Assessing Meteorological and Anthropogenic Factors on Streamflow Trends in the Ramganga River Basin in North India

Abstract

The analysis of stream flow trends of hydro-climatic variables such as stream flow, rainfall, and temperature provides useful information for effective water resource planning, design, and management. Trends in observed stream flow at seven gauging stations in the Ramganga river basin of North India were examined from 1981 to 2012 using the Mann-Kendall and Sen's slope. Lag 1 autocorrelation analyses were used to investigate the relationships between trends in stream flow and rainfall. Annual, monsoonal, and winter seasonal stream flow (p0.05) decreased gradually from upstream to downstream of the river, as did crop seasonal and decadal moving averaged standardized anomalies of streamflow for the entire basin. The streamflow's declining trend was partly attributed to higher water withdrawal, higher air temperature, and higher population, and partly to a significantly declining post-monsoon rainfall trend, particularly upstream and downstream. The changing monsoon rainfall pattern and the growing population both contributed significantly to the development of this trend.  The significant decreasing trend in stream flow at the upstream gauging station (-0.39 m3/s/year) was attributed to the significant decreasing trend in catchment rainfall (-8.40 mm/year). This study shows a strong positive correlation between stream flow and catchment rainfall (r=0.60). The Ramganga River basin is showing signs of drying up, as evidenced by the declining stream flow, post-monsoon rainfall, especially in the downstream area, and concurrently rising temperature trends. The Ramganga River basin's sustainable water management planning will be aided and made possible by the study's findings and recommendations, which will help stakeholders design strategies for stream flow restoration. This study thus highlights the urgent need for comprehensive water management planning in this basin by implementing procedures at various spatial scales that may be able to halt the trend of drying by improving river water use efficiency in a variety of sectors.