Impact of Climate Change on Freshwater Systems and Assessment of Hydrodynamics and Nutrient Dynamics in Limnology

Abstract

Aim & Significance: The research questions the impacts of climate change on freshwater systems and its hydrodynamic changes and nutrient dynamics. Freshwater ecosystems contribute significant aspects of biodiversity and ecosystem services, yet the exposure of these systems to changes in climate in terms of temperature, flow and nutrient cycling are poorly understood. The recognition of these impacts is a key aspect in successful management and safeguarding of the ecosystem. Methods: Hydrodynamic modeling and nutrient dynamics analysis were used to simulate the nutrient transport and water movement using Delft3D. Field data (streamflow, water temperature, nutrient levels (NO₃, PO₄, NH₄) of streams in the Brahmaputra River in Assam, India, were sampled at 12 sites across three seasons (pre-monsoon, monsoon, post-monsoon).Statistical methods such as multiple regression analysis and time series analysis were used to correlate nutrient cycling with hydrodynamic changes. Key Results: Findings reveal that the water temperature has risen significantly (+0.32°C per decade) and the streamflow has declined slightly (-6.8 m³/s per decade) over the last 20 years. Agricultural areas had increased nutrient levels (especially nitrogen and phosphorus) with extensive spatial and temporal changes in nutrient availability correlated to hydrodynamic changes. Conclusions & Implications: The results point to the instability of freshwater systems to climate change, in terms of nutrient cycling and ecosystem health. The findings indicate that adaptive management approaches should be implemented to deal with hydrodynamic and nutrient dynamics to alleviate the effects of climate change on water quality and ecosystem services.