TITLE:
Examining Rate of Built-Up Areas on the Vegetation Cover along River Riara Riparian within Kiambu Town, Kenya
AUTHORS:
Charles M. Mugambi, Mugwima Njuguna, Dennis Karanja
KEYWORDS:
Ecological Conservation, Urban Riparian Reserves, Vegetation Cover Index, Built-Up Area Index, NDVI, NDBI
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.10 No.3,
March
25,
2022
ABSTRACT: Urban river riparian spaces and their natural systems are valuable to
urban dwellers; but are increasingly affected and ruined by human activities
and in particular, urbanization processes. In this research, land sat and
sentinel satellite imagery apt for change detection in vegetation cover, both landsat
and sentinel imagery, covering the period between 1970 and 2021 in epochs of
1973, 1984, 1993, 2003, 2015 and 2021 years were used to establish the
correlation between vegetation cover and built-up area along River Riara river
reserve. The images were analysed to extract the built-up areas along the river
reserve, including the buildings, and the rate of human settlements, which influenced vegetation cover. Normalized Difference
Built-Up Index (NDBI) and Normalized Difference Vegetation Index (NDVI)
were computed using the Short-Wave Infrared (SWIR) and the Near Infra-Red (NIR)
bands to show the rate of change over the years. Results indicate NDVI values
were high, compared to NDBI values along river Riara in the years 1973 and 1993
implying that there was more vegetation cover then. However, in the year 2021,
the NDVI indicated the highest value at 0.88, with the complementary NDBI
indicating the highest NDBI value at 0.47. This represents a significant
increase in built-up areas since 2015 more than in previous epochs. Either,
there was a significant increase in NDBI values, from 0.24 in 1993 to 0.47 in
2021. More so, the R-squared value at 0.80 informed 80% relationship between
NDBI and NDVI values indicating a negative correlation.