Negative Effects of Human Activities on Hydrology and River Ecosystems - Term Paper Example

Client inserts his/ her name Tutor’s name Name of institution Course title Date of submission Negative effects of human activities on hydrology and river ecosystems Abstract The paper presents a detailed explanation of effects human activities on the hydrological cycle and river ecosystems. This causes severe pollution on the environment. Some of the human activities are outlined in the introduction. Further, the paper looks into the scope of the research where the research question is identified and it lies within facts about water pollution. Through a detailed study rationale, the reason for selection of the aspect of study is described as well as the study objects outlined systematically. In addition, a detailed description of the impacts of human activities on water ecosystems and the hydrology is given with emphasis on the negative effects of changes created by human activities. A literature review is conducted to synthesize information on the human activity threats and their impacts on the hydrology and river ecosystems. Finally, the limitations of previous research and the need for the search for alternatives comprehensive research methods are given with clear guidelines on what should be done in the future. A conclusion is given to sum up what has been discussed entirely with recommendations that could assist in setting strategies that could reduce tremendous impacts on river ecosystems. Introduction Human activities all over the world have increasingly challenged water managers since they are known to disrupt the hydrological cycle a great deal. The ever growing populations make it difficult to offer water supplies that are reliable and affordable. In the recent past, local communities have shown concern that human activities should not degrade water ecosystems or disrupt the much treasured economic ecosystem services. Some of the services that are affected include fishing, cultural activities and provision of recreational value such as tourism. (Owens et al, 2005) It is prudent to note that water ecosystems support human life and aquatic life. Human beings need water for drinking and for other domestic uses. However, the growing food and industrial activities have negatively impacted the river ecosystem. There is a need to address the condition of ecological requirements while considering the water ecosystem position across an array of needs for water in order to attain and sustain the resource adequately. The challenge is currently recognized as a major social- economic challenge of the 21st century according to (UNEP/GPA, 2006a). In addition, most land activities that occur in other sectors impact the water ecosystem a great deal such as agriculture, forestry, mining and urbanization. They contribute much to the changes in the hydrological cycle and the river ecosystems. Significant changes occur in the sedimentation and erosion patterns due to hydrological disruptions that occur due to the construction of dams, reservoirs and causeways. Activities which involve dredging water bodies and establishment of irrigation schemes in large scale negatively affect the river systems and the hydrology (UNEP/GPA, 2006a). Study rationale A literature review is conducted to synthesize information on the human activity threats and their impacts on hydrology and river ecosystems. Peer-reviewed articles form the basis of the literature review in addition to technical memos and government reports, which are referred to where appropriate. The literature review presented does not contain original analysis; rather, it serves as a synthetic report of information known in the scientific literature and aims to identify data gaps. It is important to note that human activities threaten the ecosystem and may negatively affect aquatic life. However, river ecosystem may also positively influence human societies and the well-being of aquatic life. For instance, the hardening of the shoreline caused by sedimentation has both physical and biological impacts that are characterized by the loss of beaches along rivers or water bodies and destroy the habitat for fish and other aquatic organisms. The study focuses on such negative ecological and hydrological effects of human activities. A systematic review and evaluation of threats that relate to human systems is presented. However, future research should contain an evaluation and analysis of the relationship between the threats and human activities in the ecosystem and establish how the systems can complement one another. This may form a good basis for the future integration of various systems, which may result in better conservation actions with regard to hydrology and river ecosystems. It is worth noting that the health of any water ecosystem is directly influenced by human activities as well as natural occurrences. The mechanisms that lead to system changes are numerous and complex in nature; however, the identification of the threats as well as their impacts is necessary in order to effectively manage the causes. In the review presented, the complex events that accompany human activity are outlined and empirical evidence is systematically offered on the causal relationships and the impacts observed on the river ecosystem and aquatic life. Study objectives Identify the various human activities and their relationships to river ecosystems and hydrology. Describe how the human activities negatively affect the river systems, and aquatic life. Identify and explain threats caused by human activities that have a high impact on hydrology and river ecosystems. Describe the geographical scope, severity and the nature of the irreversibility of various river ecosystem threats with the aim of noting the knowledge gaps in the studies that have already been conducted in aquatic and hydrological area. Present a systematic and comprehensive assessment of threats that are observed along rivers and link them to human activities that take place near the specific rivers. Literature review Literature review I. Sedimentation and erosion Sediments can be described as materials of various sizes which originate from minerals and other organic material. On the other hand, erosion entails the process of carrying away materials or sediments from their original point by action of water, wind, gravity or ice. Sedimentation occurs when the materials are deposited in either suspension or fluid form. (Smith & Smith, 1998). Figure1: The Mississippi river condition as a result of erosion and sedimentation Source: U.S geological survey According to the investigation conducted by UNEP/GPA (2006a), the effects of the changes in sedimentation and erosion patterns along the water bodies vary according to the resultant levels such as an increase or a decrease in the availability of sediments determined by the erosion levels upstream. All in all, both dimensions create grave physical and chemical impacts on water quality which negatively influence the health of aquatic life. The process of sedimentation may occur locally although its impacts are felt across the globe because currents carry sediments across the borders. Major rivers form common borders at some point which creates a platform through which sedimentation occurs and losses in volume, due to the entrapment of the suspended sediment loads from the river bordering it. In a research done in Caribbean, the Mississippi river in the Gulf of Mexico and the Amazon River in South America, it was established that the loss of volume was due to entrapment of loads in the borders of the two rivers. According to the study conducted by Owens et al (2005), increased sedimentation has adverse effects on the ecosystem. They assert that marine communities may be buried completely due to excessive sedimentation caused by erosion of materials within and outside the water body. It is thus clear that marine life like fish and other aquatic animals can completely be destroyed thus losing hydrological economic and social value for example continuous supply of fresh fish and clean drinking water to households.. Due to piling of materials in the water, there will be no free sunlight penetration which may result to low production of macrophtes that are important for aquatic organisms. Moreover, temperatures may increase to an extent of limiting vegetation growth in the water. Figure 2: A river delta before erosion Source: U.S geological survey Figure 3: The picture above shows the status of a river after erosion and sedimentation has occurred massively Results of the study indicate that a common impact of excess sedimentation is observed where the fish in the rivers are damaged by galling their body parts such as the gills through the degradation of their habitats. The gravel and other materials bury the fish eggs and fill them with foreign particles making them impossible to hatch. The available oxygen is greatly reduced thus threatening life within the water body. Nevertheless, Owens et al (2005) found out that water courses are filled up with materials which call for costly dredging activities. Worse still, it increases the risk for flooding thus affecting the hydrological cycle. Due to industrial activity that leads to release of waste products into rivers, numerous amounts of toxic chemicals and heavy metals are absorbed by sediments. The increased sediment loading along the water system environment leads to more deposition of chemicals that impact the water ecosystem negatively for instance eutrophication. (Smith & Smith, 1998). Owens et al (2005) further argues that sediments often carry a variety of much needed nutrients and mineral elements by the organisms in the water such as fish. Therefore, decrease of sediments may lead to degradation of the river ecosystem due to the limitation of basic organic matter. Moreover, the velocity of the water will be increased due to lack of sediment materials within it. This may result to more erosion downstream thus causing damage to marine ecosystems especially aquatic vegetation, invertebrates and fish (Owens et al 2005) It is precise that erosion and sedimentation is a situation that is caused by the ever increasing human activities along water bodies in the third millennium. From the literature above, it is notable that the river ecosystem and the hydrological system are greatly impacted by such activities. Increase or decrease in sediment amounts negatively impact marine life leading to revenue loss due to the interruption on human activities such as fishing and tourism. II. Water Cycle Changes The hydrological cycle changes affect the climatic condition of a region. The human activities in the world currently have automatically altered the various aspects of the water cycle system such as precipitation, temperature, rainfall, sunshine and humidity. An activity such as the continued deforestation has affected the rainfall amounts a great deal in large parts of the world. Deforestation in return has lead to limited rainfall within the affected areas which in return reduces the amount of water flowing in rivers. The animals and organisms that live in water are bound to suffer hence reduce in number drastically due to damaged ecosystem and their breeding grounds. A study performed on the hydrology in the Salish Sea ecosystem indicates that the water body is governed by high elevation in the melting of snow, mid elevation characterized by both snow melt, rain and low elevation which is dominated by rainfall as indicated by Littell.et al. (2009). Therefore, as the human activities that affect rainfall increase, a changing climate is observed especially during the rainyseason.This is associated with high levels of temperature and precipitation. These changes favor or disrupt the life system of aquatic life that thrives within river ecosystem. Salathe et al (2008) argue that changes in the condition of the weather and climate alter the condition of environmental temperatures and precipitation patterns over the region in question. Temperature and precipitation are very important for aquatic plants which support aquatic life in various ways. Any kind of alteration in their growth and development due to climatic changes may lead to disruption of marine life entirely. Moreover, human activities are known to disrupt the hydrological cycle by influencing the state of temperature and precipitation. In addition, high levels of rainfall lead to extreme erosion on the land surface which flow onto the rivers. This leads to the impacts of sedimentation that impact the life of the organisms and plants in the water. According to Littell et al (2009), precipitation patterns are characterized by great seasonality, frequency of occurrence and intensity. Extreme circumstances come along with storms and severe events which cause great damages to the river ecosystem. The gradual shift of conditions is a serious challenge to the survival of the aquatic organisms. For instance, fish produce through eggs which need some conducive conditions in order to hatch. Thus changes in water conditions may disrupt the hatching process which eventually may lead to reduced fish numbers. Other organisms are also affected in an array of aspects ranging from availability of oxygen to food which are vital for their survival in the habitat. Figure 1: The climate change model and the effects on the hydrological cycle Adapted from driver-pressure-state-impacts-response conceptual model for climate change From the above illustration, it is clear that the hydrological cycle is much affected by human deforestation and agricultural activities. These activities lead to disruption of the water cycle system which consequently changes the river system. Changes in precipitation, temperature and rainfall have impacts on aquatic life in regards to plants and animals that need specific climatic conditions for survival. Constant hydrological cycles as well as other climatic aspects determine the well being of aquatic organisms and plants. Thus human activities disrupt the serenity of such an environment hence negatively affecting the river ecosystem. III. Water acidification and the PH Due to the ever growing and advancing industrial systems, there are numerous wastes that are released into the water. This directly impacts river ecosystems since the chemicals contained clog the respiratory systems of the organisms in the water. These chemicals like spilt oil covering water surface reduces the penetration levels of oxygen and sunlight which is needed by aquatic organisms for their survival hence destroying the life within that ecosystem. On the other hand, as the water body absorbs the chemicals in addition to the atmospheric absorptions, the water PH is drastically reduced which leads to acidification as described by Orr et al (2005). According to the research conducted by Guinotte and Fabry (2008), the global water PH has gone down by 0.1 units since industrial revolution came up. This can be transformed to an increase by 30% in the level of hydrogen ions in the water. These PH changes within the river systems affect all aspects of the entire system. Not even the deep corrals survive the severe effects of such increased levels of acidity. Some aquatic plants for example marine algae, water lilies and floating hearts survive well in basic conditions hence perish completely when such condition shift from unsaturated to saturated conditions. Also, feeding, and breeding fish grounds and other aquatic organism are destroyed since they are exposed to acidic water a condition which is not conducive for their survival. In a study conducted by Feely et al (2008) in the west coast of Washington, deep acidified waters have been tested for PH on the continent shelf. Due to increased uptake of carbon IV oxide, the location experiences a potential threat to many calcifying water species. Similarly, in any river ecosystem that is affected much by human activity, acidification of the water reduces drastically the level of carbonate minerals in the water which are very important for growth and development of plants and animals in the water. In regards to data compiled by Fabry et al (2008), the presence of organisms such as foraminifera, molluscs, and echinoderms in a given ecosystem indicate reduced levels of calcification. In extreme conditions, they demonstrate dissolution of calcium carbonate in skeletal structures when the PH decreases in the water ecosystem. The community structure in the river ecosystem is altered due to the extreme PH conditions which are characterized by the decline of calcareous species in the water and the increase of non-calcareous counterparts as indicated by Wootton et al (20080. Figure 2: The pollution model highlighting water acidification and PH modifications Adapted from driver-pressure-state-impacts-response conceptual model for pollution in the salish sea ecosystem It is evident how the river ecosystem is affected negatively by human activities that alter the PH. The activities include deforestation thus reducing the amount of trees that transform carbon IV oxide to oxygen. Too much CO2 fills the atmosphere and eventually dissolves in water making it acidic. Industrialization also impacts the water ph since the chemicals released into the water have an impact in water PH. Agriculture is not an exception in regards to the use of acidic fertilizers which are swept into the rivers through run-off water. All in all, aquatic life is interrupted greatly and its population declines due to changes in the water PH. IV. Increased Imperviousness Research by Kaye et al. (2006) indicates that there are numerous changes observed in the hydrological and material fluxes that result from impacts of residential, commercial and industrial advancements. The natural vegetation is now replaced by tough materials such as roads, buildings and artificial drainage systems. The level of imperviousness is more in urban areas due to increased human activity. The tough ground created by such developments impact the level at which ground water flows since its pathways are interrupted. Water filtrations from the ground as well as water flow ranges are limited. The balance between ground and surface water flows is disrupted. According to Kaye et al. (2006), water flows are affected and thus become linear because the path through which water moves from the surface to the ground is diverted. Figure 3: Indicates the impact of residential, commercial and industrial development on river systems and the hydrology Adapted from driver-pressure-state-impacts-response conceptual model for residential, commercial and industrial development in the salish sea ecosystem Alberti et al. (2004) asserts that the impervious surfaces that are created by human activity are permanent since they remain in place for long periods and they are replaced by similar impervious structures. As a result of such imperviousness, toxins, bacteria, organic materials and other pollutants are likely to be directed to water bodies hence negatively affecting the life of aquatic plants and animals. In fact they are transported in large volumes more acutely than the way they are filtered naturally by soil and vegetation. Gregory et al. (2006) explains much how the impervious surface hinders water and nutrients from penetrating into the soil due to the impermeable cover that makes the soil layers compact. According to Krahn et al. (2007), the effect of impermeability on river systems is very rigorous. Impermeable surfaces lead to increased run off into rivers which receive highly contaminated waters. The water contains organic pollutants like oil that permanently paralyze life in the river ecosystem because they never decompose. Direct transport of pollutants occurs due to human activities that create impervious grounds. In a study conducted by Bilby and Mollot (2008), increased contaminant runoff into rivers has severe impacts for biotic conditions in the river ecosystems. Fish as well as other organisms are greatly affected by the chemical content of the run off which reduces their numbers a great deal. Higher water flow and the high levels of water volume increase the mobility of the toxins in the water hence leading to reduced organism numbers in the ecosystem. The abundance of organism in the water is determined by the serenity of the conditions. Interruption of such conditions creates an environment not suitable for the survival of organisms within the river ecosystem. (Alberti et al., 2007) Conclusion It is clear that the hydrological cycle and the river ecosystem suffer the same circumstances that are created by increasing development of human activities around the globe. In that regard, a summary of the intensity of such impacts is presented in the table below: Table 1: Illustrating hydrological Threats and their ranks Threats from Open Standards Neuman et al (2009) Open Standards ranking Where we include threats from the Open Standard process in this chapter Climate Change Very High Climate Change Residential, Commercial, Port & Shipyard Development Very High Residential, Commercial and Industrial Development Surface Water Loading and Runoff from the Built Environment High Residential, Commercial and Industrial Development Roads, Transportation and Utility Infrastructure High Residential, Commercial and Industrial Development Shoreline Armoring High Shoreline Modification Dams, Levees and Tide gates High Shoreline Modification Invasive Species (marine, freshwater and terrestrial) High Invasive and Non-native Species Point & Non-point Water Pollution High Pollution – focus on impacts to biota Unsustainable Species Harvest High Not covered – high priority for next update Air Pollution & Atmospheric Deposition Medium Pollution - incomplete Forest practices Medium Not covered Oil & Hazardous Spills Medium Pollution - incomplete Recreational activities Medium Not covered Water Demand, Withdrawals and Diversions Medium Residential, Commercial and Industrial Development – incomplete Agriculture practices Low Not covered Aquaculture practices Low Not covered Derelict Gear & Vessels Low Not covered Dredging activities Low Not covered Physical disturbance/disruption to species Low Residential, Commercial and Industrial Development – just terrestrial Military Exercises Low Not covered Mines Low Not covered Adapted from Neuman et al. (2009) Agricultural activities lead to erosion which impacts the sedimentation patterns within the river systems. Besides, the water cycle is constantly impacted by climatic changes that are triggered by human activities on land such as deforestation, mining and urbanization. Nevertheless, water acidification occurs due to chemical saturation in the water which influences life in the river ecosystem. Urbanization and other human activities increase the levels of imperviousness on the land surface. This triggers water and contaminant movement to the rivers hence extensive pollution. The river ecosystem is much affected by human activities and it is prudent if governments could devise ways in the light to eliminate some of these impacts. It is however worthy noting that human activities threaten the ecosystem and may ruin aquatic life a great deal. However, it may also contribute positively to human activity and the well being of aquatic life. For instance, hardening of the shoreline has both physical and biological impacts which are characterized by loss of the beaches along the rivers or water bodies and also ruin the habitat for fish and other aquatic organisms. The study focuses on such negative ecological and hydrological effects of human activities. A systematic review and evaluation of threats that relate to human systems is presented. However, future research should contain evaluation and analysis of the relationship between the threats, human activities in the ecosystem and establish how the systems can complement one another positively. This may form a good grounding for future integration of various systems which may result into better conservation actions applied in regards to hydrology and river ecosystems. It is worth noting that the health of any water ecosystem is directly influenced by human activities as well as natural occurrences. The mechanisms that lead to system change are numerous and complex in nature. However, identification of the threats as well as their impacts is very necessary in order to effectively manage their causes. In the review presented, the complex events that tag along human activity are outlined and empirical evidence is systematically offered on the causal relationships and the impacts that are observed along the river ecosystem and the impacts on aquatic life. Human activities not only impacts water quantity, but also cause low water quality. Overly, water is reduced downstream which adversely affect aquatic life. Low water quality limits growth of organisms in the river systems. The seasonal fluctuations in the water systems in regards to water PH, acidification and levels of imperviousness affect the organisms. Possible points of concern for future research The information analyzed above present a comprehensive review of the ecological changes that occur due to various human activities. The researchers also highlight specific effects that befall the river ecosystems such as plants and micro organisms whose favorable environment is interfered with. However, very significant gaps can be observed in regards to quantifying the degree and magnitude of such occurrences. More research is required to look into the interactions between the river ecosystems to show how the effects that disrupt a single entity affect the well being of the entire ecosystem. A competition chain should be analyzed by exploring the predation and atrophic linkages between organisms within the ecosystem. Therefore, a stronger and more systematic representation of data information is highly recommended in future research. Future research should seek identification of both spatial and temporarily river ecosystem threats with the aim of turning them into measures that can be strategically applied in the process of conservation. It is also prudent to determine the threat levels that exceed the survival limits and thus impair the ecosystem population and reproduction patterns References Alberti, M., Weeks, R. & Coe, S. 2004. Urban land-cover change analysis in Central Puget Sound. Photogrammetric Engineering and Remote Sensing, vol. 70, pp 1043-1052. Alberti, M., Booth, D., Hill, K., Coburn, B., Avolio, C., Coe, S. & Spirandelli, D. 2007. The impact of urban patterns on aquatic ecosystems: An empirical analysis in Puget lowland sub-basins. Landscape and Urban Planning, vol. 80, pp 345-361. Bilby, R. & Mollot, A. 2008. Effect of changing land use patterns on the distribution of Coho salmon (Oncorhynchus kisutch) in the Puget Sound region. 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