Solution of Laplacian equation in three dimensions $$\frac{{{{\text{d}}^2}\varphi }}{{{\text{d}}{{\text{x}}^2}}} + \frac{{{{\text{d}}^2}\varphi }}{{{\text{d}}{{\text{y}}^2}}} + \frac{{{{\text{d}}^2}\varphi }}{{{\text{d}}{{\text{z}}^2}}} = 0$$     of water in a syphon, is done by

A. Protection of banks erosion by the waves B. Control of seepage losses C. Strengthening of banks D. All the above

A. Drains B. Inundation canals C. Valley canals D. Contour canals

A. low head scheme B. medium head scheme C. high head scheme D. none of the above

A. Low sodium water B. Medium sodium water C. High sodium water D. Very high sodium water