Ram avtar | The University of Tokyo (original) (raw)
Uploads
Papers by Ram avtar
A combined study of the geophysical survey and hydro-geochemistry in the Quaternary alluvial aqui... more A combined study of the geophysical survey and hydro-geochemistry in the Quaternary alluvial aquifers of Bhagalpur district from Bihar state in central Gangetic plain of India was carried out with the objective of identifying the geochemical processes and their relation with lithological profile. Results of resistivity survey validated with borehole lithology gave us a clear picture of the geological signature of the aquifers, which support the reducing nature of the aquifer where concentration of arsenic was high. Reducing nature of the aquifer environment was shown by water samples having relatively negative Eh value. From XRD study of the soil samples, it was found that goethite, dolomite, calcite, quartz and feldspar are the major minerals for most of the samples. Output of this work concludes that resistivity survey is an economically feasible tool which can be successfully used to target arsenic-safe aquifers on wide scale.
Environmental Monitoring and Assessment, 2013
An accurate estimation of a plant's age is required for the prediction of yield and management pr... more An accurate estimation of a plant's age is required for the prediction of yield and management practices. This study demonstrates the relationship between backscattering properties (σ°) of Phased Array type L-band Synthetic Aperture Radar (PALSAR) dual polarimetric data with cashew plants' biophysical parameters (height, age, crown diameter, diameter at breast height, basal area, tree density, and biomass) in Cambodia. PALSAR σ°has shown a positive correlation with the biophysical parameters of cashew plants. The value of σ°increases with the age of cashew plants. At a young stage, the cashew plants show a higher rate of an increase in σ°compared to that at the mature stage. The σ°horizontal polarization transmitted and vertical received (HV) shows higher sensitivity to the plant's growth than σ°horizontal polarization transmitted and received (HH). High backscattering and low variations were observed at mature stage (8-12 years) of cashew plantation. Saturation in backscattering has shown from the age of about 13 years. The validation results indicate strong coefficient of determination (R 2 00.86 and 0.88) for PALSAR-predicted age and biomass of cashew plants with root mean square error01.8 years and 16.3 t/ha for age and biomass, respectively. The correlations of σ°(HH) with biophysical parameters observed in the dry season were better than those of the rainy season because soil moisture interferes with backscattering in the rainy season. Biomass accumulation rate of cashew plants has been predicted that would be useful for selection of plants species to enhance carbon sequestration. This study provides an insight to use PALSAR for the monitoring of growth stages of plants at the regional level.
A combined study of the geophysical survey and hydro-geochemistry in the Quaternary alluvial aqui... more A combined study of the geophysical survey and hydro-geochemistry in the Quaternary alluvial aquifers of Bhagalpur district from Bihar state in central Gangetic plain of India was carried out with the objective of identifying the geochemical processes and their relation with lithological profile. Results of resistivity survey validated with borehole lithology gave us a clear picture of the geological signature of the aquifers, which support the reducing nature of the aquifer where concentration of arsenic was high. Reducing nature of the aquifer environment was shown by water samples having relatively negative Eh value. From XRD study of the soil samples, it was found that goethite, dolomite, calcite, quartz and feldspar are the major minerals for most of the samples. Output of this work concludes that resistivity survey is an economically feasible tool which can be successfully used to target arsenic-safe aquifers on wide scale.
Environmental Monitoring and Assessment, 2013
An accurate estimation of a plant's age is required for the prediction of yield and management pr... more An accurate estimation of a plant's age is required for the prediction of yield and management practices. This study demonstrates the relationship between backscattering properties (σ°) of Phased Array type L-band Synthetic Aperture Radar (PALSAR) dual polarimetric data with cashew plants' biophysical parameters (height, age, crown diameter, diameter at breast height, basal area, tree density, and biomass) in Cambodia. PALSAR σ°has shown a positive correlation with the biophysical parameters of cashew plants. The value of σ°increases with the age of cashew plants. At a young stage, the cashew plants show a higher rate of an increase in σ°compared to that at the mature stage. The σ°horizontal polarization transmitted and vertical received (HV) shows higher sensitivity to the plant's growth than σ°horizontal polarization transmitted and received (HH). High backscattering and low variations were observed at mature stage (8-12 years) of cashew plantation. Saturation in backscattering has shown from the age of about 13 years. The validation results indicate strong coefficient of determination (R 2 00.86 and 0.88) for PALSAR-predicted age and biomass of cashew plants with root mean square error01.8 years and 16.3 t/ha for age and biomass, respectively. The correlations of σ°(HH) with biophysical parameters observed in the dry season were better than those of the rainy season because soil moisture interferes with backscattering in the rainy season. Biomass accumulation rate of cashew plants has been predicted that would be useful for selection of plants species to enhance carbon sequestration. This study provides an insight to use PALSAR for the monitoring of growth stages of plants at the regional level.