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Unit III : Module 8
Impacts of anthropogenic interventions in surface water storage systems
Component-I (A) - Personal Details
Role Name Affiliation
Principal Investigator Prof. Masood Ashan Siddiqui Jamia Millia Islamia Paper coordinator Dr. Suresh Kumar Bandooni Shaheed Bhagat Singh
Evening College Content Writer/Author (CW) Dr. Sanjeev Sharma Centre for the Study of
Regional Development, Jawaharlal Nehru University New Delhi
Content Reviewer (CR) Dr. Suresh Kumar Bandooni
Speaker Dr. L. Mirana Devi
Assistant Professor Mobile No. 9910100712
Email :Mirana.devi@gmail.com
Department of Geography Shaheed Bhagat Singh Evening College,
Sheikh Sarai Phase –II, New Delhi -110017
Language Editor (LE)
Component-I (B) – Description of Module
Items Description of Module
Subject Name Geography
Paper Name Water as a Resource in the Anthropocene
Module Name Impacts of anthropogenic interventions in
surface water storage systems
Unit / Module ID WR-25
Pre-requisites Objectives Keywords
2 Component-I (B) –
Impacts of anthropogenic interventions in surface water storage systems
Objectives of the Module
i. To know the importance of water in Anthropocene.
ii. To know the process of water storage system.
iii. To know the major anthropogenic interventions in water storage system.
iv. To know the impacts of human activities on water storage system.
After studying this module students will be able to describe anthropogenic interventions and their impacts on water storage systems and establish the relationship between anthropogenic activities and process of water storage system.
The role of water in the Anthropocene
Mankind’s activities gradually grew into a significant geological, morphological force during the Holocene – the post-glacial geological epoch of the past ten to twelve thousand years ago (Crutzen, 2002). In the latter part of the 18th century on the planet earth due to human‘s activities atmosphere and its environment started changing. Ecologist Eugene F. Stoermer subsequently used term “Anthropocene” with different scene in 1980, the term was widely used in 2000 by atmospheric Chemist Paul J. Crutzen. Later in January 2016, report on the Climate, Biological and Geological signature of human activities in sediments and ice cover suggested the era since the mid 20th century should be recognized as geological epoch from Holocene. The term Anthropocene reflects the increasing large number of human activities and interference in natural environment in bringing about global environmental change. Human beings has began the modification of terrestrial water cycle by interrupting river flow from high-lands to the sea and, through land-cover change, by altering the water vapours flow from the land to the atmosphere (Savenije et al., 2014). Now impacts of human activities on water resource system can be considered of global significance for future evolution of all living species. Evolution of industrialization has been called the period of Anthropocene because human have altered the planet earth ‘s natural resources i.e. scarcity of water resources and disappearing water bodies during this period have rising.
Water has no substitutes for most of the human use and all living organisms on this planet earth.
Presently human beings are using 26% of the total terrestrial evapotranspiration and 54% of the runoff that is geographically and temporally accessible (Postel et. al., 1996). The various reservoirs in which freshwater is stored are ice cap, glaciers, snow peak, soil moisture, vegetation and ground water. The construction of artificial reservoirs could increase accessible runoff by about 10% over 30 years where as population is projected to increase by more than 45.
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Unavailability of good quality and sufficient quantity of water resources in different location throughout the globe leads towards changing ecosystem pattern, energy flow, ecological degradation, changes in hydrological cycle, impacts on agricultural and industrial production, various human health threats and rising internal geo-political conflicts are major issues of disturbing water storage system (Postel et. al., 1997).
Importance of water resources
Water is the basic need to all other living organism including plant life. Water is prerequisite for existence of life on this planet earth. In fact, the human body is mostly made up of water. The availability of surface water and its quality and quantity plays a very essential role in the storage and recharging process of water resources. It plays a major role to regulate the local to global climate, weather and ecological system of the earth. Global water use has grown more or less exponentially with human population and economic development over the industrial era.
Because of the interaction of all components of the environment between atmosphere, lithosphere, hydrosphere and biosphere and the consistency of the global water cycle, any change or modification in one of these spheres will consequently lead to a modification of the hydrological cycle and water balance. In this context human activities play a special role. As a part of the biosphere it massively influences other spheres, especially through water consumption and influencing the global hydrosphere.
The demand for global water is expected to increase in all sectors by rapidly growing population.
By 2030, the world is projected to face 40% global water deficit (UN, 2016). There are a number of reasons for the increasing water scarcity. Increasing urbanization is causing specific and often highly localized pressure on freshwater resources. Globally 70% withdrawn of water is for agriculture and energy production, which currently account for 15% of the world are expected to increase by 20% through 2035 (WWAP, 2015 & 2017). Increasing industrial production will lead to increase water use with potential impacts on the water quality and quantity at local to global scale. Because of the complex bio- physical and chemical properties of water it does not only serve humans as a source of food but also as a means of production in agriculture, aquaculture, forestry, industry, energy and as a means of transport. An artificial alteration to the natural cycle of water has produced massive changes in agricultural landscape and in aquatic, riparian, wetland and other floodplain habitats. These interventions have had both positive and negative impacts on the problems that they were intended to solve. Some of these activities have greatly constrained the degree of interactions between the river channel and the associated floodplain with catastrophic effects on biodiversity.
The process of water storage system: Surface water and ground water interaction
Understanding the process and mechanism of surface water storage system and interactions with ground water is very essential. Surface water storage includes water accumulated in the soil
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surface or underground, intercepted water, i.e. the rainfall quantity retained by vegetation cover, and water retained in flooded plains, lakes, swamps, pools etc. Precipitation in different form and in general through rain on the surface of the earth can be stored in river, lakes, ponds and penetrate into the soil. When the water level will rise, it will transport to downstream to percolate in the soil and some amount will evaporate and store in the atmosphere in the form of water vapour. Surface water is very important for storage of water and to regulate water cycle (Fig.1).
Rain water can also be stored into the ground which depends upon the geological structure of the rock and pores and particles size of the soil. The pores in clay soil account for 40% to 60% of the total volume and in fine sand material it can be stored upto 20% to 45%. The process of water entering into the soil is called infiltration. Infiltered water can be stored in underground storage reservoirs and it again flow and reach back in river, lakes or other form of surface water and used and evaporate by vegetation and soil.
Fig 1. Surface water storage system (Sources: Musy, 2001) Impacts on water recharging capacity of surface water
Surface water diversion and change the water storage system in aquifers and water bodies will affect the water recharging capacity of the surface and water cycle. Direct or indirect modification of natural interaction by various anthropogenic activities along the streams, rivers,
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water bodies and changing precipitation pattern can change the interaction between surface and ground water storage system. E.g. contaminated aquifers which discharge to stream can result in long term contamination of surface water. The present information and knowledge about their process and mechanism is very limited. Surface water is directly hydraulically connected to ground water but the interactions are difficult to observe and measure (Winter et.al., 1998). The ground water have interaction with all type of surface water resources i.e. river, stream, wetlands in landscape from high mountain to coastal to the ocean and maintaining the availability of water on the surface. The movement and circulation of the water in the atmosphere and terrestrial environment is very easy to visualize but cannot be possible to visualize ground water storage system. Surface water comes from precipitation infiltration through the unsaturated zone.
Distribution is highly variables with space and time. Evaporation and transpiration process return water to the atmosphere. Evaporation and transpiration rates vary considerably according to climatic conditions, topographic and geologic feature. As a result, much of the precipitation never reaches the oceans as surface and subsurface runoff before the water is returned to the atmosphere. Pathways followed by subsurface runoff on hill slopes are shown in figure 2.
Fig. 2. Pathways followed by subsurface runoff on hill slopes (Winter et.al., 1998, https://pubs.usgs.gov/circ/circ1139/pdf/circ1139.pdf ).
Surface and ground water interface
Shallow ground water is more susceptible to contamination by human sources and activities.
Geologic features in the surface bed affect seepage pattern i.e. sand inflow seepage is greater at
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the shoreline and it decrease in a nonlinear pattern away from the shoreline. Fig. 3-4 show underground water recharge and seepage system and in Fig. 4a &b, water flow diagrams depicts that, the quantity of discharge is equal between any two flow lines; therefore, the closer flow lines indicate greater discharge per unit of bottom area. Changing meteorological condition also strongly affect water storage system in surface water beds near the shorelines.
Fig. 3. Ground-water flow paths vary greatly in length, depth, and travel time from points of recharge to points of discharge in the groundwater system (Winter et.al., 1998).
Fig. 4a. Ground-water seepage into surface water usually is greatest near shore; Fig. 4 b.
Subaqueous springs can result from preferred paths of ground-water flow through highly permeable sediments.
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Due to strong interface between surface water and ground water the recharge system between surface and ground water is affected by the environmental conditions, human activities on land surface and n in the upstream and catchment area.
Anthropogenic interventions in surface water storage system
Human activities are impacting the available global water resource system (Fig. 5). Until the industrial revolution, human activities played an insignificant role in influencing the dynamics of earth system. Now the relationship between humanity and water resource is continuously changing since the period of industrial revolution. But presently human beings and their activities exceed nature in terms of changing the biosphere and affecting all other aspects of earth functioning system. There are number of reasons for increasing human intervention in surface water storage system. The history of earth formation which formed around 4.5 billion years ago has seen many immense biological, geological and cultural events.
Human and their activities have high influenced on surface water and earth water storage system in many ways. Human interventions in the nature are increasing day by day especially after agricultural development and industrial revolution. In the most recent part of the Holocene anthropogenic impacts become much more extensive. In the second half of the 20th century humans are shifted from rural to highly urban population, agricultural industrialization by green revolution and increasing pressure of chemical exploiting surface and ground water resources, uncontrolled use of pesticides and increase in the rate of fossil fuels consumption. There is a long list of human activities and their impacts on the water system of the earth surface. Damming major river system, ecological degradation of aquatic ecosystem and their biota altered the earth’s atmospheric climatology, chemistry, snow cover, permafrost, sea ice extent, glacial ice and extra ocean volume. The rapidly increasing population is also reducing the useable supply of water in rivers, lakes and groundwater. In many places the rates of extraction of ground water for domestic and irrigation purpose are so high that aquifers are getting depleted. In addition to that unsustainable development pathways and governance failure have generated immense pressure on water resources and affecting the quality and availability of water. However, as population growth continues and standard of living rises, there is rapidly increasing impacts on all aspects of the hydrological cycles.
The planet earth capacity to sustain the growing demands for freshwater is beings challenged and unless there can be no sustainable development until the balance between demand and supply of water can be restored.
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Following are the major human interventions for terrestrial water storage system
1. Construction of engineering structure to control water flow for water resource management
2. Land use practices
3. Irrigation and extraction of ground water 4. Development of intensive agricultural 5. Construction of dams/reservoirs 6. Soil erosion
7. Changes to the surface of earth
8. Impacts of anthropogenic interventions in surface water storage system 9. Draining wetlands and loss of wildlife habitat
10. Desertification 11. Impacts on Estuaries
12. Ground water depletion and groundwater pollution 13. Diminishing Surface Water and land subsidence 14. Change in self purify capacity of water recharge 15. Salinity and salanisation
16. Salt water intrusion
17. Change in water balance and climate change
18. Redistribution of major storage pools of freshwater and change in continental runoff.
19. Impacts on the drainage basin and river system.
20. Impacts on land to ocean linkages.
21. Agricultural development
22. Unscientific and unregulated irrigation system.
23. Rapid growth of unplanned urbanization.
24. Rapid of rate industrialization and releasing of its effluents.
25. Mining/quarrying for extraction of mineral resources and construction activities.
26. Solid waste disposal on the land surface and in and around water bodies.
27. Water pollution by various human activities.
28. Climate change and its impacts on water resources and water storage system.
Some of the anthropogenic intervention and their impacts are explained in details as below:
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1. Construction of engineering structure to control water flow for water resource management:
Construction of engineering water structure is responsible for diversion of water from one part of the hydrological cycle to another. These human modifications in natural environment leads towards the reduction or increase in natural hydrological fluxes.
Under ground water is a major source for human needs and activities like irrigation and drinking in the arid and semi-arid region. The natural rates of water recharges to aquifer are very slow in the arid and semi-arid region. When the rate of extraction of water is increasing, it will transfer from aquifer to the atmosphere. The results will deplete the continental water storage and temporary increase water vapour in atmosphere through enhanced evaporation flux. Secondly, diversion of surface water for irrigation purposes internally draining basin of arid and other region result increased the rate of evaporation and loss of surface water. e.g. shrinking Aral and Caspian Sea are striking examples of this effect, where as lake Chad acted in the opposite direction but with much smaller magnitude. Net loss of water from such lakes by aquifer mining leads to net decreases in continental water storage system.
2. Land use practices:
Land use practices are assumed to have important impacts on both the availability and quality of water resources. Land use practices will directly or indirectly impacted in both positive and negative manner not only to the people living in the periphery but also the people living in the downstream region. Improved land management practices are helpful to regulate water storage system. But, other hand side inadequate land use on the water resources, might not only be felt by water users who cause them, but also by others who have some association with these area.
Different land use practices affect hydrologic regime and water quality. The groundwater recharge may be increased or decreased as a result of changing land-use practices. In order to establish linkages between upstream land and downstream water users, it is important to have a clear picture of the possible impacts of land uses on both hydrologic regime (water availability) and water quality, and the scales at which these impacts are relevant. Impacts of land use practices on water quality and storage system are like:
(i) Salinity, pesticide pollution and eutrophication due to nutrient influx, however, may be relevant in medium- to large-scale river basins as well.
(ii) These impacts may affect many downstream uses, including drinking water, industries, fisheries, animals and other agricultural uses.
(iii) Major land use practices like grazing, forestry, fisheries, mining, quarrying, urbanization and industrialization have major impacts on the hydrological regimes.
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(iv) The impacts of land use practices on water resources depend on a host of natural & socio- economic ability and awareness of the farmer’s management practices and the development of infrastructure.
Impacts of land use practices on surface water can be divided into two parts:
(i) Impacts on the mean annual runoff and overall water availability (ii) Impacts on the distribution of water availability on seasonal basis.
3. Irrigation and extraction of ground water:
Withdrawal of ground water from shallow aquifers for various human uses can reduce the availability of surface water and its storage system. Extraction of ground water over pumping and unscientific irrigation system has significant impacts on the surface water in different region.
Following are the main causes for high amount of extraction of underground water are:
1. Unregulated access to groundwater sources.
2. Affordable small electric and diesel pumps.
3. Irrigation requirement for agriculture.
4. Free availability of water in the nature.
5. Subsidized electricity and fossil fuels have leads over pumping of groundwater for irrigation.
It was observed by McGuire, 2007 and Faunt, 2009 that due to ground water over pumping and irrigation system have caused wide spread depletion of ground water drying of stream in high plains and Central valley region of USA, North China plain (Wang et.al., 2007) northwest India (Rodell et. al., 2009). The dramatic growth in irrigated agriculture and consequent demand for water is also met by diverting and or strong surface water.
However, withdrawal of water from river to spread on land accelerates the accumulation of salt through evaporation. Irrigation, water logging and salinity affect the surface water storage system. The impact of irrigation on the global water balance might observe small. However, Postal et. al., (1996) concluded that over 50% of the globally accessible runoff is currently used by humans. Inflow to the groundwater system from recharge will equal to outflow to the stream plus the withdrawal from the wall. Depleting ground water source is serious threat to the water storage system, ecology and environment. The rate of pumping of groundwater from aquifers is high and does not replenish as same rate. Recent study conducted by Richey et.al. (2015) and found that 21 of the world’s 37 largest aquifers are overdraw, 13 have declined so rapidly that they are in critical condition, with the most stresses aquifers found in poor highly populated area such as northwest India, Pakistan and north Africa.
Rapid growth of urbanization is increasing excessive ground water extraction and has depleting water table and causing land subsidence. A large numbers of the river, lakes and Inlands Sea are drying due to high amount of withdrawal of underground water. The main consequence of unlimited withdrawal of water are depleting water table, drilling of deeper wells and depletion of
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water resources. The other sources and common activities of degrading water storages system and generating ground water pollution hazards are shown in figure below:
Fig. 5. Common activities generating a groundwater pollution hazard (Source: Global Water Partnership, August 2014)
4. Development of intensive agricultural:
Agricultural Development all over the globe has been major cause for changing water storage system by anthropogenic modifications and changes in landuse cover. Demand for agriculture water is proportionally increasing with the increasing the demand for food. Increasing tillage activities on the land surface has change the infiltration and runoff aspects of water surface and affects the water recharge capacity of underground water, hydrological cycle and evapotranspiration.
High amount of irrigation facilities for longer duration in the field for crop cultivation and use of chemical fertilizers, pesticides, insecticides are affecting the surface and ground water interaction and storage system. By using these chemical applications water is contaminated by various points and non-point pollutants which is available in soil, water and air. As, a result of natural process or through mechanism of displacement and dispersal of anthropogenic activities it impacts the water storage system.
5. Construction of dams/reservoirs:
Construction of dams for flood control, irrigation, drinking, hydropower and other various purposes is also affecting water storage system. Diversion of water channel from their natural flow system by construction of hydropower and irrigation dam leads to deplete the natural water recharge system. Dam building on the other hands impounds continental runoff that would otherwise have been stored in the ocean. Dams result in the trapping of freshwater runoff and modified timing of river discharge. Diversion of water between rivers, for example for hydropower purposes, alters natural stream flow regimes, and water withdrawals contribute to increased evaporation. Storage water behind dams and loses of water due to infiltration beneath reservoir and irrigation field along with evaporation from the surface could prevent the
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equivalent of 1.5-1.8 mm/year from reaching the ocean. Anthropogenic activities have resulted in the partitioning of water between that stored on the continents and in the ocean leading to change in sea level. The balance between these negative and positive alternation can be used as a measures of net anthropogenic disturbance to the global hydrological cycle and water storage systems. Construction of dams and withdrawal of high amount of water alter surface water storage system. Operation of dams had seriously damaged the ecology and water resources in the downstream. Construction of dams on the river and damming flowing water have impacts on waterfall, rapids, and prime fish runs, are lost.
6. Soil erosion:
Soil is eroded by different tillage practices and flood irrigation for agriculture production and different mining and quarrying activities. This is highly susceptible to soil erosion and its changes the relationship and interface of surface water and groundwater change in relief through erosion of uplands and deposition in valley bottom can produce change in hydraulic gradients, which in turn determines the rates of base flow and net water storage.
Changes to the surface of earth:
Forests are the major storehouse of water in both the soil and living tissues. Increasing deforestation directly affect the hydrological cycle. Bosch and Hewlett (1982) concluded that the establishment of forest cover on sparsely vegetated land decreases water yield. The impact, however, depends very much of the management practices and the alternative land uses. Careful, selective harvesting of timber has no or little effect on stream flow. In tropical areas, afforestation can lead to decreased dry-season flows due to increased evapotranspiration.
Tropical forest clearing generally increases total stream flow by as much as 125-820 mm/year (Gornitz, 1997). Removing of vegetation cover and overgrazing and plants are not there to intercept rainfall, the pathway of water cycle is shifted from infiltration and ground water recharge to runoff, and water runs into streams or rivers almost immediately. Increased runoff necessarily means less infiltration and therefore, less evapo-transpiration and slow groundwater recharge. Lower evapo-transpiration means less moisture for local rainfall and results less surface water and groundwater may be insufficient to recharge. Soil water in the shallower root zone following disturbance is also reduced. Barren land where rate of deforestation is high leads to increase runoff, which is not stored in the aquifer and will yield lower evapotranspiration and may elevate groundwater tables as per the availability of soil quality. Deforestation also reduced the cycling rate of water between plant canopies and the atmosphere and their by effect the climate system.
7. Impacts of anthropogenic interventions in surface water storage system:
13 Changes in the hydrological cycle
Some of the anthropogenic interventions in surface water storage system are following:
Freshwater constitutes only 2.5% of the total available water on earth and 2/3 of the freshwater is located in glaciers and ice cap.
0.77% of all water (10,665 km3) is held in aquifers, soil pores, lakes, swamp, river, plant life and in the atmosphere (Fig. 6).
Water is renewable through hydrological cycle which is based on solar powered and gravitational forces. Underground water can be tapped but underground water is rapidly decline due to subsidies electricity which increases the rate of extraction of underground water. It depletes the underground water in higher rate and disconnects the surface and ground water hydrology.
The hydrological cycle play a major central role in the atmospheric process of the planet earth. Mounting historical evidence to impact the hydrological cycle is global warming and climate changes. It affects the land based water cycle system and observing many changes and recent issues of affecting water storage system. Disturbance of hydrological cycles has attracted
the attention with respect to land, atmosphere, plant physiology net primary production and cycling of major nutrients. The rainfall that is stored in the soil and then evaporates or is incorporated in plants and organisms is called green water. This is the main source of water for natural ecosystems and for rainfed agriculture and produces 60% of the world’s food. The renewable surface water runoff and groundwater recharge is called Blue water. This is the main source for human withdrawals and the traditional focus of water resource management. The conservation and management of green water and blue water is essential to regulate the hydrological cycle.
8. Draining wetlands and loss of wildlife habitat:
Wetlands play an important role in the hydrological cycle. Wetlands function to store and release water in similar manner as groundwater reservoirs. Various anthropogenic and natural activities drain the water stored in the lakes or in the form of soil moisture and water storage in plants.
Large number of industrial and housing development projects have drained off or filled natural wetlands. This storage water system will be lost by various human developmental activities. The destruction of wetlands has the same impacts as discussed in the removal of vegetation and groundwater does. Flooding is exacerbated, and waterways are polluted during wet periods and dry up during draught. In addition, drained wetlands will evaporate at lower rates than their natural counterparts and yields more variable discharge hydrograph. These wetlands are the main habitat for local and migratory birds but due to draining of wetlands the birds lose their habitat.
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Fresh water resources are also polluted by various human activities. A details description about the freshwater pollution sources, effect and constituents of concern is shown in the table 1 below:
Table: 1. Freshwater pollution sources, effect and constituents of concern
Pollution type
Primary sources Effects Constituents of
concern Organic
matter
Industrial wastewater and domestic sewage
Depletion of oxygen from the water column as it decomposes, stress or suffocating aquatic life.
Biological Oxygen
Demand (BOD),
Dissolved Organic
Carbon (DOC),
Dissolved Oxygen (DO) Pathogens
and microbial contaminants
Domestic sewages, cattle and other livestock, natural sources
Spread infectious diseases through contaminated drinking supplies leading to diarrhoeal diseases and intestinal parasites, increased childhood mortality in developing countries.
Shigella, Salmonella, Cryptosporidium, Fecal coliform (Coliform), Escherichia coli (mammal faeces – E.
Coli) Nutrients Principally runoff
from agricultural lands and urban areas but also from some industrial discharge.
Over-stimulates growth of algae (Eutrophication) which then decomposes, robbing water of oxygen and harming acquatic life. High level of nitrate in drinking water lead to human illness in humans.
Total N (organic + inorganic), total P (organic + inorganic) For eutrophication:
(Dissolved Oxygen, Individual N species (NH4, NO2, NO3,
Organic N),
Orthophosphate) Salinization Leached from
alkaline soils by over irrigation or by over- pumping coastal aquifers resulting in saltwater intrusion.
Salt build-up in soils which kills crops or reduces yields. Renders freshwater supplies undrinkable.
Electrical conductivity, Chloride (followed, post characterization by full suite of major cations (Ca, Mg), anions
Acidification (precipitation or runoff)
Sulphur, nitrogen oxide and particulates from electric power generation, industrial stack and auto/truck emissions (wet and
Acidifies lakes and stream which negatively impacts aquatic organisms and leaches heavy metals such as aluminums from soils into water bodies.
pH
15 dry deposition). Acid
mine drainage from tailings as well as mines.
Heavy metals
Industries and mining sites.
Persists in freshwater environments such as river sediments and wetlands for long periods. Accumulates in the tissues of fish and shellfish. Can be toxic to both aquatic organisms and human who consumes them.
Pb, Cd, Zn, Cu, Ni, Cr, Hg, As (particularly groundwater)
Toxic organic compounds and micro- organic pollutants
Wide variety of
sources from
industrial sites, automobiles, farmers, home gardeners, municipal
wastewaters.
A range of toxic effects in aquatic fauna and humans from mild immune suppression to acute poisoning or reproductive failure.
PAHs, PCBs, pesticides (lindane, DDT, PCP, Aldrin, Dieldrin, Endrin, Isodrin,
hexachlorobenzene)
Thermal Fragmentation of rivers by dams and reservoirs slowing water and allowing it to warm. Industry from cooling towers and other end-of-pipe above-ambient
temperature discharges.
Changes in oxygen levels and decomposition rate of organic matter in water column. Many shift the species composition of the receiving water body.
Temperature
Silt and suspended particles
Natural soil erosion, agriculture, road building,
deforestation,
construction and other land-use changes.
Reduces water quality for drinking and recreation and degrades aquatic habitats by smothering them with silt, disrupting spawning and interfering with feeding.
Total suspended solids, turbidity
Source: UNESCO (The United Nations World water Development Report 2. Available at:
https://www.greenfacts.org/en/water-resources/figtableboxes/5.htm
16 9. Desertification:
Drying of marginal soils due to overgrazing and other intensive land use on arid or semi arid soil leads to net loss of water reduction in evaporation and increased storm runoff. Desertification refers to expansion of desert or desert –like condition into adjacent area due to scarcity of water.
This is due to combined impact of adverse climate condition and human interventions in the natural water resources. Some of the world’s larger rivers do not reach the sea because large amount of reduction in surface water and dry up of streams and ponds. The Amu Darya and Syr Darya- two major rivers in Central Asia that feed the Aral Sea have been deprived of close to their entire water reserve for cotton irrigation. Depleting water source will increasing occurrence of water scarcity by natural and anthropogenic impacts exacerbate the effects of desertification through direct and long-term impacts on land and soil quality, soil structure, organic matter content and ultimately on soil moisture levels. Inadequate drainage and poor irrigation practices increased frequency of draught and drying of surface water resources. Desertification increased sand and dust storm and greater occurrence of flooding. This leads further, land and water degradation and enhanced pollution of surface and ground water, siltation, salinization and alkalization of soil.
10. Impacts on Estuaries
Diverting river water in different direction to their natural flow to the sea has serious impacts in estuaries bays and rivers in which freshwater from a river mixes with seawater. Estuaries are most productive ecosystem of the planet earth. They are rich in breeding ground for many species of fish and waterfowl. The salt concentration is increasing by diverting river flow to utilize for irrigation purposes and affecting the estuary’s ecology. Wright and Boorse (2011) have mentioned a case study of San Francisco Bay in that over 60% of the fresh water that once flood from rivers into the bay has been diverted for irrigation in the Central Valley (2.5 million acres irrigated) and for municipal use in Southern California (25 million people served).
11. Ground water depletion and groundwater pollution
The water table may rise as a result of decreased evapotranspiration, e.g. following logging or conversion of forest to grassland for grazing. Recharge may also increase due to an increased infiltration rate, e.g. through afforestation of degraded areas (Tejwani, 1993). In contrast, the water table may fall as a result of decreased soil infiltration, e.g. through non-conservation farming techniques and compaction (Tejwani, 1993). Table 2 represent the summary of land-use impacts on groundwater recharge.
Table: 2. Summary of land-use impacts on groundwater recharge.
17 Impact of land use
on recharge
Influence on Comment
Recharge rate Recharge quality Deforestation
(clearing native vegetation)
significant increases on flat
ground from initially very low
rates in arid areas
normally acceptable, but in arid
climates may result in mobilisation of salts from subsoil
zone
on sloping ground, risk of soil
erosion and eventual loss of
recharge
Pasture considered to be
‘normal rate’
especially in temperate climates
generally excellent and usually
appropriate land use for
waterwell protection zones
increasing grazing intensity will eventually trigger large nutrient losses
Dryland farming ploughing-in pasture and
existence of fallow land results
in some increase in recharge
at low intensity good, but
ploughing-in pasture can
produce a flush of nutrient
losses
intensification of crop production can lead to elevated
agro-chemical leaching
Irrigated cropping (from surfacewater sources)
substantial increases in all cases,
especially marked where flood irrigation practised
risk of diffuse pollution from nutrients and pesticides,
depending on agro- husbandry
additional hazard arises from biofuel crops or if wastewater is used for irrigation Afforestation or
reforestation
significant reduction, especially
where non-deciduous species
involved
slight tendency towards
increased salinity in some
instances
forested areas usually appropriate land use for
waterwell protection zones
Urbanisation increases from leaking water
mains and in-situ sanitation
much greater than reductions
due to making land
major pollution hazard from
nitrogen compounds, synthetic
organic chemicals and sometimes pathogens and
level of pollution hazard varies quite widely depending on style of urbanisation and hydrogeological setting
18 surface
impermeable
salinity Source: Global Water Partnership, August 2014
Also, heavy grazing may lead to reduced infiltration and groundwater recharge (Chomitz and Kumari, 1996). If the infiltration capacity is substantially reduced, this can lead to water shortages in dry seasons, even in regions where water is usually abundant, like in the case of shifting cultivation in Cherapunji province, India (FAO, 1999). Likewise, groundwater recharge can be reduced as a result of planting of deep rooting tree species, e.g. eucalyptus (Calder, 1998).
Ground water is threatened with surface water pollution in the form of seepage of pits, waste dumping site, septic tanks, and oil seepage by transport accidents. Untreated sewage from domestic and industrial effluents and dumping of waste materials are the important sources to pollute the ground water. These pollutants give birth to cholera, hepatitis, dysentery, etc.
Advantage and disadvantage of withdrawing groundwater are shown in table 3 below:
Table: 3 Advantage and disadvantage of withdrawing groundwater are shown in table
Advantage Disadvantages
Useful for drinking and irrigation Aquifer depletion from over pumping
Available year around Sinking of land (Subsidence) from
overpumping
Exists almost everywhere Polluted aquifers for decades or centuries Renewable if not overpumped or contaminated Reduce water flows into surface waters No evaporation losses Reduce water flows into surface waters
Cheaper to extract than most surface water Increased cost and contamination from deeper wells.
Source: Siddhartaha, 2013
12. Diminishing Surface Water and land subsidence
High rate of extraction of groundwater withdrawal is leads for falling water table and depleting water resources and diminishing surface water. As, water table drop, spring and seeps dry up as well, diminishing even streams and rivers to the point of dryness. When the water table drops the rate of land subsidence is also increasing. Because over the age, groundwater has leached cavities in the ground, where these spaces are filled with water, the water helps to support the overlying rock and soil. But this support is lost when the water table drops. When it happened in the cities, underground pipes break, causing leaks and wastage of domestic water and sewage pipes can also fracture contaminating the groundwater aquifers. Sinkhole is also another kind of
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land subsidence develop when as underground cavern drained of its supporting ground water suddenly collapse.
13. Change in self purify capacity of water recharge
Discharging of industrial effluent in the surface water and streams pollutes water resources.
Increasing mining and quarries activities is also affecting the water resource. These drastic consequences of such situation may affect the lives of human and hydrological cycle. These industrial activities hampered self purifying capacity of water recharging. Large number of industrial activities, directly or indirectly leads to modification of river channels, which can, in turn induce changes to aquatic environment. Some of the changes to the river systems includes- changes to depth and width for navigation, creation of flood control.
14. Salinity and salanisation
An increase in salinity of surface and groundwater can have detrimental effects on downstream water uses. High amount of irrigation for a longer period of time for crop production in the agriculture field accelerate the accumulation of salt through evaporation. Excess infiltration from the irrigated area causes the underlying groundwater level to rise and producing water logging in poorly drained soil. When the water level is close to the earth surface, capillary action allows water to rise further and evaporate from the land surface resulting in salanisation of soil and water. The impact of land uses on salinity depends on climatic as well as geological factors.
Irrigation and drainage activities may lead to increased salinity of surface and groundwater as a consequence of evaporation and the leaching of salts from soils. This is of special concern in arid areas, where subsurface drainage water always has higher salt concentrations, an increased hardness and a higher sodium absorption ratio than the supply water. Drainage from irrigated agriculture may also lead to an increased concentration of selenium in ground and surface water (Postel, 1997). A high application rate of potassium chloride fertilizer can lead to an increased leaching of chloride into groundwater.
15. Salt water intrusion
Salt water intrusion is another impact of human intervention in water storage system. Along a coastal region, when the water table goes below normal due to excessive extraction of groundwater, the normal interface between freshwater and saline ground water moves inland.
This cause saltwater intrusion which pollutes the groundwater making it usable for drinking as well as irrigation (Siddhartha, 2013). Causes and impacts of Salt water intrusion are shown in the figure 7.
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Fig. 7. Salt water intrusion situation (University of Florida, 2000) 16. Change in water balance and climate change
Climate Change is most recent factor expected to additional effect on water storage system.
Study conducted by Haddeland (2014) indicated that the impacts of man-made reservoirs and water withdrawal on the long –term global terrestrial water balance is small. But in the small river basin level land impacts of human intervention are significant. Haddeland (2014) also observed that in Asia and United States, the effect of human interventions exceeds the impacts expected for moderate level of global warming. Increasing in green house gases earth’s climate is becoming warming and hydrological cycle and surface water is being altered. Increasing global temperature means more evaporation from land surface, vegetation, soil and water bodies because evaporation increases exponentially with temperature. A wetter atmosphere means increasing in the flood events (Wright and Boorse, 2011). According to the Millennium Ecosystem Assessment report, “A changing climate can modify all element of water cycle, including precipitation, evapotranspiration, soil moisture, groundwater recharge, and runoff. It can change both the timing and intensity of precipitation, snowmelt and runoff (Wright and Boorse, 2011)”.
Conclusions
Currently, every corner of the world is facing serious and alarming problem of global water crisis. The character of renewability of water resources are possible only if water can be use wisely and manage properly without changing the bio-physical and chemical properties of water.
Otherwise these resources can be considered as non-renewable. In our every days life there are observing many signatures in the widespread increasing incidence of water scarcity, water use
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conflicts, depletion of groundwater and drying of surface water resources. The process and mechanism of water storage system are not regulating properly. Environmental natural process are changing by human interventions and rate of environmental degradation and amount of water pollutants are increasing and changing water storage systems proportionally with human economic development. Now, people and communities are experiencing the direct and indirect impacts of water crisis on their lives health and livelihood.
The potential for tapping of renewable supplies of water depends upon the magnitude and interface of surface and ground water resources. Inland water storage system encompass habitat such as lakes, rivers, marshes, swamps, flood plains, small stream, ponds and caves water are in worse condition. During 20th century more than 50% of inlands water habitats were lost by changing land use practices and land cover patterns, Modern agricultural practices and change in the agricultural system after green revolution in the form of vertical extension of agricultural field to enhance the productivity by using chemical fertilizers, insecticides, pesticides and irrigation are mainly responsible for changing water regimes. These practices for agricultural development and rapid rate of increasing industrialization have historically been the principal cause of changing water storage system in the hydrosphere, lithosphere, atmosphere and in cryosphere for different form of water. Overall supply of water resources recharge is depend on the rainfall, which contributes to renewable supplies of surface and ground water. Various anthropogenic and natural factors are affecting the pattern and distribution of rainfall which, directly and indirectly affecting the availability of water supplies to different water resources.
The supplies are inadequate to meet the present and future demand for domestic and non- agricultural use. Changing adverse climatic condition in the form of global warming and climate change is affecting the mechanism of regulating hydrological cycle.
The widespread unscientific and unauthorized extraction and use of water encouraged its wasteful and inefficient use and again added impetus for demand to grow much faster than the availability of water supply. Exploiting renewable groundwater will continue to be an option, but again it is depending on precipitation that is being increasingly polluted. Over extraction of ground water resources are resulting dry land, salinization, desertification and land become unusable for cultivating crops. Increasing salinity and water logging have affecting about 40% of the world dry land area in West Asia. Human activities are responsible for heavy pollution of the ocean and coastal zone. Overuse and misuse of water, fertilizers and pesticides in irrigated areas are increasing depth from which underground water is extracted and discharge of large quantities of untreated urban sewage and industrial effluents has resulted in increasing widespread pollution of both surface and ground water. Large stretches of most of the rivers in the mountain area are disappeared where many reservoirs are constructed or under construction for hydropower development. The downstream area became dry and having large number of water bodies is drying. These all human interventions is affecting the storage systems and altering water resource system in the present time. This is the need of the hours to think seriously and
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implement holistic approach on these different human interventions to conservation and maintain the water recharging system to save the ecology and humanity in the present and future perspective.
