Details of River System
Puducherry Region
| Sl. No. | Name of the River | Total length (km) | Unprecedented flood level (Height in mts) | Highest flood level (Height in mts) | Moderate flood level (Height | No.of breaches occurred on river banks |
| 1 | Gingee River | 34.00 | 2.60 | 2.25 | 1.20 | Nil |
| 2 | Pennaiyar | 6.00 | 2.40 | 2.10 | 1.50 | Nil |
| 3 | Guduvaiuyar | 19.30 | 1.30 | 1.00 | 0.50 | Nil |
| 4 | Pambaiyar | 13.00 | 1.50 | 1.00 | 0.70 | Nil |
| 5 | Malatar | 10.00 | 2.30 | 1.95 | 1.20 | Nil |
Karaikal region
Forming part of fertile delta, the region is completely covered by the distributaries of Kaveri river. Covered completely by a thick mantle of alluvium of variable thickness, the lie of the region is flat having gentle slope towards the Bay of Bengal in the east. It is limited on the north by the Nandalar and on the south east by the Vettar. The group of rocks known as Cuddalore formations is met with in the area contiguous to Karaikal region in Tanjore District.
| Sl. No. | Name of the river | Total length in Km | Channels Length in mts | Ayacut in Acres | N.S.L. level | N.S.L. Discharege in C/S |
| 1 | Nandalar | 15.165 | 23920 4 | 4448+311 (TN) | 1.90M | 06 C/S (99+&TN) |
| 2 | Nattar | 12.600 | 55178 | 3395+374 (TN) | 0.45M | 105 C/S (92+13TN) |
| 3 | Vanjiar | 12.300 | 16600 | 2825 | 5.0” | 63 C/S |
| 4 | Noolar | 16.620 | 74945 | 9301 | 4’6” | 208 C/S |
| 5 | Arasalar | 11.76 | 7500 | 119 | 0.90M | 6 C/S |
| 6 | Thirumalair ajanar | 10.220 | 28000 | 5815 | 1075M | 155 C/S |
| 7 | Pravadayanar | 3.350 | 4800 | 904 | 1.500M | 20 C/S |
Mahe Region
Mahe is a small area bounded on the south west by the Arabian Sea, on the north by the River Ponniyam (Moolakadavu) and on the other sides by a stretch of calcareous hills of medium height which are linked to the ghats by a series of wooded hillocks. The river Mahe which flows towards the west, divides the region into two parts
Yanam Region
The region is bounded on the east and south by the river Godavari which discharges itself into the Bay of Bengal after flowing about 14 km. towards south east. The town of Yanam is located at spot where the River Coringa and Godavari separate to divide the region into two parts, one on the east and the other on the west. The entire region is composed of a flat, monotonous terrain without any distinct topographical feature.
Reference as on April 2020 – http://www.indiaenvironmentportal.org.in/files/REV-DMAP-2008.pdf
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