Measured groundwater velocity vectors are shown in Fig. 19.18. Most of the
vectors follow GWL distribution and groundwater flowed to northward; groundwater flow velocities range from 0.008 to 0.039 cmÁmin
À1 . The average velocity is
)LJ
Fig. 19.17 GWL distribution around the peat made Weir 3 in Bengkalis Island, Riau, Indonesia on
August 22, 2017
Fig. 19.18 Groundwater flow velocity measured by PDGV around Weir 3 in Bengkalis Island,
Riau, Indonesia on August 22, 2017
562
H. Takahashi et al.