causing sickness and diarrhoea 🤢

Question 2

• What is IRRIGATION and what are the different methods of irrigation?

Answer 2

• Irrigation is the artificial application of water to the land or soil, and it is estimated that around 50% of the world’s agricultural land uses some type of irrigation.

1. SURFACE:
   ➞ is where water is applied and distributed over the soil surface by gravity. It is by far the most common form of irrigation throughout the world and is used in paddy fields across south-east Asia to produce rice, the staple foodstuff of the area.
2. SPRINKLER:
   ➞ attempts to replicate natural rainfall where water is distributed through a system of pipes usually by pumping and then spraying on to crops.
3. DRIP/TRICKLE:
   ➞ saves water and fertiliser by allowing water to drip slowly to the roots of many different plants, either onto the soil surface or directly onto the root zone.
4. SUBSURFACE:
   ➞ involves watering crops through buried plastic tubes containing embedded emitters which are regularly spaced to deliver water direct to plant roots.

• Drip and subsurface irrigation typically use less water and are more efficient, but can be more expensive to install.

Question 3

• What are the ADVANTAGES of irrigation?

Answer 3

Irrigation:
1. Improves the yield of crops and creates prosperity by increasing the living standards of people ✨

2. If reservoirs and storage facilities are built, agriculture can take place during the dry season in many tropical countries, improving yields and dams may also be able to generate hydroelectric power 🌊
3. If irrigation results in a surplus of crops being produced, this can add to the wealth of a country through exports, and it may also allow for cash crops (i.e cotton and tobacco) to be grown 🌾
4. Irrigation encourages hygienic practices, such as increased bathing and hand washing which help reduce diseases 🧼
5. Marginal, unproductive land can also become productive when watered 👍

Question 4

• What are the DISADVANTAGES of irrigation?

Answer 4

Irrigation:
1. When areas are over-irrigated or other inefficient practices are used, it leads to a process known as salinisation - this is when water evaporates in high temperatures, drawing salts from the soil to the surface.
➞ These salts are toxic to many plants and make the land unusable 🌱🧂

2. Groundwater levels can also be reduced over time leading to a lack of water in underground stores, which are not allowed to replenish 🌊
3. Excessive seepage and leakage of water forms marshes and ponds all along the channels, creating a habitat for mosquitoes - which give diseases such as malaria 🦟
4. The initial cost of irrigation projects can be very high (in dam and canal construction) and thereby it is often large industrial farmers who benefit.
   ➞ Poor peasant farmers in many developing countries will not see any rise to living standards ❌

Question 5

• What are the 4 major categories that WATER-RELATED ILLNESSES fall into?

Answer 5

1. Water-BORNE diseases:
   ➞ include cholera, typhoid and dysentery, and are caused by drinking water containing infectious viruses or bacteria - often from human or animal waste 💩
2. Water-WASHED diseases:
   ➞ include skin and eye infections, and are caused by a lack of clean water for washing 🤢
3. Water-BASED diseases:
   ➞ are spread by organisms that develop in the water and then become human parasites (e.g. schistosomiasis - aka bilharzia) which is spread by a parasitic worm 💧🪱
4. Water-RELATED diseases:
   ➞ include diseases spread by vectors which live or breed in water such as mosquitoes (e.g. malaria and dengue fever) 🦟

Question 6

• What are the METHODS that help to supply clean water to rural communities in developing countries?

Answer 6

1. SINKING WELLS and BOREHOLES: 🕳️
   ➞ can supply a regular supply of clean water, but can be expensive and require investment - often from overseas charities to provide funding.
2. SEPARATION of water from human and livestock use: 💦
   ➞ which causes contamination by fencing areas off or building separate livestock troughs.
3. SODIS (Solar Water Disinfection): ☀️
   ➞ involves filling a clean PET plastic bottle with dirty water and leaving it outside for 6 hours in the sun. A combination of UV rays and water warming in the sun will kill off bacteria and pathogens - making it safe to drink.
4. EDUCATION SCHEMES: 📚
   ➞ promote the boiling of water before use (although this requires firewood which promotes deforestation) and the provision of soap promotes hand washing before cooking and eating - increasing hygiene.

Question 7

• What is DESALINATION?

Answer 7

• Desalination is a method for providing a safe and reliable source of freshwater to help meet the demands of a growing population by separating salts through different processes that use either heat, or membranes that take away or leave the salt water behind - and use the pure, drinkable water for people to use in their every day lives.

Question 8

• What are the 6 stages of DESALINATION?

Answer 8

1. SEAWATER INTAKE:
   ➞ Seawater is drawn in from seas/oceans through specially designed intake structures.
   ↳ The water is drawn in at low speeds to prevent aquatic life from being trapped 🌊
2. FILTRATION:
   ➞ Pre-treatment filters remove solids, such as sand, seaweed and dust 🏝️
3. REVERSE OSMOSIS:
   ➞ Filtered seawater passes through 2 stages of reverse osmosis, where it is pushed through ultra-fine membranes under high pressure.
   ↳ This allows freshwater to pass through, leaving behind seawater concentrate 🔄
4. REMINERALISATION:
   ➞ Desalinated water is re-mineralised with magnesium, calcium and fluoride to meet health requirements 🏥
5. STORAGE:
   ➞ Drinking water is stored before it is distributed into the water networks where it is blended with water from existing catchments 💧
6. WATER OUTLET:
   ➞ Seawater concentrate is safely returned to the ocean through diffuser structures.
   ↳ Ocean currents dilute the concentration in seconds 🧂

Question 9

• What are the ADVANTAGES of desalination?

Answer 9

1. Desalination plants can provide clean, healthy water for dry, arid countries 🏜️
2. It can encourage tourism - for example, in Dubai, a growing tourist and commercial centre which gets 98% of its water from desalination to support economic growth 💰
3. In the Gulf States, there is plentiful solar energy to provide clean power to operate these plants ☀️

Question 10

• What are the DISADVANTAGES of desalination?

Answer 10

1. The sea water in desalination plants contain high levels of boron and bromide, and the process can remove minerals (i.e. calcium) which are essential for strong bones and teeth 🦷
2. The concentrated salt which has been removed during the process is often dumped back into the oceans, where the increase in salinity can have negative effects on the local coastal environment 🏝️
3. It can also be a very costly process - taking approximately 2 kilowatt hours of energy to produce 1 cubic metre of freshwater 💧
4. The energy often comes from burning fossil fuels, contributing to greenhouse gas emissions ⛽️

Question 11

• What are the 8 stages of PURIFICATION?

Answer 11

1. INTAKE:
   ➞ Raw water is drawn from the lake/reservoir.
   ↳ Intakes are located approximately 3 miles off shore where the water is cleaner 🌊
2. DEBRIS REMOVAL:
   ➞ Screens are used to remove fish, shells and other large debris.
   ↳ Pumps propel water throughout the treatment process ⛽
3. RAPID MIX:
   ➞ Three chemicals are added to the untreated water at a high speed.
   ↳ Powdered Activated Carbon helps eliminate unpleasant odours and tastes, chlorine conditions the water for further treatment, and Alum is added to help small particles stick together 🧪
4. FLOCCULATION:
   ➞ Mixing speed is gradually reduced to allow the Alum to form clumps which can be more easily removed 🚤
5. SEDIMENTATION:
   ➞ The clumps sink to the bottom of the sedimentation basins, trapping larger organic materials 🥣
6. FILTRATION:
   ➞ Water is filtered through sand and coal, removing smaller organic particles ⌛
7. DISINFECTION:
   ➞ Chemicals (such as, chlorine and orthophosphate) are added to the water to create safe water for drinking, business, and recreation.
   ↳ Chlorine kills bacteria and viruses, and orthophosphate reduces the danger posed by lead pipes in your home 🧪
8. DISTRIBUTION:
   ➞ Plants, towers, tanks, and water mains distribute water to homes and businesses 💧🚿

Question 12

• What are the 8 stages of SEWAGE TREATMENT?

Answer 12

1. WASTEWATER from urban areas, including toilet waste, flow through sewers to the treatment plant.
2. SCREENING involves removing bulky solids from the wastewater (i.e. nappies, face wipes, etc.).
   ➞ The grit in wastewater is also removed by sieving.
3. SEDIMENTATION removes the remaining solids and produces sludge and liquor; the sludge is removed and treated later.
4. BIOLOGICAL OXIDATION uses micro-organisms and aeration to remove the dissolved and suspended organic matter.
5. SLUDGE REMOVAL involves removing and treating the sludge as the liquor passes to the next stage.
6. FILTRATION removes the remaining suspended matter and toxins from the liquor, which is now known as ‘effluent’.
7. DISCHARGE involves the discharge of effluent to the river or sea.
8. END USES include:
   * the sewage sludge being heat-treated and used as fertiliser,
   * turned into a sludge cake and used for energy generation
   * aerobic digestion to generate biogas (used in heat and energy generation)