Monitoring Water Spread and Aquatic Vegetation using Spectral Indices in Nalsarovar, Gujarat State-India

Abstract

Nalsarovar Bird Sanctuary, a natural freshwater lake (a relict sea) that is the largest natural wetland in the Thar Desert Bio-geographic Province and represents a dynamic environment with salinity and depth varying depending on rainfall. For maintaining ecological balance in coastal and inland environments, wetlands play an important role and the changes in wetland environment can be monitored using satellite remote sensing technique. The present study was carried out using Landsat-7 TM (Feb-2002), Landsat-5 TM (Feb- 2009) and Sentinel-2 multi-spectral data (Feb-2018) covering Nalsarovar area in Ahmedabad district. The study area of Nalsarovar with 10 km buffer was extracted from the satellite digital data. Various spectral indices like Normalized difference Vegetation Index (NDVI), Normalized difference Water Index (NDWI) and Normalized difference Turbidity Index (NDTI) were generated for better identification and delineation of water body and aquatic vegetation in the Nalsarovar. The composite images of these indices were also generated to map and monitor changes in water spread and aquatic vegetation in the Nalsarovar. The water spread and aquatic vegetation in the Nalsarovar along with the land use classes were mapped using False Colour Composite (FCC) images of differed years. The result indicates that the water spread in Nalsarovar has changed from 2002, 2009 and 2018 depending on the monsoon pattern during these years. During drought year of 2002 total precipitation was very less resulting drastic reduction in the water spread in Nalsarovar. The aquatic vegetation has changed from 146.81 ha during 2002 to 510.93 ha during 2018. The land use change indicates that agriculture land, built-up, water body & wetland has increased and barren land, salt affected area has decreased. The aquatic vegetation in Nalsarovar was clearly visible on composite images generated using NDVI, NDWI and NDTI of different years. This study gives clear idea for land use change detection and water spread monitoring using two different techniques using Composite image of NDVI, NDWI and NDTI.

Keywords

• Nalsarovar
• Change detection
• Normalized Deference Vegetation Index (NDVI)
• Normalized Deference Water Index (NDWI)
• Composite Image of NDVI, NDWI & NDTI
• Normalized Deference Turbidity Index (NDTI)

References

1. Chowdary, V.M.; Vinu Chandran, R.; Neeti, N.; Bothale, R.V.; Srivastava, Y.K.; Ingle, P.;Ramakrishnan, D.; Dutta, D.; Jeyaram, A.; Sharma, J.R.; et al. Assessment of surface and sub-surface waterlogged areas in irrigation command areas of Bihar state using remote sensing and GIS. Agr. Water Manag. 2008, 95, 754–766.
2. Lacaux, J.P.; Tourre, Y.M.; Vignolles, C.; Ndione, J.A.; Lafaye, M. Classification of ponds from high-spatial resolution remote sensing: Application to Rift Valley Fever epidemics in Senegal. Remote Sens. Environ. 2007, 106, 66–74.
3. McFeeters, S.K. The use of the Normalized Difference Water Index (NDWI) in the delineation of open water features. Int. J. Remote Sens. 1996, 17, 1425–1432.
4. Mitsch, W.J. and Gosselink, J.G. (2000). Wetlands. (New York: John Wiley & Sons), P. 920.
5. Mohamed Elhag, IoannisGitas, Anas Othman, JarbouBahrawi and Petros Gikas, 2019. Water 2019, 11, 556.
6. Monirul Islam and KimiteruSado, 2006. “Analyses of ASTER and Spectroradiometer data with in situ measurements for turbidity and transparency study of lake Abashri”. International Journal of Geoinformatics. Vol. 2, 31-45.
7. Murthy T.V.R. and Panigrahy, Sushma 2011. Monitoring of Structural Components and Water Balance as an Aid to Wetland Management Using Geospatial Techniques – A Case Study for Nalsarovar Lake, Gujarat. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXVIII-8/W20, 2011 ISPRS Bhopal 2011 Workshop, 8 November 2011, Bhopal, India
8. Nirmal Kumar J. I., Hiren Soni and Rita N. Kumar, 2007. Anthropogenic Pressures of Nal Sarovar Bird Sanctuary, Gujarat, India. International Journal of Nature and Conservation. 2007. 19 (2): 209-231.

9. Nirmal Kumar J. I., Hiren Soni and Rita N Kumar, 2006. Biomonitoring of selected freshwater macrophytes to assess lake trace element contamination: a case study of Nal Sarovar Bird Sanctuary, Gujarat, India. J. Limnol., 65(1): 9-16.
10. Prigent, C., Matthews, E., Aires, F. and Rossow, W.B. (2001). Remote sensing of global wetland dynamics with multiple satellite datasets, Geophysical Research Letters, 28, pp. 4631- 4634.
11. Rouse, J. W., Haas R.H., Schell, J.A., and Deering, D.W. (1974). Monitoring vegetation systems in the Great Plains with ERTS. In: Fraden, S.C., Marcanti, E.P. & Becker, M.A. (eds.), Third ERTS-1 Symposium, 10-14 Dec. 1973, NASA SP-351, Washington D.C., NASA, pp. 309-317.
12. Sanjeev Kumar, 2009. Fauna of Nal Sa rov':lr, Gujarat, Wetland Ecosystem Series, 11, pp.1-137 + 12 plates (Published by the Director, Zool. Surv. India, Kolkata).
13. Stanley, O.D., 2004 Wetland ecosystems and coastal habitat diversity in Gujarat, India. Journal of CoastalDevelopment Volume 7, Number 2: 49-64.
14. Subramaniam, S and Saxena, Manoj, 2011. Automated Algorithm for Extraction of Wetlands from IRS Resourcesat LISS- III Data. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXVIII-8/W20, 2011 ISPRS Bhopal 2011 Workshop, 8 November 2011, Bhopal, India.