Abstract
In general, water quality mapping is done by interpolation of in situ measurement samples. Often, these parameters change with time. Due to geographic variability and the lack of budget in Nepal, such measurements are done less often. Remote sensors that collect spectral information continually can be very useful in the regular monitoring of water quality parameters. Landsat Operational Land Imager (OLI) bands have been used to estimate water quality parameters. In this work, we model two water quality parameters: chlorophyll-a (Chl-a) and dissolved oxygen (DO) using sequential minimal optimization regression (SMOreg), which implements a support vector machine (SVM) algorithm and recursive partitioning tree (REPTree) regressions. A total of 19 measurements were taken from Phewa Lake, Nepal and various secondary bands were derived from using Landsat 8 Operational Land Imager (OLI) bands. These bands underwent feature selection, and regression models were created based on selected bands and sample data. The results showed satisfactory modelling of water quality parameters using Landsat 8 OLI bands in Phewa Lake. Due to a limited number of data, cross-validation was done with 10 folds. The SVM showed a better result than the REPTree regression. For future studies, the performance can be further evaluated in large lakes with larger sample numbers and other water quality parameters.
Highlights
Water is one of the significant environments for living animals to endure
The major purpose of this study is to estimate water quality parameters using sequential minimal optimization regression (SMOreg) and recursive portioning (REPTree) regression techniques based on Landsat 8 bands
For dissolved oxygen (DO) in the SMOreg method, out of 44 bands, only 6 derived bands were used for the modeling purpose as they had a better correlation co-efficient
Summary
Living organisms inside water resources are facing a great threat from a wide range of physical processes, including land use/land cover change, pollution, and global climate change as well as human interventions [1] Lakes and their supplies store assets and fulfil both human necessities, ranging from drinking water to diversion, and natural prerequisites to help significant levels of biodiversity [2]. Due to the expanding populace developments and the fast pace of modernization and urbanization areas, as well as climate change, water quality is being deteriorated These phenomena will continue to increase even more in the future, and many types of research have recognized declining water quality as one of the most crucial threats to society [3].
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