Theis

Theis is a surname of German origin. It may also be encountered in the spellings Theiß or Theiss, reflecting regional and linguistic variations. The name appears across various professions and fields, and may be found in historical and contemporary records.

In science and engineering, Theis most often refers to the Theis solution in hydrogeology. Named after C. V. Theis, who published it in 1935, the model describes transient drawdown in a confined aquifer due to a constant-rate pumping well. The drawdown s at distance r and time t is given by s(r,t) = (Q / (4πT)) W(u), where Q is the pumping rate, T is transmissivity, S is storativity, and u = (r^2 S) / (4 T t). W is the well function related to the exponential integral E1. Theis solution enables estimation of aquifer properties from pumping tests and remains a foundational concept in groundwater hydraulics.

Beyond hydrology, Theis functions primarily as a surname and, less commonly, as a given name. It appears in historical documents and modern records in various countries, particularly where Germanic linguistic influence is present. The name’s usage and appearance can vary with language and orthography.