The objectives of this assignment are to:
GENERAL ASSIGNMENT REQUIREMENTS
Failure to observe the above requirements will result in mark penalties.
The soil water zone is one of the most important reservoirs in the hydrological cycle as it is an important interface that determines the relative amounts of input water (precipitation) that are partitioned to the outputs relative to the soil water zone (evapotranspiration, runoff, and percolation to groundwater). The conceptualization of the soil water zone as a ‘bucket’ that contains a volume of water in storage, with this storage volume changing over time in response to changes in the balance of inputs and outputs, makes understanding this important component of the hydrological cycle a bit easier.
Consider a simple water balance equation for the soil water zone:
PRECIP = AE + S ± ∆ST
See your lecture notes or text for a detailed explanation of the terms. If the input (PRECIP) is balanced by the outputs (AE + S), then ∆ST will be equal to zero; the soil may be thought of as being in hydrologic equilibrium. In general, this is only the case over relatively long periods of time (i.e. a year or more). At shorter durations, there are definitely imbalances in the water budget that create both positive and negative changes in storage (recall the seasonal surface water balance figures from lecture/text).
The short-term changes in storage in the watershed are largely manifested as changes in soil moisture. The soil water zone is a very dynamic environment, changing in water content (∆ST ) in response to water inputs from precipitation (PRECIP), and decreasing in water content due to evaporative outputs (AE), and transfers to groundwater beneath through processes such as percolation (S). Given the episodic nature of the input (e.g. rain events), these changes in storage are highly transient; on the order of hours to days.
We can describe the capacity of the soil water zone to hold water in a number of ways.
The porosity (φ) of a soil (or other geological media) may be expressed as:
φ = Vvoid/Vsample
where Vvoid is the total volume of void space in the soil sample, and Vsoil is the total volume of the soil sample. Porosity is simply the fraction of the soil sample that can be occupied by air, water or some combination of the two.
The most common way to express the amount of water contained within a soil sample is the Volumetric Soil Moisture (VSM), which is:
VSM = Vwater/Vsample
where Vwater is the total volume of water in the sample. Be mindful of the subtle difference in the expressions for porosity and volumetric soil moisture. You will see that whereas the other two terms are always going to have a value of something less than 1, however both porosity and VSM are sometimes multiplied by 100 and expressed as a percent. Finally, it should also be obvious based on the descriptions of porosity and VSM that, at saturation (i.e. there is no air in the soil voids), that VSM is at its maximum, and that it is equal to porosity.
You have been asked to assess the need for irrigation for an agriculturally intensive region. You must perform some basic water balance calculations for the two driest months of the year to determine if irrigation is required, and how much.
Luckily, the study area is completely flat, so there is no surface runoff to be considered in the soil water balance. Therefore the S term only involves the vertical movement of surplus water back down to the groundwater zone through percolation.
Area of the Field: 1500 hectares
Depth of Active Soil Water Zone: 1.00 metres (m)
Soil Porosity: 0.420
Field Capacity: 0.180 (expressed as VSM)
Wilting Point for the Crop: 0.100 (expressed as VSM)
VSM on Day 1 of the Study Period: 0.220
Evaportranspiration: 5.00 mm per day
For the sake of simplicity in this assignment, we will assume that the properties of the environment are homogeneous.
(i.e. simplified for this assignment) o Assume all values in assignment accurate to three significant digits.Tasks:
PART A: Using the data from Table 1 and information provided in this assignment, create an Excel spreadsheet that includes:
You must carefully consider how to construct the formulae for your spreadsheet in order to calculate the values required.
“IF A > B = TRUE, then A = C. IF A > B = FALSE, then A = 0”.
Excel will let you create formulas like this, and it will even ‘HELP’ you do it.
6) Produce a graph of your results. On this graph, you will present Days on the horizontal x-axis, and utilise two different vertical y-axes: Precipitation (mm/day) is to go on the left y-axis as a bar chart, and a line graph for VSM on the right y-axis. Let Excel ‘HELP’ you create a graph with two chart ‘types’ and a ‘secondary’ y-axis. The graph must be properly labeled and include a title and legend (5 marks).
PART B: Using the information provided in the required data, the calculated data, and your graph consider the following questions:
Your submission will take the form of a report on your findings. If it helps, pretend that you are producing a report for a client. It will be composed of:
**As part of the successful completion of this assignment, you must also electronically submit your clear, tidy spreadsheet that you used to perform the calculations. This is how the calculations of PART A
and B will be evaluated. You must submit it through blackboard.
TOTAL MARKS: 32. Value for the term: 15%. Due Monday Feb. 22nd at 5 pm
Table 1: Precipitation data for the 60 day long study period. Also available as an excel chart.
Day Precipitation (mm day-1) Day Precipitation (mm day-1) 1 0 31 0 2 0 32 0 3 5.0 33 0 4 0 34 0 5 0 35 0 6 3.0 36 0 7 15.0 37 0 8 0 38 64.0 9 0 39 15.0 10 0 40 0 11 0 41 0 12 0 42 0 13 0 43 0 14 2.0 44 0 15 10.0 45 0 16 0 46 0 17 0 47 0 18 0 48 0 19 0 49 0 20 0 50 0 21 0 51 0 22 0 52 12.0 23 0 53 3.0 24 0 54 0 25 0 55 0 26 0 56 0 27 0 57 0 28 0 58 1.0 29 0 59 3.0 30 0 60 2.0
Assignment Writing Help
Engineering Assignment Services
Do My Assignment Help
Write My Essay Services