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Mapping Soil Clay Content and Hydraulic Properties over an Agricultural Semiarid Plain Using Remote Sensing and Interpolation Techniques

Nassah Houda, Younes Fakir, Salah Erraki, Said Khabba, Bernard Mougenot

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 1

164--179

EN

Clay content is an important parameter governing hydrodynamics property of soils and consequently crucial to environmental management and agricultural development. The present study aims to use the textural middle infrared index (MID index) product of Landsat-8 Operational Land Images to map clay content over the Haouz plain (Central Morocco). The clay content was mapped at 30 m grid spatial resolution based on the relationship between the MID index and a large set of soil samples. Over the areas covered by green vegetation, the clay content was predicted using the ordinary cokriging technique. Then, this information was used to derive soil hydraulic properties such as the field capacity (θfc), the wilting point (θwp) and the saturated hydraulic conductivity (Ksat) by using different pedotransfer functions. The validation of the maps was performed by using independent soil samples and measurements. The results showed that the clay content is significantly correlated to MID index. The ordinary cokriging improved mapping of clay content over the Haouz plain (R2= 0.70, RMSE = 3.5%). The obtained maps of θfc, θwp and Ksat revealed a good correlation between the simulated values and the measured values.

2

Rock type discrimination using Landsat-8 OLI satellite data in mafic-ultramafic terrain

Tamilarasan Kuppusamy, Anbazhagan Siddan, Ranjithkumar Sundararajan

Geology, Geophysics and Environment

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2023

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Vol. 49, no. 3

281--298

EN

The mafic-ultramafic terrain of the Bhavani complex in southern India is considered for lithological mapping. The Landsat-8 OLI satellite data was used for the interpretation of different rock types in the study area. The satellite data were digitally processed using ENVI 5.6 image processing software. In the OLI data, excluding bands 8 and 9, the remaining seven bands were used for the generation of colour composite images, band ratios, principal component analysis and SVM classification. Reflectance spectral measurements were carried out in laboratory conditions for five rock samples collected from the study area. The XRF analysis was carried out to estimate the composition of major oxides present in the rock samples. The results obtained from XRF analysis were compared with the rock spectra in characterizing the spectral features of the rock types. The colour composite images (B543, B567, B456, and B457), PCA composite image (PC312 and PC456), band ratios (BR5/5 and BR4/3), colour composite images from band ratios, and SVM classified output are useful in delineation various rock types in the terrain.

3

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

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2023

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Vol. 24, iss. 9

71--83

EN

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.