Maybe a number of object will end up in shore coming from land through river and to the beach,metal detector it might be handy I think, For me most objects will settle in the lowest ground maybe in exit and openig inside and outside the thames in time build up and will be same level, park and historic site near the thames, is for me a good spot if not big housing state or public building for the number of people goes there and near to the river, or the area in the far end entrace of thames boundaries between rural and urban. Goodluck.