Results
Short term and long-term streamflow
observations
Discharge time series for the Gōno
River observed at the studied stations are shown in Fig. 3. The Gōno
River has a flashy regime, influenced considerably by the intensity of
precipitation. Apparently, it can be realized that the discharge records
reveal some years with low amount of flow rates. For example, 2002 to
2003, 2007 to 2009, and from 2015 to 2017. On the other hand, it can be
distinguished that there is an upward trend in the maximum streamflow
records induced by the large amount of precipitated rains. In other
words, it is obvious that the maximum streamflow in 2006 peaked at 3300
m3/s approximately, and the maximum peaks observed at
2010 and 2014 were roughly 3500 and 3600 m3/s,
respectively, Though it was not reported by the MLIT yet, in 2018 heavy
rains documented the greatest flood that occurred in Hiroshima
prefecture.
Figure 3 is here.
Fig. 3 Discharge time series during the study period
(2002-2017) observed at Awaya (red), Minamihatachiki (green), Miyoshi
(blue), and Ozekiyama (Black) stations.
Prior to information and complexity results, it is essential to briefly
comment on the discharge measurements by FAT
(QFAT ) compared to the RC
(QRC ) estimates at Ozekiyama observation site.
Demonstrated in Fig. 4, a comparison between QFATand QRC , it can be seen that both discharge
methods show very good agreement. Furthermore, it can be noticed that
FAT can capture the fluctuations that take place during very short times
scales, this feature in particular, inspired us to profoundly explore
this difference. Kawanisi et al., (2018, 2016) investigated the accuracy
of river discharge of QFAT compared to other
discharge computation methods (e.g. RC and ADCP) measured at Ozekiyama
station and examined the error structure that impair the performance of
FAT estimates, it was demonstrated that in the case of streamflow
measurements by means of FAT at the Gōno River, the maximum potential
error within low-flow circumstances is estimated as 15%.