2015 Volume 57 Issue 2 Pages 171-185
In this study, we developed a model that represents discharge from a spring and variations in groundwater height, based on 5-years (2009-2013) of observations at Otomeyama Park in Shinjuku Ward. The model was calibrated using data from 2012-2013 and validated using data from 2009-2011. We used the model to simulate the discharge for 1998-2013 and specifically investigated the impacts of impervious land cover fraction, precipitation patterns, and water main leakage on long-term trends in the spring discharge. From Detailed Digital Information (10m Grid Land Use), it was determined that land cover/land use of the subject area has remained unchanged since the 1980’s so that it does not effect spring discharge. We found that after the 1990’s, discharge from the spring varied inter-annually owing to precipitation variability. If we take into account reduced leakage from the water main, then discharge is decreasing over time.
