1 How does the amount of baseflow affect the unit hydrograph

1. How does the amount of baseflow affect the unit hydrograph? How about total stream flow during a storm? 2. If the duration of intervals of streamflow were twice the duration of the itervals of the units of precipitation, how could you apply the deconvolution method?

Solution

Baseflow

Baseflow is that volume of flow of water in the stream which is not generated by the excess rainfall or storm, but it exist with or without it. So, whenever the direct runoff(from the storm) is to be calculated, total baseflow has to be subtracted from the total runoff. Most of the times baseflow is the groundwater that comes into the stream in the form of spring water. Generally it has a lower value at the starting limb of the hydrograph and higher at the inflection point.

Affect on unit Hydrograph

As the baseflow is always subtracted or not included, it does not affect the unit hydrograph.

Affect on Total Streamflow during a Storm

Amount of baseflow remains almost constant, but it depends on the geology and the infiltration or permeability of the soil. If higher the permeability, more water will be infiltrated into groundwater and thus surface run-off will be low, because groundwater takes time to show or reflect in the stream flow. However if the soil is impermeable then there won\'t be much affect on the graph.