10.10: Questions
- Page ID
- 44628
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)1. What is the major factor that determines the effective depth of water applied in a surface irrigation system without runoff recovery? How can this factor be modified?
2. Graph an advance-recession curve that characterizes uniform water distribution. Explain each component and the required conditions.
3. Without making considerable alterations to a furrow irrigation system, what changes can a manager make to minimize runoff and deep percolation? How do these adjustments minimize water losses?
4. Graph and compare advance-recession curves for surface irrigation on a fine-textured soil and a coarse-textured soil. Explain the difference expected.
5. Given a furrow irrigated field with a medium textured soil and data below, determine: dg, dz, dLQ, dr, percent runoff, DU, and ELQ. Assume that the advance and recession curves given in Figure 10.7 and the data in Table 10.1 apply to this problem.
Q = 900 gpm N = 40 watered furrows, every other furrow watered
L = 1,200 ft Furrow spacing = 30 in
Tco = 12 h SWD = 4.0 in
You’ll need to use Tables 10.3 and 10.4 for this problem.
6. If the slope in Question 5 is 0.3%, is maximum non-erosive stream-size being exceeded?
7. What would the ELQ be for the conditions of Question 5 if a closed reuse system were installed and Rt = 0.85?
8. a. For the medium textured soil used in Question 5, determine the desired cutoff ratio to achieve maximum efficiency with a closed runoff recovery system (use Figure 10.15).
b. How many gates should be opened to achieve the cutoff ratio given in 8.a.?
c. Is the maximum non-erosive stream-size being exceeded?
d. What is the theoretical maximum efficiency for the advance time in Question 8.a. without a 1-hour recession? Assume Rt = 0.85 and loam soil (use Figure 10.15).
9. Discuss the differences in efficiency between Questions 7 & 8.
10. Does the dLQ exceed SWD in any cases given in Questions 7 or 8?
11. A farmer is making a conversion from continuous flow furrow irrigation to surge flow. Your job is to determine how to set the controller and estimate the savings in water due to surging. The following conditions apply:
Q = 800 gpm ET = 0.25 in/d
Row length = 1,200 ft Irrigation frequency = 6 d (assume SWD = ET × time interval between irrigations)
Row spacing = 30 in Net (effective) irrigation required per year = 10 in
Every other furrow is watered Field slope = 0.3%
Continuous flow: Surge flow:
Furrows per set = 45 Furrows watered per side of valve = 30
Set time (cutoff time) = 12 hr Set time = 6 hr on each side of valve (12 hr total for both sides)
Average depth infiltrated (dz) = 2.7 in Average depth infiltrated = 2.0 in
DU = 70% DU = 80%
Advance time = 9 hr Inflow time for advance = 4.5 hr
a. Determine the on-times for each surge cycle using 4 advance cycles and 2 cycles after advance is complete (post-advance).
b. Determine the gross depth applied and effective depth applied for each irrigation and for the year for both surge flow and continuous flow.
c. How much less water was applied by surging? Express your answer in inches/year and percent savings.
d. Determine the ELQ for the continuous flow and surge systems.