Areas with frequent thunderstorms have high overland flow and low infiltration rates. B. Hydrographs plot discharge levels over a period of time. 1. annual hydrographs plot discharge over a year 2. These produce short-term spikes in the hydrograph. These represent rapid rises in streamflow as overland flow is delivered to the channel following a storm.
Base flow is sustained by groundwater delivery to the channel.
It may rise or fall seasonally, depending on periods of general water surplus or deficit. 1. after prolonged drought, stream flow may drop substantially. Again, this is accentuated in colder climates as snowmelt feeds delayed delivery of winter precipitation to the channel. 3. short-term hydrographs plot discharge in association with a single storm event. This is because it takes some time for overland flow to be delivered to the channel.