AHP-based spatial analysis of water quality impact assessment due to change in vehicular traffic caused by highway broadening in Sikkim Himalaya
Applied Water Science
AHP‑based spatial analysis of water quality impact assessment due to change in vehicular traffic caused by highway broadening in Sikkim Himalaya
Polash Banerjee 0 1 2
Mrinal Kanti Ghose 0 1 2
Ratika Pradhan 0 1 2
Mrinal Kanti Ghose 0 1 2
0 Department of Computer Applications, SMIT, Sikkim Manipal University , Majitar, Sikkim 737136 , India
1 Department of Computer Applications, Sikkim University , Gangtok, Sikkim 737102 , India
2 Ratika Pradhan
3 Polash Banerjee
Spatial analysis of water quality impact assessment of highway projects in mountainous areas remains largely unexplored. A methodology is presented here for Spatial Water Quality Impact Assessment (SWQIA) due to highway-broadening-induced vehicular traffic change in the East district of Sikkim. Pollution load of the highway runoff was estimated using an Average Annual Daily Traffic-Based Empirical model in combination with mass balance model to predict pollution in the rivers within the study area. Spatial interpolation and overlay analysis were used for impact mapping. Analytic Hierarchy ProcessBased Water Quality Status Index was used to prepare a composite impact map. Model validation criteria, cross-validation criteria, and spatial explicit sensitivity analysis show that the SWQIA model is robust. The study shows that vehicular traffic is a significant contributor to water pollution in the study area. The model is catering specifically to impact analysis of the concerned project. It can be an aid for decision support system for the project stakeholders. The applicability of SWQIA model needs to be explored and validated in the context of a larger set of water quality parameters and project scenarios at a greater spatial scale.
Analytic hierarchy process; Environmental impact assessment; Geographic information systems; Sensitivity analysis; Water pollution; Highway
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Department of Computer Science and Engineering, SMIT,
Sikkim Manipal University, Majitar, Sikkim 737136, India
Introduction
Highways are essential for the development and security of
a region. However, understanding the detrimental effects
of highway projects is pivotal for environmentally
appropriate decision making. Environmental impact assessment
(EIA) involves the assessment of impacts of a development
project on the environmental attributes, including water
resources
(Barthwal 2012; Canter 1995)
. Conventional EIA
can be time consuming, expensive, and subjective
(Glasson et al. 2005; Takyi 2012)
. Moreover, conventional EIA
focuses mainly on the temporal aspect of the impacts and
undermines the importance of their spatial distribution.
Geographic information systems (GIS) can overcome these
limitations and provide an unbiased and easily interpretable
EIA
(Agrawal 2005)
.
A highway is essentially a non-point source of water
pollution. Construction and post-construction conditions
of a highway generate pollutants, which degrade the water
quality and affect the habitat of the nearby water bodies
(Wu et al. 1998)
. Highway runoff contains relatively high
concentration of pollutants as compared to the adjacent
river
(USEP 1996; Bingham et al. 2002; Gan et al. 2008)
.
Statistical models suggest that traffic volume, rainfall
characteristics, highway pavement type, and properties of
pollutants and seasons are important determinants of road runoff
composition
(Aldheimer and Bennerstedt 2003; Forsyth
et al. 2006; Granato 2013; Kayhanian et al. 2003; Kim et al.
2006; Li and Barrett 2008; Pagotto et al. 2000; Tong and
Chen 2002; USEP 1996; Yannopoulos et al. 2004, 2013)
.
These models mostly cater to highway projects of
developed countries. Applicability of these models in
developing countries remains largely unexplored. Depending upon
the nature of the highway runoff study, traffic volume can
be considered in two broad ways, namely, as average daily
traffic and vehicles during storm. Average daily traffic is a
good predictor of water pollutants like Chemical Oxygen
Demand (COD), Total Suspended Solids (TSS), and Zinc
(Zn), while it poorly predicts the levels of lead, copper, and
oil and grease
(Thomson et al. 1997; Venner 2004)
. In
contrast, oil and grease has a significant relationship with the
vehicles during storm rather than average daily traffic
(Stenstrom et al. 1982; Venner 2004)
. Correlation studies of river
water have shown COD is strongly correlated topercent
Dissolved Organic Carbon, Dissolved Oxygen, and Total
Dissolved Solids (TDS). Moreover, TSS is strongly associated
with pH and TDS
(Bhandari and Nayal 2008; Waziri and
Ogugbuaja 2010)
.
A wide variety of water quality indices are used in the
impact assessment of a highway project. However, except for
Water Quality Status Index (WQSI), all other water indices
involve predetermined weight or the importance of water
pollutants, which cannot be manipulated to see the impact
of the change in water pollutant weight on the overall impact
on water quality.
(Karbassi et al. 2011; M (...truncated)