Water Logging and Salinity

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WATER LOGGING AND SALINITY

Naheed Ghazanfar
Izhar & Associates Consulting

5.1CLASSIFICATION OF WATER LOGGED AND SALINE AREAS BY DEGREE

The existing irrigation system in Khyber Pakhtunkhwa was developed in late 1800s over a century ago. This system was designed for the farming at that time which was much lower than the cropping intensities of today. This system had limited provision for drainage, resulting in a rise in groundwater and the occurrence of salinity. |Table 5.1 | |Area Irrigated by Canals and Tube Wells | |Canal name |Area Hectares |% Total | |Kabul River System | |Kurvi Branch |5,472 |19 | |Wazir Garhi |2,160 |7 | |Pabbi Minor |2,234 |8 | |Kabal River Canal |7,229 |25 | |Total - A |17,095 |59 | |Warsak Gravity Canal | |Warsak Gravity Canal |11,188 |38 | |Pabbi Minor |909 |3 | |Total - B |12,097 |41 | |Tube Wells** |137 |  | |Note: The capacity of TWs varies 1/4 to 1/2 cusecs | |Source Khyber Pakhtunkhwa Statistics 2010 |

Water logging and salinity problems have resulted from arid climate, topography, seepage from unlined canals, poor water management, inadequate drainage, insufficient irrigation supplies and use of poor quality drainage water. Areas with water table depths that vary in different periods; from 1978 to 1998 areas with depth less than 1.5 m ranged from 9.0 percent to 18.3 percent, with similar variations observed in water tables from 1.5 m to 3.0 m and greater than 3.0 m. ( refer Map) Salinity is generally most pronounced in Nowshera District, along River Kabul and the vicinity of river Indus. This problem is often characterized by high salt content in the root inhabited layers. Some of these salts adversely affect the growth of crops and may considerably reduce the final produce. In some cases, they may even prevent germination of seeds. The osmotic or total salt effect influences the ability of plants to absorb water from the soil solution for their growth. Ionic toxicities affect various plant physiological processes; in addition excess exchangeable sodium results in soil swelling and/or dispersion causing water infiltration, aeration and root proliferation a problem.  In the early 1960s, a massive effort to control water logging and salinity was undertaken. By June 1995, surface and subsurface drainage facilities had been completed in an area of 6.02 million ha at a cost of PRs25 billion. Projects costing PRs42 billion in an area of 2.96 million ha are under construction. Drainage facilities installed up to June 1995 for controlling water logging and salinity included surface drainage and subsurface tubewell and pipe systems. Peshawar[1] Salinity Control and Reclamation Project (SCARP) (Cr 877-PAX) aimed mainly at control of water logging and salinity, increasing water availability in the irrigation system (123,600 acres of CCA), conserving and maximizing use of the available water resources through remodeling the existing irrigation system, surface drains and laying of sub-surface (tile) drains in the area.

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5.1.1 Nowshera District
The Nowshera District has an area of 169,479 hectares of which about 37 % (61,000) is not available for cultivation; while 52,536 hectares is brought under cultivation. Only 50 % ; i.e., 24900 hectare of the cultivated area is...
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