Predicting improved optical water quality in rivers resulting from soil conservation actions on land

Soil conservation not only conserves soil but it improves the water clarity of water in rivers. This improvement may be estimated by the methods shown in this paper. The approach is demonstrated on the Wairua River in Northland, New Zealand. For this river we show that visual clarity would increase relatively by approximately 1.4 times the relative reduction of sediment load. Median visual clarity would increase from 0.75m to 1.25m (making the river more often suitable for swimming) after a sediment load reduction of 50% associated with widespread soil conservation on pastoral land.