Integrating Satellite-Derived Parameters to Advance Ecohydrological Modeling of Forested Areas

The accurate representation of vegetation and its dynamics plays a crucial role in the modelling of hydrological cycle. Vegetation regulates the movement of water and energy fluxes within an ecosystem. Process based models such as Soil and Water Assessment Tool Carbon (SWAT–C) are widely used to model different water balance components such as streamflow, evapotranspiration, soil moisture and sediment yield. However, their accuracy in simulating vegetation dynamics particularly, forest growth is limited for tropical and sub-tropical regions as the original model was developed for temperate regions. The unrealistic representation of forest phenology poses a limitation in estimating the Leaf area index (LAI), evapotranspiration and sediment accurately. This study adopted a climate triggered start of season for initiating the forest growth in a dry deciduous forest in sub-tropical region rather than a fixed calendar date for each year of simulation. Remote sensing data of Moderate Resolution Imaging Spectroradiometer (MODIS) LAI was utilised to derive the various growth parameters governing the shape of the ideal plant growth cycle. Different SWAT-C configurations were tested to evaluate the effects of parameterization and dormancy adjustments. While the default model simulated streamflow accurately, the forest dynamics was captured poorly leading to inaccurate LAI estimation, overestimation of evapotranspiration and sediment yield. Overall, the results revealed that the improved model would advance ecohydrological simulation accuracy by capturing vegetation-water interactions.

Keywords: Forest dynamics, Ecohydrology, LAI, Remote-sensing.