TITLE:
Effects of Increasing Impervious Surface on Water Quality in Ile-Ife Urban Watershed, Southwestern Nigeria
AUTHORS:
Olusola-Ige Olufayo Adetoro, Victor Osarenren, Samuel Oladimeji Popoola
KEYWORDS:
Urban Watershed, Impervious Surface, Water Quality, ISAT, OBIA, Turbidity
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.10 No.12,
December
28,
2022
ABSTRACT: The urban environment has continued to experience changes from increasing impervious surfaces, which
alters the proper functioning of the ecological zones and impairs water quality
in the watershed. Impervious cover is predominantly used as an indicator to
assist in understanding and forecasting the impact of human actions and other related activities
on aquatic resources. In this study, the rate of change in land uses using the
impervious surface as an indicator, and
the percentage of imperviousness on the effect on water quality in the urban
watershed were assessed. Ile-Ife was delineated as an urban watershed, and the percentage of imperviousness from 2008 to 2016 and
the effect of imperviousness on
water bodies were assessed. The study utilized ASTERDEM, Worldview (0.46 m),
IKONOS (1.4 m), Landsat (30 m) for 2008 and
2016, GPS and Drone (10 cm). Water sampling was carried out in selected locations as generated by the impervious surface analyst tool,
(ISAT). The percentage (%) of impervious surfaces accounted for 59.4% (4567.1/7691.5ha) in 2008 and
70.3% (5408.2/7691.5ha) in 2016, from
the total number of lands investigated. The turbidity values from low to high
regions were 32.3, 55.9 and 82.4 NUT. Changes in LULC of the watershed led to
increased surface temperature, impermeable surfaces, and
decreased vegetation, which exposes the area to flooding and reduced water
quality. This study emphasized the importance of GIS and its integration into urban
changes and water quality assessment.