The drainage pattern and the trend lines of the ridges depend upon the structure of the underlying basaltic rocks of the district. These rocks interbedded with ash layers, have developed three sets of masterjoints, running approximately in directions north-south (strike direction), north-west, south-east, and north--north-east, south--south-west. The streams of the region have taken advantage of these planes of weakness in carving their valleys as is shown by the following features, streams generally run in one or other of these three sets of directions; the bends at the confluences of almost every rill with its main stream are generally rectangular; and the courses of most valleys are almost straight.

The district is drained by two chief rivers, the Girna and the Godavari, and their tributaries, the watershed between these being the Satmala range. Apart from these there are a number of small Konkan rivers draining westwards into the Arabian Sea.

Konkan rivers : Innumerable small streams flow down the western scarp of the Sahyadris draining towards the Arabian Sea.

Chondi : A small portion of the headwaters of the Chondi river rising on the scarp west of Hatgad and flowing into the Ambika river is included within the district limits.

Kavera : The Kavera rises near Pimpalsond and has a small course running north-westwards in Surgana before it joins the Kaveri outside the state.

Sasu : The Sasu or Tan river rises near Wangan in Surgana and flows in a north-westerly direction past Karanjale and Guhijambhulpada and then in a south-westerly direction to leave the district after running along the boundary for about a kilometer.

Man : The Man or Bamti river rises near Walutzira and flows west­wards and leaves the state about a kilometer and a half south-west of Umbarthana. In Gujarat state the Sasu and the Man unite to form the Auranga river.

Nar : The Nar river rises on the northern slopes of the Kem hill and has a long winding westerly course and flows below Waghdhond, Bhintghar, Umbharade and Waghadi and forms the district boundary between Madhuri and Karanjul Petare before leaving the state to join the Par outside.

Par : The Par rises on the southern slopes of the Kem hill to the east of Rokadpada (Rokri) and flows nearly due southwards for about 5 km. and then turning westwards has a long winding course throughout which it forms the boundary between Surgana on the north and Dindori and Peint on the south. Beyond this it forms the state boundary between its course a little above Bhati and Kahandulpada.

Barik : The Barik is a small river forming a tributary of the Par on the northern side taking its course in the Chowitta hill just north of Barhe. In the lower portion of its course up to its confluence with the Par it forms the state boundary. Besides Barik, the Par receives a number of small streams draining the northern part of Peint.

Damanganga: The Dawan river, known as the Damanganga in its upper course, rises near Mangone (Mangunpada) and flows southwards passing by Patali, Pawarpada, Usthala and turns westwards near Ekadare. From here it has a long winding, a deeply entrenched course to the west up to Borpada where it is joined by its tributary, the Gordi nadi. The latter rises west of Peint and after flowing a short distance westward turns southwards forming the state boundary to join the Dawan or the Daman­ganga. The principal river makes a slight bend into the district at Borpada so as to include the village of Khamshet on the right bank within the district and turns and runs westwards forming the state boundary for the rest of the course in the district leaving it to the north-west of the Deodongri village.

Val: The headwaters of the Val nadi rise on the northern slopes of Bhaskargad, Phani dongar, Harishgad and Brahma dongar (separated from the Kikvi of the Godavari system by the Brahma dongar and its northward continuation as an imperceptible water divide) and unite on the boundary of the district as the Val nadi. After a short sojourn outside the district, it re-enters the district about 2 km. south of Torangaon. Thereafter the district boundary closely approximates to the course of the river, the latter sometimes flowing a little outside and sometimes a little inside the district till it joins the Vag river. After this confluence the latter river forms the district boundary till it leaves the district west of Ozarkhed on its way to join the Damanganga river.

Vaitarna : The headstreams of the Vaitarna rise on the southern slopes of the Trimbak-Anjaneri range and combine into three southward flowing streams which unite to form the Vaitarna a little north of Dapure. The Vaitarna from here has a very winding course southwards and goes round Zarwad (Jarwar) Budruk. Due south of it, the river is joined by its tributary Alvand nadi, whose headstreams rise in the same Trimbak­ Anjaneri range on the southern slopes of the Bhaskargad, Phani dongar and Harish dongar, which form the divide between these and those of the Val river flowing northwards.

After the confluence with the Alvand river, the Vaitarna turns and flows nearly straight in a south-south-west direction cutting a deep gorge in the scarp of the Sahyadris. A small tributary from the north­west to south-east in a gorge continues the course of the Vaitarna in a remarkably deeply cut valley. A portion of this forms the district boun­dary till it is joined by the Bhima river (not the much larger river of the same name in Maharashtra), where the former leaves the district.

Bhima : The Bhima river rises in Tringalvadi hill to the north-west of Igatpuri and flows nearly due southwards as far as the railway line. Here it turns abruptly and flows north-westwards to join the Vaitarna, its lower course also serving as the district boundary. According to Prof. B. Arunachalam [op. cit. pp. 14-16. For a thorough discussion of the problem of river piracy here, vide the entire article pp. 9-24] the development of the source tributaries in a direction against the grain of the country in the Desh, the barbed wire pattern of the Vaitarna and Bhima nadi in the Desh together with the existence of elbow-like bends are all quite suggestive of river piracy, in the not too distant past by both the Vaitarna and its tributary, the Bhima nadi; traces of an older valley along the Alvand, and upper Vaitarna can also be recognised at eleva­tions of 1950-2050, as also erosional surfaces adjacent to both the streams. Corroborative evidence is also available in case of the beheaded source streams of the Darna river that has lost a considerable area of its drainage to the Vaitarna.

The Vaitarna, as well as its tributary the Bhima nadi, must have been originally, rising in the steep scarp slope of the Sahyadris, in the neighbourhood of the Thal pass.

Girna : The Girna rises just south of Cherai village at about 8 km. South-­west of Hatgad in the Sahyadris and flows nearly east along a wide bed, with high banks in some parts, but as a rule, low enough to admit of the use of water for irrigation. The stream of water during this portion of its course is comparatively small, and confined during eight months of the year to a narrow strip or sandy bed. Several dams have been built across the main stream, irrigating large areas of garden land. After its course through Kalwan, Satana and Malegaon talukas, it winds its way north­eastwards as it nears the Jalgaon frontier. The Girna in its upper course receives several rivers of nearly equal size as itself and equally useful for irrigation.

Tambdi : The first considerable stream that joins it, on the left or north bank, is the Tambdi, which similarly rises in the Sahyadris north of Hatgad and joins the Girna at Chandkapur. Just below the confluence a dam is constructed across the river. This storage has enabled the construction of a pick up weir near Thengode for diverting the water in a left bank canal to irrigate the lands on the north bank of the river as far as Ravalgaon.

Punand : The next tributary stream is the Punand rising in the range west of the Salher fort, has a fairly long southerly winding course nearly parallel to the Sahyadris before it turns and flows eastwards and south-east­wards to join the Girna at Bej. Its valley is deep and its banks steep and .rocky, and, along its channel, in the rainy season the water flows from the hills in considerable quantities and with great rapidity.

Aram : The Aram river rises just south of Salher fort and after a short southerly course flows eastwards and south-eastwards to join the Girna 5 km. below Thengode. The width of its main valley is considerable, the banks are low, and the land at the lower portion is particularly well suited to irrigated crops. The main stream is fed by almost innumerable tributaries, chiefly from the south. For example between the village of Dang Saundana and Satana, a distance of only 20 km. no fewer than fifty-seven feeders join it from the south alone.
From the northern side a little above Satana, it is joined by a few large streams such as the Hatni, itself with a large tributary stream of Kaner, and the Sukia. All these have deep beds and steep banks. The water supply is abundant in the larger streams, but the smaller are filled during the south-west monsoon only. The Aram joins the Girna about 5 km. east of Thengode.

Mosam : The headwaters of the next and northernmost tributary of the Girna rise in the Sahyadris south of Hanuman hill. The river runs east­wards past Mulher, Taharabad and Jaykheda. It is joined by a number of affluents especially from the northern side. Among the latter may be mentioned the Tungadi nala, Bhevri nala, the Alvali nala and the Vatoli nala, all draining the southern slopes of the Galna hills. The important among the south bank tributaries of the Mosam are the Kanjari nala joining at Askhede Nagar or nadi. Like the Aram, the Mosam has cut a wide valley which its waters suffice to irrigate plentifully, until the banks become too high to admit the use of the natural flow of the stream, which, in the dry weather, lies too far from them to allow the cultivators to rais by lifts, budkis. It joins the Girna about 3 km. below Malegaon.

The rest of the right or south bank tributaries of the Girna further up, those up to Malegaon are of small size but useful for irrigation. The chief of them are the Masa nadi joining the Girna just below Chandkapur, the Baindki and the Markandi draining the northern slopes of the Saptashring and Markinda hills respectively, uniting together under the name of the latter river to flow past Kalwan to join the Girna a kilometer to the north, the Khatki nala and the Kolthi nadi passing by Devla, the Kharf nadi, and the ParsuI. There are also a few minor tributary streams such as the Suki nala and the Gulandi nala.

The two easternmost tributaries of the Girna in the district, the Panjan and Maniad are much larger in size than others, but they flow in valleys which are deep and narrow arid the banks are so high that irrigation is not practicable. These characteristics are due to the fact that they are able to cut across the Satmala watershed so as to abstract some of the headwater streams draining the southern slopes. In fact this tendency is to be found even in the Parsul on a much lesser scale. These Girna tribu­taries are very active in their headward erosion because of the much lower base level of the Girna as compared with that of the Godavari.

Panjan : The panjan rises to the east of the Chandvad fort on the southern slopes of the Satmalas and after an initial southerly course, curves eastwards and then makes its way north-eastwards past Manmad by a gap cut through the
Satmalas. It drains parts of Chandvad, Malegaon and Nandgaon talukas before it joins the Girna at Panjan in the last mentioned taluka.

Maniad : The Maniad rises a little south-west of Rajapur south of the Satmala range as the Kher nala and after a short east-south-east course bounded by a ridge to the north of it, turns abruptly to a point little beyond the district, whereafter it turns abruptly northwards continuing the course of a tributary and re-enters the district. After cutting a passage in the hills near Manikpunj, it continues its northerly course and after receiving the Sakhi (Sakhambari) nala draining past Nandgaon, turns northwards to the boundary of the district. Then it forms the district boundary for some distance and then after a short course in Chalisgaon taluka of Jalgaon district joins the Girna at Saigaon in that taluka.

Bori : Here it may be mentioned that the Bori nadi, another indepen­dent tributary of the Tapi besides the Girna, rises a little above Mahad and Chirai on the southern slopes of the Galna hills and has a small course eastwards within the district. .

Godavari : The Godavari, or the Ganga as it is locally called, is the most celebrated river not only of this district, but of the whole of the peninsular India. The principal course lies just below the scarp of the western side of the Trimbak amphitheatre, where is a temple, reached by a flight of well built steps. A larger and more distant branch takes its rise in the ridge that joins the Trimbak and Brahma mountains in a region of higher rainfall owing to greater exposure to moisture bearing winds. But here there is no imposing natural formation to lend its aid in supporting the divine origin of the stream, so this branch is neglected in favour of its smaller rival. After passing the town of Trimbak, the Godavari turns to the west, cutting a deep and rocky bed through the Ghat matha country. After about 15 km. it receives the abovementioned tributary, called the Kikvi, on the north.

Kashyapi : The Kashyapi (Kas) river rising a little above Wagira in the Sahyadris and augmented by the waters of the Wotki and the Muli, is the next stream to join the Godayari. Just at this confluence is constructed the Gangapur dam, whose storage backs up both the main river and its tributary, the Kashyapi. Five kilometers further to the east, at Jalalpur, the Godavari is met by the Alandi, a small stream flowing from the north. A few hundred metres below the meeting point, the Godavari dashes down in a narrow chasm in a bed of rocks, some 10 metres high, and owing to the narrowness of the passage and the height of the rocky walls, the fall is accompanied by a noise far above what would be expected from the average body of water that passes through. About 450 metres below the falls of Gangapur, the bed of the river is crossed by a remarka­bly well marked dyke of the kind usually found in trap formations. It has been worn down by the stream, but at each bank the broken edges are so clean cut as to give it the appearance of a wall built by a human agency; and this is, in fact, the character it bears among the neighbouring villagers. About 10 km. east of Gangapur the river passes the town of Nasik. Here it turns slightly southwards, and at the bend near the point of its entry into the town, a second ridge of rocks crosses the bed, causing a slight fall of about 2 metres. Numerous temples stud the banks, and the bed of the river is a succession of masonry pools used in ceremonial ablutions, and with a sort of quay on the right bank where the markets are usually held. About half a kilometer south, the river bends sharply to the east, washing the base of a high cliff formerly the site of a Moghal fort, but which is now being eaten away by the action of floods.

About 3 km. below Nasik, the Godavari receives the Nasardi on the right, a small but important stream rising 16 km. west of the town in the Anjaneri range. From this stream the chief water supply of Nasik is drawn, being conducted by a channel to a sort of basin in the town. Below this the main stream widens but rocks still obstruct its course. The banks continue high, but become more earthy as the river flows east. About 25 km. below Nasik is the confluence of the Godavari and one of its tributaries, the Darna. The stream occupies, for nine months in the year, a small space in a wide and gravelly bed, the greyish banks being four to six metres high, topped with a deep layer of black soil. A few kilometers after its meeting with the Darna, the Godavari swerves to the north-east, till the Banganga, from the north-west, meets it on the left. The course of the main stream then tends more decidedly south. At Nandur-Madhmeshwar, the Kadva, a second large affluent, brings considerable increase to the waters of the Godavari. Taking advantage of this as well as of the Lake Beale storage on the Darna, a dam has been constructed here with left and right bank canals which irrigate lands in Nasik and Niphad talukas and also the Kopargaon taluka in Ahmadnagar district. After a course from Trimbak of about 100 km. the Godavari leaves Nasik for Ahmadnagar district.

Darna : The Darna rises on the northern slopes of the Kulang hill fort in the Sahyadris about 13 km. south-east of Igatpuri. Though the straight line distance from the source to its confluence with the Darna is only about 50 km., it has a very long and winding course as much and half again of that distance. Its banks are like those of the Godavari below Nasik, of no great height, but broken by scores of small streams, making the pas­sage along the banks of the river very difficult for laden carts. It is crossed by a bridge at Chehedi on the Nasik-Poona road, on the way to Sinnar. The bed is for the most part wide and sandy, though at times, the water flows over rocks. A dam is constructed across the Darna near Nandgaon village giving rise to the storage known as Lake Beale, which is visible for considerable distance while travelling by train from Bombay to Nasik on the right hand side. This has enabled the construction of a pick-up weir on the Godavari river at Nandur-Madhmeshwar to divert the water into the Godavari canals.

On the right bank, at Belu, the river Darna receives the Kadva, not the large river of that name, but a small stream flowing north-eastwards between Mhordan-Katlia hills on the west and Kalsubai-Bitangad-Patta range on the east in the south-eastern part of Igatpuri taluka. On the left bank the Darna has only three tributaries of any size, and they hold little water during the hot season. They are the Waki, the Unduhol and the Valdevi.

Vaki : The Vaki nadi rises in the Dhoria hill and flows in a general southerly direction and passing between Igatpuri and Ghoti joins the Darna. A little below this confluence on the opposite side, another small tributary draining from the south joins the Darna taking advantage of the continuing structural line of weakness.

Unduhol : The Unduhol nadi rises to the south of Anjaneri hill and flows in a south-easterly course and turns in a northerly direction to the north of Kavnai hill and has a very long winding course trending to the east before it joins the Darna below the Darna dam.

Valdevi : The Valdevi river rises on the eastern slopes of the Anjaneri hill and flows in a general easterly direction passing by Ambe Bahula and Deolali and joins the Darna near Chehedi.

Dev : The Dev nala rises on the scarp slope connecting the hills of Aundha and Patta forts and drains the Sinnar plateau running in a general north-easterly direction. After passing a little to the south of Sinnar it runs nearly due east till it is joined by a tributary, the Bhokhan nadi flowing from the south to the north at Dharangaon, where it turns northwards to continue the course of the tributary. Devpur, from which the river derives its name, is located on the eastern bank about a kilometer below the confluence. On nearing the Godavari river it turns north-eastwards and then eastwards to join it opposite to Kolgaon. On account of its long course and a sizable area drained by it, deltaic deposition has resulted where it empties in the Godavari thus broadening the main river which here flows in braided channels between two or three islands.

Jham : The Jham river, the easternmost tributary of the Godavari on the south bank, flows nearly-parallel to the Bhokhan nadi and joins the main river outside the district.

Banganga : Among the north bank tributaries, the Banganga rises a little to the north-west of Ramsej hill and flows in a general easterly course passing by Ozar where a dam crosses it to divert the water into canals on both sides for irrigation. After passing Sukene it joins the Godavari.

Kadva : The Kadva rises in the Sahyadris to the north-west of Dindori in the angle between the former and the Satmala range, and crosses Dindori from north-west to south-east. It is rocky both in bed and bank, but the bed is wide, and the average volume of water is small compared with the area through which it flows. Irrigation works of considerable importance have been established on it.

The Kadva is joined by several tributary streams mostly from the north or the left bank. The chief of those joining on the right bank is the Kolwan rising in the Sahyadris to the south of that river. At Waghad it is crossed by a dam giving rise to the Waghad tank used for irrigation. Further below it is joined by the Dhaman nadi from the south flowing past Dindori, at about two km. above its confluence with the Kadva near Rajapur.
The Kadva is joined on the left bank by several streams draining the southern slopes of the Satmala ranges.

Unanda : The Unanda is the first of these having a long course nearly parallel to the Satmalas and receives several small streams draining its slopes. Among these are the small Dev nadi flowing past Vani, the Parasheri river flowing by Pimpalgaon Basavant, the Netravati nala flowing by Vadner, the Vainatha nodi joining it near Niphad and formed by the union of two rivers, the Vadali flowing by Vadali Bhoi and the Shelu.

Gui : The Gui nadi rises in the Satmalas just west of Chandavad and is joined at Maralgoi by a similar stream, the Pimpalad nadi, rising a little further west and flowing past Lasalgaon. After a long course southwards, it joins the Godavari just outside the limits of the district. East of Gui there are a number of similar small tributaries of the Godavari, all of them joining outside the limits of the district. They are the Genu, the Gorakh, the Augusti, the Narandi, the Kol and the Dev. The last one forming the easternmost tributary of the Godavari id the district flowing in Yeola taluka is a small stream different from the larger one of the same name flowing in Sinnar.
It is to be noted that many of the streams flowing eastwards from the scarp in Desh have too wide valleys to have been formed by the river now flowing through them. The anomaly of the wide valleys can be attributed to the fact that the rivers that flow down in their midst formerly rose much farther west than they now rise, and that the broad plains were .at considerable distances from the sources of the rivers. The crest of the Sahyadris may be considered to have been much farther west than it now is. This is also borne out by the occurrences of remnant higher peaks west of the main Sahyadrian scarp indicating the retreat eastwards of the scarp. The explanation is to be found in the much greater energy of the west flowing streams already referred to in the case of the Vaitarna as compared to that of the east flowing rivers.