Effects of sand mining on land use/land cover on river environment in developing countries: A case study of Ava River in Enugu State, Nigeria

Abstract

Sand mining contributes immensely to economic development. However, this activity when carried out in a river environment can affect the land use and land cover of the area. The study objectives include mapping, quantifying and assessing the landuse/land cover (LULC) changes of Ava River from 2007 to 2019 and projection from 2020 to 2025 and 2031. The paper discusses pre-existing LULC maps from the past (2007, 2013 and 2019), present (2020-2025) and near future (2026-3031). The study used Geographical Information System (GIS) and remote sensing data to estimate the changes in LULC of the study area in the various periods. The images were classified using a supervised classifier yielding three LULC maps of the Ava River environment. The classification grouped the area into six main LULC types. The result showed no change detection in the built-up area from 2007 to 2013 but increased by 26.15% in 2019. The mining area increased by 8.19% from 2007 to 2019.Riverbank also increased by 12.81% from 2007 to 2019.The correlation analysis used showed a positive relationship between the built-up area and sand mining as well as the river bank morphology. In 2019, sand mining activities in the Ava River site covered an area of approximately 389325.60 m2 and it was predicted that in 2025 and 2031, the affected area would increase to 485397.12m2 and 611753.52m2 respectively. The study reveals that sand mining activities in the Ava River environment are causing the river bank to widen. This may have an adverse effect on the erected buildings very close to the riverbank in the near future if not controlled. The study showed significant change detection across the periods. These detected changes would serve as a scientific basis upon which decision-makers can design policy guidelines on sand mining, river environment protection, conservation and management in developing countries.