Baseflow Estimation
It is commonly known that the sources of water flowing in streams and rivers are baseflow and runoff. Baseflow is the component of surface water flow derived from groundwater which has discharged from the subsurface. Runoff is water which flows on top of the land surface until it joins a stream or water which falls as rain on the stream. The amounts of baseflow and runoff in streams vary with time, topography, landuse, geology and climate.
On this webpage baseflow and runoff are estimated using a mathematical filtering technique on average daily streamflow data collected by the United States Geological Survey (USGS). This interface partitions streamflow data between baseflow and runoff using an algorthim devised by Lyne and Hollick in 1979 which was transformed into a FORTRAN program by United States Department of Agriculture and Texas A & M University. Additional information about baseflows in North Carolina can be found on our What is Baseflow? page. A slightly modified version of the FORTRAN program is used in the partition analysis below. If you are unsure of the id or you are looking for a gage outside of North Carolina you may search for any gage using this link to USGS NWIS Gage Mapper application, find the id of interest (check for daily data by filtering gages) and type or copy and paste the id into the form below.
Why do streamflow partitions?
- It may help improve our estimate of how much groundwater is available.
- Land use or rainfall or groundwater use changes may affect the amount of baseflow over time.
- Combined with water quality analyses, partitioned streamflow could indicate if a source of pollution is derived from runoff or baseflow.
- Tracking baseflow over time and comparing current baseflow to the historical record is an indicator of drought.
- Analysis of baseflow recession curves may yield a better understanding of how groundwater discharge rates vary.
Lyne, V., and M. Hollick. 1979. Stochastic time-variable rainfall-runoff modelling, Hydrology and Water Resources Symposium, Institution of Engineers Australia, Perth, 89-92.