Multi-temporal Multi-spectral and Radar Remote Sensing for Agricultural Monitoring in the Braila Plain

The objective of the paper is to investigate the sensitivity of Landsat OLI and C-band radar signals to monitor an agricultural area affected by soil salinization and land degradation. The chosen test area - Braila Plain has the special particularities such as: dry climate, high annual average temperatures (9-110C), very dry and hot summers which cause a large potential evapotranspiration and conduct to a moisture deficit in soil, alkaline soils, winter winds with an average speed of 2.7 - 3.4 m/s. The soil type and climate conditions favor the culture of maize (50%), wheat and successive crops (16%), alpha-alpha (18%), sugar beet (6%), sunflower (7%), vegetables and other crops (3%). Taking into account the soil type, climate conditions and geomorphological characteristics of the studied area, the paper focuses on evaluation of Sentinel-1 sensor capabilities to monitor soil degradation and surface soil moisture. A multi-temporal series of Sentinel-1 data gathered from October 2014 until January 2015 is used. Crop growing stages are investigated with multi-temporal Landsat OLI and MODIS data. The normalized difference vegetation index (NDVI), specific leaf area index, land thermal index, soil moisture index and soil salinity information are retrieved from Landsat data. The potential evapotranspiration is computed from MODIS data to evaluate the effects of soil salinity on growing crops. The results confirm soil degradation and the synergy of using multi-spectral and radar data for crops monitoring.