Geospatial Analysis of Land Cover Change Impact on Flood Risk in Anambra East Local Government Area of Anambra State, Nigeria

Abstract

This study was driven by the need to determine the effect of vegetation loss, topography 
modification and structural development to persistent flooding in Anambra East Local 
Government Area of Anambra State. The research employed Geographic Information System 
and Remote Sensing methodology for its data gathering, visualization and spatial analysis. 
Multi-temporal Landsat TM, ETM+ and OLI of 2001, 2012 and 2023 imageries were obtained 
at 11years interval. The LULC analysis revealed the dominance of five (5) classes - Bare Land, 
Built Up, Dense Vegetation, Farmland/Sparse Vegetation, and Water Body. The Built-up and 
water Body classes were observed to consistently increase over time in the study area. Built
up increased by 22.1sq km from 2001 to 2023, and water bodies increased by 1.2 sq.km. Dense 
vegetation though appreciated to 26.6sq.km within the period but was confined mainly in 
southern part and along Oyi River valley. However, Farmland/sparse vegetation lost 17.6sqkm 
of its spatial extent within the same time, and Bare land lost its 32.4sqkm spatial extent too. It 
was observed that built-up class and paved surfaces increased both in spatial extent and 
density over the period, and extended heavily along Anambra River floodplains. It was further 
observed that continuous extension of built up into flood prone areas posed dangers of 
increasing overland flow, constricting the natural river flow, braiding river channels, aiding 
river depositional processes and increasing chances of severe flooding in the area during 
torrential rainfalls. The study therefore recommended among others that government should 
enforce extant city and building regulations and initiate intensive agro forestry and green belt 
developments along Anambra River and areas experiencing massive urbanization to regulate 
surface runoff and annual inundation of the river banks