Analytical Essay Sample on the Impact of Human Activities on Natural Hazards

Analytical Essay Sample on the Impact of Human Activities on Natural Hazards Natural hazards are naturally occurring phenomena that have disastrous impact on humanity. These phenomena had been in existence even before the advent of humanity. The hazardous dimension of these natural phenomena are in the context of the impact that such a phenomenon would have on human population in the area affected by that phenomenon. In this essay, the effect that human activity has on these natural hazards would be analyzed. Some human activities may be exacerbating the factors that cause the natural hazard, like the impact of excessive and unplanned logging on floods and droughts. In certain other cases the human activities may cause subsequent or supplementary hazards to a primary hazard event, like building dams in earthquake prone zones may lead to flash floods and landslides in the event of a rupture. A hazard can be defined as an event that has the potential to cause harm. This potential may be on account of its unexpected timing of occurrence or the actual intensity of the event itself. Human societies can withstand these events within a normal scale of occurrence. However, human societies become vulnerable when these events occur unexpectedly or are of an intensity or duration that falls beyond that normal scale (O’Hare and Rivas, 2005). Natural hazards can be broadly classified under the heads of geological, hydrological, climatic and diseases. This essay would limit its scope to analyzing causal relationships, if any, of human activities on landslides, floods and drought and the secondary hazards triggered by those activities in the event of an earthquake. Of all human activities that have a direct or indirect impact on natural hazards, deforestation is by far the most significant. Deforestation is the removal or destruction of forest cover of an area. It may occur due to unscientific logging practices without regeneration and may be accompanied by subsequent conversion to non-forest usage like agriculture, pasture, urban, mining or industrial development, fallow or wetland. At a very broad level, it has been argued that deforestation is a major cause of global climatic changes. It has been predicted that removal of forest cover will lead to violent and unpredictable environmental fluctuations. At a smaller landscape, deforestation has a direct bearing upon the climatic, hydrological, edaphic and biological aspects of that area. Deforestation is associated with higher levels of soil erosion and landslides, sedimentation in river beds and changes in fluvial geomorphology (Haigh, 1984). Quite a few of these effects of deforestation have a direct bearing on the natural hazards that will be covered in this essay. One of the major functions of a forest is to maintain the humidity level in the atmosphere. Trees withdraw groundwater through their roots and transpire the excess water through their leaves. Forests return a major part of the rainfall received by them through evapotranspiration. Annual evapotranspiration in tropical moist lowland forests ranges up to 1500 mm per year, with transpiration accounting for a maximum of 1045 mm per year (Bruijnzeel, 1990). This process of evapotranspiration in the leaves of trees takes the latent heat of evaporation from the surrounding atmosphere. Thus evapotranspiration has a cooling effect on the atmosphere that aids precipitation. Deforestation denies the atmosphere of this cooling effect and is thus a contributing factor to lowering of annual rainfall in an area. Further, the effects of deforestation generally compound the severity of drought. Lack of trees translates to the lack of root fibers that hold the topsoil. In the event of a drought, the topsoil flakes and gets blown by the wind, leading to severe dust storms. This phenomenon had devastated the American Great Plains for close to a decade in 1930s. The dust bowl covered farming areas in Colorado, Kansas, north west Oklahoma, north Texas and north east New Mexico. The fertile soil of the plains was exposed due to lack of vegetation cover and actions of the plow. These farming techniques that led to severe soil erosion, coupled with prolonged periods of extremely low rainfall, led to a series of severe dust storms that ranged up to the Atlantic coast. Much of the fertile topsoil was lost in the Atlantic (Cartensen et al., 1999). Direct causal relationship between human activity and drought is yet to be conclusively established. However, there are studies available that point to a positive correlation between the two. For example, climate-modeling studies have indicated that the 20th century Sahel drought was caused by changing sea surface temperatures. These changes were due to a combination of natural variability and human induced atmospheric changes. The anthropogenic factors in this case were rise in greenhouse gas levels and aerosols (GFDL Climate Modeling Research Highlights, 2007). The effect of human activities like deforestation is rather more direct and pronounced in case of hydrological hazards like fluvial floods. Fluvial floods occur when the discharge of a river exceeds its bankfull capacity. Forests create deep, open textured soils that can hold large quantities of water. When the forest cover is removed through logging, the soil becomes compacted. More rainwater is converted to runoff or near surface flow and less proportion percolates as groundwater. Research has shown significant increase in monthly runoff following logging activities (Rahim and Harding, 1993). The runoff rainwater carries with it considerable amounts of loose soil particles. Removal of vegetation cover through excessive logging activities or overgrazing leaves the soil bare. In such a situation, the upper layer of the soils becomes susceptible to erosion by surface runoff. These suspended soil particles are deposited on the riverbeds. The effect of this type of soil erosion by surface runoff is even more pronounced when the deforestation happens in the riparian zones as well. With time, this sedimentation decreases the depth of the riverbed and, thereby, the water carrying capacity of that river. When the flow of water in the river increases due to a variety of reasons like rainfall, seasonal melting of ice etc, that river can no longer contain the flow within its channel due to reduced drainage efficiency. This excess water inundates adjoining areas causing floods. The effect of soil erosion and subsequent sedimentation of the riverbeds enhances both the occurrences of floods and the area affected by floods. The impact of deforestation driven soil erosion is particularly severe in mountainous terrain. In the western Himalayas, comparison of bedload sediments trapped from parallel streams found that the sediment loads from undisturbed forest were five-seven times smaller than from deforested areas covered by grass and scrub. Deforested areas had a much smaller depth of soil and in many places large patches of underlying bedrock had become exposed ( Haigh et al., 1998). The result of this type of soil erosion on floods is amply demonstrated in the river systems in peninsular Malaysia. Malaysia is located in the equatorial belt and receives very heavy rainfall throughout the year. Peninsular Malaysia has a dense river network. The largest of around one hundred river systems is the Pahang. The runoff along exposed hillsides on the upper courses of the rivers lead to heavy soil erosion and major silting in the lower courses. Peninsular Malaysia has a major tin mining industry and disposal of unwanted tin mining tailings in watercourses has greatly accentuated the silting process. This has majorly worsened the flood situation, both in terms of inundation area and duration of flooding. The effect is particularly severe in Perak and Selangor (Chan and Parker, 1996). The type of natural hazard that is most closely linked to human activity is the landslide. A landslide can be defined as the movement of a mass of rock, soil or debris downward a slope. These occur on steep slopes of hilly terrains that demonstrate certain inherent factors like susceptible rock structure, weak material or slope form. The preparatory factors actively produce the changes that make slopes more vulnerable to a slide, without actually causing it. Some preparatory factor may ultimately become the triggering factor and start the landslide. In some other cases, geological or climatic events like earthquakes or rainstorms initiate the movement. Human activities cause some of the more widespread preparatory factors. Removal of forest cover from mountain slopes deprives the soil of the binding force of the roots of vegetation, thereby making it more vulnerable. Removal of the toe of the slope renders the mass above, unstable. This is because the lateral buttressing support for the bulk of the slope that lies on top of the excavated area is removed. Human activities like building of roads or quarrying of minerals are responsible for this type of preparatory factor. In many cases, human settlement on the slopes alters the original surface drainage of that area, eventually rendering it hydrologically unstable. The effects of human activity in the preparatory factors of a landslide were demonstrated in the landslide at Abbotsford, South Island, New Zealand on 8th August 1979. Deforestation, quarrying and modification of surface drainage further endangered the geologically unstable slope. Heavy rainfall and leakage from city water supply pipeline finally triggered the massive landslide (Pacione, 1999). Human activity like construction of roads can have a major impact on the vulnerability of a mountain slope. For example, the Indian Central Himalayas have seen major increase in road construction activities after the war with China in 1962. Many of these roads are poorly designed and constructed. This has dramatically increased in the occurrences of landslides in the region (Ives, 2004). Human intervention on the natural drainage of a slope as a major contributing factor to a landslide is amply demonstrated in the multiple occurrences of landslides on the hill slopes of La Paz city in Bolivia. La Paz region has considerable human settlements that are on unconsolidated slopes. These slopes are frequently wetted to saturation and forced to move. Some of these factors are natural, like seasonal convective showers of high intensity, flooding of lowers slopes by the rivers and streams draining that rainfall and water seepage from fluctuating water tables of adjoining lake Titicaca basin. However, the water saturation of the slopes is exacerbated by the human settlement on the slopes. Much of such settlements are unplanned, self-help housing that have no access to public sanitation and drainage systems. Waste water from such houses are drained directly on to the slopes. These factors have led to repeated landslides in the La Paz region in the past (O’Hare and Rivas, 2005). Another type of mass movement that is seen in plain areas is subsidence. Subsidence is vertical sinking of materials. In many unplanned cities, the city has sprawled into areas not covered by municipal water distribution network and indiscriminate ground water usage through bore wells have severely depleted water tables. In some cities like Mexico and Bangkok, the drained soil has compacted, leading to subsidence. In some other regions like the Raniganj – Jharia coal belt in India, improper mining excavations and inappropriate filling of excavated tunnels have led to widespread subsidence. In certain cases, though human activity does not cause a natural hazard, it may lead to secondary hazard events subsequent to the occurrence of a primary hazard. A case in point is the building of a very high multipurpose dam at Tehri in the Himalayan region in India that may be susceptible to seismic activity. In the eventuality of an earthquake and subsequent rupture of such a high dam, a tremendous flash flood is inevitable on the lower courses of the river, accompanied by major landslides as well (Ives, 2004). Thus, it can be concluded that human activities have some impact on occurrence of natural hazards. For some hazards like landslides and subsidence, there is direct, causal relationship between human activity and hazard occurrence. In some other cases like drought and floods, unscientific and unplanned exploitation of natural resources exacerbate natural hazards. In yet other cases, human activity compounds the effect of a natural hazard by triggering other hazard events that follow.

Most Common Answer on the ACT Guess C

Most Common Answer on the ACT Guess C SAT / ACT Prep Online Guides and Tips Everyone knows that, when guessing on a multiple-choice test, the best answer to choose is C...right? A friend of a friend swears by it, it’s served you well in the past (maybe?), and it’s become such a commonly known â€Å"fact,† such an undisputed strategy, that you may feel as if you were born knowing it- †when in doubt, pick C and move on.† But does this time-honored tradition of picking C when in doubt actually work on the ACT? And if not, what can you do to improve your odds when guessing? Let’s look at the facts. Why You Should Answer Every Question on the ACT First of all, there is no penalty for choosing a wrong answer on the ACT, so make sure tonever leave a question blank. You'll earn one point for every correct answer you choose and zero points for any blank or wrong answers, so it doesn'thurt you to make a guess. If you don't knowan answer and guessit wrong, you'll earn the same number of points that you would have had you left it blank (zero). And if you guessthe question right, you'll earn yourself one point! Now when you're forced to guess on a question for whatever reason, you'll have to decide between thetwo main types of guessing: educated guessing and blindguessing. So let's break down how and when to go about making each type of guess. Educated Guessing You can make an educated guess when you: understand the gist of a question, butdon't have the timeto workthrough it completely, don't quite know how to work through a question completely, or you're torn between a few answer options. But if you've got some idea of what the answer can (and- just as important- what it can't) be, it's time to eliminate some answer choices and make an educated guess. For example, let's look at an ACT math problem: Even if you don't have enough time to completely work through the problem or don't know all the steps, just a little knowledge of lines and slopes will tell usthat the answer will be B, C, or D. Why? Because our given slope is $-{2/3}$and a negative slope will fall down towards the right when drawn through our given point (2, 5). This means we can eliminate answer choices A and E immediately. (Spoiler alert: D is the right answer.) BlindGuessing But let's say you've come up against a question and you have absolutely no clue where to begin. Or maybeyou've got ten seconds left on the clock and fifteen questions still left unanswered. You know that leaving a question blank is tantamount to throwing your points out the window, so now it's time to make a blindguess. There's no time for educated guessing or eliminating answer choices- you just have to fill in a bubble. Butwhen you have to make a blindguess like this (or multiple blind guesses), are you better off choosing C than any other answer choice? Let's see. Don't let their cheerful smiles fool you- three of them are hiding the wrong answer, dun dun DUN. Fact or Fiction: Is C the Most Common Answer on the ACT? The idea that C is the best answer to choose when guess-answering a question on a multiple choice test rests on the premise that ACT answer choices are not truly randomized.In other words, the implication is that answer choice C is correct more often than any other answer choice.After all, if the answer key were truly randomized, then why should C be any more likely to be the right answer than any other option? [Note: the ACT switches between using A, B, C, D (andE on the math section) and F, G, H, J (and K on the math). H is the equivalentto C.] Some (or even many) of your high school teachers likely still design their tests by hand, which means that their answer keys will not be statistically random.No matter how much your teachers try to randomize their choices, human beings are NOT random and cannot properly randomize a series.For instance, a truly random sampling will actually produce bizarre strings of patterns- e.g., five AB’s in a row, or twenty questions without a D- and most people do not (or cannot) create these patterns when they try their best to be â€Å"random.† Fortunately or unfortunately, this is NOT the case on the ACT. Unlike many of the tests you take in high school, ACT answer keys are completely computer generated. And computers are very good at being random. This means that the answer choices will have a statistically even distribution of 1 in 4 for each answer choice letter (or1 in 5 on the math section): there is no most common answer on the ACT. So, ultimately, guessing C (or any letter!) will give you the correct answer only a statistical 25% of the time(20% on the math section). Which meansit's NOT true that choosing C will give you a better rate of success than choosing any other letter for your blind guessing. What to do, then? So How Should You Guess? If C isn't the most common answer on the ACT, then which letter should you guess? The truth is that it doesn't matter which letter you pick, only that you stick to the one you choose. The best strategy,and the one that will maximize your overall point gain,is to pick your favorite letter and fill it infor every blind guess. Maybe that letter is A/F or B/G - it doesn't matter. Just be sure to stick with it every single time. So definitelygo ahead and choose C/H to be your designated letter if you like it best! (Just don't expect C to be any betteran answer choice than A, B, or D.) But maybe you're thinking that sounds completely illogical. Why should you fill in the same letter over and over? Why Does Sticking to One Letter Increase Your Odds of Guessing the Right Answer? Your overall score will improve if you stick to choosing the same letter again and again when making blind guesses. This isbecause people are never truly random. If you’re making "random" blind guesses in a spread, you will almost certainly reduce your overall guesses odds, because your best attempt at random guessing cannot replicate computer-generated randomness. But by sticking to your designated letter when making blind guesses, you are re-introducing an element of randomness. Let’s see this in action to better demonstrate why this works. Scenario: It’s crunch time and you’ve run out of minuteson the clock. You have 15 questions left to goand only a few seconds to bubble in your answers. This means you don’t have time to even look at the questions, so you must try to make the best blind guesses you can and maximize your point-gain. You are left with two options: make a random guess spread, or fill in every letter with the same answer choice. Let’s see how each option does when compared to a real ACT answer guide (in this case, we are using the first 15 answers of the 2015/2016 ACT reading section answers, with all F, G, H, J's converted to A, B, C, D's.) (Note: for our random spread, we tried to guess as randomly as we could without looking at the answer key, and for our consistent letter, we simply went with C.) â€Å"Random† Spread Consistent Guess (C) Correct Answers A C A C C D B C C A C C A C B B C D D C A B C C D C B B C D C C A A C D C C C C C D D C B By choosing a random spread, we earned 2 points out of a possible 15.But by sticking with one answer choice, we earned 4 points. Ultimately, sticking to the sameletter won't work better for each individual question, but on average and over a spread, the strategywill let you maximize your overall point-gain. Oh, statistics, you strange creature. The Take-Aways So is C the most common answer on the ACT? No! But is it the best letter to choose when you're in a bind and don't know what the right answer choice is? Well, that's more complicated. Always remember that it'sin your best bet to eliminate answer choiceswhenever possible. But if you can't, and you must make a blind guess, then stick to one letter and run with it every time. If you want this letter to be C (and it's equivalent, H), then go right ahead! Just make sure you stick with it every single time. C isn't any better or worse than any other letter, or any more likely to be the correct answer, but if you decide to stick with it for every blind guess you make, you'll be better off than trying to be "random." What's Next? Blind guessing strategy is great in a pinch, but elimination is always better! Check out our guides on how to make your best guesses on the ACT, how to eliminate answer choices on the ACT math section, and how to avoid the top elimination pitfalls that many students make. Want to get more ACT practice? Check out all the free ACT tests available online and gauge how you're scoring by checking out what falls into a "good" and "bad" ACT score. Want to improve your ACT score by 4 points or more? Check out PrepScholar's test-prep programour five day free trial. Want to improve your ACT score by 4 points? Check out our best-in-class online ACT prep classes. We guarantee your money back if you don't improve your ACT score by 4 points or more. Our classes are entirely online, and they're taught by ACT experts. If you liked this article, you'll love our classes. Along with expert-led classes, you'll get personalized homework with thousands of practice problems organized by individual skills so you learn most effectively. 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