Study on the relationship between surface water and groundwater transformation in the middle and lower reaches of Songhua river basin.

To precisely delineate the transformation dynamics across several temporal and spatial scales in the middle and lower portions of the Songhua River basin in Heilongjiang Province, China, characterized by numerous irrigation zones and frequent transitions from surface water to groundwater. The SWAT-MODLFOW model, developed on the QSWATMOD2 platform, was validated using river runoff data and groundwater level observations. Consequently, the delay of precipitation on groundwater levels and the correlation between surface water and groundwater dynamics in the middle and lower portions of the Songhua River basin were modeled.