The glacierised mountain catchments of the Himalayan region serve lives and livelihoods for millions of people living downstream. When water (or streamflow) flows from headwaters to floodplains, the water resources are widely utilised for many activities such as agriculture, drinking water, and hydropower. The activities and processes (such as land-use change and snow and glacier melt) in upstream areas affect the spatial and temporal distribution of water resources to downstream regions. In the context of climate change, the hydrological regime of the Himalayan river systems is likely to be affected which might change the water availability for downstream people. The understanding of the hydrological dynamics is crucial for sustainable planning and management of water resources of the Himalayan region. However, the lack of hydro-meteorological data in the region, especially in high-altitude areas, hinders the process of understanding the system dynamics. In this context, the present study is intended to analyse the upstream-downstream linkages of hydrological dynamics in the Kosi river basin of the Himalayan region. The study attempted to understand the hydrological system dynamics of the Kosi river basin using the process oriented and distributed hydrological model. Similarly, the model application also enables to understand the impact of land-use and climate change on hydrological regime. The understanding of process characteristics of precipitation and runoff generation derived from the modelling application was instrumental in recognising the upstream-downstream relationship.