Author(s): Razia Akter Chowdhury, Towhida Rashid and Sirajul Hoque
Book Name: Dhaka Megacity: Geospatial Perspectives on urbanization, Environment and Health
Editor(s): Ashraf Dewan, Robert Corner
Publisher: Springer Science- Business Media. Dordrecht. The Netherlands
The objective of this chapter was to explore the potential of Landsat TM data, calibrated by in situ measurements, to map the spatial distribution of water quality in the rivers and lakes of Dhaka. The relationship of satellite brightness values and ground measurement was established through correlation and regression analyses. The results showed that the ratio of TM1 and TM3 was highly correlated with Secchi disk transparency (SDT), a measure of water clarity, while total suspended sediment (TSS) was strongly correlated with brightness values in the near-infrared portion of the electromagnetic spectrum. Regression analysis indicated that TM1 and the ratio of TM1/TM3 was the best predictor for SDT, and TM3 and the ratio of TM1 and TM3 was suitable for the estimation of TSS in waters. Maps of SDT and TSS are presented that illustrate the spatial variation of water quality in the inland water systems of Dhaka.
Chowdhury, R. A., Rashid, T. and Hoque, S. (2013) "Assessing surface water quality using Landsat TM and in situ data: an exploratory analysis" In Dhaka Megacity: Geospatial Perspectives on urbanization. Environment and Health, Dewan, A. and Corner, R. (eds.). Springer Science- Business Media. Dordrecht. The Netherlands, pp. 301-318