Water Sources: Nature's Gift To Life On Earth

Water is a precious natural resource on planet Earth and is found all around us. Every living organism on our planet requires water for its survival, and humans use it for drinking, cooking, bathing, cleaning, and washing, among other things. Water is also used in large quantities by factories and large industries to produce various products required for human welfare. There are two primary sources of water: surface water and groundwater. The primary water sources used for drinking, cooking, washing, farming, and other commercial uses are surface water, groundwater, and collected rainwater. These primary water sources depend on rainfall and snow, which form part of the hydrological cycle.

Groundwater and springs

Groundwater is a vital source of water, and it is found all over the world. It is a primary source of drinking water, alongside cisterns and springs. Groundwater is also used for irrigation in agriculture, as well as for industrial reuse and for drinking water.

Groundwater is formed when water soaks into the ground and travels through rocks and sediments. This process is known as groundwater recharge. The water then encounters a confining layer, often clay or other impervious material, which does not allow the water to seep further down. The water then flows across this layer until it reaches the surface. This emergence of groundwater at the land surface is what we call a spring.

Springs occur in various forms and are classified by several factors, including the rock type in which the spring occurs, how it was formed, the temperature of the water, and the flow of the spring. For example, seepage springs usually occur in sand, gravel, or organic materials and are generally found in depressions or valley bottoms. In contrast, artesian springs occur when the pressure of the groundwater becomes greater than the pressure from the atmosphere, resulting in water being pushed straight up out of the ground.

Springs have been a source of fascination throughout history and have been used for various purposes, including public bathing, watering livestock, and as a source of drinking water.

Rainwater harvesting

Rooftop rainwater harvesting is used to provide drinking water, water for livestock, water for small irrigation, and a way to replenish groundwater levels. Rainwater is a relatively clean and absolutely free source of water. It is socially acceptable and environmentally responsible. It promotes self-sufficiency and helps conserve water.

Rivers, lakes, and reservoirs

Lakes are another vital source of water, accounting for about 20.9% of freshwater on Earth. They are often connected to rivers, which flow in and out, facilitating water movement, nutrient transportation, and species migration within ecosystems. Lakes can form through various natural processes, such as tectonic activity, wind and water erosion, or the movement and melting of glaciers.

Reservoirs, on the other hand, are artificial water bodies created by humans by building dams on rivers or lakes. They serve multiple purposes, including providing water for human needs and generating electricity through hydroelectric power. The construction of reservoirs can significantly impact the local habitat, affecting both humans and various plant and animal species. Smaller reservoirs are more suited for lining and covering, and proper treatment is necessary to address physical, microbiological, and chemical contamination.

While ponds and lakes are generally well-accepted as water sources, reservoirs are often built in regions with water scarcity to ensure a continuous and easily accessible supply of water for various sectors, including agriculture and industry. The availability of surface water from these sources depends on rainfall, with supply varying between wet and dry seasons and different years.

Water treatment and reuse

Water is everywhere on Earth, in the air and clouds, on the surface in rivers, oceans, ice, plants, and in living organisms, and even inside the Earth. However, most of this water is not freshwater and is not suitable for human use. The available natural water is not pure, and excluding rainwater, it contains salts and minerals that make it unfit for consumption. The primary sources of drinking water are surface water, groundwater, and collected rainwater.

Water reuse can be classified as planned or unplanned. Unplanned water reuse occurs when communities or cities draw their water supplies from rivers that receive treated wastewater discharges from upstream communities or cities. Planned water reuse, on the other hand, refers to water systems designed with the specific goal of reusing a recycled water supply. An example of a planned water reuse project is the West Basin Wastewater Treatment Plant in California, which uses reverse osmosis to remove impurities from wastewater.

Water recycling offers both resource and financial savings. Treated wastewater can be used for agricultural and landscape irrigation, industrial processes, and environmental restoration. It can also be used for non-potable purposes such as irrigation in public parks and golf courses, cooling water for power plants, and toilet flushing. By reusing water, communities can reduce pollutant discharges, such as nitrogen, and improve water quality.

Ocean water and desalination

The Earth is a watery place, with water found almost everywhere on the planet. Oceans are the largest storehouse of water on Earth, with over 96% of all water on the planet existing in the oceans. Ocean water, however, is saline water, which contains significant amounts of dissolved salts and is not suitable for human consumption. Freshwater, which accounts for only about 3% of all water on Earth, is the water that serves our everyday needs.

Desalination is the process of removing the dissolved mineral salts in water to make it suitable for human consumption or agricultural purposes. It is not a new process, with distillation desalination being one of mankind's earliest forms of water treatment. In ancient times, many civilizations used this process on their ships to convert seawater into drinking water. Today, desalination plants are used to convert seawater to drinking water, especially in arid regions of the world, and to treat water fouled by natural and unnatural contaminants. According to a 2019 study, there are approximately 16,000 desalination plants in operation across 177 countries, producing around 95 million m3/day of freshwater.

Distillation is one method of desalination, where seawater is boiled, the steam is captured, and then condensed back into water. However, this method requires a large scale to be useful to large populations, and it is also expensive and energy-intensive. Other methods of desalination include reverse osmosis, where water is passed through filters, and electrodialysis.

Desalination is particularly important in areas affected by freshwater scarcity, many of which are located near the sea. Seawater desalination will likely become a key process in countries with higher water stress.

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