Report of hydrological observations at the Jozankei Experimental Watershed (January 2002 to December 2007)

摘要

At the Jozankei Experimental Watershed (JEW) in the national forest near Sapporo, the stream runoffs for two small adjacent basins and the precipitation have been surveyed since 1987 as research on forest hydrology in a snowy cold region. The observation data from 1991 to 2001 were published recently, and full-year data were available for each of these years. This report describes the daily data of runoff and precipitation for the 6 years from 2002 through 2007 and the results of a forest resources survey conducted in 1998. Major events from 2002 to 2007 were as follows. The water level gauge was equipped with a potentiometer in May 2002, so that water level data could be recorded with a digital logger. The steel plates to which the V-notch blades were attached and the wire screens to prevent detritus from clogging the notch were replaced with new ones, and the pools of the gauging weirs were dredged from January to March 2003. The new screens clogged frequently during flooding, so the upper parts of screens were cut out and replaced with larger-mesh screens in September 2006. The stand for the rain and snow gauge was replaced with a new one in November 2005, because the previous stand was ramshackle and seemed to cause the precipitation to often not be measured.