Spectral Response at Different Water Depth Standing in the Field

Abstract

Water availability and irrigation management can be estimated in agricultural fields through observation of field water storage. In order to calculate runoff and recharge through these fields, the water depth stored in the haveli fields must meet certain requirements. Remote Sensing data obtain through Satellite in all visible and NIR region might be helpful for such requirements. An experimental study is made to assess the utility of different bands for depicting depth of storage in field. Spectral reflectance was recorded on different depth from 0 to 100 cm of water. Ground Truth Radiometer (GTR) was used to conduct the experiment. Experimental observation shows the variation in reflectance with different depth of water stored in 1 m3 ponding water. It has been observed that spectral response shows variation under different storage level and different time of observation. To minimize error on observation the readings were taken under uniform sunshine condition and wind velocity. The Radiation under wavelength 0.4 and 1.1 µm was used to collect response in reflectance from experimental fields. The increase in reflectance with was observed with decrease in water level. This could be due to visibility of bottom soil in lower depths. A comparison between experimental response data and satellite image data of indicate that there is variation on band 4 and similar trend on band 1, 2. Mixed tread was observed in band 3. A clear decrease in reflectance up to 50 percent was observed when water storage depth increase up to 90 cm but then it started increasing. Similar variation was observed for observation with a depth of more than 1 m. Satellite data is more stable as compared to GTR data.