Soil erosion - Causes and Effects



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Soil erosion - Causes and Effects



 

Erosion is a natural and continuous process. Soils are created through erosion of parent material and either local deposition elsewhere. Erosion, is defined as the detachment or uptake, and transport over a certain distance of material of the upper layer of the earth crust by an agent, like water, wind or ice. This mass movement of soil particles, is part of the process of soil degradation. Before erosion takes effect, the degradation process often has started with qualitative changes in the soil, like loss of nutrients, loss of organic materials, reduced soil life and loss of soil structure.

Soil erosion is one of the forms of soil degradation along with soil compaction, low organic matter, loss of soil structure, poor internal drainage, salinisation, and soil acidity problems. These other forms of soil degradation, serious in themselves, usually contribute to accelerated soil erosion.

Soil erosion may be a slow process that continues relatively unnoticed, or it may occur at an alarming rate causing serious loss of topsoil. The loss of soil from farmland may be reflected in reduced crop production potential, lower surface water quality and damaged drainage network.

Soil erosion is a naturally occurring process on all land. The agents of soil erosion are water and wind, each contributing a significant amount of soil loss each year in different countries.

Water erosion depends on four factors: rainfall, soil type, slope gradient, and soil use/vegetation cover. Loss of soil structure becomes often most visible in encrustation of the soil.

Both rainfall and runoff factors must be considered in assessing a water erosion problem. The impact of raindrop on the soil surface can break down soil aggregates and disperse the aggregate material. Lighter aggregate materials such as very fine sand, silt, clay and organic matter can be easily removed by the raindrop splash and runoff water; greater raindrop energy or runoff amounts might be required to move the larger sand and gravel particles.

Soil erosion potential is increased if the soil has no or very little vegetative cover of plants and/or crop residues. Plant and residue cover protects the soil from raindrop impact and splash, tends to slow down the movement of surface runoff and allows excess surface water to infiltrate.

Wind erosion less common, but again takes place after vegetation has been lost and when soil particles are loosened. Early signs of wind erosion include deposition of sand particles around plants and micro-ripples on the surface of exposed areas. The final extreme is the classic sand desert dune structures. The lack of windbreaks (trees, shrubs, residue, etc.) allows the wind to put soil particles into motion for greater distances thus increasing the abrasion and soil erosion. Knolls are usually exposed and suffer the most.

Sheet erosion is the most common form of erosion. Unprotected soil particles are loosened by trampling, through wind erosion and by the impact of rainfall. The soil particles are then transported by rainwater surface flow to the river and stream systems. Sheet erosion is characterized by a general lowering of the soil level, leaving raised pedestals where the root mass of the remaining vegetation protects it. Sheet erosion is soil movement from raindrop splash resulting in the breakdown of soil surface structure and surface runoff; it occurs rather uniformly over the slope and may go unnoticed until most of the productive topsoil has been lost.

Rill erosion results when surface runoff concentrates forming small yet well-defined channels. These channels are called rills when they are small enough to not interfere with field machinery operations. The same eroded channels are known as gullies when they become a nuisance factor in normal tillage.

Gully erosion is the most obvious and dramatic demonstration of erosion, although in most areas actually less significant in terms of total land degradation. Gully erosion rarely occurs without sheet erosion. It can also be triggered by erosion along livestock tracks, footpaths and road edges. The process can start with "rills" and end up with gullies that are tens of meters deep.

There are farms that are loosing large quantities of topsoil and subsoil each year due to fully erosion. Surface runoff, causing gull formation or the enlarging of existing gullies, is usually the result of improper outlet design for local surface and subsurface drainage systems. The soil instability of fully banks, usually associated with seepage of ground water, leads to sloughing and slumping of bank slopes. Such failures usually occur during spring months when the soil water conditions are most conductive to the problem. Poor construction, or inadequate maintenance, of surface drainage systems, uncontrolled livestock access, and cropping too close to both stream banks has led to bank erosion problems.

The effects of soil erosion are complex. Some of the impacts may appear to be reversible by suitable soil conservation programmes and improving cultivation practices, whereas there are other types of degradation which are irreversible. The latter type includes land lost by gulling, or cases of severe sheet erosion where the soil cover has been removed to a great extent. In cases where degradation is reversible it is generally difficult to assess the actual extent and impact of land degradation as farmers do convert their land to less demanding uses or increase the level of inputs. Methodologies for prediction of soil erosion have been developed since the early thirties.

Many farmers have already made significant progress in dealing with soil erosion problems on their farms. However, because of continued advances in soil management and crop production technology that have maintained or increased yields in spite of soil erosion, others have not been aware of the increasing problem on farmland. Awareness usually occurs only when property is damaged and productive areas of soil are lost.

Certain conservation measures can reduce soil erosion by both water and wind. Tillage and cropping practices, as well as land management practices, directly affect the overall soil erosion problem and solutions on a farm. When crop rotation or changing tillage practices are not enough to control erosion on a field a combination of approaches or more extreme measures might be necessary. For example, contour plowing, strip cropping, or terracing may be considered.

18. Прочтите и письменно переведите текст 15Д:

Text 15D

Soil degradation

 

Among the land used for agriculture and forestry, soil is an important component. The intense and increased pressure on land leads to its degradation and pollution, which may result in a partial or complete loss of its productive capacity. Soil degradation can be described as a process by which one or more of the potential ecological functions of the soil are harmed. These functions relate to bio-mass production (nutrient, air and water supply, root support for plants) to filtering, buffering, storage and transformation (e.g. water, nutrient, pollutants). Soil degradation is defined as a process that lowers the current and/or future capacity of the soil to produce goods and services. Two categories of a soil degradation process are recognized, displacement of soil material (e.g., soil erosion by water forces or by wind forces) and soil deterioration covering chemical or physical soil degradation.

Soil degradation is on the increase worldwide, especially in the countries within the tropics. Mismanagement of arable areas by farmers and grazing areas by livestock owners is one of the major causes of soil degradation. More sustainable management of lands would reduce environmental pressures. Conservation tillage, i.e. reduced or no tillage, is the key to sustainable arable land management as it protects the soil resources, increases the efficiency of water use and, of special importance in semi-arid areas, reduces the effects of droughts.

Land/soil degradation can either be as a result of natural hazards or due to unsuitable land use and inappropriate land management practices. Natural hazards include land topography and climatic factors such as steep slopes, frequent floods and tornadoes, blowing of high velocity wind, rains of high intensity, strong leaching in humid regions and drought conditions in dry regions. Deforestation of fragile land, over cutting of vegetation, shifting cultivation, overgrazing, unbalanced fertilizer use and non-adoption of soil conservation management practices, over-pumping of ground water are some of the factors which comes under human intervention resulting in soil erosion.

The United Nations Environment Program (UNEP) formulated a project proposal for Global Assessment of the Status of Human Induces Soil Degradation. This was achieved with the help of more than 200 soil scientists and environmental experts worldwide. The project also received active advice from the International Society of Soil Science. Regional cooperators were asked to delineate on a standard topographic base map units showing a certain homogeneity of physiography, climate, vegetation, geology, soil and land use. Within each delineated map unit, soil degradation, its relative extent within the unit and the type of human intervention that has resulted in soil degradation during the post-war period were also indicated. The regional results were then generalized and compiled as a world map.

The program developed methodologies to create soil and terrain databases. The main objective of the program was to strengthen global awareness of policy-makers and decision makers of the danger resulting from inappropriate land and soil management.

Lesson 16. EFFICIENCY AND EFFECTIVENESS IN SOIL REMEDIATION

 

1. Прочтите следующие слова:

 

Combustion, ignition, explosion, implicit, attenuation, hamper, priority, contamination, chemical, remediation, highlight, pollution, constraint, probability, delay, representation, cleaning-up, multifunctionality.

 

2. Прочтите и переведите следующие группы слов:

 

Remediation strategy; pose no harm to humans; a growing awareness; chemical properties; planning constraint; dispersion of pollution; due to air emission; to restore multifunctionality; industrialized countries; increase in productivity; may hinder; specific developments; economic burden; environmental balance.

 

3. Запомните следующие слова и словосочетания :

 

acceptability (n.) – допустимость

additive (adj.) – добавочный, дополнительный

aggregating (n.) – сбор, совокупление

ambiguity (n.) – неопределённость, двусмысленность

attenuation (n.) – уменьшение, истощение

burden (n.) – бремя, груз, ноша

challenge (v.) – вызывать, оспаривать, подвергать сомнению

chemical properties – химические свойства

combustion (n.) – окисление, сгорание

compartment (n.) – отделение

contaminated sites – загрязненные участки

discretionary (adj.) – предоставленный на собственное усмотрение

dispersion (n.) – разбросанность, рассеяние

environmental performance – характеристика окружающей среды

excavate-pumb-and-treat – помповые раскопки и обработка

explosion (n.) – взрыв, вспышка

exposure (n.) – подверженность (риску)

fossil fuels – допотопное (неочищенное) горючее

grasp (v.) – схватывать, понимать, воспринимать

hamper (v.) – препятствовать

ignition (n.) – воспламенение

implicit (adj.) – безоговорочный, подразумеваемый

indices (pl.) –(index) – показатели

in terms of environmentаl merit – в смысле качества окружающей среды

internalization of the values – (зд.) внутренняя стоимость

issues (n.) – спорные вопросы

merit (n.) – качество, существо

net environmental benefit – чистая выгода для окружающей среды

outcome (n.) – результат, выход, последствие

performance (n.) – 1. характеристика, производительность; 2. коэффициент полезного действия; 3. выполнение

publicly owner sites – участки, которыми владеет государство или общественность

remediation (n.) – восстановление, лечение

risk attenuation process – процесс уменьшения риска

time-dependent profile – профиль, зависимый от времени

wait-and-see attitude – выжидательная позиция

 

4. Прочтите и переведите следующий текст:

 

Text 16A

Soil Pollution

 

Soil pollution has become a priority in many industrialized countries after the inventory of various locations in which contamination was posing a risk to people and the environment.

The effects of soil contamination are different:

- soil pollution is a source of risk for humans and ecosystems, which are (potentially) affected by direct exposure to the contaminated surface or by indirect exposure, for instance through contaminated ground water;

- soil contamination is a source of risk for ground work (like pipelines or utility network) due to the chemical properties of the contaminant and the risk of ignition and explosion, for instance for fuel contamination;

- for publicly owner sites, a polluted area is a severe planning constraint, since the site use may be impossible or limited to a specific soil functionality (e.g. an industrial storage facility);

- for privately owned sites, a polluted area is a heavy economic burden of remediation expenditures (a net cost for the company) and of soil usage;

- the presence of polluted areas may hinder and delay some specific developments which imply land use and ground work (like the provision or maintenance of infrastructures);

- remediation expenditures do not offer any increase in productivity, merely the possibility of removing a source of risk and a planning constraint.

The ultimate objective of the operations is to eliminate the risk to a man and the environment and to prevent the dispersion of pollution, that is to restore multifunctionality in the shortest possible time. Soil multifunctionality requires that the soil on the site after sanitation should pose no harm to humans, animals or plants, regardless of the use of the site, the type of soil, the type of pollutants and the local situation. This is a very demanding objective, totally driven by environmental quality considerations. There is, however, a growing awareness that other criteria should be included when assessing remediation strategies. One of the reasons is that the costs involved in multifunctional operations are no longer political defendable. There is also a growing recognition that clean-up operations do not necessarily lead to a positive environmental balance. Soil remediation requires the use of resources (like energy and clean water) and may lead to a net transfer of contamination to other compartments (for instance, due to air emissions). Therefore, the single perspective implied by the multifunctionality may result into an approach which disregards many relevant concerns for soil remediation.

 

 

5. Найдите синонимы среди следующих слов:

 

Properties, hinder, embrace, cover, purpose, merely, aim, characteristics, humper, simply, aim, objectives.

 

6. Найдите антонимы среди следующих слов:

 

Directly, timely, private, unnecessarily, negative, said, public, positive, unregistered, untimely, systematic, indirectly, necessary, unsaid, registered, haphazard.

 

7. Переведите следующие сочетания слов с русского на английский язык:

 

Загрязнение почвы; непосредственная подверженность; повышение производительности; растущая осведомленность; землепользование; восстановление почвы; самое короткое время; тяжелое экономическое бремя; источник риска; операции по очистке.

 

8. Переведите следующие предложения с русского на английский язык:

 

1. Расходы на восстановление не предполагают никакого повышения в производительности. 2. Почвенная многофункциональность требует очистки почвы. 3. Загрязнение почвы - источник риска для земляных работ. 4. Конечная цель операции - устранить риск человека и окружающей среды. 5. Очень важно предотвратить распространение загрязнения. 6. Невозможно ограничить функциональность почвы. 7. Баланс восстановления окружающей среды не может быть всегда положительным.

 

9. Образуйте имена существительные от следующих глаголов:

 

To interpret, to know, to apply, to assume, to pollute, to consider, to recognize, to combine, to evaluate, to assess, to value, to represent, to attach, to provide, to achieve, to depend, to treat.

 

10. Составьте предложения, используя следующие слова:

 

1. Requires, process, the, of, use, resources, remediation, natural. 2. Awareness, been, a, has, achieved, growing. 3. Multifunctionality, aimed, at, are, measures, these. 4. Computed, yearly, are, costs. 5. Clean-up, of, operations, Merit, the, based, are, evaluation, an, on, Environmental, Index. 6. Through, interviews, assessed, weights, are. 7. Approaches, some, are, fundamental, there.

 

11. Заполните пропуски предлогами:

 

1. The overall environmental balance ... remediation may not be always positive. 2. The application ... remediation techniques may significantly cut costs, although leave many sites polluted ... a considerable time. 3. These factors are the negative side ... the remediation. 4. ... clean-up polluted soil is necessary. 5. Remediation expenditures do not offer any increase ... productivity.

 

12. Поставьте к каждому предложению максимальное число вопросов:

 

1. Soil pollution is a source of risk. 2. The presence of polluted areas may delay some specific developments. 3. To eliminate the risk to a man is the ultimate aim of the operations. 4. One should assess remediation strategy. 5. Clean-up operations lead to a positive environmental balance.

 

13. Перепишите предложения, заменив модальные глаголы эквивалентами. Переведите их на русский язык:

1. Soil remediation can lead to a net transfer of contamination to other compartments. 2. The polluted areas must delay some specific developments. 3. Scientists can consider multifunctionality as the soil-related interpretation of sustainability. 4. This framework could show how to combine risk reduction. 5. In order to respond to the application need a more comprehensive evaluation framework must be considered.

 



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