This chapter aimed to explore downstream change of diurnal, monthly, and yearly minimum, mean, and extreme channel flowChannel flow pursuing damming using traditional to advance approaches. The study further tried to predict flow in the near future. Trend, variability, instability, periodicity, range of variability (RVARange of Variability Approach (RVA)), failure flow estimation, machine learning (MLMachine Learning (ML)), etc., were applied to assess flow change and prediction. All types of flow assessment techniques reported declining minimum, mean, maximum, flow in damDam downstream river. A marked reduction in peak flood discharge by a 66% in monsoonal flows was detected. In other seasons also the same trend was found. Increase of low-flow days and lowering of high-flow days in post-dam period were detected. Significant reduction of flood frequency in post-dam period is caused for ceasing water flow to the floodplain wetlandFloodplain wetlands and leading them in stress.