Hydro-Meteorological Data Consistency, Trend Detection, and Network Evaluation in the Upper Ganga Basin under a Changing Climate

The Himalayan region strongly influences India's climate and hydrology and serves as a major source of water for the Indo-Gangetic plains through rainfall, snowmelt, and glacial melt. Reliable long-term hydro-meteorological data are essential for effective water resources planning and climate change assessments. This study analyses hydro-meteorological data from the India Meteorological Department and the Central Water Commission for the Upper Ganga Basin (UGB) up to Rishikesh, using data validation, trend analysis, and network assessment techniques. Spatial homogeneity analysis identified 24 abnormal rainfall events during 1972–2016, while double-mass curve analysis revealed significant inconsistencies at 8 of 30 stations. Trend analysis indicates an overall increase in precipitation during the monsoon season and at the annual scale across the UGB. Increasing trends in the number of rainy days were observed at several stations during the pre-monsoon and monsoon seasons. In contrast, decreasing trends were observed during the winter and post-monsoon seasons. Trends in temperature and river flows were also evaluated. The hydro-meteorological network assessment indicates that the existing station network is generally adequate for capturing rainfall variability; however, reactivation of discontinued stations is recommended in accordance with WMO guidelines. Entropy analysis identified potential locations for new observation stations. Evaluation of gridded and reanalysis datasets showed that GPM-IMERG satisfactorily represents monthly precipitation over the UGB and can serve as a suitable alternative dataset. In contrast, ERA5-Land and IMDAA datasets exhibit a significant cold bias and underestimate local temperatures in the Himalayan region, limiting their direct applicability for local-scale temperature studies.