Understanding Water Cycle to Solve Environmental Pollution

Earth has been considered the Blue Planet for its abundant water that encompasses the majority of the earth's surface, making it appear blue. It is one of the most commonly used substances and is required for the survival of all living things. Hydrology is the study of water within the environment and can determine the makeup of water and its applications towards sustainable practices and lifestyles. The distribution of water through the water or hydrologic cycle can also determine how much is available for human consumption and how much is trapped in other forms that are not accessible. The use of freshwater resources is inevitable, but overexploitation, alteration, and contamination have to be taken into account when considering sustainable management methods.

Water, a compound element consisting of one oxygen and two hydrogen bonds, is a transparent, colorless, and odorless substance that makes up a large sum of earth's living matter. Even with water making up 71% of the earth's total surface area, only 5% of it is freshwater available for human extraction. The remaining 96% is comprised of saltwater found in larger bodies of water such as oceans and deltas. Understanding the interactions of water within the earth's ecosystems can help create sustainable management practices of freshwater within human operations. A study taken by NASA Earth Observatory provides a detailed look into where the earth’s water is distributed. It shows that out of all freshwater 30% is trapped underneath the earth's surface, 68% is held in glaciers/ice, and the remaining freshwater contained in lakes/rivers contribute to the only percentage usable by humans.

Hydrology or the study of water within the disciplines of meteorology, climatology, glaciology, and oceanology was defined in 1991 as, “The science that deals with those aspects of the cycling of water in the natural environment that relate specifically with the continental water processes, namely the physical and chemical processes along the various pathways of continental water (solid, liquid, and vapor) at all scales, including those biological processes that influence this water cycle directly; and with the global water balance, namely the spatial and temporal features of the water transfers (solid, liquid and vapor) between all compartments of the global system.” A system closely studied by hydrologists is the passage of water from the atmosphere to the earth or water cycle. Condensation, precipitation, surface/groundwater flow, and evaporation/transpiration provides an outline into understanding the cycle of water. The amount of water in the air is determined by perceptible water or the water width layer covering the entire earth. The distribution variability of water in the air varies from location to location because of the alterations in time and space. The role of atmospheric condensation is not only important within the water cycle, but it also provides the main source of energy transfer between the earth’s surface and the atmospheric bilayer. Through the changing rate of evaporation from land to air and water’s nine-day lasting rate in the atmosphere, condensation provides redistribution of heat and radiation coming from the sun. It also acts as a sponge for absorbing excessive greenhouse gasses that tend to trap in heat released by the sun and discharging them back at lower temperatures. The flow of colder temperatures within the air helps to achieve perfect conditions for the process of precipitation. Within the water cycle, precipitation isconsidered to be the most important step due to its ability to halt its cycle if water ceases to flow between the earth's surface and the atmosphere. Precipitation encompasses several methods to make the transference of water to land possible. Supersaturation comes about by the depletion of air’s water-holding capacity alongside the drop in temperatures. Other mechanisms to induce supersaturation include raising air to higher elevations through heat ascension or movement over high terrain such as mountains. Once air exceeds saturation, formations of ice crystals and water droplets may commence. The first steps of condensing water typically stay in a form light enough to stay suspended and the continuous growth of these droplets depends on the rate of diffusion of water within the air and their collision with neighboring drops. Once the collection of water gets too heavy, precipitation can occur in numerous ways. Drizzle, rain, sleet, hail, and dew are a few examples of precipitations in multiple forms. As precipitation falls and makes contact with the earth's surface, water can have one of two options. It can either turn into surface flow/runoff or percolate into the soil as groundwater.

Overland and free-flowing water are models of surface runoff that can lead to future problems within urban hydrology. Overland flow occurs on surfaces that have high water tables, saturated soils, and little to no permeability. Free surface flow has limited restrictions and regularly starts with the emergence of groundwater or after some environmental incidents such as rainfall, destruction of water barriers, or snow. These two forms of groundwater flows create multiple small streams that accumulate to form rivulets similar to stream networking. Eventually, the multitude of networks connect and form larger rivers which then ends up in standing bodies of water such as lakes and oceans.

Considered to be the second most important step within the water cycle, evaporation is the transformation of water from a liquid to a gas. Large amounts of energy from external forces are used to separate water molecules from bodies of water. This, in turn, allows the molecules to transform into a vaporous state. Overland, transpiration or the transport of water and moist air through a plant’s stomata and evaporation work in sync and is often known as evapotranspiration. Except for some water being redirected to groundwater or environmental use, the entire water cycle continues to repeat itself until there is a cause for change.

The overexploitation of the water cycle as a consequence of human interaction has become a growing problem as water is continuously used by human and environmental systems. Ecosystem services are only a snapshot of the overall use of water. It provides processes that are helpful for the sustainability of human lives and surrounding ecosystems. To fully understand the true value, limitations, and potential of water, scientists have to study waters' current functions and then determine the best strategies for protecting the limited resource that is still available. Ecosystems can use flowing (streams) and stagnant (lakes, wetlands) water for detoxifying pollutants found in air and soil, production and control of soil formations, growth and abundance of vegetation, and maintaining a balance of water between the earth and the atmosphere.

A case study taken by the U.S. Geological Survey estimated that as of 2015, the amount of water used in the United States totaled up to 87% (281,000 Mgal/d) of freshwater and 13% (41,000 Mgal/d) of saline withdrawals. The study focused on eight major systems (public supply, domestic, irrigation, livestock, aquaculture, industrial, mining, electric power) to determine what all of the water resources are used for. Electric generation, irrigation, and public supply made up over 90% of total water use and mining, livestock, industrial, domestic, and aquaculture rounded to the remaining 10%.

Energy is a byproduct that requires water for hydroelectric generation, but at the same time is used by water for fuel extraction and processing. As energy sectors fluctuate and expand, the amount of water required will also change. Scientists identified the term water footprint to estimate “the volume of water needed for the production of goods and services consumed by the inhabitants of the country.” Biofuel, fossil fuel, nuclear fuel, and electric generation are four points focused on when estimating the water consumption of energy production. The second most water-based process would be irrigation or the application of water to agricultural and horticultural practice that maintains plant growth, weed management, chemical distribution, harvesting, and other farm regiments which provide benefits for improving landscape diversification and increased crop/pasture productivity. Irrigation practices were first constructed to supply farmers with water that was not readily accessible. But as agriculture has expanded, so does the demand for better irrigation practices that also require more water. The use of different irrigation systems such as furrow, low-flow, level basin, flood/border can vary from location to location due to the diversity in technological services/connections and differences of environmental resources.

Public supply refers to water removal by water companies, whether private or public. It is classified as public when they have water connections with fifteen plus organizations or supply at least 25 people with water. During the year 2015, 87% of the US population relied on water provided by the water companies, but a lot of the water is redirected towards commercial, domestic, and industrial uses. This is equivalent to over 39,000 million gallons of water utilized per day.

Aquaculture focuses on raising water-borne organisms for food, conservation, and ecosystem restoration while livestock management uses water to control their animal operation facilities and other farming necessities. In total, the combination of these two practices utilizes around 10,000 million gallons of water per day or 3% of all the available water. Similar to livestock management, mining and industrial applications only use a very small portion of water to maintain their processing facilities and element extractions.

The distribution of water between surface and groundwater has increased in variability due to economic and industrial growth, but with increased production comes the problem of overexploitation and contamination of the remaining freshwater. The changes in freshwater availability are impacted greatly by external factors because of population growth and development. Even so, not all changes are caused by human disruption. Through long-term alteration in global or regional climate patterns or climate change, has led to the modification of earth's water systems and is expected to increase the magnitude of altered hydrological operations for future generations. Some cases of varying water contamination and availability include large amounts of water discharged from water surfaces, seasonal river flow changes in areas with winter snowfall due to early melting, precipitation falling as rain instead of snow from increased atmospheric temperatures, and water resource management systems falling behind because the peak water flow is happening earlier in the season and limiting the collection of freshwater from melting ice caps and snow. By natural cooling and regulation systems, earth has been able to maintain constant atmospheric temperatures by cycling greenhouse and reflected energy from the earth's surface into the atmosphere. With this said, greenhouse gasses have become one of the largest contributors to global climate change and its effects on freshwater sources. The increase in greenhouse gases into the atmosphere by the burning of fossil fuels and electric productions have put strains on the earth's natural cycling system and trapped more energy on earth’s surface than what is manageable. Solar energy is usually used as a power source for parts of the water cycle, but because excess energy is being held with the earth’s atmosphere, it is speeding up the rates of water transformation. Consequences of a faster-flowing water cycle include: increasing ocean temperatures, rising sea levels from the melting ice, reduced protection from extreme storm surges, floods becoming more frequent, and negatively affecting coastal zone management which impacts the water quality of freshwater estuaries. Low elevation freshwater resources are more vulnerable to salinization and affect drinking water resources and freshwater ecosystems.

The amount of water required for human applications is a reasonable justification for resource extractions all around the world, but it does not take into account the harmful waste leaking into water sources by overexploitation and the misuse of water management practices. A majority of water contamination caused by human interference include fertilizer leaching from agricultural management, manure runoff and infiltration into surface and groundwater systems by livestock waste, and point-source and nonpoint-source pollution from industrial facilities.

Humans once primarily practiced their skills as hunters and gathers. However, once the practice of agriculture was developed the presence of hunter gather instincts progressed to the point of today’s large scale food production and population growth. Today as agricultural practices continue to develop and become more industrialized, new resilient crops are being produced with some drawbacks. Consequences of industrialization contribute to massive amounts of contamination including pesticides/fertilizers, pathogens, and sediments entering surrounding bodies of water from soil erosion. Livestock production within the agricultural sector accounts for about 30% of total land use and is considered one of the top three major contributors towards water contamination. Through non-direct contamination, livestock practices such as: the addition of antibiotics and vaccines through feed, and destruction of ecosystems within aquatic estuaries leach contaminants (metals, pathogens, elements) into fresh extractable groundwater resources. The majority of water used for livestock management and facility maintenance returns back into the environment as manure/wastewater containing various quantities of nutrients, pathogens, heavy metals, hormones and antibiotics. Over two-thirds of all antibiotics sold in the U.S are used to vaccinate livestock within the stressful, unsanitary, and cramped concentrated animal feeding operations. The use of so many antibiotics creates large amounts of resistant bacteria that further spread into surrounding communities and contribute to the severe human health threats. Studies found that 162,000 people die each year due to antibiotic-resistant bacterial infections. Crop agriculture, on the other hand, is the second-highest cause of the reintroduction and spread of pollutants into aquatic ecosystems. As a result of the increasing population and the demand for more food, agricultural lands have had to be expanded and more synthetic nutrients and fertilizers are used within the soil to produce higher crop yields. The result of these practices can have drastic effects on freshwater and surrounding ecosystems if not controlled. Not only does synthetic fertilizers harm the climate by creating a dangerous greenhouse gas (nitrous oxide), it can also cause severe damage to surrounding areas by nutrient runoff. Heavy storm surges that cause an increase in surface water accumulations and flow can pick up soil manure/fertilizers and transports them into neighboring rivers, lakes, and oceans. One consequence of nutrient buildup in water systems is the growth of algae which has become prominent in some areas and causes dead zones within aquatic ecosystems. Chemicals contaminating water sources through the use of pesticides and fertilizers also can impact human health as well as the surrounding ecological community. Contaminated water in the environment containing pesticides can cause child developmental delays and cancer.

Why water management? If water is recycled by the water cycle, is it necessary to create a management plan for future freshwater use? Earth’s water is a finite resource but its salt to freshwater ratio and inability to meet the needs of a growing population are only a few reasons why “planning, developing and managing water resources to ensure adequate, inexpensive, and sustainable supplies and qualities of water for both humans and natural ecosystems can only succeed if we recognize and address the causal socioeconomic factors, such as inadequate education, corruption, population pressures, and poverty.”

Over time, water is the one resource that continues to be dynamic even with the changing climate and ecosystems. It provides hydroelectric energy, a governing system for diversity among riparian and aquatic ecosystems, controlled transport for waste products, and sources of beauty and attraction for human enjoyment. To plan water management is to take into account all of the reasons why it is a scarce resource. Pollution causes degradation of ecosystem and public health, flooding results in property damage and loss of resources, causes limited resource because of varied water distribution, overexposed ecosystem services due to urban/industrial development and reclamation of rivers and wetlands, and the expense of extracting clean water to meet the needs of the people. Through the study of water systems, two approaches have been developed and by combining these two, scientists can create a unified management policy. Grassroots or bottom-up is a system that creates plans from the bottom up and incorporating stakeholders earlier rather than later. Stakeholders are eventually going to be affected by the outcome of the conversation so integrating their opinions can help solidify their commitment and the success of the future project. This strategy of water control takes into account all the little details, does not rush to conclusions with insufficient data, and hopes to see the management of water as effective and efficient as possible. Command and control or top-down planning is the second approach to water control and usually based around reports and data that best suits the needs and goals of the company. Stakeholder opinions are not considered and most decisions are made through the authority of institutions.

To address the water problems of today, we need to understand the water problems of the past. Hydrology helps determine the natural and altered flow of water through the water cycle and how its uses within industrial systems such as irrigation, electric power, and public supply can negatively impact human health and surrounding environmental systems if not managed correctly. To counteract the negative effects of water contamination, scientists and major corporations use applied management policies to determine the reasons why water is such a scarce resource and how creating water management solutions can prevent freshwater contamination and alter human practices to more sustainable methods.