Re-constructing the river bed using the streamline-generation method.

River bed reconstruction plays an essential part in supporting the hydrodynamic simulation and understanding the morphological processes of a river. The streamlines can be solved using Laplace equations. The equation is first numerically solved in a computational environment and then adapted to the whole considered physical field to solve the resulting streamlines in a physical domain. One of the goals of this research is to determine the bottom line of the riverbed, and doing this through a field survey is very expensive, the methods presented in this research help a lot in reducing costs. By determining the concave line, the path of the flood in the river bed is determined, so one of the practical achievements and efficiencies of this research is flood trending at a low cost. In the present study, the bottom line is determined for the meandering Qinhe River, a distributary of the Yellow River, China, and Gaz River, located in Khuzestan Province, Iran. The method is based on the following steps:•Reconstruction of 2D river based on the Laplace equation.•Use the Finite Element Method to solve streamlines in the physical domain.•Use the Finite Difference Method to solve streamlines in the physical domain.

The stability enigma of hydraulic vulnerability curves: addressing the link between hydraulic conductivity and drought-induced embolism.

Maintaining xylem water transport under drought is vital for plants, but xylem failure does occur when drought-induced embolisms form and progressively spread through the xylem. The hydraulic method is widely considered the gold standard to quantify drought-induced xylem embolism. The method determines hydraulic conductivity (Kh) in cut branch samples, dehydrated to specific drought levels, by pushing water through them. The technique is widely considered for its reliable Kh measurements, but there is some uncertainty in the literature over how to define stable Kh and how that relates to the degree of xylem embolism formation. Therefore, the most common setup for this method was extended to measure four parameters: (i) inlet Kh, (ii) outlet Kh, (iii) radial flow from xylem to surrounding living tissue and (iv) the pressure difference across the sample. From a strictly theoretical viewpoint, hydraulic steady state, where inflow equals outflow and radial flow is zero, will result in stable Kh. Application of the setup to Malus domestica Borkh. branches showed that achieving hydraulic steady state takes considerable time (up to 300 min) and that time to reach steady state increased with declining xylem water potentials. During each experimental run, Kh and xylem water potentials dynamically increased, which was supported by X-ray computed microtomography visualizations of embolism refilling under both high- (8 kPa) and low-pressure (2 kPa) heads. Supplying pressurized water can hence cause artificial refilling of vessels, which makes it difficult to achieve a truly stable Kh in partially embolized xylem.