Connected Oscillation System in Lake Nakaumi and Lake Shinji

Abstract

Lake Nakaumi and the Sea of Japan are connected by Sakai Channel, while Lake Shinji and Lake Nakaumi are connected by Ohashi River, and temporal variations in water level of Lake Nakaumi and Lake Shinji are mutually related to the oceanic tide.
Then the characteristic and mechanism of their surface oscillation should be clarified as a system connected for the tidal oscillation. We constructed a simple linear model to get an analytical solution for surface oscillation in such a unique system, taking account of river inflows and water flux coefficient through water ways. We got a stationary oscillatory solution with a boundary condition of sine - type tidal oscilla-tion, and decided numerical parameters and coefficients by using in situ records of water level and water currents.
Numerical comparison between the results from our Connected Oscillation Theory and observed water levels shows an approximate accordance, but the numerical analysis is needed for more exact estimation of oscillation including wider ranges of amplitude and period of tide and river discharge.