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Spatiotemporal Dynamics of Water Quality Indicators in Koka Reservoir, Ethiopia

Lookup NU author(s): Dr Maria-Valasia PeppaORCiD, Professor Claire Walsh



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2023 by the authors.The science and application of the Earth observation system are receiving growing traction and wider application, and the scope is becoming wider and better owing to the availability of the higher resolution of satellite remote sensing products. A water quality monitoring model was developed using Sentinel-2 satellite remote sensing data set to investigate the spatiotemporal dynamics of water quality indicators at Koka Reservoir. L1C images were processed with an Atmospheric correction processor ACOLITE. The months from June 2021 to May 2022 and the years 2017 to 2022 were used for the temporal analyses. Algorithms were developed by using regression analysis and developing empirical models by correlating satellite reflectance data with in situ Chlorophyll-a (Chl-a), turbidity (TU), and Total suspended matter (TSS) measurements. All of the analyzed parameters have determination coefficients (R2) greater than 0.67, indicating that they can be turned into predictive models. R2 for the developed algorithms were 0.91, 0.92, and 0.67, indicating that good correlations have been found between field-based and estimated Chl-a, TU, and TSS, respectively. Accordingly, the mean monthly Chl-a, TU, and TSS levels have ranged from (59.69 to 144.25 g/L), (79.67 to 115.39 NTU), and (38.46 to 368.97 mg/L), respectively. The annual mean Chl-a, TU, and TSS vary from (52.86–96.19 µg/L), (71.04–83 NTU), and (36.58–159.26 mg/L), respectively, showing that the reservoir has been continuously polluted over the last seven years. The spatial study found that the distributions of Chl-a, TU, and TSS were heterogeneous, with Chl-a being greater in the south and southwest, and TU and TSS being higher on the western shore of the reservoir. In conclusion, these results show that there are spatial as well as temporal variations on water quality parameters. The proposed algorithms are capable of detecting optically active water quality indicators and can be applied in similar environmental situations.

Publication metadata

Author(s): Assegide E, Shiferaw H, Tibebe D, Peppa MV, Walsh CL, Alamirew T, Zeleke G

Publication type: Article

Publication status: Published

Journal: Remote Sensing

Year: 2023

Volume: 15

Issue: 4

Print publication date: 01/02/2023

Online publication date: 20/02/2023

Acceptance date: 17/02/2023

Date deposited: 20/03/2023

ISSN (electronic): 2072-4292

Publisher: MDPI


DOI: 10.3390/rs15041155


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Funder referenceFunder name
UK Research and Innovation’s Global Challenges Research Fund (GCRF)