MATCHING NATURAL-WATER COLORS TO MUNSELL STANDARDS

Color of natural waters strongly influences their aesthetic appeal, su itability for recreational use, and aquatic habitat, but methods for r outine specification of color have been lacking. An improved method ha s been developed for specifying water colors in the field. The water c olor, seen through an underwater viewer, is matched directly to Munsel l standard patches observed simultaneously. The Munsell color-matching method was verified versus measurements of the underwater light field , made with a submersible spectroradiometer in 20 different natural wa ters in New Zealand (mainly lakes), which varied widely in color and o ther optical characteristics. Hue, the most important color attribute of natural waters, could be matched accurately; the saturation and bri ghtness less so. Color standard patches are not available covering the full range of typically dark water colors, but fortunately, brightnes s can be measured with simple submersible light sensors. The Munsell c olor matching method seems suitable for routine water resources survey and monitoring.