A RIVER FLOW ROUTING MODEL BASED ON DIGITAL DRAINAGE NETWORK

On the basis of Digital Elevation Model （DEM） data, watershed delineation and spatial topological relationship were proposed by the Digital Elevation Drainage Network Model （DEDNM） for the area upstream of the Hanzhong Hydrological Station in the Hanjiang River in China. Then, the Muskingum-Cunge method considering lateral flow into the river was applied to flood routing on the platform of digital basin derived from DEDNM. Because of considering lateral flow into the river, the Muskingum-Cunge method performs better than the Muskingum method in terms of the Nash-Sutcliffe model efficiency coefficient and the relative error of flood discharge peak value. With a routing-after-superposition algorithm, the Muskingum-Cunge method performs better than the Muskingum method in terms of the Nash-Sutcliffe model efficiency coefficient and the relative error of flood discharge peak value. As a result, the digital basin coupled with the Muskingum-Cunge method provides a better platform for water resources management and flood control.

Internal Water Flows and Particles Abstraction in Daphnia

The operational function of the trunk limbs (thoracic appendages), of Daphnia, P3 and P4, is a long-term disputed definition between “solid walls”, sieving filters. Sieving is unlikely process for routine particle collection, particle capture is not a simple mechanical process and not by sieving alone. Analysis promotion supported by direct observational examination of the in-vivo cinematographic slow-motion film and magnified solid photos of tethered Daphnia by high-speed camera (250 frames per second) resulted in a definite interpretation presented in this paper. The Daphnia’s feeding mechanism achieves particles abstraction not by sieving. The existence of two internal alternate water flow routs was indicated: Lateral and Median. These micro flow structures are suggested as vulnerability reduction.

High-efficiency calculation method for watershed rainfallrunoff routing using one-dimensional dynamic wave equations

Efficiency in solving the Saint-Venant equations for watershed rainfall-runoff routing is important in flood hydrology. This paper presents a high-efficiency numerical solution of one-dimensional dynamic wave equations(HEDWE) for watershed rainfall-runoff routing, in which the full momentum equation is written as a quadratic equation with only one unknown variable Q, water depth is derived from the continuity equation using the two-step predictorcorrector method, and the discrete scheme is the explicit upwind scheme. The results of numerical tests showed the HEDWE approach has several major advantages. 1) It is a stable numerical method, even for an initially dry area. 2) Its computational efficiency is higher than 4.76E+05 times/s. 3) It can be used for overland flow, river flow, and combinations thereof. The primary disadvantages of the HEDWE approach are its unsuitability for rapidly varying flow, such as dam-break floods.