Chapter 9
Assessment of Stream Flow Impact
on Physicochemical Properties of Water
and Soil in Forest Hydrology Through
Statistical Approach
Malabika Biswas Roy, Pankaj Kumar Roy, Sudipa Halder,
Gourab Banerjee, and Asis Mazumdar
Abstract Forests affect the hydrology of watersheds in various ways with different
hydrological parameters such as evapotranspiration, infiltration, intercepting cloud
moisture, surface runoff, and groundwater. Sikkim, a part of northeastern India, a
hilly area, is basically a critical terrain condition, and collection of secondary and
primary data might be a challenging task to assess overall impacts, particularly on
hydrological services. Three micro-watersheds, categorized as undisturbed,
semidisturbed, and disturbed catchments covering a distance of 12 km at Geyzing,
located in West Sikkim, were selected for this research work. Hydro-meteorological
instruments were installed and recorded data for 4 years in three micro-watersheds to
monitor the impact of forest cover on stream discharge and water quality. A
composite rectangular weir was installed at field level to accommodate measuring
stream discharge during the monsoon period as well as the pre-monsoon period.
Water and soil quality parameters were analyzed during the monsoon as well as the
pre-monsoon period. The overall impact of forests on the hydrological regime of a
watershed is twofold. First, comparatively less discharge from a forest watershed
during the rainy months shows that the forest controls excess runoff downstream.
Second, forests induce infiltration, which leads to more uniform flow all year from
the dense forest watershed stream. Conversions to forestland would have the potential to reduce erosion and subsequent sedimentation, as well as reduce levels of
nutrients and pesticides in surface runoff and groundwater. These improvements in
water quality can be a function of lower amounts of runoff and leaching as well as
lower concentrations of potential pollutants.
M. B. Roy
Women’s College, Kolkata, India
P. K. Roy (*)
FISLM, School of Water Resources Engineering, Jadavpur University, Kolkata, India
S. Halder · G. Banerjee · A. Mazumdar
School of Water Resources Engineering, Jadavpur University, Kolkata, India
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
M. N. Islam, A. van Amstel (eds.), India: Climate Change Impacts, Mitigation
and Adaptation in Developing Countries, Springer Climate,
https://doi.org/10.1007/978-3-030-67865-4_9
207
Assessment of Stream Flow Impact
on Physicochemical Properties of Water
and Soil in Forest Hydrology Through
Statistical Approach
Malabika Biswas Roy, Pankaj Kumar Roy, Sudipa Halder,
Gourab Banerjee, and Asis Mazumdar
Abstract Forests affect the hydrology of watersheds in various ways with different
hydrological parameters such as evapotranspiration, infiltration, intercepting cloud
moisture, surface runoff, and groundwater. Sikkim, a part of northeastern India, a
hilly area, is basically a critical terrain condition, and collection of secondary and
primary data might be a challenging task to assess overall impacts, particularly on
hydrological services. Three micro-watersheds, categorized as undisturbed,
semidisturbed, and disturbed catchments covering a distance of 12 km at Geyzing,
located in West Sikkim, were selected for this research work. Hydro-meteorological
instruments were installed and recorded data for 4 years in three micro-watersheds to
monitor the impact of forest cover on stream discharge and water quality. A
composite rectangular weir was installed at field level to accommodate measuring
stream discharge during the monsoon period as well as the pre-monsoon period.
Water and soil quality parameters were analyzed during the monsoon as well as the
pre-monsoon period. The overall impact of forests on the hydrological regime of a
watershed is twofold. First, comparatively less discharge from a forest watershed
during the rainy months shows that the forest controls excess runoff downstream.
Second, forests induce infiltration, which leads to more uniform flow all year from
the dense forest watershed stream. Conversions to forestland would have the potential to reduce erosion and subsequent sedimentation, as well as reduce levels of
nutrients and pesticides in surface runoff and groundwater. These improvements in
water quality can be a function of lower amounts of runoff and leaching as well as
lower concentrations of potential pollutants.
M. B. Roy
Women’s College, Kolkata, India
P. K. Roy (*)
FISLM, School of Water Resources Engineering, Jadavpur University, Kolkata, India
S. Halder · G. Banerjee · A. Mazumdar
School of Water Resources Engineering, Jadavpur University, Kolkata, India
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
M. N. Islam, A. van Amstel (eds.), India: Climate Change Impacts, Mitigation
and Adaptation in Developing Countries, Springer Climate,
https://doi.org/10.1007/978-3-030-67865-4_9
207