Freshwater-saltwater boundary detection using mobile sensors part I: Drifter deployment

Due to a reduction in the supply of freshwater in estuaries, saltwater can intrude deeply into river channels. We focus on the freshwater-saltwater boundary detection problem, and identify a point on the boundary that reflects the degree of salinity intrusion via deploying mobile drifters with powered propellers. Our approach consists of deploying two drifters to explore the boundary in different directions and obtaining the estimate of the point based on the estimates from these two drifters. We show that the proposed algorithms can achieve an arbitrarily accurate estimate under certain assumptions on the salinity field.