By Leah Crane
When scientists assess environmental risk in any particular geographical region, they need as many data as possible relating to the area’s past. Often, though, those data are limited by the existence of scientific instruments: Precise measurements only go back so far in history. When scientists predict the likelihood and severity of future flooding in particular, historical data are often limited to imprecise written descriptions of past flood events. In a new paper, Salinas et al. built a framework to incorporate historical records written before the advent of scientific instrumentation into the estimation of flood probabilities.
There are many different types of historical flood records, all of them with differing degrees of imprecision. For example, a recollection of “the river left its banks” yields less information than “the flood covered the ground, ruining the crops,” which is less precise still than “the river rose to the city walls, so high that people standing on the bridge could wash their hands in the floodwaters.” The new framework applies a membership function to each written record, defining the likelihood that the event described belongs in a fuzzy set...