Hydrology: Infra-Red Divining Rod

Of the 13 billion gallons of rain that fall every day on the island of Hawaii, a mere 3% is retained by the land. Much of the rest soaks rapidly through permeable soil and rock and seeps into the sea. The continuous loss leaves three-quarters of the island with no streams or lakes to supply fresh water. Now, as a serendipitous byproduct of volcano research, scientists have found new freshwater sources that may not only enable Hawaiians to move into previously uninhabitable areas, but could also help meet the needs of the island’s growing population for generations to come.

The discovery of Hawaii’s untapped fluid assets was made by University of Michigan and U.S. Geological Survey scientists while they were charting temperature variations in the vicinity of Kilauea, the island’s largest volcano crater. In an old B-25 bomber crammed with infra-red scanning equipment, they mapped the volcano’s hot spots; then they enlarged their thermal survey by following two great rifts that led from the crater to the sea. Under the shore, and in nearby coastal waters, their infra-red detector revealed just the opposite of what they were searching for: large areas that were not hotter, but as much as 12° cooler, than their surroundings.

Cold Stills & Hot Springs. Geologist William Fischer, who headed the survey, soon recognized the significance of the findings: like an aerial divining rod, the infra-red scanner had spotted streams of cool, fresh rain water flowing out into the ocean. After completing the volcanic survey, the B-25 flew back and forth over Hawaii’s entire coastline, eventually detecting a total of 219 shore areas that might have underground fresh-water springs. In one 5-sq.-mi. area in Hilo Bay, the scientists estimate, the discharge of fresh water amounts to 100 million gallons a day. Using the infra-red data, the U.S. Geological Survey has just published an atlas of Hawaii’s coastal areas pinpointing the location of the underground fresh-water flows. The maps will help Government and private developers to find sites for wells that can provide fresh water for the construction of communities in coastal areas where none existed before.

Infra-red detection of underground fresh water will soon be possible anywhere in the world. Fischer is currently working on infra-red instruments for the Geological Survey’s EROS (Earth Resources Observation Satellites) program, hopes to have it aboard a satellite by 1969. Once in operation, it might serve to find water under deserts, chart the best locations for wells and discover new hot springs for resort sites. It could even help the U.S. Internal Revenue Service by searching the Southern hill country for the hidden cold springs that are needed for the operation of illegal stills.