Irrigation, Drainage & Pumping Systems

Hydraulics of Soil and Water Conservation Structures:

• Statement (A) is Correct: Underestimating peak design discharge or inadequate spillway capacity leads to overtopping and piping, the primary modes of structural failure.
• Statement (B) is False: Open channel flows and hydraulic spillways have free surfaces dominated by gravity forces; therefore, their hydraulic similitude and scale modeling are governed by the FROUDE NUMBER, not the Reynolds number.
• Statement (C) is Correct: According to open channel specific energy theory, for a given discharge and specific energy head $E$, there exist two possible alternate depths of flow (one subcritical and one supercritical).
• Statement (D) is Correct: Siltation at the downstream apron or exit channel raises tailwater levels, creates backwater, and reduces effective head and discharge capacity.

Mechanization of Contour Bund Construction:

• Buck-Scraper Functionality: A buck-scraper is an animal-drawn or tractor-mounted earthmoving implement designed specifically for excavating, carrying, and dumping soil over short hauls ($15 - 50\text{ m}$). It shapes trapezoidal contour bund embankments with maximum soil moving efficiency compared to ordinary plows or ditchers.
• Other Implements:
• V-ditcher: Used primarily for cutting shallow drainage and irrigation ditches.
• frame ridger: Used for laying out field ridges and checks.
• Mouldboard plough: Used for primary tillage and inversion.