Integrated Analysis of Changes in Rice Cropping Systems in the Mekong River Delta, Vietnam, by Using Remote Sensing, Gis and Hydraulic Modeling

Rice is cultivated in the Mekong River Delta of Vietnam under various cropping systems and cultivation techniques, influenced largely by environmental conditions. This paper describes a study on the dynamic changes in rice cropping systems in response to changes in agro-hydrological conditions resulting from infrastructure interventions to prevent salinity intrusion. Multi-date cloud-penetrating radar imagery were used to map the spatial distribution of different ricebased cropping systems. Changes in cropping systems were determined using secondary data and field surveys. Changes in hydrological and salinity conditions following the phased construction of sluices to control saline water intrusion were quantified by secondary data and validated hydraulic and salinity simulation. GIS was used for integrating data from various sources into a spatially coherent database, and for analyzing and understanding the influence of changing bio-physical conditions on the evolution of cropping systems. The results show that the phased construction of sluices effectively pushed the salinity intrusion boundary toward the southwest, and that farmers tend to be risk averse in adjusting their cropping systems to changing environmental conditions. We found a strong relationship between the dry season rice crop areas and areas that are free of salinity in February. The knowledge base and the analytical results of such a study provide the relevant authorities with a rational basis for water resources planning and management, which greatly influences agricultural production and farmer livelihood in the delta. Implications on further studies to predict changes that will result from future expansion of areas protected from salinity intrusion are discussed.