An experimental study of Roman dropshaft hydraulics

Abstract

In Roman aqueducts, series of vertical dropshafts were used to dissipate the kinetic energy of the flow: i.e., the dropshaft cascades. A re-analysis of Roman dropshaft hydraulics is conducted with physical model tests. Three basic flow patterns are observed. The results demonstrate that the vertical dropshafts could be very efficient energy dissipators and re-oxygenation structures, under appropriate flow conditions. The optimum operation of Roman dropshaft is discussed and an analytical model is developed to predict these conditions. Further the performances of aqueduct dropshafts are compared with modern dropshaft designs, and the operation of dropshaft cascades is discussed. Additional material is available upon request. RésuméCertains aqueducs romains étaient équipes de cascades de puits de rupture, concues pour briser l'énergie cinétique de l'écoulement. On a conduit une série de tests sur modèles physiques pour ré-analysei l'hydraulique des puits de rupture romains. Les résultats démontrent trois régimes d'écoulement. Dans des conditions optimales. les puits de rupture sont des systèmes de perte de charge tres efticaces. Ces conditions optimales ont été déterminées avec des modèles physiques et analytiques. Les performances des puits romains sont aussi comparées avec celles de puits modernes. et on discute aussi de l'opération des cascades de puits. Sur demande. Pauteur peut fournir de plus amples informations.

The Hydraulics of Roman Aqueducts: What Do We Know? Why Should We Learn?

“…Only four shafts located on a steep slope were likely to be dropshafts. The hydraulics of Roman dropshafts was recently investigated (Chanson 2002b(Chanson , 2004(Chanson , 2007. Figure 6 shows the full-scale model of a rectangular dropshaft installed on the Yzeron aqueduct at Recret.…”

“…6). Chanson (2000Chanson ( , 2002b presented the first documented survey of Roman dropshaft structures. It showed the existence of single dropshaft construction as well as complex cascades (or series) of dropshafts.…”

“…The energy dissipation system was essential to ensure normal downstream flow operation and to prevent scour and damage to the structure. Three types of structures were used : (a) a smooth steep chute followed by some hydraulic jump dissipator, (b) a stepped chute, and (c) some dropshaft or dropshaft cascade (Chanson 2000(Chanson , 2002b. Short sections had a steep stepped invert gradient (Fig.…”

Digital Publishing, Indexing, and Ethics: Implications in Civil and Hydraulic Engineering and Research

“…The statement was misleading and incorrect. The work derived from an experimental study conducted two years earlier by myself and my students, and was published in a refereed technical report (Chanson 2002). In this instance, the journal editor reviewed the technical report, received independent advice from the technical report's referee, and ultimately discarded the dishonest review.…”

“…In a few instances, some unscrupulous individuals copied my documents (Chanson 1993(Chanson , 2002; numerous photographic works), and published these under their own name(s). In another case, an individual used my experimental data without a single acknowledgment or citation.…”