Experimental surface runoff hydrographs from linear impervious subcatchments for rainfalls of extremely high...

Area of Science:

• Hydrology
• Environmental Engineering
• Fluid Dynamics

Background:

• Surface runoff modeling is crucial for urban water management.
• Existing methods like the nonlinear reservoir and unit hydrograph methods have limitations.
• Accurate simulation of runoff hydrographs is essential for predicting flood events.

Purpose of the Study:

• To develop and validate an improved physical model for lab-scale surface runoff hydrograph simulations.
• To analyze dimensionless hydrographs and compare them with existing models.
• To investigate the relationship between rainfall intensity and runoff phase time.

Main Methods:

• Conducted lab-scale experiments on a linear impervious plane subcatchment.
• Applied model rains of varying intensities and durations.
• Utilized digital online data processing for high-resolution flow rate determination.
• Analyzed experimental hydrographs in dimensionless form.
• Compared results with nonlinear reservoir and unit hydrograph methods.

Main Results:

• Observed wave-like fluctuations in flow rate as runoff peaked.
• Derived a power-law equation relating dimensionless phase time to rainfall intensity.
• Developed an averaged dimensionless runoff hydrograph.
• Approximated the averaged hydrograph using the DR-Hill-Zerobackground and Weibull models.

Conclusions:

• The improved physical model accurately simulates surface runoff hydrographs.
• The derived dimensionless relationships enhance generalization and comparison capabilities.
• Findings are significant for modeling urban runoff, especially during high-intensity rainfall events.