Highlights We use Landsat TM and ETM+ data for water quality assessment of Rawal Lake. We estimate TSI of the Lake using in situ SDT, Chl-a and TP values. We estimate the tropic condition of Rawal Lake using TSI values. Recommendations are made to preserve the water quality of the Lake.
Abstract Satellite imagery holds significant potential for monitoring regional lake water clarity. This study addresses the use of satellite data and ground observations for the assessment of Rawal Lake water clarity in Pakistan. Satellite data from Landsat sensor for the years 2009–2013 are used to model Secchi Disc Transparency (SDT). Landsat images within ±3days of the measured SDT data is used for the development of a regression model. The results of this study show that ETM+ band3 and band1/band3 ratio is the reliable predictor of SDT with R 2 values of 0.725 and 0.793 respectively. The modeled SDT is further used to estimate the Trophic State Index (TSI) and trophic condition of Rawal Lake. In addition, the in situ Chlorophyll-a (Chl-a) and Total Phosphorus (TP) concentration are used to calculate the TSI of the Lake. The Mann–Kendall (MK) statistical test shows that the increasing trend in TSI based on SDT is significant (τ =0.523). The trophic condition of Rawal Lake indicates that the Lake falls under the hypereutrophic category, that is, highly polluted and extremely unhealthy for the purpose of drinking.
Landsat ETM+ Secchi Disc Transparency (SDT) retrievals for Rawal Lake, Pakistan
Advances in Space Research ; 56 , 7 ; 1428-1440
2015-06-29
13 pages
Article (Journal)
Electronic Resource
English
Secchi disc , SDT , Chl-a , TP , TSI , Trophic condition
Landsat ETM+ Secchi Disc Transparency (SDT) retrievals for Rawal Lake, Pakistan
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