ALBERT

Description: The Indian region experiences an atmosphere-ocean-land driven phenomenon known as Indian Summer Monsoon (ISM) characterized by abundant precipitation, a crucial source for the hydrological cycle are greatly explored on a large-scale forcing. There is still much to discover about local scale processes that affect the hydrological cycle, such as interactions between the land and atmosphere under the influence of natural or human forcing. The interactions between soil and vegetation have an impact on the hydrological cycle, the atmosphere, and CO〈sub〉2〈/sub〉 uptake mainly through evapotranspiration (ET). It is crucial to understand how processes that are natural or caused by human intervention can affect the uptake of carbon and ET. Further, it is observed that ET persists over post-monsoon period which is also responsible for the ecosystem productivity in drier period. Such features are not yet explored due to the lack of understanding.Here, with satellite data and observations, we demonstrate how the soil-vegetation continuum can functions as a natural water capacitor, storing the monsoon pulse and releasing the moisture to the atmosphere through ET particularly in dry periods. We discovered that the post-monsoon terrestrial water cycle over India is driven by the water held by the soil-plant continuum and it is dependent on the preceding precipitation or other input as forced by humans (irrigation). For different land-use cover, we have explored how unique soil-vegetation capacitor effect can have specific role in maintaining the land-atmosphere interactions during drier periods where rainfall is very scanty or scattered or there is human forcing.

Description: Climate change response assessment of the Himalayan river flows is a complex problem due to multiple contributors: rainfall, snowmelt, and glacier melt. Due to a lack of data availability and models that consider all of the factors mentioned above, the number of studies in this approach is constrained. For instance, the variable infiltration capacity (VIC) model does not consider glacier melt. In our work, we combine a glacier-melt model with VIC and validate the model's results using daily streamflow observations from five river basins in the Himalayas. In all basins, our model replicates streamflow with Nash-Sutcliffe estimates over 0.65. The sensitivity analysis shows that the contribution from snowmelt decreases substantially in all five basins, with the highest decrease of 36% in Dudh Kosi (DK) in a warm and dry scenario. The glacier-melt increases (15%–70%) in a warmer environment with its present volume but decreases (3%–38%) substantially when the volumes are reduced to half. However, such a decrease is found to be compensated by increased precipitation in a wetter scenario with a net increase of 3%–13%. For both the RCP4.5 and RCP8.5 scenarios, climate model simulations indicate that the Sutlej basin's spring start periods are decreasing while they are increasing for the DK basin. The centre of streamflow in the Sutlej and Arun basins shows declines of more than six days, indicating higher flows early in the year and lower flows later. Understanding different streamflow components is also important to understand how extreme precipitation events translate into hydrologic extremes.