9.4.3 Flow Regulation and Groundwater Recharge
The riparian vegetation affects the river flow and is termed as safety valve of the
watershed (gov.mb.ca). The reason for designating riparian ecotone as safety valve is
the vegetation, which slows the water flow, thus reducing the intensity of flood
further downstream of the river channel. This not only controls flood but also the
upland water flow into the river, thus maintaining the river flow. Hydrologically,
riparian ecotones are considered as discharge areas through which water flows
before reaching surface water (Gundersen et al. 2010) (Fig. 9.2).
These areas are often characterised by a high groundwater table and superficial
subsurface flow created by groundwater exfiltration (Gundersen et al. 2010). As the
vegetation slows down the water velocity, it in turn increases the retention time of
water in this zone enhancing the groundwater potential of that region (Swanson et al.
2017). The reduction in the speed of water allows increase in absorption of water into
the soil, thus replenishing groundwater reserves (Swanson et al. 2017). The percolation down into the ground is also dependent on soil types of the region. The silt
texture of the soil acts as a sponge to aid in groundwater recharge and underground
storage. Not only this, the water stored in the ground seeps into the river through
lateral connectivity during lean season, thus maintaining river flow throughout the
season (https://www.nrcs.usda.gov/). Riparian vegetation in the riparian ecotone is
thus important to maintain the river flow, prevent flood and recharge the groundwater (Fig. 9.2).
9.4.4 Maintaining River Channel Environment
The riparian vegetation has proved to play a crucial role in maintaining the river
environment, viz. river water temperature and organic-inorganic inputs into the river.
The types of vegetation affect the intensity of light reaching the river water; the
dense canopy lowers the river water, whereas the open canopy raises the river water
(Garner et al. 2017) (Fig. 9.2).
Maintaining the river temperature is essential to prevent the faster rate of chemical speciation subsequently leading to rise in pollutant levels in the river water. The
temperature also influences the dissolved oxygen content of the river. The optimised
temperature of river water is also essential for the biological activity of the river
diversity. The autochthonous input from the vegetation near the river plays an
essential role in the river biotic life. Organic matter from riparian ecotones, such
as leaves, twigs, logs and stems that fall from the buffer into the water, are the main
source of food for aquatic macroinvertebrates (Mayer et al. 2006). The debris or
wood from vegetation traps additional leaf litter and wood. Macroinvertebrates use
the wood as habitat, living inside the wood, under residual bark and on surfaces that
protrude out of the water (Mayer et al. 2006) (Fig. 9.2).
208
S. Sharma et al.
The riparian vegetation affects the river flow and is termed as safety valve of the
watershed (gov.mb.ca). The reason for designating riparian ecotone as safety valve is
the vegetation, which slows the water flow, thus reducing the intensity of flood
further downstream of the river channel. This not only controls flood but also the
upland water flow into the river, thus maintaining the river flow. Hydrologically,
riparian ecotones are considered as discharge areas through which water flows
before reaching surface water (Gundersen et al. 2010) (Fig. 9.2).
These areas are often characterised by a high groundwater table and superficial
subsurface flow created by groundwater exfiltration (Gundersen et al. 2010). As the
vegetation slows down the water velocity, it in turn increases the retention time of
water in this zone enhancing the groundwater potential of that region (Swanson et al.
2017). The reduction in the speed of water allows increase in absorption of water into
the soil, thus replenishing groundwater reserves (Swanson et al. 2017). The percolation down into the ground is also dependent on soil types of the region. The silt
texture of the soil acts as a sponge to aid in groundwater recharge and underground
storage. Not only this, the water stored in the ground seeps into the river through
lateral connectivity during lean season, thus maintaining river flow throughout the
season (https://www.nrcs.usda.gov/). Riparian vegetation in the riparian ecotone is
thus important to maintain the river flow, prevent flood and recharge the groundwater (Fig. 9.2).
9.4.4 Maintaining River Channel Environment
The riparian vegetation has proved to play a crucial role in maintaining the river
environment, viz. river water temperature and organic-inorganic inputs into the river.
The types of vegetation affect the intensity of light reaching the river water; the
dense canopy lowers the river water, whereas the open canopy raises the river water
(Garner et al. 2017) (Fig. 9.2).
Maintaining the river temperature is essential to prevent the faster rate of chemical speciation subsequently leading to rise in pollutant levels in the river water. The
temperature also influences the dissolved oxygen content of the river. The optimised
temperature of river water is also essential for the biological activity of the river
diversity. The autochthonous input from the vegetation near the river plays an
essential role in the river biotic life. Organic matter from riparian ecotones, such
as leaves, twigs, logs and stems that fall from the buffer into the water, are the main
source of food for aquatic macroinvertebrates (Mayer et al. 2006). The debris or
wood from vegetation traps additional leaf litter and wood. Macroinvertebrates use
the wood as habitat, living inside the wood, under residual bark and on surfaces that
protrude out of the water (Mayer et al. 2006) (Fig. 9.2).
208
S. Sharma et al.