Integrated water quality assessment of open water bodies using empirical equations and remote sensing techniques in Bangweulu Wetland lakes, Zambia

Abstract

Water quality assessment is essential for conserving aquatic ecosystems and human consumption. However, monitoring several water quality parameters in open water bodies poses significant challenges, resulting in gaps and limitations. While the Water Quality Index (WQI) integrates various water quality parameters, its spatial application has not yet been thoroughly evaluated. To address these issues, this study was conducted to establish an integrated remote sensing approach for comprehensive monitoring of water quality. Utilising Sentinel 2 data alongside on-site/lab water quality measurements, various relationships were established. The calculated mean WQI from on-site/lab data was 35, while from remotely sensed data was 41. Linear relationships (R²) between WQI and various water quality parameters such as chloride (0.712), sodium (0.705), TDS (0.705), turbidity (0.628), and EC (0.704) were observed. These relationships facilitated the transformation of water quality parameter maps into WQI maps, the WQI maps were then integrated into one WQI map showing the overall water quality status of the Bangweulu Wetland lakes. Both on-site/lab and remote sensing methods indicated that the concentrations of water quality parameters in the Bangweulu Wetland lakes is lower (better) than the local and international recommended limits, with a calculated WQI falling within the ’Good’ category. This indicates that the water is fresh, clean, and suitable for various purposes including ecological preservation, agriculture, aquaculture, recreation, industrial use, and human consumption. The findings offer insights into the general status of water quality in open water bodies, identifying hot spots and potential sources of water pollution with implications for future management practices.