2.1. Data Acquisition
The observation system has been set up over the conveyance channel of m
wide rectangular cross-section, at the coordinates 31 15 33.2 N 35 29
20.2 E which falls on the point 2.4 m upstream from the downstream end,
operating with a Campbell data logger connected to a VAISALA
multi-weather sensor and a Campbell water level sensor. The data logging
interval usually is 10 minutes, but it switches to 1 minute if the
rainfall depth in the last 10 minutes is equal to or greater than 0.2
mm. If there is no rainfall for 12 hours, then the logging interval
returns back to 10 minutes. As a result of the numerical experiment
using the finite volume model for the two-dimensional shallow water
equations (Unami et al. 2009), a functional relationship between the
observed water depth and runoff discharge is determined as
where is the cross-sectional area,
and is the hydraulic radius. This formula differs from the standard
uniform flow formulae due to the curving alignment and non-uniform
channel bed slopes of the conveyance channel. An auxiliary raingauge of
a tipping-bucket type is located at the coordinates 31 15 41.2 N 35 29
39.5 E, 566 m apart from the observation system.