Impacts of Human Activities on the Water Cycle at Local and Global Levels - Literature review Example

Name Course Tutor Date Introduction Human activities are accused of attributing to major changes in environmental cycles. Protocols laid in important workshops meant to demystify the mitigation measures have however been put under review from time to time due to constant criticism faced by environmental activists. It should come to the attention of all protagonists that these activities really have to be contained or else the globe shall soon be facing extreme environmental catastrophes other than those currently faced. The major cycles that are exposed distortion from human activities include: carbon, water and nitrogen. This article seeks to investigate on how human activities have negatively impacted on the water cycle both at local and global levels. Impacts of Human Activities on the Water Cycle The definition of human activities has undergone a revolution to become what it is right now. According to Jermar (1987), human activity is a variation of input or output to the ecosystem that is either purposeful or non-requested. These activities have drifted the natural water cycle’s original equilibrium framework beyond irreversible limits. Ellis (1999) further classifies human activities into qualitative and quantitative due to the importance attached to each of them. The earth is a closed ecosystem in which the survival requirements for both flora and fauna encounter a cycle from one state to another. It should therefore be noted with care by all the environmental stakeholders that these activities severely disrupt the original cycle that has always catered for life (Seen Environmental Learning). Figure: A schematic indication of the normal water cycle (Seen Environmental Learning). Water circulates from the earth surface to the atmosphere in a continuous manner to form a water cycle. In order to understand the water cycle better, the sun heat energy vaporises water from the water bodies which condense thereby forming clouds which fall in form of rain or snow in a distributive manner (Kreger). Through runoff, water penetrates to the surface becoming ground water which then seeps into the lakes, oceans and streams. Purposeful or non-requested human activities have been slotted in before these cycles are complete thereby disrupting the nature in a quantitative and qualitative manner (University of Illinois). To begin with the one of the most important human activities both for survival and this discussion is the agricultural venture. Water management practices carried out all over the world for the sake of sustaining agriculture are immense with some of them causing the worst cases of degradation on the environment. The increase in irrigation activities affiliated to Agriculture pose a lot of dangers in the diminishing of this renewable resource. These activities are responsible for the lowered water levels in the natural rivers and lakes, the disappearance of water catchment areas and subsequent oxygen deficits encountered by marine life, diversion of water from their main causes have caused rivers and lakes to dry and the pesticides or fertilizers applied to boost production have had a major impact on the quality of water hence pollution (Gautier). 20% of cultivated land in the world entirely depends on irrigation as the main source of water attributing in order to contribute 40% of food ( Food and Agriculture Organization of the United Nations). Utilized agricultural area is therefore a major contributory factor for both qualitative and quantitative aspects of the ware cycle. Agricultural intensification in European countries for example has an irrigated land not less than 30% with quantitative aspects of human activities more rampant in the south. In a quantitative analysis carried out to ascertain the real effects of human activities on the water cycle in Europe, France was found to divert 65% of its water sources towards the realization of hydropower which is also another human activity in discussion. Greece and Spain topped the list of those countries that use up to 70% of its water in irrigation (Sciences and Ellis). The effectiveness of irrigation is described as the ratio between water abstracted and water that is actually consumed by the plant. This may vary from one soil type to the other according to the latitudes, water distribution and the irrigation systems deployed by the farmers. It is evident that apart from the loss of water through the irrigation system do not necessarily count towards the accumulating the catchment areas. This water is lost in the profile while some of it finds its way towards being recycled by other farms that have bored underground water holes. The water joining the ecosystem is diversely affected by the irrigation system being applied by the farmers. This means that if proper irrigation systems are practiced change may be achieved within the water cycle ecosystem. Water abstraction really counts towards its scarcity because of the consequences of diversion to manmade courses. In most developed countries water abstraction accounts to more than 80% of the utilized water sources. Subsoil water is considered as quality due to the natural filtration properties various layers of soil that exist below the surface. Most environmental agencies have resorted to saving the catchment areas for the enhancement of quality (Sciences and Ellis). Due to global warming, the evapotranspiration rates are on the increase thereby translating to a high consumption of water by plants. The rate at which water is consumed by plants depends on the climatic factors, soil type, cultivation practices, irrigation methods employed by farmers and infrastructural status. Farmers are advised to use effective methods such as drip irrigation in which up to 95% of the water is utilized by crops. These are the desperate moves by the conservation agencies to save the water cycle through minimizing water abstraction even as agricultural activities continue to intensify in a bid for food security. As much as the activists continue to campaign for usage of effective irrigation methods, it has come to the attention of researchers that salination and soil erosion due to human activities cannot be easily curbed. In salty soils the farmers are forced to use a lot of water which does not seep back to the ecosystem (Shepley, Whiteman and Hulme). The water cycle has also been affected by pollution as a result of non-point pollutants that emanate from the farms. The nitrate fertilizers and pesticide solutions used in farms have affected the quality of water emitted to the catchment areas. This water is deemed as unsafe for both human and animal consumption thereby dictating a diminished level of this vital commodity. The nitrates for example seep with ease to the ground water aquifers and although it is easy to treat this water from the farms most of the farmers do not practice it. On the other hand the highly soluble pesticides being used in the farms have been persistently accused of pollution. These chemicals seep to the ground causing fatalities on organisms and humans who are likely to drink it. To be more specific atrazine, bentazone and simazine compounds that are used in the treatment against pests and disease cannot be treated off the waste water (Gausl and Casteele). As the world advances towards post-modernization and industrialization, there is one factor that shall always remain constant. Increasing urbanization has pronounced impacts both quantitative and qualitative on the nature of water cycle. The increase in urban populations and the need to build the basic infrastructure such as roads, houses and drainage have modified the nature into impervious tracts that are inaccessible by water. Rainfall results to high velocity runoffs instead of seeping into the underground catchments. Also, this water is unlikely to recharge the underground system as some of it finds its way to impermeable rocks that are not likely to benefit the ecosystem. Urbanization is also considered the reason for high water salinity, nitrogenation and contamination by other compounds such as petroleum products (Khazai). Urbanization has been found not only to have intense effects on underground water but also the underlying aquifer and the quality. The urban expansion is not properly planned by those involved posing as difficulties to the future generations in terms of water sources since water usage continues to double every year. Other activities such as deforestation meant for expansion of the urban centres has brought about aridity which is the main cause of diminished underground water due to lack of cover. In some cities, a rise in underground water has been reported by up to 0.5m in the Middle East. This recharge has been attributed to the recharge of water aquifers due to losses of water from the main streams, septic and underground tanks which pose as a hazard to the future generations. The impacts of urbanization depend on the prevailing conditions at the area of study. These include the climate, economy, hydrology and hydrogeology (Khazai). The quantitative impacts of urbanization include floods which have caused building of embankments in order to secure the population. Excess water is collected in the underground catchment areas due to an increase in the number of absorber wells. The deteriorating systems of water supply in the urban centres also cause a lot of water wastage due to pipe corrosion owing to the poor quality of water. Waste water disposal through dilution methods have led to a lot of waste of this precious commodity. Ground water quality has also been affected by chemicals which have been used at the treatment plants for the sake of purification (Khazai). Water is used for various purposes in industrial operations. These may be cleaning, cooling, steam generation, as a raw item and transporting of dissolved substances. Accurate assessments carried out on industries clearly indicate that water consumption is very high and at some point unnecessary. During industrial processes most of the water evaporates away and some of it degenerates to the waste streams. Water from industries contain by products and solid wastes which pose a great danger to the environment. This water is often discharged to the streams and some of it seeps into the underground catchments. Some of the waste water contains compounds that are likely to react with the underground aquifers therefore barring the natural cycle from continuing. A good example is where a permeable aquifer rock is rendered impermeable due to industrial emissions (United Nations World Water Development Report 2). The stabilization in industry in 1980s has seen the water usage drop beyond the unimaginable levels. With a bid by the industrialists to cater for the rising population, the water usage shot up in the end of the 20th century reverting back to the normal standards of usage seen in 1970s. With such high usage of water resources by the industries, the impacts on the water cycle has been felt both in the quantitatively and qualitatively. Various industrial sectors attribute to the poor water cycle in various magnitudes as per the past researches meant to ascertain the same. The quantitative negative impacts of industrialization on the water cycle include the high volume of usage which has led to diminish and even drying of some water catchment areas. Direct disposal of sewer into the sea and other open water masses has led to a large loss of marine lives due to the qualitative impacts on the water sources and key players in the water cycle. Open treatment of the waste water by industries has given rise to seepage of this water into the underground thereby disrupting the normal water cycle (United Nations World Water Development Report 2). To expound further on this issue, reclamation of water does not mean that waste as a result is incorporated into the industrial system. This waste is incorporated into the Agricultural lands and municipal parks for recycling but in the real sense this water is not in its pure state and can cause poisoning due to a disrupted cycle. The chemicals and heavy metals that are produced by the industries contaminate the water aquifers or bodies by lowering the biochemical oxygen demand (BOD) which also disrupts the oxygen cycle in return. The disrupted water cycle leads to increased population of bacteria and algae which renders the water bodies lifeless for such organisms as fish. The volume of water used by the industries is high that the levels of pollution are also projected to be high. The industries also affect the water cycle through gases such as nitrogen compound and sulphur which are distributed through the air causing acid rains – a major disruption of water cycle and marine life too (United Nations World Water Development Report 2). Electricity is considered as essential as water in the global setup as it is used for the realization of human industrial dreams. Electrical power generation is responsible for high levels of water abstraction for the purpose of cooling. Hydropower generation for example requires large amounts of high potential energy water in order to generate electricity. The impact of this activity is earnest considering the large amounts of water used in producing electricity are channelled back to the sources. Building of manmade dams and water channels has however brought about elevated wastage since the water resources used in building these structures and their infrastructure such as remote access roads has brought high water cycle disruption. The manmade dams are yet another impermeable regions in which underground water access is difficult due to the concrete base. The disruption of water resources is not major in the hydroelectric power production sector; however it reduces the flow of water upstream and downstream (Strosser, Vall and PLötscher). In cases where hydroelectric activities are mismanaged, the impacts may be massive on marine life due to disrupted water flow (Science Learning Hub). The geothermal power plants utilize heat from the ground in order to generate industrial and household electricity. Geothermal plants are utilized in more than 90 countries worldwide according to the latest statistics. This electric sector attributes to 0.03% of the total electricity consumed around the globe. The utilization of water in its operations is considered to be high risk event on the water cycle it is literally pumped to the ground where rocks are believed to be hot. This water is heated and released as steam which is then tapped for electricity generation. Soon afterwards it is pumped out for hydroelectric power production. During this process water is lost to the permeable rock and even polluted with sulphur, chloride and fluoride compounds. Unlike hydroelectric power generation this process causes pollution of the underground water catchment areas. Ground water is also affected by the superficial additions brought about by human activity in a bid to increase the amount of steam harvested for the sake of boosting power generation. If released to the surface water bodies, contaminated water may have adverse effects on land organisms and marine life due to the high concentrations of lethal substances contained herein (Govorushko). Conclusion The water cycle is very important to the survival of flora and fauna both terrestrial and marine. Human activities affect this cycle rendering it incomplete, polluted or ineffective contrary to its original form. Among the human activities that are successfully discussed in this article with regard to the water cycle are: Agriculture, industrialization, urbanization and power generation. Their qualitative and quantitative impacts have both been given the importance they deserve to the ecosystem water cycle. Works Cited Food and Agriculture Organization of the United Nations. Water, Agriculture and Food Security. 2012. 11 April 2013 . Gausl, I. and K. Vande Casteele. "Assessing the contamination risk of five pesticides in a phreatic aquifer based on microcosm experiments and transport modelling at Sint-Jansteen (Zeeland, the Netherlands)." Netherlands Journal of Geosciences (2004): 101-112. Gautier, catherine. Oil, Water, and Climate. Cambridge: Cambridge University Press, n.d. Govorushko, Sergey M. . Natural processes and human impacts. New York: Springer, 2012. Jermar, M. K. Water Resources and Water Management. Amsterdam: Elsevier, 1987. Khazai, E. "Impact of urbanization on the Khash aquifer, an arid region of southeast Iran." Impacts of Urban Growth on Surface Water and Groundwater Quality (Proceedings of IUGG 99 (1999): 211-17. Kreger, Chris. Water Cycle. 10 November 2004. 10 April 2013 . Science Learning Hub. Humans and the water cycle. 2 June 2009. 13 April 2013 . Sciences, International Association of Hydrological and Bryan Ellis. Impacts of Urban Growth on Surface Water and Groundwater Quality. Wallingford: IAHS, 1999. Seen Environmental Learning. "Natural Resources and their Management." Seen Environmental Learning Information Sheet no 2 (2012): 1-9. Shepley, Martin G., et al. Groundwater Resources Modelling: A Case Study from the UK. London: Geological Society, 2012. Strosser, Pierre, Maria Pau Vall and Eva PLötscher. Water and agriculture: contribution to an analysis of a critical but difficult relationship. 1999. 9 April 2013 . United Nations World Water Development Report 2. Water: a shared responsibility. Oxford: Berghahn Books, 2006. University of Illinois. A Summary of the Hydrologic Cycle: bringing all the pieces together. 2010. 10 April 2013 . Read More