Indian Journal of Geo-Marine Sciences Vol. 44(11), November 2015, pp. 1734-1741

Assessment of Environmentally Sensitive Area and Desertification Severity using GIS for an Indian Region - District,

*K.Vani, M.Ramalingam, S.S.Ramakrishnan, M.Priya Muthu Ramalakshmi, & M.Muneeswaran Institute of Remote Sensing, Anna University, Chennai - 600 025, Tamil Nadu,

Received 01 August 2014; revised 10 October 2014

Desertification is one of the fundamental hazards threatening the arid and semi-arid regions on ecological as well as economic perspective. Mapping and quantifying the land degradation have become urgent tasks in order to avoid the depletion or deterioration of the resources we need to know the causes for the depletion. In this study, the desertification status and the severity of desertification were studied using remote sensing and field data at , Tamil Nadu region, in south India. Modified Medalus method was used to identify the ecological sensitive areas (ESA) with landuse, climatic controls, soil quality, ground water quality and demographic factors. A number of indexes were prepared from the above parameters and the severity was identified by Environmental Sensitivity Area Index (ESAI). The desertification severity was classified into three classes such as low, moderate and high. The desertification severity from 2003 to 2012 was increased from moderate (1.34) to severe (1.42) at and taluk, which is located in the western side of the study area. Results showed that climate and demographic pressure were the most important indicators for describing desertification process in the study area.

[Keywords: Desertification; Desertification Severity, Land degradation; Medalus; Environmental Sensitivity Area.]

Introduction UNCOD has noted that, mapping and quantifying the potential hazard zones for Desertification as a process of development purpose and timely mitigating this degradation in arid ecosystems is wide spread in hazard3. arid regions of the world. This process is influenced by biophysical, chemical and Over the years, a number of methods biological factors and it affects such ecosystems and models are developed to analyze the as plants, soil and human activities1. In the desertification process. Provisional methodology recent years, the government of India has for assessment and mapping of desertification planned to execute many projects to combat hazard was one of the major excercise used for desertification. However, it seems that due to assessing the desertification and land the extensive arid area the government is not degradation4. But when it comes to local level, adequate and need much attention together with only limited studies were carried out to assess long-term effective national and international the land degradation. Medalus model is one of cooperation to combat desertification. the best examples among them, which later Desertification is one of the fundamental named as environmentally sensitive areas hazards threatening the arid and semi-arid (ESA)5. This model was developed for regions on ecological as well as economical Mediterranean regions and provides good result perspective. The 1977 United Nations for that countries6, 7. This method identifies the Conference on Desertification (UNCOD) in environmentally sensitive areas by the use of a Nairobi described that, desertification as the number of indexes8. This is very useful method diminution or destruction of the biological for determining different classes of vulnerable potential of the land2. Recently, it was redefined areas to desertification9. This model successfully as “Land degradation in arid, semi-arid and dry used in some Middle-East countries 7,8,12,14. sub-humid areas resulting from various factors, including climatic variations and human In India, desertification is considered as activities3. It can be a serious hazard over socio- one of the major problems in recent years economic development as well as a barrier to because of it is overpopulated. More than 30% sustainable development on global communities. of the geographical area is undergoing the VANI et al.: ASSESSMENT OF ENVIRONMENTALLY SENSITIVE AREA AND DESERTIFICATION 1735 process of land degradation11. Mapping the land foothills have rich loamy soil with good degradation is important to understand the vegetation cover. Plains with black cotton soil desertification process. But, very limited studies (locally known as cortisol) are underlying have done land degradation mapping in India 11, calcareous formations. Virudhunagar district 12,13. Main scope of the study is to map does not have any perennial rivers. Vaippar, desertification to the local level and assessing Arjuna Nadi, and Gundar constitute the river the severity of the land degradation process by network of the district. Numerous streams and using two different years of data. For this study, rivulets, activated by the monsoon, feed these the modified Medalus model was used for ESAI rivers. The study area receives the rainfall under over two different year data. The severity was the influence of both southwest and northeast estimated based on the change detection. monsoons. However, the northeast monsoon chiefly contributes to the rainfall in the district. Materials and Methods Most of the precipitation occurs in the form of cyclonic storms caused due to the depressions in Area selected for this study was the the Bay of Bengal. Virudhunagar district, it is located in the southern part of Tamil Nadu (Figure 1). It has an LISS IV data from the two time frames area of 4419.06 sq. kms. The District lies (March 2003 and March 2012) have been taken between 9° 12’ and 9° 46’ north latitude and 77° and used for this study. Geometric correction 20’ and 78°25’ east longitude. and radiometric correction were carried out for the above images. All the images were georeferenced and converted to UTM projection, WGS 84 datum. All the statistical data were collected from Department of Agriculture, Government of Tamil Nadu and Government of India.

Desertification severity depends on various parameters and the quantification should consider all the major parameters which are involved in this process. The adopted methodology is explained in the following Figure 2. Based on the Medalus method, only the parameters which are suitable for the study area were taken for desertification quantification assessment. And some of the sub-indicators are also modified according to our study area. For vegetation quality index, a landuse classification proposed by SAC (ISRO) was used to study the desertification severity. There are five indexes Figure 1: Map showing the Virudhunagarstudy area. prepared for this study based on the factors like Insets show the location of the study area in Tamil Nadu state and India. climate quality, soil quality, vegetation quality, demographic quality and ground water quality. Virudhunagar district is The ground water quality index and soil quality physiographically divided into two types; the index have been calculated from the ground higher elevated lands and Flat plains. A major verified information. Each sub-indicator was portion of the district is covered by plain quantified according to its quality and given a topography. Eastern slopes of the Western weightage between 1.0 and 2.0 by the factorial Ghats cover a small part of Srivilliputhur and scaling technique and classified as high, taluks. Black soil plains of moderate and low. After that, the indicators are Sivakasi, Virudhunagar, , , grouped and combined in quality layers such as Tiruchuli and Kariapatti are the remaining area. Climate Quality Index (CQI), Soil Quality Index The average height of the hills of the eastern (SQI), Vegetation Quality Index (VQI), slopes of the Western Ghats is 1500 m, though a Demographic Quality Index (DQI) and Ground few peaks rise to the extent of 1750 m. The 1736 INDIAN J. MAR. SCI., VOL. 44, NO. 11 NOVEMBER 2015

Water Quality Index (GQI). Then, the ESAI was area comes under the semi arid and the CQI prepared by the following equation (Eq 1)14. states that, the quality is decreased from the years 2003 to 2012 from 1.14 to 1.31. The ESAI = (CQI * SQI *VQI * DQI * GWQ)^(1/5) eastern side villages get low rainfall in these (Eq 1) years and the ET also reduced in these portions of the district. In 2003, have high severity and in 2012, Sattur and shows high severity and the remaining taluks have moderate severity. Aridity index shows that, Sattur and Virudhunagar taluk has turned from semi-arid zone (2003) into an arid zone (2012). The has turned into semi arid from sub humid in these periods. Other areas remained as semi-arid area, but the ET was getting lower in that period because of the low rainfall and vegetal degradation.

Figure 2 Methodology flowchart for the Medalus method

On the basis of computed ESAI, the quality of desertification was assessed for two years from 2003 to 2012.

Results and Discussion

The General physiogeographical condition of this study area shows, most of the Figure 3 Climate Quality Index of Virudhunagarfor area comes under semi-arid region. After the 2003 computation of ESAI, a detailed analysis was carried out for all the parameters and discussed below.

Indicators that considered for the climate indices are precipitation, evapo- transpiration and aridity index. Figures 3 and 4 shows the Climate Quality Index (CQI) of the study area for the two different years.

Aridity index was calculated by the most used FAO-UNESCO bioclimatic index (1989). According to that, if the ratio of annual precipitation and evapotranspiration (ET) is less than 0.3 it is classified as arid zones; the ratio which is <0.5 and >0.3 is classified as semi arid zones; and the ratio which is >0.5 and <0.75 Figure 4 Shows Climate Quality Index of Virudhunagar classified as sub humid zones. The overall study for 2012 VANI et al.: ASSESSMENT OF ENVIRONMENTALLY SENSITIVE AREA AND DESERTIFICATION 1737

The Soil Quality Index (SQI) has been Indicators that considered for the Vegetation assessed using the following parameters: Quality Index (VQI) are landuse/landcover for texture, electrical conductivity, soil depth, the two different years as per SAC (ISRO). The organic matter and slope. The most dominant national classification system for desertification soil group is clay and followed by sandy clay, status mapping (Ajai et al 2009) was taken in sandy clay, loam and sandy loam. The SQI VQI preparation, which is shown in Table 1 & index was derived and shown in the Figure 5. 2. All the four indicators are grouped and ranked The center region of the study area is completely as very low, low, moderate and high. The covered by clay soil and the second dominant following Figures (6 and 7) show the Vegetation soil type is sandy loam which covers the east Quality Index of the study area for 2003 and and west part of the study area. The slope played 2012. Eastern side of the study area has a less important role in this area because, most changed in the severity from low to moderate of the area is a flat plain and only the eastern over the years. part has some slope impact. This is one of the major reasons for not considering the erosion in Table 1 & 2. National classification system for this study. The electrical conductivity of the desertification, status mapping soil is very low in almost 70% of the area and 20% of the area comes under the moderate and LEVEL 1 LEVEL2 another 10% has low EC. The soil depth is very low in this district. 64.2 % of the area comes Agricultural Land Fallow Land under shallow soil depth and another 35.8% Open/Dense Forest, comes under very shallow. Overall, the analysis Forest Land Open/Dense Scrub forest, shows that Virudhunagar District is covered by Forest blanks a prevalence of medium quality soils. Open/DenseScrub land, Sandy area-Riverine Waste Land Salinization / Alkalinization Barren rocky/Stony Waste Others Man made (mining/Quarrying, Industrial Effluents, Urban Aggregation etc.,)

LEVEL 3 SEVERITY INDEX

High 1

Moderate 2

Low 3 Figure 5 Soil Quality Index of Virudhunagar for 2003 1738 INDIAN J. MAR. SCI., VOL. 44, NO. 11 NOVEMBER 2015

the DQI for 2003 and 2012. From 2003 to 2012, some part of the fallow land is again used for agriculture purposes. But overall, agricultural land decreased over the years. Water bodies remain the same condition. Apart from that, the built up area has increased more than 100 % during this time period. Earlier (2003), it was 14.27 % and increased to 26.12% in 2012. The degraded land increases from 2003 to 2012 from 27.4 % to 29.6 %.

Overall population density increased from 415 to 461 km2, but the western part of the study area has a higher population density than other area because of the industrial development. Especially Sivakasi and Rajapalayam areas are very known for industrial activities such as fireworks, printing and match box industries. It influences the population density over the years and the difference Figure 6 shows the VQI of Virudhunagar for 2003 between 2003 and 2012 is 23% in Sivakasi & 22.6 % in Rajapalayam. The places around Virudhunagar town and Rajapalayam town are known for tourism activities in this study area, it gives additional pressure on demographic quality. Based on the analysis of all indices, It is the major factor that causes desertification severity in Virudhunagar district.

Figure 7 shows the VQI of Virudhunagar for 2012

The Demographic Quality Index[DQI] was assessed using the following parameters: land use, population pressure and socio- economic factors such as transportation, industrial development and habitation extension. The landuse of the study area has been classified as: agricultural land, fallow land, built-up, water Figure 8 Demographic Qualtiy Index of Virudhunagar for bodies, and degraded land. Figures 8 and 9 show 2003 VANI et al.: ASSESSMENT OF ENVIRONMENTALLY SENSITIVE AREA AND DESERTIFICATION 1739

Figure 10 Ground Water Quality Inedx of Virudhunagar Figure 9 Demographic Qualtiy Index of Virudhunagar for for 2003 2012

Water table, Electrical conductivity (EC), Chloride value and Sodium absorption Ratio (SAR) are considered for GWQI. Ground water quality has changed all over the study area from 2003 to 2012. Figures 10 and 11 show the GWQI for 2003 and 2012. The electrical conductivity has changed in the southern part and the northern part of the study area from moderate to very poor. In the western part, some places the ground water quality has changed from moderate to severe. The Chloride value of these areas changed from very good condition to good condition and water table value also reduced in some areas in the Sivakasi and Virudhunagar taluk because of anthropogenic activities and low precipitation Figure 11 Ground Water Quality Inedx of Virudhunagar over the study years. The sodium absorption for 2012 ratio has changed minor level in this area. With the use of the equation 1, the ESAI Water table also turned from good condition to was developed for 2003 and 2012. Figures 12 moderate in the central part of the study area and 13 identify areas with verified severity of and in the western part, part of the Srivilliputhur land degradation 2003 and 2012. Most part of taluk has turned from low to very low stage. So, the study area, the moderate severity has turned all the four parameters played an important role into high in the year 2012. In Sivakasi & in the ground water quality reduction and Srivilliputhur taluk the changes occurred more chloride value played the dominant role among than any other area. Apart from that, the them. Virudhunagar taluk also has some severe land degradation problem over the years. 1740 INDIAN J. MAR. SCI., VOL. 44, NO. 11 NOVEMBER 2015

In 2012, Srivillliputhur and were severely affected when compared to 2003. In 2012, Rajapalayam and Virudhunagar areas were moderately affected in the study area. Results showed that climate and demographic pressure were the most important indicators causing desertification process. Normally this location is known for water scarcity and this analysis shows that the human activities play an important role in accelerating desertification process of this study area. The developed model may be used to determine the desertification process and distinguish the areas affected by desertification in the study region and the regions with similar characteristics. Figure 12 Environmentally Sensitivity Area Index Map of Virudhunagar for 2003 Conclusion The severity of land degradation varies from place to place because of various parameters. In this study, a regional model was developed by modifying the MEDALUS method in which desertification parameters were collected in the study area using GIS. Five composite indices each comprising several sub- indicators are analyzed. Results show that climate and demographic pressure were the most important indicators for desertification process in the study area. This model can assess the extent, intensity and severity of desertification process in the target area. In addition, there is scope for improvements when recent data are available. Figure 13 Environmentally Sensitivity Area Index Map of Virudhunagar for 2012.

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