Category: Geography Notes PPT

Fen is one of the wetlands types and wetlands are considered as one of the most important and diverse ecosystems. They serve an important role in feeding and nesting sites for various species and also one-third of the rare and endangered species of the Earth depends upon the wetlands directly or indirectly which makes them more important. In this article, we will learn about one of the wetland types i.e. Fens, which are biological hotspots where peat formation, as well as water presence throughout the year, can be seen. This topic plays an important role in Geology and Environmental Studies.

The Ramsar Convention of 1971 in Iran is related to wetlands and under the text of the Convention (Article 1.1), wetlands are defined as: “areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres”. According to the estimates of UNEP-World Conservation Monitoring Centre, roughly 6% of the Earth’s land surface are wetlands of which 2% are lakes, 30% bogs, 26% fens, 20% swamps, and 15% floodplains. 

Fen Meaning

It is derived from the term “Fenn” which was an old English word which supposed to have a proto-German origin. It is one of the types of wetlands and wetlands work as transitional zones between the terrestrial and aquatic ecosystems. It is a type of wetland where peat formation can be seen and which is fed by both grounds as well surface waters which are rich in minerals. Besides fens, bogs are also called peat formulating wetlands and both these are also known as mires. Water chemistry of fens is considered to be its unique feature which leads to having more minerals as well as more pH level as compared to bogs. It also consists of grasses, wildflowers, sedges, etc. The term “carr” is also associated with fens wetlands and is a type of fen where this wetland supports trees.

Definitions

Some of the standard definitions are mentioned below.

• The Environmental Protection Agency defines fens as “peat-forming wetlands that receive nutrients from sources other than precipitation” (EPA 2008) and as “freshwater peat-forming wetlands covered mostly by grasses, sedges, reeds, and wildflowers” (EPA 2004).

• The National Wetlands Research Center of the U.S. Geological Survey defines fen as “waterlogged, spongy ground containing alkaline decaying vegetation characterized by reeds, that develops into peat” (NWRC 2007).

• According to the textbook Wetland Ecology: Principles and Conservation, Paul A. Keddy offers a somewhat simpler definition of a fen as “a wetland that is usually dominated by sedges and grasses rooted in shallow peat, often with considerable groundwater movement, and with pH greater than 6.”

Features

The various features of fens are mentioned below.

• The water level in fens wetlands is present throughout the year. It fluctuates very little because the water table here is high. The stability of water in this type of wetland is stable.

• The water should not be drained along with the land close to it in order to prevent the area from drying and prevention of over weeds.

• A low level of oxygen leads to the decaying of the dead plants slowly which leads to peat formation in the fen.

• Due to the accumulation of peat in fens, the input of groundwater can be reduced or cut off which leads to making fens ombrotrophic. Fens can become more acidic in this way and can transit to big wetlands as well.

• Though they can be found all over the world most of the fens wetlands are found in the Northern Hemisphere especially in between mid to high latitudes.

• The composition of species can differ due to change in the chemistry of water but mostly they are dominated by sedges & mosses.

Types of Fens

These can be of the following types:

• One of the most common types of fens is sloping fens which are formed at the base of the mountains or hills. Because of the slope water discharges here from the landscape lying above. In the below diagram, the green area denotes the area of fen. 

• Another type of fens is basin fens which are used to originate as lakes or ponds as these are consist of partially decomposed plants. Generally, these are flat and occur at the margin of open water. As we can see in the diagram, water is being received from both the sources say ground and surface and when it is stable, floating peat mats can be seen.

 

Importance

We have learned about fen meaning and its features. The importance of fens are mentioned below:

• Fens are one of the most important types of wetlands.

• It contains a variety of flora and fauna. 

• It supports that vegetation that flourishes in fertile swamps as well as in bogs along with various animal species as well.

• It helps in the prevention of overflowing of the rivers by preventing sediments to flow into the rivers. 

• They work as groundwater discharge sites.

• They work as important shallow aquifers indicators.

• These wetlands serve as a home to black mad fish which is considered a rare species.

• They are an important biodiverse ecosystem that serves as a habitat for endangered as well as rare species.

Flora & Fauna

Due to the high level of mineral content and high pH level, it supports more diversity than bogs as it receives more water from the ground and surface. 

• According to the EPA, Whereas bogs are dominated by mosses, fens often are covered by rushes, sedges, grasses, and wildflowers. Some fens have parallel ridges of vegetation that form perpendicular to the downslope flow of the water, with less productive hollows separating these ridges (EPA 2008). 

• The examples of flora species found in pools are Beaked sedge, Whorl grass, Needle spike-rush, Sweet grasses, Common reed, Swamp meadow grass, and in typical fens are Flat sedge, Blysmus compressus, Great fen sedge, Lesser tufted sedge, Lesser pond sedge, Davall’s sedge, Dioecious sedge, Brown sedge, Tufted sedge, Slender sedge, Flea sedge, Greater pond sedge, Common spike-rush, etc whereas in fen carr are Narrow small-reed; Calamagrostis stricta Purple small-reed, Tussock sedge, Cyperus sedge, Wood club rush, etc.

• If we talk about fauna, then insects and insects eating species are common here like mosquitoes and horseflies, etc. along with insect-eating birds, as well as insect-eating mammals like shrews, voles, and muskrats, etc.

Conclusion

Thus, to sum in the end we can say that fens are one of the important types of wetlands that serve as transitional zones and 26% of the total wetlands are fens. Here, peat formation can be seen and consists of water content from both the ground as well as a surface which leads to having high mineral content and high pH level. This type of wetlands is also similar to bogs but there are many diverse wetlands as compared to bogs and if the pH level of these wetlands gets lowers it can be transitioned into bogs as well. It supports various kinds of flora and fauna as well. In this article, we have covered what fen, fen meaning, features, importance, and other related aspects which will help to understand one of the types of wetlands.

The geoid is the shape taken by the ocean surface which would take under the influence of gravity and rotation of the earth, without any presence of winds and tides. The geoid surface is not only limited to the ocean but is extended through the continents as well through very narrow hypothetical canals. John Carl Friedrich Gauss was the first to describe it, and said that the geoid surface was the ‘mathematical figure of the Earth’. In the concept of the geoid a smooth but irregular surface the shape of which is the result of the uneven distribution of the mass within and on the Earth’s surface.

Concept of the Geoid

According to the concept of the geoid, which defines the shape taken by the surface of the ocean and also extends through the continents, the geoid earth surface is irregular but smoother than the actual physical surface of the Earth. Typically, the surface of the Earth is represented by the idealized mathematical representation of an ellipsoid. The difference between ellipsoid and geoid surface is that the ellipsoid is the smoothest representation of the surface while the geoid is an irregular representation of the surface of the Earth. 

This is because the irregular shape of the geoid earth takes into account the influence of gravitation and the rotation of the Earth but does not take into account the forces of winds and tides. Because of this, the geoid surface of the Earth deviates from the smooth ellipsoid within the range of +85 m (physical surface height of Iceland) to -106 m (physical surface depth of southern India). But this isn’t as relevant to the physical feature of the Earth’s surface as the actual range is from + 8848 m height of Mount Everest to -11,034 m depth of Marianas Trench. 

As the parameters used to define Geoid, a Geoid surface in common parlance is said to be an earth-like surface. All the points on the geoid earth surface are said to have the same effective potential. In the process to define geoid, as the gravitational force is taken into consideration, the sum of the gravitational potential energy and the centrifugal potential energy is defined as the effective potential which is the same on all points of the geoid. Hence, it is an equipotential geoid surface with respect to gravitational potential. 

As per the concept of the gepoid the force of gravity on the surface of the geoid is perpendicular to all the points. On the surface of the geoid, the plumb lines point perpendicular and the water levels are parallel to the geoid only when gravitational and rotational acceleration are working together. The difference between ellipsoid and geoid is clearly visible when comparing between the two surfaces, it is clearly visible that the surface level of the geoid is higher than the reference surface of ellipsoid when the gravity anomaly is positive, and when the gravity anomaly is negative, the surface level of the geoid is lower than the reference surface of the ellipsoid. 

The difference between the geoid surface and the other surfaces is clearly visible in the following diagram: 

Another representation of the geoid surface is shown below in which the colours represent the rise in the height and fall in the depth of the geoid surface:

Determination of the Geoid Surface

There are many mathematical methods that help to determine and calculate the surface of the geoid. The undulations, i.e. the smooth up and down movement of the geoid surface, are calculated by various approaches combined together. Calculation of the undulating surface is challenging mathematically. Hence, because of this many of the GPS receivers that are handheld have built-in undulation lookup tables which are helpful in determining the height above sea level. The stokesian approach is the one that is widely used for the calculation of undulating surfaces. The precise solution of the geoid given by Vanicek and co-workers improved on the Stokesian approach for the computation. The solution obtained as such enables the accuracy to be in the range of millimetre-to-centimetre which is an order-of-magnitude better than the previous classical situations. 

Many of the calculations of the undulations of the geoid surface use approaches such as least-squares collocation, fuzzy logic, artificial neural networks, radial basis functions, and geostatistical techniques to estimate the uncertainties displayed in the undulations of the geoid. Out of all of them, the geostatistical approach has been defined as the most improved technique while utilizing for the prediction of the geoid undulation. 

Determination of the Surface of Other Celestial Bodies

The concept of the geoid has been applied not only to Earth but also to the other celestial bodies present in the Solar system. It has been extended to other planets and moons and also to the asteroids. An example of such a case is the ‘areoid’ which is the geoid equivalent of Mars. The areoid of Mars has been measured by the use of flight paths of human-made satellite missions such as the Mariner 9 and Viking. From the data collected for the areoid, the main difference from the reference ellipsoid is found at the Tharsis volcanic plateau which is an elevated region of terrain and is of the size of the continent. The same difference is visible for the antipodes found in the region.

In oceanography the term “cline” is used to describe a thin and typically horizontal layer within a fluid with greatly varying properties over a short vertical distance. When this thin layer or cline has a strong vertical salinity gradient within the body of water, then it is known as Halocline. The halocline plays a significant role in the vertical stratification. Along with the temperature, the salinity also contributes to the density of seawater. This can be understood by the example that if there is 1 kg/m3 increase in salinity, then the sea-water density increases by around 0.7 kg/m3. This affects the seawater environment and has a profound effect on the life of organisms. 

Effects of the Halocline Layer

From the halocline definition it is clear that the layer is high in salt content. The effects of such a layer because of the conditions as described in the halocline definition are more commonly found in places with high temperatures such as mid-latitudes. Because of the excess of evaporation and over precipitation in the middle-latitudes the surface waters have more salt contents as compared to the deep waters. In such regions, the surface waters are relatively warmer than the deep waters and because of that there is a certain destabilizing effect in the vertical stratification of the halocline layer. This destabilization leads to a process of mixing known as salt fingering, that results in the mixing of the salinity across the vertical stratification. 

Another significant role played by the halocline layer is in the high latitude region. In such regions for example, in regions of the Arctic Ocean, Bering Sea, and the Southern Ocean, the water present on the surface is actually colder than the water present in the depth. Here, the condition of increased density in the specific layer of salinity as identified by the halocline definition helps in keeping these waters separate and isolate the deep water from the surface water. Because of this separation, ice is formed on the surface of the sea level as it is cold and does not melt away because of heat transition from the warmer waters present in the depth. The halocline layer also limits the escape of the carbon dioxide gas into the atmosphere in the high latitude regions. 

The halcolines are also found in fjords and poorly mixed estuaries, the place where the freshwater from rivers and streams gets mixed with ocean surface. 

As a small experiment, it is possible to create and see a halocline in a drinking glass or any transparent vessel. For this experiment, the fresh water is to be slowly poured over a significant amount of salt water, with the help of a spoon that is held horizontally at the water-level for preventing the mixing of the two different types of waters. As the water is being poured or after it has been poured, for some amount of time, a hazy interface of salt layer can be easily seen. This hazy salty layer is the halocline. It becomes visible because of the varying refractive index across the boundary. 

Other common occurrences of haloclines are the water-filled limestone caves that are near the ocean. The less denser fresh water from the land forms a layer over the salt water from the ocean. For any of the underwater cave explorers, such as halocline divers that cause an optical illusion of air space present in the caverns. When the halocline divers pass through the halocline layer, the layers get perturbed. 

Different Types of Clines

There are different types of clines. Some of them along with their descriptions are listed below:

• Chemocline: This is the layer under which different types of clines are classified. It is a cline based upon the chemistry of the particular layer. 

• Thermocline: This layer is the cline which is identified on the basis of the water temperature. 

• Pycnocline: It is the layer which is identified on the basis of the water density. 

The halocline is a subtype of chemocline. There are possible combinations of the clines as well. For example, sometimes thermocline and halocline exist together as a vertical gradient. And as mentioned above thermocline and halocline i.e. effect of increased temperature and increased salinity leads to an increase in the density of that layer which is the pycnocline layer. Thus, thermocline haloclines together form a pycnocline layer and have the corresponding effect on the surrounding environment. 

The cumulative water on the earth is a hydrosphere. Water on the surface of the earth, underwater, and the air is included in the hydrosphere. The hydrosphere of the earth may be liquid, vapor, or ice. On the surface of the Earth, water is in the form of oceans, lakes, and rivers. It is also found under the earth, in wells and aquifers. Water vapour, as fog and clouds, is most noticeable. Glaciers, ice caps, and icebergs are the frozen portion of Earth’s hydrosphere. The frozen portion of the hydrosphere is called the cryosphere. In a cycle, the water flows by the hydrosphere. Water forms in the clouds, and then in rain or snow falls to the Earth. The rivers, lakes, and oceans absorb this water. Then it evaporates into the atmosphere and restarts the loop. This is nothing but the Water cycle. 

Distribution Earth’s Waters 

Water is very unevenly distributed on the surface of the Planet. Just 3% of the surface water is fresh; the rest of the 97% is contained in the ocean. 69% of freshwater is present in glaciers, 30% in the land, and less than 1% in rivers, lakes, and swamps. In other words, only 1% of the water on the surface of the earth can be used by humans and 99% of the amount is underground.

Climate Change

The combined water mass on, under, and around the surface of the Earth is the hydrosphere. The majority of it can be found in the oceans, with freshwater only representing 2.5 percent of the sphere and much of it in glaciers, permanently covered by snow at pole areas and mountains. The rest is in lakes and rivers. The hydrological cycles that are powered by the sun and transfer water continually around the world by exchanging molecules of water from plants and oceans and back to and around the ecosystem keep freshwater quantities at a constant level. The wheels on the hydrology mechanism moving water in and out of the hydrosphere are evapotranspiration, condensation, precipitation, infiltration, runoff, and subsurface flow. In these cyclic processes, water is converted into liquid, solid, and gas (vapor). The atmosphere is cooled as it evaporates; water condenses releases energy and warms the environment. It hydrates life on the earth and plays a role in moving energy from the terrain to the aquatic environment, through erosion and the motion of minerals. Life will cease to exist on this planet, without these cycles and water itself. In fact, water is approximately 60% of our body weight.

Water Cycle

Water is stored in the hydrosphere in a variety of storages that can be described in many distinct ways. Storages are present in numerous spheres of the Earth’s system: geosphere (even in oceans, seas, lakes, rivers and marshes, cryosphere-ice and snow, lithosphere-ground waters, rocky waters, and earth’s crust) and biosphere (living organisms, flora, and fauna).

Water Chemistry

In general, geochemists defined the hydrosphere (often called the aqua sphere) as the water vapour, liquid, solid, present, and dissolved in the soil, on and about the earth’s surface. The atmospheric water vapour and condensed water are generally included, but the hydrosphere produces water that is immobilized by integration into mineral structures in rock. In reality, the chemical composition of the water has been established during the processes of the hydrological cycle on the Earth that link the hydrosphere and the atmosphere. Water, a universal solvent, is enriched by a wide variety of various substances in gas, solid, and liquid states that produce huge variability of natural water forms from a perspective to their chemical makeup and interact with all elements in the natural landscape and are influenced by natural and man-made elements.

Anthropogenic Influences

While the hydrosphere still operates to the same forces as it has always, people have played an unmistakable role in shifting the balance. In general, the global water balance has had relatively little effect on these impacts and the direct exploitation of the hydrosphere has little chance of affecting global water storage and cycle management. On a regional scale, however, the last thousand years have been spent attempting to temporarily and spatially redistribute water supplies. Weirs, canals, and reservoirs were built in order to monitor runoff times and more recent times to relocate water supply from the surface of the reservoir with accidental loss of evaporation. Irrigated farming often diverts ocean-based flows, most of which are returned by evapotranspiration into the atmosphere. People are thus paying for the privilege of redirecting water to the environment with greater losses.

The Consequences of Regulated System 

In addition to what would be expected of climate variation, the results of this controlled mechanism include slightly lower total discharge, ecological effects of altered inputs to the Pacifica, and modified sediment budgets because of sediment traps behind dams. One unintentional impact of the modified hydrograph was a decrease in the surface salinities of autumn and winter from the mouth of Columbia to the Aleutian Island chain, along the North American coast, with possible negative environmental implications for endangered salmon runs.

Regional water balance also is impaired by the use of agricultural and domestic water by underground water, at rates increasingly higher than natural water recharge and leading to flooding of groundwater. Surface and groundwater contamination, although it has no physical impact on the water cycling itself, contributes in addition to the effects on equilibrium in other biogeochemical processes to depletion of freshwater resources.

The change in land use has resulted in one of the biggest human impacts on the hydrological cycle. Altering the surface of the soil and natural vegetation in a specific area disturbs the natural balance of precipitation, evapotranspiration, and runoff. This effect is also exaggerated by the fact that land-use changes (e.g. agriculture and rural development) are often linked to the above-mentioned physical changes.

The global hydrological cycle, in particular, because people have not had great success in controlling the ocean and atmospheric water balance, which are the largest and most vulnerable reservoirs within the system, would probably not have much effect on this and other direct human hydrological impacts. The indirect changes, particularly climate change caused by human beings, are far more likely to have important effects on the hydrological cycle.

Human Activities that Affect the Hydrosphere

It should be evident at this point that the hydrosphere plays a vital role in Earth’s survival, and that the specific characteristics of water make it possible for various essential processes that are chemically impossible otherwise. Sadly, there is a range of threats to our hydrosphere and, due to human activity, the majority of threats. Two of these concerns will be addressed: pollution and overuse and strategies to solve these problems.

Pollution 

Hydrospheric pollution is an important problem. Sometimes only stuff like plastics, bottles and oil and so on are thought about when we talk about pollution. But any chemicals in the hydrosphere that are not what they need to be are pollutants. Animals and plants which live in the water bodies of the Earth are specially adapted to survive under certain conditions. These species can not survive if these conditions are modified. Thus, whole marine environments are subject to pollution. Material from humans and factories, such as nitrogen contamination, such as fertilizer ruins, which cause eutrophication, and toxic trace elements, such as aluminium, mercury, and copper are among the most common types of hydrosphere pollution. Most of these elements originate from mining or industry.

Overuse of water 

We said earlier that only a very limited amount of water is available in the hydrosphere as freshwater. Despite this, humans are consuming more and more water until the amount of water that is available is rapidly approached. The situation is critical, particularly in countries such as South Africa, where water supplies are naturally dry and limited. Water in South Africa is expected to be unable to satisfy rising water demand in South Africa between 2020 and 2040. This is partly because of population growth, but also because business needs are rising and evolving. This must be a very frightening thought for each of us.

Concerns

Rising Sea Levels

An increasing number of people and habitats worldwide would have an effect on the rising maritime levels. The measurements of tidal gauge indicate a global increase in sea levels of 15-20 cm and the IPCC suggested that ocean waters expand because of increasing temperatures and the melted mountain glaciers and ice-capes. The IPCC suggested a development. Most glaciers in the world are retreating because of global climate change, and several scientific studies show that melting has increased. This would have a big impact on the global level of the sea. For example, a decrease as in previous cuts in the ice sheets of the West Antarctic and Greenland will result in a sea-level increase of 10 meters or more. This would result in drowning coastlines worldwide. 

Decrease in Arctic Sea Ice

Over the past few decades, the level of Arctic sea ice has decreased significantly. Latest NASA studies show that Arctic sea ice declines by 9.6 percent per decade. Such ice dilution and retreats will affect the salinity of the ocean, heat balance, and animal habitat. For instance, polar bears decline as thin ice populations because they are more stranded from the ground, are forced to swim long distances, and many drown on the way. The loss of marine ice often impacts Albedo of Earth’s surfaces’ reflectivity. The darker seas retain more heat and fewer white patches of ice on the surface.

Change in Precipitation Events

Rainfall rises can lead to flooding and landslides, while a decrease results in droughts and wildfires.   For instance, the changes that are associated with an El Niño event in the ocean currents off Peru can result in changes in weather patterns across North America. Modifications in monsoon patterns due to elevated temperatures can cause droughts for monsoon-dependent areas around the world. Hurricanes will become even more disastrous for humans in the future, growing in intensity with rising sea surface temperatures.

Melting Permafrost

The permafrost of the tundra melts with rising temperatures. This affects the people who most often live in this climate, as houses sink and become volatile. The effect is not only immediate, but scientists also fear that the melting permafrost releases vast quantities of carbon dioxide and methane that were previously stored into the atmosphere in frozen organic material, thereby impacting the ecosystem for longer. The addition of greenhouse gases will fuel global warming further by trapping atmospheric heat.

Human Impact on Hydrosphere

Let us look into Human Impact on Hydrosphere. Modern society’s practices have a serious impact on the cycle of hydrology. Dynamic constancy is disrupted by the discharge into the surface and subsurface water systems of hazardous chemicals, harmful contaminants, and other industrial waste as well as the infiltration of mineral fertilizers, herbicides, and pesticides. The nature of the hydrosphere has also been seriously affected by the inadvertent and intentional release of oils, inappropriate sewage waste disposal, and thermal pollution. There are three main issues in the current debate:

Each demonstrates human interventions and their far-reaching impact on the hydrological cycle.

Eutrophication

Historically, aquatic environments were categorized as either oligotrophic or eutrophic. The nutrients nitrogen and phosphorus are poorly fed in oligotrophic waters, and their concentrations are low. As a result, photosynthesis produces no organic matter in such waters. Eutrophic waters, on the other hand, are nutrient-rich, with high concentrations of nitrogen and phosphorus and, as a result, high concentrations of plankton due to high biological productivity. These aquatic systems’ waters are typically muddy, and lakes and coastal marine systems can be oxygen-depleted at depth. Eutrophication is characterized as high biological productivity caused by increased nutrient or organic matter input into aquatic systems. This increased biological productivity typically results in a decrease in lake volume due to the accumulation of organic detritus. Natural eutrophication happens as organic matter fills in the gaps in aquatic systems; it differs from cultural eutrophication, which is triggered by human activity. This is typical of aquatic environments that have been artificially enriched with excess nutrients and organic matter from waste, agriculture, and industry. Lakes that are naturally eutrophic can contain 75–250 grams of carbon per square meter per year, whereas lakes that are eutrophic due to human activity can support 75–750 grams per square meter per year. Culturally eutrophic aquatic environments often have extremely low oxygen concentrations in bottom waters. This is especially true in stratified systems, such as lakes during the summer, where molecular oxygen concentrations can fall below one milligram per liter, a critical level for a number of biological and chemical processes.

Acid Rain

Human-caused emissions of sulphur dioxide and nitrogen oxides into the atmosphere, mostly from fossil-fuel combustion, have resulted in the acidification of rain and freshwater aquatic environments. Acid rain is a worldwide problem that has been well known in eastern North America and western European countries. Nitrate and sulfate concentrations in precipitation are closely associated with pH over the eastern United States—the lower the pH of rain, the higher the concentrations of nitrate and sulfate. Until the late twentieth century, such low pH values and increased nitrate and sulfate concentrations were found in rains in western Europe and North America. Because of strict air quality controls, the pH values of precipitation in these areas have risen dramatically since then. Other areas of the world, such as China, that have industrialized since the late twentieth century without enacting effective air pollution controls, have seen similar pH declines in precipitation.

Buildup of Greenhouse Gases

The greenhouse gases (so-called because of their heat-trapping “greenhouse” properties) released into the atmosphere are one issue caused by human activity that is undoubtedly affecting the hydrosphere globally. Carbon dioxide has gained a lot of attention as one of the greenhouse gases emitted by anthropogenic activities. Carbon dioxide measurements in ice bubbles and continuous carbon dioxide concentration measurements in air samples collected at Mauna Loa, Hawaii, since 1958 indicate that the atmospheric concentration of more than 400 ppmv is approximately 45 percent higher than its late 1700s value of 275 ppmv (see also Keeling curve). Most of this rise is attributed to carbon dioxide emissions into the atmosphere from the combustion of coal, oil, gas, and wood, as well as slash-and-burn activities associated with deforestation, practices (as, for example, those adopted in the Amazon River basin). The ocean is the part of the hydrosphere that is most affected by carbon dioxide emissions.

Humans have a significant influence on all spheres. Pollution in the atmosphere is caused by harmful factors such as the use of fossil fuels. The accumulation of waste in landfills has an effect on the geosphere. The hydrosphere is affected as waste is pumped into the oceans. Overfishing and habitat loss can also reduce the diversity of life in the biosphere. However, people all over the world are trying to make things better. Recycling activities are growing all over the world, and businesses are looking for new ways to reduce their reliance on fossil fuels. People in the United States alone are recycling six times more than a decade ago. That adds to the positive human impacts on the hydrosphere. 

Conclusion

The hydrosphere of the Earth consists of all the water on the planet that can be contained in the oceans, glaciers, rivers, streams, groundwater, or water vapour. It is constantly in motion, moving water and heat throughout the atmosphere as water vapour and precipitation. The oceans (which cover more than 70% of the Earth’s surface) absorb massive quantities of solar energy and radiation. Thermohaline circulation, also known as the conveyor belt, transfers absorbed heat from the equator to the poles in order to control and moderate the Earth’s atmosphere. Previously, as the conveyor belt changed speeds, it had an effect on the global atmosphere and temperature. It is crucial to comprehend how the hydrosphere interacts with the other spheres and how this impacts global climate change. There are several urgent problems that must be tackled that are specifically relevant to the hydrosphere.

Khadir or Khadar are the low-lying areas, also called Nali or Naili. Khadar areas are vulnerable to floods and often have parts of former river beds that were made available for cultivation when the course of a river changes. It is sticky and retentive with moisture when wet.

Khadir formation is composed of fresh alluvial soil that is comparatively higher in the river’s new silt content, is topped up with every flood cycle, as well as is very fertile.

In northern Haryana, which is the abundant prairie tract between both the Ghaggar river and the southern limits of the depression of the Saraswati canal, the Khadir is also called Nali. According to the khadar map, these regions get flooded during the rains.

Khadar and Bangur

In the Indo-Gangetic regions of North India and Pakistan, Khadar basha and Bangur are words being used in Hindi, Punjabi, Sindhi, and Urdu to understand the two different kinds of river plains and alluvial soils. In the Doab areas, the areas of Bangur and Kadir are commonly found. Some villagers may have both the areas of Khadar as well as Bangar under their annual limit.

Difference Between Khadar and Bangur

 

Khadar

Khadir or Khadar also known as Nali or Naili are low-lying lands that are river floodplains and are often narrower than unflooded bangar zones. Flood-prone Khadar lands occasionally include portions of old river beds that became usable for agriculture after a river changed channel. When wet, it retains moisture and becomes sticky.  Khadir soil is made up of newly deposited alluvial soil with a greater fresh silt content from the river, which is renewed with each flooding cycle and is frequently quite fruitful.

 

The lush prairie tract between the Ghaggar river and the southern boundaries of the Saraswati channel depression, which floods during the rains, is known as the Khadir or Nali in northern Haryana. Khadar is an alluvial soil that can be found all throughout the floodplains.

Khadar refers to low-lying portions of a river floodplain that are often narrower than unflooded bangar sections. When the channel of a river changes, segments of former river beds that were once viable for farming become vulnerable to floods in Khadar regions. Old alluvial soils such as khadar have often been subject to changes in climate during their development. This is particularly the case in areas that have existed as alluvial valleys or basins for hundreds of thousands to millions of years

Khadar is more prolific than bangar and is nearly regenerated every year. Because the Indo-Gangetic plains are divided into doabs (zones between two rivers) by a slew of Himalayan rivers, the Indo-Gangetic plains are made up of alternating rivers, khadir, and bangar regions. The doabs’ centres are made up of bangar, while the peripheries, which line the rivers, are made up of khadir. Old alluvium is called Bhangar. It contains calcareous deposits locally known as ‘Kankar’.

 

Soil is not very fertile. And hence not suitable for agriculture. Newer alluvium is called Khadar. It contains new alluvium. Used extensively for agriculture. Has no calcareous deposits. It has a lighter colour, a sandier texture, and is more porous. Near the riverbeds, this creature was discovered. Almost every year, a new layer of alluvium is deposited by river flooding. As a result, they are the Ganges’ most fertile soils. The Khadar-rich flood plains of Punjab are referred to as ‘Betlands’ or ‘Bets’ by locals. The rivers in the Punjab-Haryana plains have large Khadar floodplains surrounded by bluffs known locally as Dhayas. These bluffs reach heights of up to 3 meters.

The little ice age(LIA) was a period of cooling which occurred after the medieval warm period. Even though the little ice age was not the true ice age period, the term was first introduced into the scientific literature in 1939 by François E. Matthes. It has been traditionally defined as the period which extended from the 16th to the 19th centuries. Few of the other experts have other views on the timeline and some prefer the timespan from about 1300 to about 1850. 

The earth observatories such as the NASA Earth Observatory have noted particularly three cold intervals in which the one began in 1650, another in 1770, and the last in 1850. All the cold intervals were separated by intervals of slight warming. There are many reports that suggest that the timing and the areas that were affected by the little ice age suggested that there were largely independent regional climate changes rather than a globally synchronized increased glaciation.IT is believed that there was modest cooling of the northern hemisphere during the little ice age period. 

In this article, we are going to discuss what little ice age is, little ice age cause,

little ice age effects and other factors related to it.

Little Ice Age Effects

The little ice age was a period that had regional cold conditions and lasts for a period between 1300 to 1850. The term little ice age has been questionable as there was not a single and well-defined period that lasted which had a prolonged cold condition. Noticeably there were two periods of the little ice age, the first period begins around the year 1290 and continued for more than two centuries till the 1400s. After the first period, there was a warmer period in the 1500s and after it, there was another cold period which is considered to be the coldest period of all the three. The second period started in the year 1645 and lasted till the year 1715. During this coldest phase of the ice age, the conditions were very bad as the average winter temperature in North America and Europe was as low as 2-degree celsius.

Throughout history, there is a considerable amount of evidence that supports the little ice age such as the complete freezing of the Baltic sea and many rivers and lakes in Europe. During this period pack, ice had expanded far south into the Atlantic making shipping to Iceland and Greenland impossible for months on end. Winter used to be very cold and whereas the summers were often very cool and wet. Due to all these conditions, there were widespread failures while harvesting the crops, there was famine and also a huge population decline as many people could not bear the harsh cold conditions. The snowline and the tree lines dropped and the glacier advanced which led to the destruction of many houses and farmlands in the process. The majority of the population were reduced to poverty as they lost their lands and also many starved to death as there was not enough food for everyone and as a result of this, there was an increased level of unrest in the society. 

Areas Involved in the Little Ice Age

• During the little ice age, the areas were generally one degree Celsius colder than the present temperature. In Europe, many of the Baltic seas completely froze and so did many rivers and lakes. Winters were very cold and prolonged which reduced the growing season by weeks. The bitter winters led to a widespread crop failure and there was also population decline. 

• As there was a widespread crop failure, the prices of the grains increased exponentially, and also the production of wine became very difficult in most of the areas and the commercial vinegar also vanished in many regions of England. As many lakes and rivers were frozen, fishing in northern Europe was also badly affected. Flooding and the occurrence of the threatful storms increased and in the mountain regions, the treeline and snowline dropped. In addition to all the problems, the glaciers advanced in the Alps and Northern Europe which led to the destruction of many towns and farms. 

• There has been evidence that supports the idea that glaciation was increased due to the mountain glaciers and it hit a number of widely spread regions outside Europe in the early twentieth century which included New Zealand, Alaska, and Patagonia. Advancing of the glaciers differed in different regions, which suggested that they may not represent a globally synchronous increased glaciation but it suggested that they represent largely independent regional climate changes. 

• Due to this reason, much evidence suggests and does not support the idea that there was a globally synchronous period or an event of cold or warmth over these intervals and that is the reason this period is referred to as the ‘little ice age’.

• The conventional terms such as the ‘the little ice age’ and the ‘Medieval Warm Period’ appear to have limited usefulness in describing trends in the hemispheric or the global mean temperature in the past centuries. 

• The little ice age could be considered as an age when there was modest cooling of the Northern Hemisphere and during this period the temperature was less than one degree celsius. 

• The hardest-hit area during the little ice age was Iceland. It was very difficult to bring the ship ashore anywhere along the coast. It became an impossible task to grow grains or even hay crops in Iceland during this period. The volcanic activity made life even harder and during the little ice age, Iceland lost half of its population. 

• In Scandinavia, many farms were destroyed due to the advancing ice of glaciers and the meltwater streams. In the high mountains(Alps), the glaciers advanced and destroyed many towns. Ice-dammed lakes busted many times and as a result of that destroyed hundreds of buildings and killed thousands of people. 

Dating of the Little Ice Age 

• There is no specific time to prove when the ice age began but a series of events before the climatic minima are considered to be the cause.

• Based on radiocarbon dating of roughly 150 samples of the dead plant material with the roots intact which was collected from the ice caps of the Baffin islands and Iceland, it states that cold summers and the ice growth began between the year 1275 and 1300 which was followed by a substantial intensification from the year 1430 to 1455. 

• Climate reconstruction which was done based on the glacial length shows no variation from the year 1600 to 1850. Their fore tit has been believed that any several dates ranging over 400 years may indicate the beginning of the little ice age. 

• It is believed that in the year 1250, the Atlantic pack ice began to grow. The cold period was enhanced by the massive Samalas volcanic eruption in the year 1257.

• It is believed that the event in which radiation dating plants that were killed by the glaciation happened between the year 1275 to 1300. 

• In the year 1300, the warm summers stopped being dependable in Northern Europe. 

• The great famine started in the year 1315 and lasted till 1315 and so did the rain which killed many people and destroyed acres of lands. 

• The worldwide glacial expansion which is also known as the Grindelwald Fluctuation began in the year 1560 and lasted till 1630. 

• The little ice age ended in the early 20th century or the later half of the 19th century. 

Little Ice Age and Europe

• During the little ice age in Europe, despite the difficulties which many people were facing in the marginal regions, the culture and the economy were generally flowering. People of Europe started to transform their surrounding environment during the  17th and 18th centuries where there was an expansion in agriculture and also there was large-scale reclamation of the land. 

• The little ice age also coincided with the maritime expansion of the European and the creation of seaborne trading and later colonial empires such as the Portuguese, Spanish, which were followed by the Dutch, English, and European nations.Sea trading was successful due to the development of the shipbuilding technology which was a direct response to the climate pressures and the trading strategies.

• Art and architecture were in boon during the little ice age period. The winter landscape paintings can be considered as the direct result of the little ice age. This painting showed the viewers many things such as the ice-skaters enjoying themselves, which was considered as the sign that people at that time were more capable to withstand the harsh winter conditions and that they also had enough food. 

• In the isolated regions such as the high alpine areas of Switzerland, Iceland, or the highlands of Scotland, the unfavorable weather conditions of the little ice age such as the cold springs and harvest raisin as well as the longer winters had a strong influence on the grain prices and were the drivers for the local famines. 

• The little ice age was characterized by the increased droughts and the increased flood frequency in central Europe. The impact of the little ice age differed in different parts of Europe, some regions thrived while others struggled. 

Little Ice Age Cause

Many of the scientists do not have an exact idea, but few scientists have identified seven possible causes of the little ice age which are orbital cycles, decreased solar activity, altered ocean current flow, volcanic eruptions, the inherent variability of the global climate, and the fluctuation in the human population.

Volcanic Activity 

• It is believed that the cool conditions in different regions during the little ice age might have been the influence for the explosive volcanic eruptions such as the eruption of Laki in Iceland in the year 1783 and again on Sumbawa island in the year 1815. When the volcanoes erupt they propel gases and ash in the stratosphere which then reflect the incoming solar radiation.

• Volcanic eruptions have been linked to the conditions of lower average temperature around the world which may have lasted a few years. 

• There has been an argument about the volcanic eruption between the scientist were some scientist have speculated an idea that such volcanic eruptions might have the strength and might have extended the negative phase of the NAO which resulted in bringing cooler conditions in the northern hemisphere, however, there are other scientists who have argued that the explosive volcanic eruptions may be linked to the warmer winter conditions across northern Europe. 

Orbital Cycles 

• For the past two thousand years, orbital forcing from the cycles in the earth’s orbit around the sun has eventually caused a long-term cooling of the northern hemisphere that continued throughout the medieval ice age and the little ice age.

• The rate of Arctic cooling is about 0.02-degree Celsius per century and this was the trend that was believed to continue in the future but due to the rise in the global temperatures around the planet which is a direct result of excessive greenhouse gases emissions, there has been a sudden reversal of the trend.

Ocean Circulation

• Another possibility of what was the cause of the little ice age could be that there was a slowing of the thermohaline circulation. The thermocline circulation might have been interrupted by the introduction of a large amount of freshwater into the North Atlantic which could have been possibly caused by a period of warming before the little ice age which is known as the Medieval Warm period.

• There has been speculation that the shutdown of the thermohaline circulation could have happened again as a result of the present warming period. 

Fluctuation in the Human Population 

It has been speculated that the increased human populations which were living in the higher latitudes could have caused the little ice age through deforestation. The increase in human population is also one of the main reasons for the increase in global warming all around the world.