Hydrographs of drainage basins
Large basins receive more precipitation than smaller basins, therefore they have a larger Water moves across the surface of the earth becoming a stream, tributary or river (transfer).. Larger size also means a longer lag time as water has a longer distance to travel to reach the main river.
An elongated basin will produce a lower peak flow and a longer lag time than a rounder basin. Basins with a higher drainage density (number of tributary rivers) collect rain water more quickly, therefore the lag time will be shorter.
Type of slope
Flow can be faster down a steep slope, resulting in a steeper rising limb and a shorter lag time.
Rock/soil type
A type of rock which allows water to pass through its joints and cracks, eg limestone. mean rapid infiltration and little overland flow, resulting in a shallow rising limb.
Rock which does not allow water to pass through it, eg granite. will lead to an increase in overland flow and a steep rising limb.
Water soaks or filters into the soil (transfer). is generally greater on thick soil, although less porous soils, such as clay, act as impermeable layers.
Other factors
Urbanisation, with bare concrete and tarmac forming impermeable surfaces, creates a steep rising limb and shortens the time lag.
In urban areas concrete, tarmac and buildings will channel precipitation to gutter and drainage systems quickly. This water will quickly reach the sewer and river systems, shortening the lag time.
Forest areas will intercept the precipitation, creating a shallow rising limb and lengthening the time lag. Vegetation will intercept precipitation and store and absorb it, therefore preventing the water moving quickly into the river.