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Spatial Assessment and Mapping of Water Quality in Lake Sentani (Indonesia) Using In-Situ Data and Satellite Imagery

Tanjung Rosye Hefmi Rechnelty, Indrayani Ervina, Hamuna Baigo, Agamawan Lalu Panji Imam, Alianto

Ecological Engineering & Environmental Technology

2023

Vol. 24, iss. 9

71--83

This study aims to examine the water quality of Lake Sentani using both in-situ data and satellite remote sensing data. In-situ data was taken in July 2023 at 18 sampling sites, including temperature, DO, pH, TDS, and water transparency. In-situ data is also used to develop and validate algorithms for estimating water quality from satellite remote sensing data. Multi-temporal Landsat-8 satellite imagery was used to spatially and temporally map the surface water quality of Lake Sentani. In-situ data showed temperature, DO, pH, TDS, and water transparency ranging from 29.3°C to 31.8°C, 1.7 mg/L to 7.9 mg/L, 7.75 to 8.64, 23 mg/L to 46 mg/L, and 2.28 m to 2.94 m, respectively. Only water transparency does not meet the quality standards for water quality (class 1 and class 2), while the other parameters meet class 1 to class 3 quality standards for surface water samples. The accuracy of the algorithm used and the resulting one has a low Mean Absolute Error value, namely 0.81 (temperature), 0.37 (DO), 4.84 (TDS), and 0.12 (water transparency). The temperature and TDS concentrations from the satellite imagery data ranged from 28.110°C to 33.918°C, and 7.829 mg/L to 102.702 mg/L, respectively. Both of these parameters still meet water quality standards. The DO concentrations ranged from 2.228 mg/L to 12.562 mg/L, and water transparency ranged from 0.424 m to 3.151 m. The concentration of DO and water transparency do not meet quality standards in several parts of Lake Sentani, especially in November and August.

Kinetic description of microwave Raman regime free-electron laser in the presence of helical wiggler and guiding magnetic fields

Mishra P. K.

Optica Applicata

2007

Vol. 37, nr 1-2

195-204

A full dispersion relation obtained for free-electron laser by kinetic approach based on the method of characteristics in the presence of circularly polarized, periodic, static helical wiggler magnetic field and guide magnetic field incorporating the detailed relativistic particle trajectories is reduced to Raman regime approximations. The temporal and spatial growth rates are evaluated in microwave region. A detailed analysis has been done for temporal and spatial growth rates in Raman regime, especially for microwave region. The spatial growth rate is more than that of temporal growth. The results have been compared with available results obtained by other techniques.