Technical Definitions of Irrigation, Drainage, Leaching & Water Management

Definitions of Irrigation and its vital Components.

No water resources development organizations in the country know the correct technical definitions of Irrigation, Drainage, leaching, and Water Management. This ignorance has become the source of wrong planning and execution of mega projects that resulted in failure and waste of billions of dollars like WAPDA projects of SCARP’s, N.D.P. Kachi Canal, Water Management, drainage, and storage projects. I therefore give their technical definitions to avoid failure of projects. All projects should be planned according to their technical definitions.

Definition of Irrigation

"It is defined to include irrigation, drainage and flood control all of which relate to the moisture control of crops in the field".

Definition of Drainage.

Drainage is the essential part of irrigation works, collecting the water that leached the salts out of soil and evacuating it outside the area, as well as separating the "reclaimed layer" from the sub-soil to avoid raising the water table with the resultant retrogression. Drainage prevents a rise in water, keeping the later at a depth that will not harm root development and maintain salt and water balance". Soluble salts can only be removed out of the area if sub-surface horizontal tile is provided and not the Tube wells. WAPDA provided vertical tube wells that pump injurious drainage effluent and is used as irrigation water that destroys land invisibly and gradually. A tube well cannot remove salinity and sodicity from the soil.

Note: -SCARPs and NDP were not designed to provide sub-surface tile drainage as per its definition. Therefore, they failed.

Definition of Leaching.

"Leaching is the process of dissolving and transporting soluble salts by downward movement of water through the soil".

Note: - {Definitions of Drainage and leaching clearly indicate to provide surface and sub­surface tile drainage to carry away the dissolved drainage effluent out of the area to protect root development. SCARPs and NDP have no such sub-surface drainage component: therefore they are complete failure}

Definition of Integrated Comprehensive Water Management (ICWM).

"Water Management is defined as the combined processes of storage, diversion, conveyance, regulation, measurement, distribution and application of the rational amount of water at proper time and removal of excess water from the farms to promote increased production economically, in conjunction with improvement of agricultural practice and institutional arrangement".

Note: - The definition of ICWM clearly shows that it is the integrated process of all of its components to avoid all wastage of water as well as to physically remove excess salts and water by drainage of the root zone of crops out of the area and adopt water efficient agricultural practices.