Ecosystem models have difficulty predicting plant drought responses, partially from uncertainty in the stomatal response to water deficits in soil and atmosphere. We evaluate a 'supply-demand' theory for water-limited stomatal behavior that avoids the typical scaffold of empirical response functions. The premise is that canopy water demand is regulated in proportion to threat to supply posed by...

Satellite-based active microwave sensors not only provide synoptic overviews of flooded areas, but also offer an effective way to estimate spatially distributed river water levels. If rapidly produced and processed, these data can be used for updating hydraulic models in near real-time. The usefulness of such approaches with real event data sets provided by currently existing sensors has yet to...

[1] Hydraulic diffusivity controls fluid pressure and hence affects effective normal stress during rupture. Models suggest a particularly spectacular example of fluid pressurization during the Mw = 7.6 1999 Chichi earthquake when pressurization may have reduced highfrequency shaking in the regions of large slip if the fault was sufficiently sealed. We investigate in situ hydraulic diffusivity w...

An adaptive Helmholtz resonator was designed and adapted to hydraulics. The resonator was controlled by openand closed-loop controls so that 20 dB attenuation of the peak-to-peak value of the pulsating pressure was maintained. The closed-loop control was noted to be better, albeit it was slower because of its low pressure and temperature variation, which caused variation in the effective bulk m...

An essential part of an automated MPD control system is the hydraulic model, which in many cases is the limiting factor for achievable accuracy of the system. A lot of effort has therefore been put into developing advanced hydraulic models that capture all aspects of the drilling fluid hydraulics. However, a main drawback is the resulting complexity of these models, which require expert knowled...

Predicting root water uptake and plant transpiration is crucial for managing plant irrigation and developing drought-tolerant root system ideotypes (i.e. ideal root systems). Today, three-dimensional structural functional models exist, which allows solving the water flow equation in the soil and in the root systems under transient conditions and in heterogeneous soils. Yet, these models rely on...

Physical modelling of hydraulic systems results in systems of differential and algebraic equations (DAEs) that are normally stiff. This is because they often include multiple temporal scales and present complex and non-linear behaviour. The simulation of these stiff DAEs in real time demand small time steps, in order to achieve algorithm stability, because explicit fixed step solvers are usuall...

unsaturated hydraulic conductivity, K, expressed as a function of the soil water content, u, or the soil water Hysteresis has been found in both the hydraulic conductivity, K, pressure head, c, and the relation between u and c must vs. pressure head, c, relationship, and the soil water content, u, vs. c relationship. This limits the application of a unified solution for be specified before anal...

Development of numerical methods for hydraulic fracture simulation has accelerated in the past two decades. Recent advances in hydraulic fracture modeling and simulation are driven by increased industry and research activity in oil and gas, a drive toward consideration of more complex behaviors associated with layered and naturally-fractured rock formations, and a deepening understanding of the...