People might not think about swales for flood mitigation but I’ve now experienced first hand just how effective they are in this situation as well as in times of drought. In times of drought we release our grey water into the swales fertigating them but on the other extreme, whilst experiencing floods from a 280 ml in two days, our swales have worked brilliantly filling up to perfection, catching and storing water and nutrient and slowing the velosity and speed of the water and slowly releasing it over several days afterward. So swales are a great flood mitigation tool. The ducks had a ball swimming in them and the trees now look superb benefiting from all the nutrient retention and a deep slow soak. So glad i have them.