Forum Pakistan

(From the Sanskrit, 'Sindhu' - 'river', called by other geographers Sinthos, in Pushtu, Abba-Sin- 'The father of rivers', Darya- 'river' -the local name within Sindh province) The Indus is one of the biggest rivers in Asia, with a length of 2,900 km. and a basin of some 960,000 sq. km. The mean discharge of water at Hyderabad is 33,850 cu.metres per sec. The Indus has its source in China, on the slope of the Kailas Range in the Tibetan Plateau, at an altitude of 5,300 metres above sea level. The upper reaches lie mainly in *Kashmir, the middle and lower reaches in the *Punjab and *Sindh. The river flows into the Arabian Sea, forming a delta of 8,000 sq.krn. The chief tributary, flowing into the Indus from the north east, is the Panjnad, formed by the confluence of the Punjab's five rivers the *Jhelum, *Chenab, *Ravi, *Beas, and *Sutlej. Other major tributaries are the Shinghar, *Gilgit, and Kabul from the north west. In its upper third, the Indus flows almost due north-west along the bottom of a deep tectonic valley between the *Himalayas and the *Karakoram Ranges. Below the confluence with the Gilgit the Indus rushes through a number of narrow mountain gorges. It then turns to the south-east at Jalkot. Near Abbottabad the gigantic Tarbela Dam makes use of the flow to provide hydro-power. At the western extremity of the Salt Range (33°N. lat.), the river enters the Indo-Gangetic Plain. This sector of the Indus lies at the western border of the Himalaya. From its source to the plain has descended from a height of 5,100 metres the river.

About 28 per cent of the river's drainage basin, or 270,000 sq. km to below 200m above sea level is in mountainous regions above the town of Attock. No other river on the subcontinent has such a vast drainage area in the mountains. In the upper and middle reaches there are many rapids, and in the stretches where the river is squeezed into a sequence of narrow gorges 20 to 50 metres wide, the velocity of the stream rises. Navigation here is not possible.

The speed of the current falls sharply in the lowlands, where the river spreads to 1-6 km. wide. In the lowlands the slow flowing Indus divides into braided channels. At Attock 1,600kIn from the sea, its width is 100-375 metres, its depth is 14-40 metres and the velocity of the current is 9.20 km per hr. Above the confluence with the Panjnad the river is 500 metres
wide and 4 metres deep and the velocity of the current is 8 krn. per hr. Downstream the width increases to 1-2 krn. reaching, at times of maximum water, a width of 5.7 krn. Near the town of Dera Ismail Khan the river can be 20-22 krn. wide.
In its lower reaches the Indus flows along the western borders of the sand deserts *Thal and *Thar. Here the river meanders and often changes its course. There are numerous sandbanks, islands, and old abandoned river beds. Near Thatta where the delta reaches the ocean, the river divides into several channels.

In its upper course the Indus is mainly fed glaciers, in the middle course by underground waters, and in the plain by rainfall. Floods occur mainly in the summer or monsoon season. On average about 68 per cent of the discharge falls in the three months of the rainy season July to September. The total volume of the discharge in the ba in is 220 cu.km., of which only 94 cu.krn, reaches the mouth of the river. In drought years the water of the Indus may not reach the ocean at all. This is partly accounted for by high evaporation, the losses from which, during flooding alone, sometimes reach 28 cu.km, However, the main reason is the large consumption of water for irrigation, which amounts to 70 per cent of the discharge. In this, as well as in the size of the irrigated areas, which are more than 12 million hectares, the Indus tops the list of the world's rivers. The sediments carried by the river amount to 450 million tons a year. The *Indus Valley is one of the most ancient centres of agriculture. In recent years the intensive development of irrigated farming in the plains sector of the river has caused water logging which has led to salinity of the irrigated fields and rendered them unusable.