In any river ecosystem, water flow plays an important role
in controlling the growth and root expansion of aquatic plants
(Barko et al. 1986; Biggs 1996). The flow also has a strong
influence on the physical structure of the aquatic environment
and the life-history strategies of riverine plants (Haley
2009). Changes in flow volume and velocity have been
reported to affect the biomass and composition, colonization,
establishment and persistence of aquatic plants
(Butcher 1993; Franklin et al. 2008). The impact of flow
change is more apparent in a regulated river where a dam or
water gate has been constructed. Generally, hydrological
schemes for drainage control are designed according to
water utilization and/or flood management purposes. Such
controls may cause unsuitable flow for aquatic plants in the
river system. Unfortunately, aquatic plant habitat conservation
has not been considered as part of irrigation management
in most rivers of Thailand. The river water quality could
therefore be gradually decreasing due to the deterioration of
the habitats. Understanding the interaction of water flow,
aquatic plants and related environmental factors is necessary
for sustainable utilization of river resources