CVEN 9625 Fundamentals of Water Engineering
Assignment 1 - Evapotranspiration
Total Marks 40 (10 marks for the quality of presentation)
Question 1 (15 marks)
The following information is available for a project site:
• Latitude = 35°S
• Longitude = 152°E
• Elevation = 0 m (at sea level)
• Average Albedo = 0.2
Jun-Aug Sep-Nov Dec-Feb Mar-May
Air Temperature (°C) 17 21 24 20
Relative Humidity (%) 65 70 70 60
Wind Speed (m/s) 2.2 2.4 2.3 2.1
Average sunshine hours 8 8.4 8.7 7.6
Estimate the following using the above information:
Potential Evaporation for an open water body using the Penman Monteith equation
Reference crop evapotranspiration using the Penman Monteith equation
Potential evapotranspiration for a farm growing wheat that was planted in September
Plot all the estimated evapotranspiration rates on the same graph paper and comment on
the results obtained. State any assumptions that were made in the analysis.
Question 2 (15 marks)
Given a fully developed and growing pasture well rooted (evenly) to 0.5m at the location
described in Question 1, compute and plot the daily actual evapotranspiration and total
soil moisture in the top 0.5m soil profile between October 20 and November 12. The
following soil properties may be used:
θw (soil moisture content at wilting point) = 0.10
θf (soil moisture content at field capacity) = 0.23
θs (soil moisture content at saturation) = 0.42
Assume the soil was at field capacity on October 20 and 40 mm rain occurs on November
1, and another 50 mm on November 8. Plot the daily soil moisture percentage for the top
0.5 m root zone and the daily actual evapotranspiration between October 20 and
November 12. Note that any water above saturation would result in overland flow from
the soil. Soil water content between saturation and field capacity would decrease to field
capacity due to infiltration. So if there were no evapotranspiration, the soil moisture
should remain indefinitely at field capacity. For calculation purposes assume that the
water comes down to the field capacity at a very fast rate.
NOTE: For simplicity, the same hydro-meteorological values may be assumed for Oct 20
– Nov 12, as were calculated for Sep-Nov in Question 1.
NOTE: You are expected to submit a document which has as tables (that are formatted
and nicely presented) key calculations from Excel or other platforms to support your
discussion and conclusions. Detailed calculations, if needed, should be included in an
appendix. The main assignment should have mostly words, figures and tables – marks
will be based on your interpretation and discussion.
NOTE: Quality of presentation will be judged by use of clear, convincing arguments,
figures and tables. Expectation is that your submission will resemble a professional
looking engineering report. This should be a short document summarising your responses
to each question (mostly words and a few figures/tables that are well formatted) and an
appendix with nicely formatted tables and figures presenting details for the marker to see
and assess incase additional information is needed.