Back
 JWARP  Vol.11 No.4 , April 2019
Study on the Applicability of Landsat-8 Images as a Tool for Monitoring the Trophic State of Lake Guiers (Senegal)
Abstract:

In this study, an algorithm to transform LANDSAT 8 images of Lake Guiers into chlorophyll-a concentration maps was developed. The objective was to see the feasibility of this method as a mapping tool for monitoring the trophic state of the Lake. The available data are 15 in-situ measurements of the CHL-a content of Lake Guiers’ water using a Micro FLU device and images of the lake acquired in 2013 and 2016 by the LANSAT 8 OLI sensor. A series of correlation tests (simple linear functions, multi-variables, or containing two- order terms) were performed between the spectral sensor signal of June 19, 2016 LANSAT 8 image (“corrected” and converted into reflectance) and the CHL-a content of Lake waters measured on the same day of the satellite record. This was, to find the best regression equation that can be inferred to develop an algorithm to transform LANDSAT 8 image into CHL-a concentration maps. The best equation obtained by correlating the ground truths and the reflectance ratios of the visible and near infrared bands (B2, B3, B4 and B5), is as follows:


where B2 = Blue band, B3 = Green band, B4 = Red band, B5 = NIR band. The obtained R2 is 0.703 (e.g., a correlation coefficientof 0.84), revealed that the measured concentrations are well reproduced by the regression model. Applying this model to the 2013 and 2016 image data revealed the monthly variations of the lake CHL-a contents and their seasonal evolution and interannual variations. The obtained results are quite consistent with those from similar studies and provide valuable information regarding Lake Guiers’ vulnerability to algal development. The calculation and analysis of the variability of the CHL-a contents over the study period made it possible to evaluate the trophic state of the Lake, which shows a general tendency for eutrophication process, leading to a progressive degradation of the quality of the water resource.
Cite this paper: Diédhiou, C. , Diop, S. , Faye, G. , Moshod, T. and Wade, S. (2019) Study on the Applicability of Landsat-8 Images as a Tool for Monitoring the Trophic State of Lake Guiers (Senegal). Journal of Water Resource and Protection, 11, 434-447. doi: 10.4236/jwarp.2019.114026.
References

[1]   I.S.E. (1983) Lake Guiers: Environmental and Development Issues. Proceedings of I.S.E. Symposium, 9-11 May 1983, 506 p.

[2]   Niang, A. (1999) Environmental Monitoring and Water Quality Management of Lake Guiers. PhD Thesis in Physical Geography, FLSH, Department of Geography, UCAD, Dakar, 348 p.

[3]   Spitzer, D. and Dirks, R.W.J. (1985) Contamination of the Reflectance of Natural Waters by Solar-Induced Fluorescence of Dissolved Organic Matter. Applied Optics, 24, 444-445.
https://doi.org/10.1364/AO.24.000444

[4]   Baban Serwan, M.J. (1993) Detecting Water Quality Parameters in Norfolk Broads, U.K., Using Landsat Imagery. International Journal of Remote Sensing, 14, 1247- 1267.
https://doi.org/10.1080/01431169308953955

[5]   Miller, R.L., Mckee, B.A. and D’sa, E. (2005) Monitoring Bottom Sediment Resuspension and Suspended Sediments in Shallow Coastal Waters. In: Miller, R.L., Del Castillo, C.E. and McKee, B.A., Eds., Remote Sensing of Coastal Aquatic Environments, Springer, Berlin, 259-276.
https://doi.org/10.1007/1-4020-3100-9_11

[6]   Gitelson, A., Mayo, M., Yacobi, Y.Z. and Ben-Avraham, Z. (1995) Chlorophyll Distribution in Lake Kinneret Determined from Landsat Thematic Mapper Data. International Journal of Remote Sensing, 16, 175-182.
https://doi.org/10.1080/01431169508954386

[7]   Dekker, A.G., Voss, R.J. and Peters, S.W.M. (2002) Analytical Algorithms for Lake Water TSM Estimation for Retrospective Analysis of TM and SPOT Sensor Data. International Journal of Remote Sensing, 23, 15-35.
https://doi.org/10.1080/01431160010006917

[8]   Lathrop, R.G. (1992) Landsat Thematic Mapper Monitoring of Turbid Inland Water Quality. Photogrammetric Engineering and Remote Sensing, 58, 465-470.

[9]   Olmanson, L.G., Brezonik, P.L., Finlay, J.C. and Bauer, M.E. (2016) Comparison of Landsat 8 and Landsat 7 for Regional Measurements of CDOM and Water Clarity in Lakes. Remote Sensing of Environment, 185, 119-128.
https://doi.org/10.1016/j.rse.2016.01.007

[10]   Bilgehan, N., Karabork, H., Ekercin, S. and Berktay, A. (2009) Mapping Chlorophyll-a Through In-Situ Measurements and Terra ASTER Satellite Data. Environmental Monitoring and Assessment, 157, 375-382.
https://doi.org/10.1007/s10661-008-0542-9

[11]   Brivio, P.A., Giardino, C. and Zilioli, E. (2001) Determination of Chlorophyll Concentration Changes in Lake Garda Using an Image-Based Radiative Transfer Code for Landsat TM Images. International Journal of Remote Sensing, 22, 487-502.
https://doi.org/10.1080/014311601450059

[12]   Mbaye, A.D. (2013) Environmental and Social Management Project Scheme for Resoring the Lake Guiers Socio-Ecological Functions. PREFELAG, Final Report, 48 p.

[13]   Cogels, F.X., Carn, M., Niang, A. and Gac, J.Y. (1993) The Quality of Lake Guiers Waters 1. Qualitative Assessment 2. Colleteral Effects of Development Activities in the Senegal River 3. Primary Use of a Model for Qualitative Management. Doc. Multigr, ORSTOM EEC, 52 p.

[14]   Cogels, F.X. (1994) The Quality of Surface Waters in the Senegal River Delta and in Lake Guiers. ORSTOM Documentary Fund, 48 p.

[15]   Gac, J.Y., Cogels, F.X., Niang, A. and Coly, A. (1994) General Study of the Lacustrine System and of Its Management Problem. Doc ORDTOM, 69 p.

[16]   Brezonik, P., Kevin, D., Menken and Bauer, M. (2005) Landsat-Based Remote Sensing of Lake Water Quality Characteristics, Including Chlorophyll and Colored Dissolved Organic Matter (CDOM). Lake and Reservoir Management, 21, 373-382.
https://doi.org/10.1080/07438140509354442

[17]   Mancino, G., Nolè, A., Urbano, V., Amato, M. and Ferrara, A. (2009) Assessing Water Quality by Remote Sensing in Small Lakes: The Case Study of Monticchio Lakes in Southern Italy. iForest, 2, 154-161. https://doi.org/10.3832/ifor0507-002

[18]   Han, L. and Jordan, K.J. (2005) Estimating and Mapping Chlorophyll-a Concentration in Pensacola Bay, Florida Using Landsat ETM+ Data. International Journal of Remote Sensing, 26, 5245-5254.
https://doi.org/10.1080/01431160500219182

[19]   Chander, G., Markham, B.L. and Helder, D.L. (2009) Summary of Current Radiometric Calibration Coefficients for Landsat MSS, TM, ETM+, and EO-1 ALI Sensors. Remote Sensing of Environment, 113, 893-903.
https://doi.org/10.1016/j.rse.2009.01.007

[20]   ERDAS IMAGINE (HexagonGeospatial, Version 2014).
https://www.hexagongeospatial.com/resources/support

[21]   Olmanson, L.G., Kloiber, S.M., Bauer, M.E. and Brezonik, P.L. (2001) Image Processing Protocol for Regional Assessments of Lake Water Quality. Water Resources Center and Remote Sensing Laboratory, Univ. of Minnesota, St. Paul.

[22]   Wu, C., Wu, J., Qi, J., Zhang, L., Huang, H., Lou, L. and Chen, Y. (2010) Empirical Estimation of Total Phosphorus Concentrations in the Mainstream of the Quintang River in China Using Landsat TM Data. International Journal of Remote Sensing, 31, 2309-2324.
https://doi.org/10.1080/01431160902973873

[23]   DHI/Tropis (2005) Development of the Management Scheme for Lake Guiers, PLT (Long-Term Water Project). Final Diagnostic Report, 222 p.

[24]   Ba, N. (2006) The Phytoplankton Community of Lake Guiers (Senegal): Types of Functional Associations and Experimental Approaches of the Regulating Factors. Doctoral Thesis in Ecology, Department of Biology, FST, UCAD, Dakar, 159 p.

[25]   Diop, S., Wade, S. and Tijani, M.N. (2016) Feasibility Analysis of MERIS as a Tool for Monitoring Lake Guiers (Senegal) Water Quality. Journal of Water Resource and Protection, 8, 100-119.
https://doi.org/10.4236/jwarp.2016.81009

[26]   RAPPEL (Regroupement des Associations Pour la Protection de l’Environnement des Lacs et des cours d’eau de l’Estrie et du haut bassin de la rivière Saint-François) (2009) Suivi de l’eau-été 2009. Lac Long Pond; Réd. M. Dubois, Sherbrooke, 14 p. [RAPEL—Regrouping Associations for the Protection of the Environment of the Lakes and Waterways of Estrie and the Upper Saint-François River Basin: Water Monitoring, Summer 2009, Lake Long Pond; Redaction by M. Dubois, Sherbrooke, 14 p].
http://laclongpond.org/sites/laclongpond.org/files/Ete%202009_Suivi%20Eau_Long_Pond_1.pdf

[27]   Kansas Department of Health and Environment, Bureau of Water (2011).
http://www.kdheks.gov/water/download/tech/Duration_Frequency_final_Jan27.pdf

 
 
Top