Here is a compilation of term papers on ‘Groundwater’ for class 6, 7, 8, 9, 10, 11 and 12. Find paragraphs, long and short term papers on ‘Groundwater’ especially written for school and college students.
Term Paper on Groundwater
Term Paper Contents:
- Term Paper on the Meaning of Groundwater
- Term Paper on the Occurrence of Groundwater
- Term Paper on the Geomorphic Work of Groundwater
- Term Paper on the Quality of Groundwater
- Term Paper on the Causes of Groundwater Depletion and Contamination
- Term Paper on the Pollutants of Groundwater
- Term Paper on the Conservation of Groundwater
Term Paper # 1. Meaning of Groundwater:
The water present in the pore spaces of regolith (the layer of loose and unconsolidated materials lying over the bedrocks is called regolith) and bedrocks (bedrocks are those rocks which have not been weathered and eroded) below the ground surface is called groundwater.
The main source of groundwater is rainwater and melt-water which infiltrates downward through the pore spaces of surficial materials and collects in large quantity in aquifers of varying sizes and locations. Aquifers refer to the storage pools of groundwater lying below the ground surface.
The groundwater is also called subsurface water or underground water but the latter is not in use. Sands form most ideal aquifers but permeable sandstones also form extensive aquifers. The percolating water fills the pore spaces of regoliths and permeable rocks. This process is known as saturation of regoliths and rocks. When almost all of pore spaces are filled with water, the zone is called saturated or phreatic zone.
The upper level of the saturated zone is called groundwater table or simply water table (fig. 19.1). The zone lying above the water table is unsaturated and is called unsaturated zone or vadose zone or aeration zone because the pore spaces of the regoliths and permeable rocks are partly filled with water and partly with air (fig. 19.2).
The position and movement of groundwater become complicated when there is arrangement of alternating aquifers and impermeable beds. The impermeable bed separating two aquifers is called aquiclude because it obstructs or impeds water movement between two aquifers (fig. 19.2). When an aquifer is zagged between two impermeable beds or aquicludes there is produced a confined water reservoir which gives birth to artesian wells.
When an aquiclude lies between two aquifers, the water table of upper aquifer is called perched water table (fig. 19.2). There is seasonal and annual fluctuation in the depth of water table of groundwater through percolation of rainwater and therefore water table rises but during long period of drought there is considerable fall in water table.
Term Paper # 2. Occurrence of Ground Water:
During and after rains large portion of water is absorbed by the soil mass. The absorbed water then travels downwards. While moving downwards it replenishes the soil moisture deficiency. Surplus water then travels further down and ultimately becomes static.
As such soil mass can be divided into two main zones:
(1) Unsaturated zone of soil; and
(2) Saturated zone of soil.
The water which exists in the unsaturated zone is called soil water and is held in pores of the soil particles by some force or the other. This water is readily used by plant roots. Strictly speaking the water which exists in the saturated zone is called groundwater.
In the saturated zone of soil the water particles surround the soil particles to such an extent that all soil particles are completely submerged in the water. Whenever some extra infiltration water comes it has no scope to go further down. It then spreads in lateral direction and submerges the soil particles of the overlying layers. In this way the extent of zone of saturation goes on increasing.
Term Paper # 3. Geomorphic Work of Groundwater:
The geological or geomorphic work of groundwater includes chemical erosion of soluble rocks at the surface by surface water and below the surface by percolating and moving groundwater, limited transport of eroded materials in suspended form and deposition of solutes.
It may be pointed out that the geological work of groundwater is exceedingly slow because of its very slow rate of movement. Only that part of chemical erosion of carbonate rocks at the ground surface is included in the geological work of groundwater which is related to the infiltration of rainwater.
i. Erosional Work:
Besides erosional work, groundwater also facilitates slumping, debris slides and fall and landslides on steeply inclined hillslopes because groundwater acts as lubricator. The erosional work of groundwater is performed through the mechanism of corrosion or solution, corrasion or abrasion, attrition and hydraulic action but the last three types of erosion are not effective because of exceedingly slow movement of groundwater and thus corrosion or chemical erosion is the only effective method of denudation of carbonate rocks (such as limestones, dolomites, chalk etc.) by surface and subsurface water (groundwater).
Rainwater mixed with atmospheric carbon dioxide (CO2) and organic CO2 becomes active solvent agent and disintegrates and dissolves carbonate rocks at the surface and below the surface to form numerous types of solutional landforms. According to R.M. Garrels there are seven variables which control limestone solution viz. (1) partial pressure of CO2, (2) H2CO3 (carbonic acid), (3) HCO3- (bicarbonate ion), (4) CO32- (carbonate anion), (5) H+ (hydrogen ion), (6) OH– (hydroxyl ion) and (7) Ca2+ (calcium cation).
The following chemical processes reveal the chain of exothermic reversible and non-reversible reactions right from the formation of limestone (CaCO3) to its dissociation (solution).
Calcium hydroxide (Ca(OH)2 is formed due to reaction of water (H2O) with calcium oxides (CaO) in the following manner:
Calcium carbonate (CaCO3) is formed due to reaction of Ca(OH)2 with carbon dioxide (CO2) in the following manner:
Carbon dioxide (CO2) when dissolved in water forms carbonic acid (H2 CO3):
Carbonic acid is easily dissociated into positive hydrogen ion (H+) and negative bicarbonate ion or hydrogen carbonate ion HCO3– which produces source of acidity in the solution as given below:
Calcium carbonate dissociates in pure water into a metal cation (Ca2+) and carbonate anion (CO32-) during the process of dissolution in the following manner:
Calcium carbonate reacts with CO2 and H2O or say carbonic acid (H2CO3) to form calcium bicarbonate (Ca(HCO3)2 which is soluble in water:
It may be pointed out that the amount of carbonate rocks depends on temperature, partial pressure of atmospheric carbon dioxide, organic carbon dioxide, the chemical composition of carbonate rocks (calcium carbonate-limestones, magnesium carbonate – dolomite, and chalk), joints of the rocks, nature and rate of flow of groundwater, contact time of solvent (water) and carbonate rocks, route of water flow etc. There is inverse relationship between temperature and solubility of carbon dioxide and positive relationship between the dissolution of carbonate rocks and temperature.
ii. Depositional Work:
As the chemical erosion (dissolution) of carbonate rocks continues, the groundwater or say solvent receives more and more solutes and becomes saturated with sediments. Since the movement of groundwater is exceedingly slow it cannot transport enough materials. Thus, chemical erosion and deposition go together.
Larger sediments immediately settle down whereas suspended fine materials kept in solution form are deposited due to following factors:
(1) Due to obstruction in the flow path of groundwater and consequent decrease in the flow velocity of the solvent.
(2) Due to evaporation of water because of increase in temperature and consequent decrease in the volume of groundwater and increase in solute-water ratio.
(3) Due to decrease in solution capacity of groundwater etc.
Deposition of sediments takes place at various places in various forms e.g.:
(i) At the floor of caves,
(ii) Along the ceiling of caves, and
(iii) In the rock joints etc.
Term Paper # 4. Quality of Groundwater:
Based on the characteristic features of a majority of ground waters in use with the farmers in different regions of the country and the above indices that describe the nature of hazards on soil and crops, irrigation waters have been broadly grouped into good, saline and alkali waters. Depending on the degree of restrictions, the two poor quality water classes have been further grouped each into three homogenous subgroups Table 12.13.
High salinity groundwaters are mostly encountered in arid parts of northwest states like Rajasthan, Gujarat and Haryana. Alkali waters are found mainly in semiarid parts of India, where annual precipitation varies between 500 and 700 mm. High RSC waters are common in central and southwestern Punjab.
TABLE 12.13: Grouping of poor quality groundwater
Term Paper # 5. Causes of Groundwater Depletion and Contamination:
Groundwater is an integral part of the environment, and hence cannot be looked upon in isolation. There has been a lack of adequate attention to water conservation, efficiency in water use, water re-use, groundwater recharge, and ecosystem sustainability.
An uncontrolled use of the borewell technology has led to the extraction of groundwater at such a high rate that often recharge is not sufficient. The causes of low water availability in many regions are also directly linked to the reducing forest cover and soil degradation.
Pollution of groundwater resources has become a major problem today. The pollution of air, water, and land has an affect on the pollution and contamination of groundwater. The solid, liquid, and the gaseous waste that is generated, if not treated properly, results in pollution of the environment; this affects groundwater too due to the hydraulic connectivity in the hydrological cycle.
For example, when the air is polluted, rainfall will settle many pollutants on the ground, which can then seep into and contaminate the groundwater resources. Water extraction without proper recharge and leaching of pollutants from pesticides and fertilizers into the aquifers has polluted groundwater supplies.
In addition, leachates from agriculture, industrial waste, and the municipal solid waste have also polluted surface and groundwater. Some 45 million people the world over are affected by water pollution marked by excess fluoride, arsenic, iron, or the ingress of saltwater.
Term Paper # 6. Pollutants of Groundwater:
i. Metals:
In general, ground water is mostly chemically and microbiologically non-polluted and thus safe for drinking and cooking in addition to agricultural or industrial uses. But in recent decades there were enormous amount of reports of ground water contamination of arsenic, fluoride or nitrate. This contamination causes serious health hazards in the long run.
It is well-known that ground water contamination with toxic metals principally takes place due to leaching from toxic waste dumps or from crustal layer of earth through biotransformation. Agricultural chemicals also leached into upper aquifers and thus contaminate the ground water.
ii. Nitrate:
Nitrate in ground water is primarily derived from mineralization of soil organic matter or from use of excessive nitrogen fertilizers. The nitrate content in supply water ranges from less than 1 mg NO3– per lit to around 50 mg NO3 per lit. The limit of 50 mg NO3 per lit was originally set to protect babies against methanoglobinaemia.
This is a condition where more than about 10% of the haemoglobin in the blood is converted into the methanoglobin form. It is a reversible condition, but death can occur only if more than 40% of the haemoglobin in the blood is converted because of reduced oxygen carrying capability. The condition methaenoglobinaemia occurs in young infants with high nitrate level in well water used for making milk formulae.
It has also been suggested that a high nitrate can reduce the body assimilation’ of iodine, thus causing goiter. It has also been suggested that an increased nitrate intake through drinking water carries an increased risk for bearing a malformed child in pregnant women.
iii. Arsenic:
Ground water arsenic contamination is known over the years in various parts of the world. However, the major incidence noted in Indian subcontinent is in West Bengal and Bangladesh region, where a vast tract is under the arsenic calamity. Several thousands of people are suffering from chronic arsenicosis through drinking of contaminated ground water.
The problem relating to arsenic contamination in ground water of West Bengal was first noticed in 1978 through a short study made by School of Tropical Medicine, Kolkata. Then, with the initiative of Public Health Engineering Dept., Govt. of West Bengal, an elaborate study was made during 1988-91 for making detailed report on the status of arsenic contamination of ground water.
All Indian Institute of Health & Hygiene, Central Ground Water Board, Centre for Man and Environment, State Water Investigation Directorate, and School of Environmental Sciences (Jadavpur University) participated in the detailed investigation on the said aspect.
The report indicates the fact that along a linear NNW-SSE tract extending from Kaliachak in Malda through Raninagar in Murshidabad, parts of Nadia and North 24 Parganas up to Baruipur in South 24 Parganas, the ground water between 10-80 m below ground level has been found to contain arsenic, at places above permissible Level of 0.05 mg/liter.
The area forms a part of the Ganga- Brahmaputra delta having a near surface succession of quaternary sediments of varying thickness. The arseniferrous belt lies entirely within the upper delta plain (UDP) characterised by a series of meander belts formed by rivers.
Arsenic content of ground water tapped at some depth within the same zone varies between wide limits. However, the maximum arsenic content occurs in ground water in the 20-60 m range, ranging from < 0.01 mg/lit up to a maximum of 2.0 mg/lit. There was no water samples (collected from ponds or dug- wells) containing arsenic above 0.01 mg/lit.
It has been established beyond doubt that water of the intermediate aquifer is polluted with arsenic. Neither the shallow first for the deep (third) aquifer contain arsenic above the permissible limit. The ground water in arseniferous areas is characterised by high iron, arsenic, Ca, Mg and bicarbonate with low chloride, sulphate and fluoride. The pH is about 7 to 8, which is very ideal for leaching of arsenic.
Further, it is speculated from the lithological and minerological analysis that the sources of the arsenic in the groundwater is primarily in the clayey sediments immediately above and intercalated within the intermediate aquifer.
These sediments were perhaps transported from the Chhotanagpur-Rajmahal highlands and deposited in sluggish meandering streams under educing conditions. Under such conditions arsenic got deposited partly as arsenious minerals, partly absorbed on surfaces of minerals or clay particles and the rest as organic complexes.
Arsenic content in ground water as measured in some areas of West Bengal is given in Table 11.8:
In many areas of West Bengal, the ground water-of shallow depth in particular—is contaminated with higher quantity of arsenic. It is now felt urgent to identify those sources and prevent the inhabitants not to consume such water.
In contrary, deeper tube well or dug well does not contain appreciable amount of arsenic. So it is wise to provide them either some deeper tube well or dug well or alternative source of treated surface water for drinking.
As the dissolved inorganic arsenical substance can make complex with various alum, it can easily be precipitated and then filtered for removal of contaminated arsenic. Many trials has already reached a great deal of success.
Yet much is needed to develop for promotion of efficacy at grass-root level. Chemical investigation with respect to routine urine and blood test for arsenic determination or its deposition in hairs or nails among the affected population is still quite inadequate.
Some arsenic removal technology currently adopted in arsenic affected area:
Further, the status of arsenic in crops and vegetable grown under shallow irrigation was not at all assessed in depth. There were enormous scopes for studying of arsenic in the ecosystem as a whole in near future.
iv. Fluoride :
Like arsenic, fluoride contamination was also reported since mid 1970s, in some districts of West Bengal and Assam. Earlier there were reports of surface water (dug well) contamination of fluoride in Andhra Pradesh. Due to such contamination, exposed community suffers very much in both short-term and long term basis.
There were reports of bony deformity and associated problems of locomotory organs .The children are more susceptible than the adults. There is a great need for identification of contaminated areas and also need for supply of clean non-contaminated water for cooking and drinking.
Government efforts to deal with the problem of fluoride contamination have focused primarily on providing safe drinking water through various schemes and the distribution of de-fluoridation plants at household and community levels. However, the main constraint to the success of these schemes has been lack of maintenance of these plants.
The Rajib Gandhi National Drinking Water Mission set up 427 de-fluoridation plants across the country, many of which are not in operation today. DANIDA initiated a rural water supply and sanitation project scheme in Karnataka’s four districts that include de-fluoridation. Central Government also proposes to provide 50,000 household water filters to families and groups of people at sub-sidised rates of Rs. 1,500-2,500 each.
An interesting scheme is being implemented in Punjab, where Uruguay gifted a modular water-treatment plant, the first of its kind in India, to the village of Talwandi Sabo. It was successfully implemented and now the Punjab Government has signed a MoU with the Uruguay Government for installing 20 such plants at a cost of Rs. 20 lakh each.
The compact plant requires little space, and purifies water with a mix of coagulation, sedimentation and filtration. According to the Ministry of Rural Development, fluoride mitigation centres are to be set up across the country. Currently in the first phase, centres are being proposed in three states of Andhra Pradesh, Rajasthan and Gujarat to increase the availability of potable water in villages.
Some technology intervention for removal of fluoride is given:
v. Iron :
In most places in India, iron is also a major contaminant of ground water, so also drinking water too. There is also need for iron removal.
Control measures include providing alternate sources of water free from iron or treating iron contaminated water to within permissible limit of 1 mg/l with the help of iron removal plants. For treating iron contaminated water, the Rajib Gandhi Drinking Water Mission has approved the installation of 16,415 plants, out of which 9,355 plants have already been commissioned.
Iron removal from water supply can involve complex choices. The selection of an appropriate iron removal equipment would depend on the type and quantity of iron in the water, the characteristics of the water supply, other water treatment equipment in use, and the user’s requirements for cost, convenience of usage, and maintenance.
Term Paper # 7. Conservation of Groundwater:
It is important to realize that groundwater is not a resource that could be utilized unmindfully simply because it is available in abundant quantities. Problems and issues such as water logging, salinity, agricultural toxins, and industrial effluents, all need to be properly looked into.
Other than legislation and checks to conserve and improve the quality of groundwater, society itself plays a very important role. During the last decade there has been a rising awareness among the common people on the need for conservation and development of groundwater. Water use has to be integrated effectively with water regeneration, as was done in many traditional technologies.
Renovation of forest tanks in drought-prone regions will have a significant impact on wildlife and forest cover. Similarly, in some urban cities there is a need to regenerate groundwater aquifers because of the high degree of dependence on them for drinking water. Rainwater harvesting schemes have been taken up in many cities and even made compulsory in some of them.
Temple tanks need to be renovated and urban wetlands protected. All these will contribute to a rise in the groundwater level and a reduction of salt water ingress. Community awareness and management of freshwater resources should be enhanced.
The government should implement effective groundwater legislation and regulations through self-regulation by communities and local institutions. External support agencies should support freshwater resource management. Environmental restoration should be promoted along with household water security.
No single action whether community based, legislation, traditional water harvesting systems, or reliance on market forces will in itself alleviate the crisis in India. The effective answer to the freshwater crisis is to integrate conservation and development activities—from water extraction to water management—at the local level; making communities aware and involving them fully is therefore critical for success. All this will ultimately pave the way for combining conservation of the environment with the basic needs of people.
In India, the Water (Prevention and Control) Act was passed by the Parliament in 1974, and by 1990 all the states adopted the act. In 1986, the Environment Protection Act was passed by the Parliament. Under both these acts, the states and the central government developed environmental norms for air emissions and wastewater discharge for different types of sources.