Soil And Water Conservation

Step 1: Understand the purpose and components of terrace design.
Terracing is an engineering practice to control runoff and erosion on sloping land. A complete design must consider all aspects of the structure's geometry, location, and hydraulic function.
Step 2: Evaluate each component listed.
- A. Proper spacing of terraces: The vertical and horizontal spacing between terraces is critical. It determines how much area each terrace must handle and is calculated based on soil type, slope, and rainfall.
- B. Location of terrace: The placement of terraces on the landscape, often starting from a key contour or ridge line, is a fundamental part of the layout and design process.
- C. Design of channel with adequate capacity: Each terrace includes a channel to convey the collected runoff. This channel must be designed with the correct grade and cross-section to handle the peak runoff from its contributing area without overtopping or causing erosion.
- D. Development of farmable cross section: The terrace bund and channel must be shaped in a way that is stable and allows for farming operations to be carried out efficiently and safely.
Step 3: Conclude the correct combination.
All four elements are essential components of a comprehensive and functional terrace design.

Step 1: Analyze and match the terms based on standard wind erosion principles. The terminology in LIST I is non-standard, requiring interpretation.
- A. Wind break: This is a row of trees or shrubs planted to reduce wind speed and control wind erosion. It is a IV. Vegetative barrier for wind erosion. (A IV)
- C. Coarse soil particles: The largest particles moved by wind are rolled or pushed along the surface. This process is called I. Surface creep movement. (C I)
- B. Boraxing soil particles: "Boraxing" is not a standard term. It might be a severe typo. If it refers to very fine dust particles that are lifted high into the air, this would correspond to II. Suspension movement. (B II)
- D. Floating soil particles: This likely refers to particles that are lifted and bounce along the surface, which is the definition of III. Saltation movement. (D III)
Step 2: Compile the interpreted pairings.
The logical pairings based on this interpretation would be A-IV, B-II, C-I, D-III. This combination matches option (D). While the terms "Boraxing" and "Floating" are unusual, this matching provides the most physically coherent explanation for the wind erosion processes described.

Step 1: Visualize the geometry of the bench terrace.
A bench terrace replaces a steep slope with a series of flat steps (the terrace) and steep risers. The original land slope is the ratio of the total vertical drop to the total horizontal distance.
Let VI be the Vertical Interval (height of the riser) and W be the width of the flat terrace.
Step 2: Relate the components to the original land slope.
- The vertical drop for one terrace unit is VI.
- The horizontal distance for one unit consists of the terrace width (W) and the horizontal base of the riser.
- Since the riser slope is 1:1 (vertical:horizontal), its horizontal base is also equal to VI.
- Total horizontal distance per unit = W + VI.
Step 3: Set up the slope equation and solve for VI.
The original land slope is given as 25%, which means a slope of 0.25. Substitute the given terrace width, m: