The Punjab plain comprises mainly the province of Punjab. It is the gift of River Indus and its five eastern tributaries- Jhelum, Chenab, Ravi, Sutlej and Beas. The plain spreads from the south of Potohar plateau up to Mithankot, where Sulaiman Range approaches river Indus. The Punjab plain is almost a featureless plain with a gentle slope southward averaging one foot to the mile. The only break in the alluvial monotony is the little group of broken hills(100 ft-1,600ft.) near Sangla and Irana on either side of the Chenab. The entire plain is extensively irrigated by a network of canals. This system has been greatly expanded and improved in recent years by the construction of link-canals, dams and barrages as a result of the Indus Water Treaty with India, which awarded the three western rivers (Indus, Jhelum and Chenab) to pakistan, and the three eastern rivers (Ravi,Sutlej and Beas) to India. Tarbela Dam on river Indus and Mangla Dam on River Jhelum, which have water storage capacities of 11.1 million acre ft. and 5.55 million acre ft. respectively, need a special mention. Irrigation water is supplemented by summer and winter rains(15-20 inches) so that a variety of crops is raised, the major onces being wheat, rice, cotton and sugarcane. The region has earned the name of granary of Pakistan. However, the blessings of canal irrigation have not been without a curse, which render about 100,000 acres of land unproductive every year through waterlogging and salinity. The menace has been greatly controlled through salinity control and reclamation projects. Agricultural development boosted urbanization and industrialization so that the region has emerged as the most important economically developed area of Pakistan, containing over 56 per cent of the population and most of the commercial and industrial centres of the country, such as Lahore (2,922,000), Faisalabad (1,092.000). Multan (730,000), Gujranwala (596,000), Sialkot (297,000) and Gujrat (154,000).
The south eastern section of the region known as cholistan is under-developed. This tract is parched and thirsty. The summer temperature average 51.7 oC and the area remains under the grip of extremely hot winds. The surface of this desert consists of a succession of sand dunes rising in places to a height of 500 ft. with vegetation peculiar to sandy tracts. There is no soil down to the lowest depth except sand; bitter water is, however, sometimes found at depth of about 80-100 ft.
The Potohar Upland, commonly called the Potohar Plateau, lies to the south of northern mountains and is flanked in the west by River Indus and in the east by River Jhelum. This 1,000-2,000 ft.(305-610 m) upland is a typical arid landscape with denuded and broken terrain characterised by undulations and irregularities. These are a few outlying spurs of Salt Range in the south, and those of Khair Murad and Kala Chitta Range in the north. Two seasonal streams-Rivers Haro and River Soan-flow from east to the west and after crossing the region in the north and in the middle respectively, fall in the Indus. River Kanshi traverses the eastern part of the plateau from north to south and drains into River Jhelum. These rivers and other hill torrents have cut deep valleys and are of little use for irrigation. Agriculture is thus almost entirely dependent on rainfall of 15-20 inches and on the small dams built in the catchment areas of the streams.
Fields of wheat, barley, jowar, bajra and pulses are found in valley bottoms and on the terraced slopes along river banks. A new economic factor has been introduced by the establishment of a few factories in Rawalpindi and Islamabad and a large industrial area in the Taxila-Wah-Hassanabdal triangle,where a large cement factory was already in existence. The region is particulary known for its oilfields in Khaur-Dhulian neighbourhood, the ancient civilization sites in Soan valley, the ruins and the Buddhist University at Taxila and the new capital, Islamabad, which stands north of the old city of Rawalpindi(806,000) at the southern slops of Murree hills, the popular Holiday resort of the country. Salt Range The ramparts of the Salt Range stretching from east to west in the south separate potohar upland from the Punjab plain. The average height of the Salt Range is about 700 metres, but near Sakesar in Sargodha district, it rises to 1,500 metres, making summer pleasant. The southern face is remarkably steep, dissected and intensely arid. But, the northern slope is gentle and has sparse vegetation of oleanders and wild olives. The top of the range is a narrow belt of isolated plateaus and basins, where, sparse stunted trees and fields of wheat and maize are found. However, the real importance of the salt mines lies in the large deposits of pure salt at Khewra and Kalabagh and the large seams of coal at Dandot and Makerwal. Punjab Plain