[A-HW20] Materials transport and nutrient cycles in watersheds; Human and climate impacts

[AHW20-08] Estimation of lacustrine groundwater discharge into Biwa Lake

*Kunyang Wang¹, Mitsuyo Saito², Shin-ichi Onodera¹, Fandy Tri Admajaya¹, Syuhei Ban³, Noboru Okuda⁴, Yuta Shimizu⁵ (1.Hiroshima University, 2.Okayama University, 3.The University of Shiga Prefecture, 4.Research Institute for Humanity and Nature, 5.National Agriculture and Food Research Organization)

Keywords:LGD, lacustrine groundwater discharge, Biwa Lake, SWAT Model

The quantification of lacustrine groundwater discharge (LGD) in water is one of the most important indicators of water cycle in lakes by carrying large nutrient loads. The Yasu River is one of the important water sources of Biwa Lake. This paper using Geographic Information System technology, and based on the analysis and prediction of the land use change in Yasu River basin. The water balance was simulated using the Soil and Water Assessment Tool (SWAT2012). Model calibration and uncertainty analysis were performed with sequential uncertainty fitting (SUFI-2). The correlation coefficient and the Nash–Sutcliffe coefficient is higher than 0.50. The results shown that total groundwater accounted for 41.77% of the rainfall and 62.82% of them are shallow groundwater. At the same time, nitrogen and phosphorus are also released to the river with groundwater, continuous impact on the water and water quality of the Biwa Lake.