Intercomparison of global river discharge simulations focusing on dam operation --- Part II: Multiple models analysis in two case-study river basins, Missouri-Mississippi and Green-Colorado

We performed a twofold intercomparison of river discharge regulated by dams under multiple meteorological forcings among multiple global hydrological models for a historical period by simulation. Paper II provides an intercomparison of river discharge simulated by five hydrological models under four meteorological forcings. This is the first global multimodel intercomparison study on dam-regulated river flow. Although the simulations were conducted globally, the Missouri-Mississippi and Green-Colorado Rivers were chosen as case-study sites in this study. The hydrological models incorporate generic schemes of dam operation, not specific to a certain dam. We examined river discharge on a longitudinal section of river channels to investigate the effects of dams on simulated discharge, especially at the seasonal time scale. We found that the magnitude of dam regulation differed considerably among the hydrological models. The difference was attributable not only to dam operation schemes but also to the magnitude of simulated river discharge flowing into dams. That is, although a similar algorithm of dam operation schemes was incorporated in different hydrological models, the magnitude of dam regulation substantially differed among the models. Intermodel discrepancies tended to decrease toward the lower reaches of these river basins, which means model dependence is less significant toward lower reaches. These case-study results imply that, intermodel comparisons of river discharge should be made at different locations along the river’s course to critically examine the performance of hydrological models because the performance can vary with the locations

An innovative approach for temperature control of massive concrete structures at early ages based on post-cooling: Proof of concept

This study proposes a new methodology for the embedment of flexible PVC hoses (with the shape/geometry of the intended cooling pipes) that allows their removal a few hours after casting (i.e. after setting), while allowing that water is pumped through the circular cavity afterward (through a flexible/impermeable sleeve placed to shield the exposed concrete cavity). The PVC hoses are initially filled with oil under pressure, which are deflated a few hours after casting (particularly after setting is identified), and removed without relevant constraints due to their reduction in diameter inherent to deflation. All components and materials embedded into concrete (hose, sleeve) are fully recoverable after the end of the temperature control period, avoiding the loss of materials, with important financial and sustainability gains. This paper intends to show the proof-of-concept carried out in laboratory context conditions, highlighting the features that led to the selection and phasing procedure of the solution proposed.The authors gratefully acknowledge the Foundation for Science and Technology (FCT) for the financial support to: the Research Unit RISCO (FCT/UID/ECI/04450/2013), the Research Unit ISISE (POCI-01-0145- FEDER-007633); the post-doc scholarship grant SFRH/BPD/116022/2016; the Research Project IntegraCrete PTDC/ECM-EST/1056/2014 (POCI-01-0145-FEDER-016841). The author Miguel Azenha also gratefully acknowledges the very rich discussion held with the colleague Paulo Ramísio (University of Minho) on a unrelated matter, that ended up giving birth to the idea forwarded here. Collaboration with Raul Fangueiro and Carlos Mota in the selection of the pipe to use in this work is also gratefully acknowledged