WRRCTR No.93 Quality and Quantity of Nonpoint Pollution Sources in Rural Surface Water Runoff on Oahu, Hawaii

Abstract

The quality and quantity of rural runoff was the subject of a field study conducted on the island of Oahu. The study investigated surface water runoff from three rural land uses: an undeveloped forested area, a sugarcane field, and a pineapple field. A 37.85-l (l0-gal) tipping bucket sampler was used to collect composited runoff samples at each site and to record the volume of runoff associated with each sample. The results of this study show that storm water runoff from undeveloped areas is the major contributor of nutrients, COD, and sediment, into wet weather stream flow. Furthermore, it establishes that nutrients and COD in this type of runoff are primarily in sediment-associated forms.

The sugarcane field samples included storm runoff and irrigation tail water. The sample results indicate that cane field runoff in central Kunia was lower in most water quality parameters than the forest runoff in Manoa. Insufficient samples due to dry weather prohibited a thorough analysis of pineapple field runoff.