IMPACT ASSESSMENT OF NATIONAL HIGHWAY EXPANSION ON ENVIRONMENTAL QUALITY IN HIMACHAL PRADESH
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Date
2018-10
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UHF,NAUNI
Abstract
ABSTRACT
The investigation entitled “Impact Assessment of National Highway Expansion on Environmental
Quality in Himachal Pradesh” was conducted during 2016 and 2017 in the Department of Environmental
Science, YSP University of Horticulture and Forestry, Nauni Solan, Himachal Pradesh. The study aimed at
determining the impacts of National Highway expansion activities on ecosystem services like soil, water, air
quality, microclimate, soil carbon sequestration as well as on socio economic status of habitants. In order to
prepare management plan roadside vegetation distribution and its pollution tolerance potential was also assessed
through Air Pollution Tolerance Index. Impact of national highway expansion on soil, water and air quality was
evaluated spatially by considering horizontal distances of 0-5, 5-10 and >20 m and seasonally taking summer,
monsoon and post monsoon seasons. The study revealed that expansion activities decreased soil organic carbon
by 30 per cent in the soils disturbed by expansion activities as compared to control site which resulted in a
carbon loss of 1058.82 Mg C ha-1 from the soil. The highly disturbed soil of 0-5 m registered Cd, Pb, Fe of
0.023 mg kg-1, 0.335 mg kg-1, 24.32 mg kg-1, respectively and was above prescribed permissible limit. The soil
heavy metal accumulation decreased with increased horizontal distance from point of expansion activity. The
highway expansion activities resulted in the felling of 22,332 trees consequently reduced carbon sequestration of
2647.92 t ha-1. In the surface water sources adjoining to highway expansion activities the COD ranged from
14.81 to 20.30 mg l-1 and was 1.5 per cent higher than the prescribed permissible limit. Concentration of heavy
metals Cd, Cr and Pb in surface water ranged from 0.004 to 0.018 mg l-1, 0.030 to 0.071 mg l-1, 0.144 to 0.261
mg l-1, respectively. In ground water sources it ranged from 0.004 to 0.010 mg l-1, 0.034 to 0.052 mg l-1 and
0.127 to 0.207 mg l-1, respectively and was above the prescribed permissible limit. Ambient air quality
deterioration was observed due to PM10 concentration which ranged from 74.56 to 116.77 μg m-3 and was above
permissible limit. The seasons of the year also exerted significant influence on the distribution of air pollutants
in the atmosphere. The most of the national highway expansion was on fallow and barren land (94.39 %) and
exerted very less impact on cultivated land. The expansion activities have influenced the microclimate of the
region with significant rise of 0.30 oC and 0.042 oC mean maximum and minimum temperature as well as
decrease in rainfall. Amongst the commonly growing tree and shrub species Toona ciliata as well as Adhatoda
vasica and Murraya koenigii emerged as pollution tolerant species which can be selected for revegetating the
area around the national highway. The ecologically fragile area of national highway needs to be managed by
enhancing carbon sequestration in soil and plant biomass through planting indigenous air pollution tolerant
species. The plantation may help in regulating water, air quality in biogeochemical cycles of the affected areas
of national highway. Water harvesting structure needs to be installed to collect rain and runoff water to recharge
the ground water table. Installation of solar lights in place of electric lights is need of the hour to lessen the CO2
emissions.
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