Identification of seasonal variation of water turbidity using NDTI method in Panchet Hill Dam, India

Abstract

Sedimentation in reservoir is a common problem in any multipurpose river valley project and is effective upon the performance of it. Every dam has an estimated volume of water holding capacity at the time of inception, but it gradually reduces by siltation. The presence of sediments in water causes turbidity and it slowly precipitates on the floor of the reservoir. Normalized difference turbidity index (NDTI) is a remote sensing technique widely used to identify the water turbidity, which is the ratio of red and green bands of solar spectrum. In Panchet Dam actual rate of siltation exceeds the assumed rate that fills up the entire reservoir area at a faster rate. In this situation, the study has been conducted to explain the variation of water turbidity of the dam throughout the year 2015. Major findings of the study indicate that the turbidity level jumps from 60 NTU to 700 NTU in the monsoon. High turbid water covers 50.57%, 64.22% and 52.79% area of the reservoir in July, August and September, respectively. In contrast, coverage of low turbid water is more than 71.68% in the months of February and June. The medium turbid water covers less than 35.82% area throughout the year except the months of September and October. High level of correlation exists (R2 = 0.900) between NDTI values and total suspended sediments concentration in mg/L (N = 15, p < 0.05) with minimal RMSE (13.59). Variation of seasonal turbidity and different types of turbidity are significant at 95% (p < 0.05) level of significance. The paper is an attempt to probe into the seasonal variation of water turbidity of the dam with the application of NDTI method and related statistical measures.