1) (20 points) Determine the evapotranspiration rate in the drainage basin of the Peconic River (Eastern Long Island) by using the hydrologic balance equation and discharge and precipitation data.
a) Download the discharge and precipitation data for the Peconic river at Riverhead, and three precipitation stations in the area: Bridgehampton, Greenport Powerhouse, and Riverhead Research Farm. The data are in tabulated text format (.TXT). Save the file and open it in EXCEL. Make sure to save it immediately as an EXCEL file, e.g. PECONIC.XLS. Look at a map that shows the location of the streamgage (Riverhead, Long Island).
b) (6 points) Plot the discharge rate and the precipitation at Riverhead as a combination diagram with two Y-scales as a function of time. Discharge should be plotted as a line, precipitation as bars. Make sure that the axes are properly labeled. Print the graph.
c) (4 points) Explain in a few sentences the relationship between discharge and precipitation.
d) (4 points) Make the best estimate of total precipitation for the drainage area using the data for the three weather stations. The size of the drainage area is given in the data file.
e) (6 points) Determine the average evapotranspiration
rate
for
the two given months using the precipitation and discharge data
given.
Assume that the groundwater is in steady state, i.e. there is no
change
in storage. How much (%) of the precipitation is lost by
evapotranspiration
in the basin? Tip: your answer should be in the range of 1 to
100%.
2.) (10
points)
Measurement of changes in volume of water in an evaporation
pan
is a
standard technique for estimating potential evapotranspiration.
United
States Class A evaporation pans are cyclindrical with the
following
dimensions: depth = 10.0 inches, and diametrer = 47.5 inches. An
evaporation pan can be considered a hydrological system with an
inflow,
outflow, and storage volume. Evaporation from pans is not the
same as
evaporation from natural surfaces for a range of reasons. For
example,
water temperatures in shallow pans will be much more variable
than
temperatures in a nearby lake. Evaporation measured in pans is
adjusted
by a factor called a pan coefficient to convert to an estimate
of
potential evapotranspiration.
b) Calculate the flux of latent heat from
the
water in the pan to the atmsophere (W m-2).
3) (4 points) Laminar flow table
Please describe in a couple of short
paragraphs what we did with the laminar flow table and how the
results relate to Bernoulli law. Look again at the outline
of the exercises we did.
4) (10 points) Weir experiment
This table (Weir_2_7_2012.xls, will update on Tuesday) contains data obtained with the Weir experiment in Mudd. Plot the discharge rate Q as a function of H1.5. Do it with the data of all groups, first individually, then all data combined. Set the intercept to 0 and determine the slope of the graph (this is an option when you fit the data with a line). How well do the data plot on a straight line? Do you have any explanation for the data points that do not fit the general trend? What value did you obtain for the experiments for Cd? (g=9.81 m s-2). Watch the units!
5) (x points) Bernoulli experiment