Comparison of CANWET and HSPF for water budget
and water quality modeling in rural Ontario
Syed I. Ahmed, Amanjot Singh, Ramesh Rudra and Bahram Gharabaghi
ABSTRACT
This study comparatively evaluates the Hydrological Simulation Program-FORTRAN (HSPF) model and
the Canadian ArcView Nutrient and Water Evaluation Tool (CANWET) for non-point source pollution
(NPS) management in rural Ontario watersheds. Both models were calibrated, validated, and applied
to a 52 km
2
headwater rural watershed known as the Canagagigue Creek near Elmira in the Grand
River basin, Ontario, Canada. A comparison of the simulated and observed values for stream flow,
surface runoff, subsurface runoff, evapotranspiration, and sediment yield showed that (Better
Assessment Science Integrating Point and Nonpoint Sources) BASINS/HSPF and CANWET models
have similar capabilities to simulate various hydrological processes at the watershed scale. The
seasonal stream flow comparison between observed and simulated values from HSPF and CANWET
showed Nash-Sutcliffe efficiency (Nash-E) coefficients of 0.80 and 0.72, respectively. The monthly
comparison between the simulated and observed stream flow yielded Nash-E coefficients of 0.88
and 0.94 for HSPF and CANWET, respectively. Overall, both models predicted the components of the
annual, seasonal, and monthly water budget accurately. There was a considerable difference in the
monthly simulated sediment yield by both models. This difference is consistent with the surface
runoff variation predicted by both models. Both models predicted sediment yield with early winter
and spring storms which is typical for southern Ontario.
Syed I. Ahmed (corresponding author)
Ramesh Rudra
Bahram Gharabaghi
School of Engineering,
University of Guelph,
Thornborough Building,
50 Stone Road,
Guelph, Ontario,
N1G 2W1,
Canada
E-mail: sahmed@uoguelph.ca
Amanjot Singh
Credit Valley Conservation Authority,
1255 Old Derry Road,
Mississauga, Ontario,
L5N 6R4,
Canada
Key words | modeling, sediment, water budget, water quantity
INTRODUCTION
In the last few years, researchers have attempted to address
the problem of non-point source (NPS) pollution by combin-
ing the relationship between land management practices
and water quality degradation. Under Tier 1 of the Ontario
Source Water Protection Act by Ministry of Environment
(MOE), Ontario, conservation authorities, and other govern-
ment agencies are currently involved in assessment of water
budget at watershed scale to quantify drinking water sources
(MOE ). Two systems, the surface water system and
groundwater system, are being analyzed and different tools
have been researched for quantifying elements of both sys-
tems individually and in integration. Understanding the
environmental conditions and watershed hydrological
characteristics is the first step to quantify and protect the
water resources of the area.
In the last few decades, the modeling approach has
become more common to address the issue of water
resources pollution from NPSs. Field monitoring studies
have been limited due to their requirements of high
financial and time investment. Hydrologic modeling
approaches have been proven to be more versatile, as
they have been effectively used to simulate a variety of
environmental conditions and soil-water management
practices needed to prevent water quality degradation
(Saleh & Du ; Wang & Linker ; Walton &
Hunter ). Some of the widely used watershed scale
models are: AnnAGNPS (Bingner & Theurer ), Soil
and Water Assessment Tool (SWAT) (Arnold et al. ),
Hydrological Simulation Program-FORTRAN (HSPF)
(Bicknell et al. ), and Canadian ArcView Nutrient
53 © IWA Publishing 2014 Water Quality Research Journal of Canada | 49.1 | 2014
doi: 10.2166/wqrjc.2013.044