The northwestern slopes of the Aravalli Range are influenced by the blown sands of the Thar desert, which has almost choked the drainage channels. Only seasonal streams feed the drainage of the Luni river. The Luni has several tributaries- mostly seasonal. The main tributaries are the Lilri, Rajpur, Guhiya, Bandi, Sukri, Jawai and Jojri. In the northern portion of Rajasthan are the shallow beds of the now mostly seasonal rivers Ghaggar (Identified by some as a remnant of the ancient Saraswati river), and its tributary Chautang (possibly ancient Drishadvati).
The hydrography of the southeastern slopes is better defined. The hills have protected this region from the desert sands, and the Banas and Sabarmati flow in opposite directions with numerous perennial effluents. In the case of the Chambal-Banas system, the Chambal and Banas bear signs of super-imposed drainage following a Mesozoic upwarping of the Range and the Deccan Trap activity respectively. These structural relations have influenced the past hydrography of the Aravalli and its neighborhood, though the present drainage pattern is said to be devoid of any geologic control. All the major streams have base-levelled their courses and their curve of erosion is free from irregularities.
The river Chambal, identified with the Charmanvati of Sanskrit literature, rises near Mhow, in Madhya Pradesh, and enters Rajasthan about 200 miles (320 km) from its source. Thereafter, it breaks through the Aravalli plateau and continues to flow northeastwards. Near the city of Kota, the Chambal is a broad sluggish stream, flowing between overhanging cliffs and rocks. These until recently, were covered with thick brush –wood and forests. The Chambal joins the river Yamuna (also Jamuna), 25 miles (40 Km) south-west of Etawah in Uttar Pradesh. Its tributaries include the Kali Sindh, Parvati, Chhoti Kali Sindh and the Banas.
The Banas rises from the Aravalli range, about five kilometres from Kumbhalgarh, and joins the Chambal at Rameshwar, a sacred site in Madhya Pradesh, near Sawai Madhopur, after flowing about 500 kms through Udaipur, Bhilwara, Tonk and Sawai Madhopur districts of Rajasthan. The Berach and Kothari rivers join the Banas near Mandalgarh. The Khari meets the Banas near Deoli. The Banas flows southwards in its initial course, till it meets the Gogunda plateau. It then turns eastwards and enters the plain near Nathdwara. Continuing east-nor’eastwards, it approaches the hills near Mandalgarh, where the tributaries, Berach and Kothari join it. The Banas then flows in northerly direction towards Tonk, before turning to the east and joining the Chambal.
Its tributary, the Berach, rises in the hills north of Udaipur, where it is known as the Ahar river in its initial course. (The Ahar river bears the same name as a village called Ahar- which was once known as Aghatpur, and was an early capital of Mewar. It has lent its name to the copper using c. third-second millennia BC Ahar Culture, described in the next chapter). From Udaipur, the Berach takes an easterly course, turning northeastwards near Chittorgarh, to eventually join the Banas west of Mandalgarh, after a course of almost 200 kms. The valleys of the Berach river are frequently deep and narrow. Most (though not all), of its course is perennial. The three main tributaries of the Berach are the Wagli, Wagan and Gambhiri. These tributaries all flow south to north and parallel to each other.
The other two major tributaries of the Banas are the Kothari and Khari. The Kothari rises from the Aravallis near Dewair and flows east for 145 kms before joining the Banas a few kilometers north of its confluence with the Berach. The Khari rises in the hills north of Deogarh. It flows in a northeasterly direction, initially, and then flows east, joining the Banas near Deoli. The Khari has a sandy bed and is dry for the major part of the year. The Dai, Sodra and Mashi are other tributaries that rise from the northern part of the Aravalli hills and flow eastwards to meet the Banas.
The main river of the Dungarpur-Banswara region (called ‘Vagar’), in the extreme south, is the Mahi, with its main tributaries the Som, and Jakam. Smaller seasonal river and rivulets which flow through the area now covered by the modern district of Dungarpur include the Majhan, Vatrak, Bhader, Gangali, Sapan and Veri Ganga. In the eastern part of this ‘Vagar’ area, comprising the erstwhile state, and now district, Banswara it is the Anas, Kagdi and Nal tributaries which are important.