40-Application of remote sensing for the assessment of water quality - A case study of Tawa reservoir

Abstract

An attempt has been made to quantify the relationship between the variation in IRS-IALISS- I radiance data and field measured change in secchi disc depth. Secchi disc depth was measured for 47 predetermined sampling locations on reservoir surface water. At extinction depth (secchi depth), water samples were collected from all the sampling locations. Suspended sediments of eight locations representing various reaches of the reservoir were selected for mineralogical, particle size and optical properties analysis. The LISS-I radiance value in band 1 (0.45-0.52pm) band 2 (0-52-0.59 im) and band 3 (0.62-0.68 im) were used in a regression analysis. The coefficient of correlation between observed and estimated values was r= 0.92 for SD, indicating that the equation could accurately predict the water clarity (SD) for this reservoir on new occasions from IRS-IA-LISS-I spectral data. It is shown that mineral composition and optical properties of suspended sediments influence the reflected radiance of water quality. It is concluded that IRS-IA-LISS-I data provide a useful means of mapping water quality in reservoir.