One of the chief Rigvedic Rivers, as per the Hindu scripts and texts, Saraswati River is also famously known as Ghaggar-Hakra River.In the early Rigvedic ‘Nadistuti’ hymn Saraswati River is mentioned between the east of Yamuna and west of Sutlej . But later in the other Vedic scriptures like Tandya and Jaiminiya Brahmanas as well as the Mahabharata it is mentioned that the Saraswati River dried up in a desert. This river is a trans-boundary between the two neighbouring countries India and Pakistan . Also this river flows through both the nations together only in the monsoon.
In the area prior to the Ottu barrage, the Saraswati River is anciently known as the Ghaggar and where it crosses this barrage it becomes Hakra. The Ghaggar river acts as a tans-boundary river to India in the monsoon weather whereas the Hakra, which is an extension of Ghaggar in India becomes the dehydrated canal in Pakistan. The Ghaggar originates from the Shivalik Mountains of the Himachal Pradesh and runs through the states of Punjab,Haryana and even flows through some parts of Rajasthan. Two irrigation channels are supplied by this river in Rajasthan.
The dehydration of this river is caused by detention of the tributaries by the Yamuna River and Indus River System . Also the cutting down of trees: Deforestation and overgrazing are the other reasons of the dehydration of the river later and the desiccation in most of its drainage basin. Though originally all these events took place much before than 1900 BCE, it is believed by some historians, researchers and environmentalists that all this might have taken place in the 1900 BCE itself.
It is believed that about some 10,000 years ago, during the liquefaction of the Ice Age glaciers in the Himalayan Mountain Ranges, the Ghaggar River was flowing in full strength, which can be understood by the broad palaeo-channel of this river. Also it is seen that it gradually joined the currently waterless canal of the Hakra River, which led to the river pouring into the Rann of Kutch.
In the year 1998 debates regarding the contemporary Tons River which was earlier the upper portion of the Saraswati River, had taken place. It is said that the Tons River was supplied by the glaciers in the Himalayas and formed the major upper part of the Saraswati River. This River features some of the stones of quartzite and metamorphous stones at is plateau, but the lower terraces of these basins do not seem to have such type of stones.
Also there have been surveys which show that this river has been a part of several important dynasties and also it is demonstrated that Bronze Age deposits coming from the Himalayan glaciers are not to be found beside the Ghaggar-Hakra. Hence it may be concluded as per these surveys that the Saraswati River did not originate from these towering mountains.
Reference:Maps of India