Modeling the groundwater fluctuation in Sphagnum mire in northern Hokkaido, Japan

This research aims to investigate the role of wetland parameters in controlling the response of groundwater level (GWL) towards hydrologic condition and climate condition in Sphagnum mire of Sarobetsu Mire, northern Hokkaido, Japan. Hourly data of GWL, rainfall, and climate of summer for year 1993, 1994, 1997, 2003, 2008, and 2009 are used for modeling GWL fluctuation at point E on the observed area. The GWL modeling in this research adopts the philosophy of Sugawara's tank model, which involved c(1) as a function of soil porosity, c(2) as a function of rainfall rate, and c(3) as a function of soil hydraulic conductivity and slope. Parameter optimization of the model is undertaken by adjusting c(1), c(2), and c(3). The model is quite successful in imitating the behavior of GWL on observed area indicated by average NS value of about 70%. The best-fit model of each year of simulation shows that the value of c(1) and c(3) is 1.3 and 0.0, respectively. The value of 0.0 for c(3) indicates that there is no discharge coming out from the system. The value of c(2) varied and depended on the rate of rainfall and evapotranspiration. The research also found that basically c(2) is the ratio between rainfall and evapotranspiration. The model also indicates very small or almost no effect of lateral water balance such as lateral inflow from or to other sources on surrounding the observed area. (C) 2011 Published by Elsevier B. V. Selection and/or peer-review under responsibility of School of Environment, Beijing Normal University.