GIS Aapplications in Detecting heavy Metal Contamination in Rivers
Madhurima Katiyar, Mitika Garg, Akansha Srivastava
pursuing M.Sc in GEOINFORMATICS
Symbiosis Institute of Geoinformatics, Pune
INTRODUCTION:-
Rivers of Asian continent are the chief transporting agents of continental weathering products as they supply about 30% of the global sediment input to the world’s ocean. The Indus and Ganges- Brahmaputra rivers contribute as much as 20% of the global sediment input Ganges River is placed as the third largest transporting river in the world. The investigation of sediments from the hydrosphere has recently become a major subject of interest in research as they reflect the current quality of the system and provide information on the impact of man. Human activities (urbanization, industrialization, mining, etc.) promote the accumulation of polluted sediments in the nearby river system, which is considered be safe disposal site for contaminated sediments. Contaminants in river system can be investigated by analyzing either the water and the suspended material or the sediments. The study of sediments play key role, as they have long residence time. River sediments, therefore, are important sources for the assessment of man-made contamination in rivers. Our main focus is how one can go for easy going analysis through GIS softwares in detecting heavy metal contamination in rivers.
When any element is added to our environment beyond certain limit, it becomes hazardous to our environmental system and this is called POLLUTION. Those elements which are responsible for causing pollution, called POLLUTANTS. There are number of pollutants which are released directly or indirectly by our ANTHROPOGENIC activities into our environment like HEAVY METALS. Our interest is to understand the occurrence, distribution of heavy metal in river sediments of the Ganges say Gomati River (tributary of the Ganga River) as Ganga river system is one of the largest river systems of India
As Computers are now able to process maps -both individually and along with tabular data and “crunch” them together to provide a new perception – the spatial visualisation of information specifically the Geographical Information System (GIS) which is a tool which allows synergism of map data and tabular .So the advent of computers has changed the scope of information processing -whether as an end-user application or for technology support data in the most efficient manner on. Ganges River serves as a lifeline for about 400 million people living in its alluvial and delta plains, one of the most densely populated and highly agricultural regions of the world. Heavy metals in water and sediments of the Ganges River may have a substantial adverse effect on the environment of alluvial plain and delta regions due to their toxicity and accumulation in microorganisms, plants, animals and humans. Hence, knowledge of heavy metal concentration and distribution in sediments is of fundamental importance in an environmental study of the GOMATI RIVER.
STUDY AREA:
The Gomti, Gumti or Gomati River is a tributary of the Ganges River The Gomti originates near Madho Tada, Pilibhit, India. It extends 900 km (560 miles) through Uttar Pradesh and meets the Ganges River near Saidpur After 240 km the Gomti enters Lucknow, through which it meanders for about 12 km. At the entrance point water is lifted from the river for the city’s water supply. The major sources of pollution in the Gomti are:
- Industrial waste and effluent from sugar factories and distillaries.
- Domestic waste water and sewage from habitations.
The river collects large amounts of human and industrial pollutants as it flows through the highly populous areas of Uttar Pradesh. High pollution levels in the river have negative effects on the ecosystem of the Gomti, threatening its aquatic life.. The river flows in the great alluvial plain, which is of Pleistocene-Holocene origin, and redistributes the primary weathered sediments of the Gangetic alluvial plain derived from the Himalaya. It flows over 750km in a SE direction and joins the Ganga River near Varanasi. In the middle of its course the passes through the Lucknow urban area. Lucknow is a capital city in the Gangetic plain, with an urban population of more than 1.6million and some industrial units .The urban effluents, including industrial and municipal waste, flow into the freshwater river through small open drainages. These drainages are Kadar Nala, Daliganj Nala, New Hyderabad Nala, and Haidergarh canal. The river is characterized by sluggish flow throughout the year, except during the monsoon season, when heavy rainfall causes a manifold increase in the runoff. The post monsoon season is associated with the depositional phase of the river due to low water discharge.
IMPACTS ON LIVING BEINGS:-
The fish had died as dissolved oxygen level of the river water had dipped too low .The dissolved oxygen levels dipped to as low as one milligram per litre (mg/l). Over the years, Gomati has become the most polluted river in Uttar Pradesh. Monitoring by the state pollution control board reveals the water is unfit for consumption.
GOMATI RIVER SEDIMENTS:-
The river sediments are made up of fine sand, silt, and clay. The fine silt and clay(<20 micrometer fraction) content in the sediment samples ranges from 6 to 40% with an average of 20%. The XRD analysis shows the dominance of Quartz, followed by feldspar and mica.
HEAVY METAL IN SEDIMENTS:-
Metal concentration in the Gomati river sediments at Lucknow area show varying and different behavior influenced by urbanization. The results of the chemical analysis of the samples are presented below-
- cadmium (fraction in micrometer)
Average—1.30, medium—0.61, minimum—0.26 and maximum—3.62 - iron (fraction in micrometer)
Average—5.16, medium—5.12, minimum—4.32 and maximum—6.11 - Copper (fraction in micrometer)
Average—70, medium—55, minimum—33 and maximum—147 - Chromium (fraction in micrometer)
Average—160, medium—155, minimum—115 and maximum—204 etc.
Downstream profiles of these heavy metals show interesting features at sampling stations G5, G6, and G9, where the river receives waste water effluents from urban drains. Total metal concentration in the fraction <20 micrometer of the sediments vary in the range of 115-204 for Cr, 440-845 for Mn, 432000-61100 for Fe, 18.6-25.9 for Co, 45-86 for Ni, 33-147 for Cu, 90-389 for Zn, 25-77 for Pb, and 0.26-3.62 mg/kg for Cd. At station G5, Co, Cr, and Ni concentrations decreases, while Cd, Cu, Pb, Zn increases downstream, at station G9, the river receives urban effluents from Haidergarh canal. The variations in the metal concentrations at the G5, G6 and G9 stations are possibly due to variations in the water chemistry of the river at the urban Nala confluence.
Cd, Cu, Cr, Pb, and Zn concentrations of urban effluents indicate important anthropogenic inputs to the river. This causes the increase of metal concentration in the downstream sediments. While Fe and Co levels remain constant, Mn concentration continuously drop in the downstream section.Ni concentration drop rapidly after the confluence of Khadar Nala and subsequently increase again to reach the previous level within the urban limits.
GIS :-
Geographical Information System (GIS) which is a tool which allows synergism of map data and tabular data in the most efficient manner. Now-a-days GIS has been playing a great role in carrying out an easy going analysis. It has number of applications which force us to be a part of GIS, it involves some important tasks like
- Organizing integrated spatial and non-spatial databases using the GIS tools in a systematic manner. The spatial data -consisting of maps from remotely sensed data and also conventional sources
- Integration or the synthesis of the spatial and non-spatial information within the framework of a coherent data model and linkages between the different datasets
- Generation of spatial outputs, supported by tables/charts, to help the developmental planning and decision-making
APPLICATIONS OF GIS:-
1.)when we keep our focus on such a long stretch of river and we carry out our analysis on such a large scale then for such a large scale analysis GIS softwares are the keyplayers.We gather different types of data like-
- Data about concentration of heavy metal in water.
- Data about concentration of heavy metal in sediments.
- Data about concentration of heavy metal in suspended particles.
So for such a voluminous data it’s difficult to handle them in paper sheets so to have proper arrangement and proper record we require the assistance of GIS softwares as they help not only in the developmental planning but also in decision-making. So not only we have proper record of information but also one can easily update the information i.e. not possible in hand sheets as it become a tedious job. For easy going analysis GIS softwares play key role. As we know that anthropogenic activities are basically responsible for bringing heavy metals into our river system. In analysis part, geochemical maps of metals(Cd,Cr,Cu,Ni,Pb and,Zn) are digitized through GIS software and the layers of drainage pattern, land use map, heavy metal concentration of surveyed area are also added to this analysis.
This will tell us the sources of heavy metal concentration present in water bodies passing through industrial area, which in turn leads to their adverse effect on different land units, like agriculture, urban areas, etc so on the basis of above mentioned fact assume number of industry in an area and some of them are present in the adjacent region of a river system. So by going through some OVERLAY OPERATIONS one can easily come to know that which area is more prone to contamination
STEP I—
Suppose we have two layers, one layer is of landuse say agriculture and other layer is of water body say river. So if we go for operations in ARC VIEW 3.2 we will come to know that which area is having more proximity to river. Such operations are need to be performed between different layers of the same region because then we come to know the interrelationship.
As here landuse unit and river system, both layers belong to the same region. When we do the overlay operation then we come to know the relation of both these layers with each other.
STEP II:-
After getting the final overlaid layer of agriculture and river, we again perform this operation in taking into account this layer with another layer say layer of industry and urban area so this final
is telling us that which industry is adjacent to river so that river will be enriched in that particular industrial effluent. As a result of this knowledge one should focus his study on that flood plain which is adjacent to particular industry as most of the industrial effluents are dumped into the river system which affect the near by portion of flood plain. On the basis of above mentioned overlay operation one can easily make the prediction about urban areas. As those urban areas which are adjacent to industries have more exposure to diseases.
EXAMPLE OF SUCH OPERATION IN GOMATI RIVER STUDY:-
If the above mentioned figure of Gomati River is considered and some operations are performed on different layers of region then we will have result like this.
This all is possible, when we go for ARC VIEW 3.2 software. First digitize the Gomati River of Lucknow region and make a new theme as a line. Afterwards locate the different sampling stations in an area along with urban effluent sites of a region and make a new theme as a point layer. Now join these two layers (line and point layer) the final layer will be formed. Then one of the tools of ARC VIEW i.e. geoprocessing is used for further operations. According to above mentioned figure the final layer is explicitly showing the location of different sampling stations. There are ten Sampling stations, let’s consider content of different sample stations. The following content of heavy metal is present—
Now on the basis of above data, the G9 sampling station having highest content of heavy metal. So with the help of GIS SOFTWARE esp. ARC VIEW 3.2 one can create BUFFERS. First we can build query for highlighting the highest content of heavy metal of a sampling station. When we build this query the G9 station is highlighted, afterwards we can create buffer say 200m around G9 station and we can focus our study only to that zone.
ADVANTAGE OF CREATING BUFFER AROUND G9 STATION:-
As a Government body we can confine the construction or establishment of new things. Like restricting some private or other bodies for any urban settlement or any other type of construction in the buffer zone of G9 SAMPLING STATION as it is highly prone to heavy metal contamination so hazardous to everyone.
2) Remote Sensing data is a classic source of data on natural resources for a region and provides a record of the continuum of resource status because of its repetitive coverage. Remotely sensed data in the form of satellite imageries can be used to study and monitor land features, natural resources and dynamic aspects of human activities. Now-a-days satellite imageries have been playing key role in assessing polluted water. As different range of EMR (electromagnetic radiation) are used and their properties easily get changed as per the quality of water is concerned.
This factor is of fundamental importance in understanding the quality of water, and for that we take assistance from different satellites like LANDSAT, IRS. But it has some drawback, like water is highly dynamic in nature so we can’t totally rely on this factor for the analysis of heavy metal. Therefore river sediments are important source for the assessment of heavy metal contamination in river. For easy analysis of river sediments one can go for DEM (Digital elevation model), recording a topographic representation of terrain of the earth or another surface in digital format. It implies the attitude/elevation of the point contained in the data. Steps involve in the preparation of DEM are mentioned below-
STEP A: – Topographical Maps
STEP B: – Georegistration of images of maps in ERDAS IMAGINE 8.5.
STEP C: – Preparation of vector layers of spot heights and drainage in ARC VIEW 3.2.
STEP D: – Preparation of DEM (Digital elevation model).
Utility of DEM in analysis of polluted water of GOMATI RIVER:–
After making the DEM of flood plain of GOMATI RIVER, we keep our focus on the sediment coverage of flood plain and their varying thickness. The varying elevation or thickness of sediments help in their assessment as the contamination is supposed to be higher where the accumulation of sediment is high. So directly or indirectly DEM help us to make assumptions about the content of heavy metals. If we keep our focus on above mentioned urban effluent sites (different nalas) and we prepare contour maps of 2m or 5m depending upon the scale in ARC VIEW 3.2.
We will come to know that the concentration of contours along GOMATI RIVER is highly variable, which in turn tells the varying surface morphology that ranges from circular to elliptical and many more. During monsoon season large part of river basins are inundated by water due to low relief, which migrate into major rivers of the GANAG PLAIN say GOMATI RIVER, in summers and winter seasons, this source of water make easily infiltration into the groundwater of the alluvium. The major fluvial processes of rivers are thus principally controlled by monsoon rainfall.
CONCLUSION:-
Like other known pollution episodes around urban regions where rivers are affected by human activities, the GOMATI RIVER in LUCKNOW presents a good example that can be used to compare and contrast the effect of Urbanization .on the distribution of heavy metal in river sediments. Recently deposited river sediments show increased heavy metal concentrations due to urban waste effluent discharged into the river. Compared with background values, the average enrichment factors are around 2 for Pb and Cr, 4 for Zn and Cu, and 11 for Cd, indicating the anthropogenic source of these heavy metals in the river sediments. It is evident from the present study that the urbanization process has a great influence on transportation and accumulation of these toxic heavy metals in the GOMATI RIVER and all this information is processed, managed, manipulated, analyzed and modelled through GIS SOFTWARES. As it has ability to handle multiple-layers of information in the spatial domain and allow for the integration and modeling of these parameters to arrive at inputs to decision-making.
The present data can provide useful information for pollution control strategies and urban centers located along the Ganga River system. The best example for explaining the utility of GIS in decision making about the settlements of different industries is ATLAS ZONING. Zoning is a legalized and institutionalized form of land use management
- To identify locations for siting of industries.
- To identify industries suitable to the identified sites.
This methodology involves preparation of maps of various themes and uses of overlay procedure & GIS (Geographical Information System).As it identify locations for siting of industries which in itself minimize the exposure of hazardous elements to urban areas.
SOURCES:-
I.B.Singh
Department of Geology, University of Lucknow,
Lucknow 226007, INDIA.
