Arid Land Development and Combating Desertification in Pakistan - Combating Desertification in Asia, Africa and the Middle East - page 227

However, due to heavy soil erosion, caused by deforestation in the catchments,
these reservoirs are silting up, thus reducing the capacity of power generation and
availability of irrigation water. Barani lands are subjected to heavy soil erosion,
primarily due to improper land use by crop cultivation, livestock grazing and
illegal removal of vegetation cover. Deserts have acute problems of shifting sand
dunes and salinity. The irrigated areas are infested with the twin-menace of water
logging and salinity. Because of mismanagement of Suleiman Rod Kohi areas, there
is substantial damage to crops and property by flash floods. Underground water
resources in western dry mountains of Balochistan are shrinking, due to very little
recharge, overexploitation of the meager quantity of water for horticulture and crop
cultivation. The productivity of rangelands is hampered by heavy livestock pressure.
The arid coastal strips and mangrove areas are under increased environmental stress
from reduced fresh water flows, sewage and industrial pollution and overexploita-
tion of other natural resources.

2.2 Key Issues Related to Desertification

• Wa t e r e ro s i o n
•Windero ion
• Depletion of soil fertility

• Deforestation

• Livestock Grazing Pressure

• Loss of Biodiversity

• Water logging and Salinity

• Drought and Flooding

• Socio-economic constraints

2.3 Extent of Desertification

According to Shah and Arshad ( 2006 ) the nature, geographic extent and severity
of desertification is reaching alarming proportions. The extent of area affected by
salinity and sodicity is presented in Table 12.6 . In the majority of the soils on the
plains in Pakistan, the rainfall is usually low and the evapotranspiration is higher
than the annual precipitation resulting in build up of salts in the soil profile and their
accumulation on the soil surface. At country level, 6.28 million ha of area is affected
with salinity and sodicity. The majority of salt-affected soils are saline-sodic in
nature. These salt affected soils are causing potential reduction in yield. Salinity
and sodicity are associated with irrigation but these also occur as a consequence of
soil formation process over the centuries. At present over 2.8 million ha are affected
by salinity/sodicity in Pakistan. Water logging, salinity and sodicity have reduced
the drainage capacity of the soils resulting in lower soil fertility, decline in crop
yields and loss of biodiversity.