Department of Biological and Agricultural Engineering

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Browsing Department of Biological and Agricultural Engineering by Author "Deng, Zhi-Qiang"

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    Downstream hydraulic geometry relations: 2. Calibration and testing
    (American Geophysical Union, 2003-12-04) Singh, Vijay P.; Yang, Chih Ted; Deng, Zhi-Qiang
    Using 456 data sets under bank-full conditions obtained from various sources, the geometric relations, derived in part 1 [ Singh et al., 2003 ], are calibrated and verified using the split sampling approach. The calibration of parameters shows that the change in stream power is not shared equally among hydraulic variables and that the unevenness depends on the boundary conditions to be satisfied by the channel under consideration. The agreement between the observed values of the hydraulic variables and those predicted by the derived relations is close for the verification data set and lends credence to the hypotheses employed in this study.
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    A fractional dispersion model for overland solute transport
    (American Geophysical Union, 2006-03-18) Deng, Zhi-Qiang; de Lima, M. Isabel P.; Singh, Vijay P.; de Lima, Jo?�o L. M. P.
    Using the kinematic-wave overland flow equation and a fractional dispersion-advection equation, a process-oriented, physically-based model is developed for overland solute transport. Two scenarios, one consisting of downslope and the other of upslope rainstorm movements, are considered for numerical computations. Under these conditions, the hydrograph displays a long-tailed distribution due to the variation in flow velocity in both time and distance. The solute transport exhibits a complex behavior. Pollutographs are characterized by a steep rising limb, with a peak, and a long, stretched receding limb; whereas the solute concentration distributions feature a rapid receding limb followed by a long stretched rising limb. Downslope moving storms cause much higher peak in both hydrographs and pollutographs than do upslope moving storms. Both hydrographs and the pollutographs predicted by the fractional dispersion model are in good agreement with the data measured experimentally using a soil flume and a moving rainfall simulator.