This set of equations can be solved numerically at each runoff time step to determine how an inflow hydrograph to the LID unit is converted into some combination of runoff hydrograph, sub-surface storage, sub-surface drainage, and infiltration into the surrounding native soil.
42.
This set of equations can be solved numerically at each runoff time step to determine how an inflow hydrograph to the LID unit is converted into some combination of runoff hydrograph, sub-surface storage, sub-surface drainage, and infiltration into the surrounding native soil.
43.
The linear assumptions underlying UH theory allows for the variation in storm intensity over time ( i . e ., the storm " hyetograph " ) to be simulated by applying the principles of superposition and proportionality to separate storm components to determine the resulting cumulative hydrograph.
44.
An "'instantaneous unit hydrograph "'is a further refinement of the concept; for an IUH, the input rainfall is assumed to all take place at a discrete point in time ( obviously, this isn't the case for actual rainstorms ).
45.
A study by Cook et al . ( 1985 ) found an increase in mean annual runoff, instantaneous discharge, and hydrograph peak flow as a result of urbanization : " . . . changes in land use coincided with changes in volumetric and time distribution aspects of hydrologic response ".
46.
This method involves building a graph in which the discharge generated by a rainstorm of a given size is plotted over time, usually hours or days . It is called the unit hydrograph method because it addresses only the runoff produced by a particular rainstorm in a specified period of time-the time taken for a river to rise, peak, and fall in response to a storm.
47.
The result can be an additive effect ( i . e . a large flood if each subcatchment's respective hydrograph peak arrives at the watershed mouth at the same point in time, thereby effectively causing a " stacking " of the hydrograph peaks ), or a more distributed-in-time effect ( i . e . a lengthy but relatively modest flood, effectively attenuated in time, as the individual subcatchment peaks arrive at the mouth of the main watershed channel in orderly succession ).
48.
The result can be an additive effect ( i . e . a large flood if each subcatchment's respective hydrograph peak arrives at the watershed mouth at the same point in time, thereby effectively causing a " stacking " of the hydrograph peaks ), or a more distributed-in-time effect ( i . e . a lengthy but relatively modest flood, effectively attenuated in time, as the individual subcatchment peaks arrive at the mouth of the main watershed channel in orderly succession ).
