Contour bunding or contour farming is sustainable land management practice of planting or farming across a slope. The following are measures adopted for controlling waterlogging are ?
? Canal lining
? Crop rotation and optimum use of water
? Provision of intercepting drains
? Reducing intensity of irrigation
? Improving natural drainage system and providing an efficient drainage system.

Solonetz soil is anor name for sodic soil or alkali soil or black alkali soil. These are formed by excess accumulation of alkalies such as Na, K, etc. Such soils have low salt content but high Exchangeable sodium.

The shallow surface drains are in turn connected to outlet drains, which are large enough to carry maximum flood water of catchment area from shallow drains, and even from underground tile drains.

Surface drains are needed for crops cultivated on flat lands to remove excess irrigation water, whereas subsurface drains are needed for soils having poor internal drainage and high water table. So, refore for maximum productivity of crops both surface and subsurface drains are sometimes essential especially in regions of high water table.

The salt concentration in water extracted from a saturated soil defines salinity of soil.

When a canal is unlined n re room for seepage losses through side slopes, and bed of canal. This leads to rise of water table in adjoining areas due to percolation of water, which ultimately leads to waterlogging.

The normal cultivation operations such as tilling, ploughing is difficult in wet soils. The cultivation operation becomes impossible if free water may rise above surface of land in extreme cases. Such land is called swampy land.

Since shallow surface drains are designed to carry normal storm water and excess irrigation water. These are designed for normal runoff from storm water, but we have to take excess irrigation into account. So, for maximum discharge shallow surface drains are given a trapezoidal cross sectional shape.

Volume of water passing drain in one day = (1/100 x 12 x 10⁴) = 1200 m³/day
Volume of water passing drain in one second = (1200/24 x 3600) = 1/72 m³/sec
Q = 1/72 m³/sec
Q = 1/n x A x R^2/3 x S^1/2
A = ?D²/4, P = ?D, R = A/P = D/4
1/72 = (1/0.015) x (?D²/4) x (D/4) x (0.5/100)
On solving value of D = 17.4 cm
Use D = 20 cm.

If a particular is continuously submerged under due to floods, this paves way for growth of water plants like weeds and grasses e.t.c. and obstructs natural surface drainage flow causing waterlogging.