Trend analysis of hydrological parameters of Ganga River

Ganga River basin, being the largest river basin in India, adheres with its social and spiritual importance for the country. Although many studies have been conducted on the Ganga basin, however, trend observed in flow and sediment yield in Ganga River has been scarcely studied. Alteration in flow pattern and sediment transport in rivers brings remarkable impact on river geomorphology and entire ecosystem of the region. The present paper attempts to identify trends observed in Ganga River in terms of annual maximum and annual minimum discharges, water and sediment yield during monsoon season. The trend analysis was accomplished by performing the Mann-Kendall (M-K), Sen’s slope, and innovative trend analysis at various gauging sites along the river for the monsoon months. Significance of trend tests were tested at 5% significance level. Innovative trend analysis (ITA) revealed non-monotonicity within the time series and provided more detailed understanding of changes in hydrological changes. While observed annual maximum discharge showed a negative trend at almost all the sites, annual minimum discharge showed positive trend at gauging sites upstream of confluence of Yamuna River. Data of discharge and sediment load for monsoon months also revealed declining trends at most of the gauging sites. Water and sediment yields at all sites except Gandhighat showed a negative trend. Decline in trend of sediment and water yield is more pronounced in Western Ganga Plain (WGP) as compared to Eastern Ganga Plain (EGP). Incorporating these trends can be helpful for various water management projects in the future. Both climatic factors and human intervention appear to be responsible for the alteration in flow pattern of Ganga River.