सिंचाई, जल निकास एवं पंपिंग प्रणाली

Application of Pump Affinity Laws for Rotational Speed:

• Affinity Law Formulation: For a given centrifugal pump of fixed impeller diameter, developed head ($H$) is directly proportional to the square of rotational speed ($N$):
  $$\frac{H_2}{H_1} = \left(\frac{N_2}{N_1}\right)^2$$
• Given Parameters:
• $N_1 = 1,500\text{ RPM}$
• $H_1 = 10\text{ m}$
• $N_2 = 1,650\text{ RPM}$
• Computation:
  $$\frac{N_2}{N_1} = \frac{1,650}{1,500} = 1.1$$
  $$H_2 = H_1 \times (1.1)^2 = 10 \times 1.21 = 12.1\text{ m}$$

Direct Rotary Well Drilling and Drilling Fluid Functionality:

• Direct Mud Rotary Drilling: In conventional hydraulic direct rotary drilling, a viscous colloidal slurry of bentonite clay and water ('drilling mud') is pumped continuously down through the rotating drill pipe and extruded through nozzles in the bit.
• Mud Functions: The drilling mud cools and lubricates the bit, carries cuttings upward through the annular space to the surface settling pit, and forms an impermeable mud cake along the borehole wall to prevent hole collapse without requiring casing during drilling.

Well Spacing and Well Interference Principles:

• Statement (I) is True: In production irrigation wells, well interference causes overlapping cones of depression, mutually increasing pumping drawdown, raising dynamic head, consuming extra electrical energy, and reducing discharge per well. Hence, irrigation wells are spaced at least twice their radius of influence ($S \ge 2R$) to prevent mutual interference.
• Statement (II) is True: For vertical drainage wells (skimming or dewatering tubewells deployed to combat waterlogging and lower a shallow water table), deliberate overlapping interference between cones of depression is required to pull down the water table continuously across the entire intermediate area without leaving high water table ridges between wells.