Spatio-Temporal Analysis and Modelling of Water Quality in Mahanadi River Basin

Abstract

Water is life. But if the quality of water is poor, it may become poison. Scientists and researchers have opined that the quality of water available to a society is an important factor in determining the quality of life as a whole in the society. Urban, industrial and agricultural activities, increasing consumption of water resources as well as natural processes such as change in precipitation inputs, erosion etc. damage surface water quality. Therefore, assessment of surface water quality is required as it directly affects public health. In our study, we have selected Mahanadi river basin which lies predominantly in Chhatisgarh and Odisha. During the last few decades, many water quality monitoring programs are used for reliable estimates of the water quality in view of the temporal and spatial variations in hydrochemistry of river in this region. Eight gauging stations were selected in total for collecting the data for various water quality parameters viz.,pH, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Electrical Conductivity, Nitrogen as nitrate (NitrateN), Total Coli-form Bacteria(TC), Fecal Coli-form Bacteria(FC), Chemical Oxygen Demand (COD), Nitrogen as ammonia (NH4-N), Total Alkali (TA) as CaCO3, Total Hardness (TH) as CaCO3. Analysis of water quality was done by PCA and PFA techniques. The spatial analysis was done using GIS interpolation technique of Inverse Distance Weighted method. Then a physical water quality model was created using SWAT. The coefficient of determination for the calibration period (1991-2000) was found to be 0.75 for the discharge at Tikarapara (selected outlet) and for validation period (2001-2010) R2 came to be 0.66 using SUFI2 which showed the model predicts the flow satisfactorily. For the water quality BOD and DO (important parameters as found by PFA) were selected for the calibration and validation. The R2 came out to be 0.863 and 0.726 for BOD and DO respectively in calibration period. And for validation period the values were 0.785 and 0.688 respectively.