climate

The general climatic regime controls the total volume of runoff in
any region through its effect on the water balance. In a broad sense,
over a time scale long enough that storage changes average out (are
negligible), and over a region large enough or with boundary defined
so that inflows (surface and subsurface) are negligible, the water
balance may be stated as
P = Q + E (1)
where P is the precipitation rate, Q the runoff rate, and E the
evapotranspiration rate. This equation indicates that the precipitation
input is disposed of either into runoff or evapotranspiration. In
general the climatic regime controls the overall proportioning. Here
groundwater recharge supplying baseflow is included in Q. Because
the quantities in equation (1) must be positive, this equation places
limits on the values of Q and E given any specific P. Both Q and E
are constrained to be less than P. This may be visualized in a space
where E is plotted versus P
Thank you to Christina Bandaragoda and Yasir Kaheil, graduate
students at Utah State University who helped tremendously with
preparation of online material. Thank you to Mark Zachry and
Christine Hult in the English Department at Utah State University
for help on the pedagogy of online education. This module was
developed using database technology by 3GB Technologies
(http://www.3gb.com). David Brandon and Bill Reed at the
National Weather Service Colorado Basin River Forecast Center
collaborated on the production of this module.
This material was prepared by the Utah State University, Utah Water
Research Laboratory under a Subaward with the University
Corporation for Atmospheric Research (UCAR) under Cooperative
Agreement No. NA17WD2383 with the National Oceanic and
Atmospheric Administration (NOAA), U.S. Department of
Commerce (DOC). The statements, findings, conclusions, and
recommendations are those of the author and do not necessarily
reflect the views of NOAA, DOC or UCAR.