Mapping Paddy Rice Using Sentinel-1 SAR Time Series in Camargue, France

Hassan Bazzi,Mehrez Zribi,Emile Ndikumana,Dominique Courault,Hatem Belhouchette,Nicolas Baghdadi,Dinh Ho Tong Minh,Mohammad El Hajj

doi:10.3390/rs11070887

Abstract

This study proposes an effective method to map rice crops using the Sentinel-1 SAR (Synthetic Aperture Radar) time series over the Camargue region, Southern France. First, the temporal behavior of the SAR backscattering coefficient over 832 plots containing different crop types was analyzed. Through this analysis, the rice cultivation was identified using metrics derived from the Gaussian profile of the VV/VH time series (3 metrics), the variance of the VV/VH time series (one metric), and the slope of the linear regression of the VH time series (one metric). Using the derived metrics, rice plots were mapped through two different approaches: decision tree and Random Forest (RF). To validate the accuracy of each approach, the classified rice map was compared to the available national data. Similar high overall accuracy was obtained using both approaches. The overall accuracy obtained using a simple decision tree reached 96.3%, whereas an overall accuracy of 96.6% was obtained using the RF classifier. The approach, therefore, provides a simple yet precise and powerful tool to map paddy rice areas.

Highlights

Rice is a staple food resource for more than half of the world population
The Random Forest (RF) classifier produces an overall accuracy of 96.7% whereas the decision tree gives 96.3% overall accuracy
Using the proposed decision tree, 325 rice plots were misclassified as non-rice plots, whereas using the RF classifier 266 rice plots were misclassified as non-rice plot according to the RPG data

Summary

Introduction

Rice is a staple food resource for more than half of the world population. It plays an important role in the global economy, food security, and water use. In 2017, rice was classified by the FAO (Food and Agriculture Organization of the United Nations) as the second most produced cereal in the world [1]. Considered as an important reservoir of biodiversity, the Camargue region of South France is the main producer and supplier of rice in France. Rice in Camargue plays an important role in the hydrological balance of the region [2].

Methods

Results

Conclusion