Journal of Agricultural, Life and Environmental Sciences ISSN:2233-8322(Print) 2508-870X(Online)

Hydrological connectivity has been proposed and utilized as an important concept to understand surface and subsurface flow processes in watershed hydrology. This can be beneficial for characterizing soil moisture variability in complex and spatially heterogeneous landscapes. Existing hydrological models have limitations in adequately explaining subsurface characteristic patterns connected with flow path continuity in unsaturated regions. Therefore, to better understand the subsurface flow spatial distribution and to improve the soil hydraulic parameter properties in hydrological modeling (Soil and Water Assessment Tool, SWAT), the parameters were revised by applying the hydrological connection algorithm based on the physical soil and land surface properties, and the model performance was evaluated. Firstly, the correlations between the soil moisture data and weightings were calculated using soil properties (sand% and clay%), normalized difference vegetation index (NDVI), and the topographic index which are related to the soil moisture spatial distribution characteristics. The hydrological connectivity analysis was performed according to various thresholds based on these weightings and using new spatial distribution data which combines physical properties. Subsequently, the available water content (Sol_AWC) and saturated hydraulic conductivity (Sol_K) variables, which are closely related to soil moisture estimates in the SWAT model, were revised according to the connectivity index. The results of this study showed that the spatial variation of soil moisture can be explained well using the hydrological connectivity index based on the physical properties, and that the existing model performance can be improved using the corrected (spatially distributed) soil hydraulic parameters.