The physical surface of the earth is in constant change: abundant water resources give rise to new growth, cities expand, what was once forest is converted to farmland. Man causes some of these transformations; others are merely the result of the changing of the seasons. In this work, we have used remote sensing images extensively to keep track the changes in the river in between 2000 to 2015 and a timeseries change map in the Narayani River, that affects the several thousands of people every year and destroy crops in thousands of hectares every year. The satellite images acquired by Landsat, provided were downloaded for 2000, 2005, 2010 and 2015. Atmospheric correction was done to achieve the best results and then applied support vector machine to delineate the rive course in all three years. In order to overcome the SLC problem in 2005 and 2010, a gap filling algorithm has been implemented. As the resolution of multi-spectral images is 30m and the panchromatic image is 15m, we took the advantage of the high resolution panchromatic images and thus use the pan-sharpning algorithm to obtain the higher resolution multi-spectral images that can give the better information about the smaller objects in the field. The results show that in between 2000 to 2015 there is not significant changes in the river course but here are few more vulnerable areas where the river can affect frequently. But due to its very wide river course, and the vegetation/trees grown along the bank of Narayani rivers in last fifteen years supported to control the flooding significantly in the nearby residential area and the agricultural area, still there are some vulnerable places where every year water overflows from the river to the residential and agricultural area primarily in Divyanagar and Meghauli are more vulnerable in Chitwan and in some parts of the Nawalparasi.