The curve number and phi(4)-index models each provide a simple one-parameter relationship between storm-event rainfall and runoff. It is shown that the curve number and 4-index models can both be used to segregate the...The curve number and phi(4)-index models each provide a simple one-parameter relationship between storm-event rainfall and runoff. It is shown that the curve number and 4-index models can both be used to segregate the rainfall hyetograph into initial abstraction, retention, and runoff amounts. However, the principal advantages of the 4-index model are that both rainfall distribution and duration can be explicitly taken into account in calculating runoff, and the 4 index is more physically based than the curve number. The quantitative relationship between the curve number and the 4 index is presented and validated with field measurements. Knowing the relationship between the curve number and the 4 index is useful in that it facilitates using the extensive database of curve numbers in the more realistic 4-index model in calculating a runoff hydrograph from a given rainfall hyetograph. It is demonstrated that conventional adjustments to curve numbers can be largely explained by variations in storm duration, which suggests that variable rainfall duration can possibly be an essential factor in accounting for deviations from the median curve number of a catchment.展开更多
Surf-zone hydrodynamics forced by oblique wave shoaling and breaking on beach slopes were investigated.The results showed that in wave-basin experiments with incident angles in the range of 15°-30°,wave brea...Surf-zone hydrodynamics forced by oblique wave shoaling and breaking on beach slopes were investigated.The results showed that in wave-basin experiments with incident angles in the range of 15°-30°,wave breaking was initiated at a breaker coefficient of around 0.67,which was significantly less than that predicted from empirical relations based on normally incident waves for a given beach slope and deep-water wave steepness.The measurements also showed that subsequent saturated breaking occurred at a breaker coefficient of around 0.47 that was inde-pendent of beach slope in the range of 1∶10 to 1∶100.This result is likely applicable to both oblique and normally incident waves.It is shown that the measured wave heights and longshore velocity profiles in wave-basin studies can be reasonably well predicted by theory with proper ad-justments to the process parameters.Best-match formulations were identified for quantifying bottom friction,eddy viscosity,and energy loss due to surface rollers.展开更多
文摘The curve number and phi(4)-index models each provide a simple one-parameter relationship between storm-event rainfall and runoff. It is shown that the curve number and 4-index models can both be used to segregate the rainfall hyetograph into initial abstraction, retention, and runoff amounts. However, the principal advantages of the 4-index model are that both rainfall distribution and duration can be explicitly taken into account in calculating runoff, and the 4 index is more physically based than the curve number. The quantitative relationship between the curve number and the 4 index is presented and validated with field measurements. Knowing the relationship between the curve number and the 4 index is useful in that it facilitates using the extensive database of curve numbers in the more realistic 4-index model in calculating a runoff hydrograph from a given rainfall hyetograph. It is demonstrated that conventional adjustments to curve numbers can be largely explained by variations in storm duration, which suggests that variable rainfall duration can possibly be an essential factor in accounting for deviations from the median curve number of a catchment.
文摘Surf-zone hydrodynamics forced by oblique wave shoaling and breaking on beach slopes were investigated.The results showed that in wave-basin experiments with incident angles in the range of 15°-30°,wave breaking was initiated at a breaker coefficient of around 0.67,which was significantly less than that predicted from empirical relations based on normally incident waves for a given beach slope and deep-water wave steepness.The measurements also showed that subsequent saturated breaking occurred at a breaker coefficient of around 0.47 that was inde-pendent of beach slope in the range of 1∶10 to 1∶100.This result is likely applicable to both oblique and normally incident waves.It is shown that the measured wave heights and longshore velocity profiles in wave-basin studies can be reasonably well predicted by theory with proper ad-justments to the process parameters.Best-match formulations were identified for quantifying bottom friction,eddy viscosity,and energy loss due to surface rollers.
