Chapter 2 Physical Features 2.0 General The proposed Cauvery (Kattalai) - Vaigai - Gundar Link Project is conceived to irrigate the drought prone areas of Central and Southern regions of Tamil Nadu. The link Project envisages diversion of 2252 Mcum of water from the existing Kattalai barrage across river Cauvery in Tirumanimuttar sub- basin of Cauvery basin to provide irrigation, domestic and industrial water supply in seven districts of Tamil Nadu viz. Tiruchirappalli, Karur, Pudukkottai, Sivaganga, Ramanathapuram, Virudhunagar and Thoothukudi. The link project will extend irrigation for 3,37,717 ha. utilizing 1746 Mcum of water besides provision of 131 Mcum and 197 Mcum of water towards domestic and industrial use. This chapter deals with the physical features, such as Geographical disposition, Topography and Physiography. Geology of the basin areas, river system and command area proposed to be benefitted under the link canal. 2.1 Geographical disposition The project area of Cauvery (Kattalai) – Vaigai - Gundar link canal is located in Tirumanimuttar sub-basin of Cauvery basin, basin area of the streams between Cauvery and Vaigai, Vaigai basin and basin area of the streams between Vaigai and Vaippar in Tamil Nadu. The Cauvery (Kattalai)- Vaigai-Gundar link canal is proposed to take off from the existing Kattalai barrage on its right bank near Mayanur village in Krishnarayapuram taluk of Karur district at latitude 100 57' 11'' N and longitude 780 13' 56'' E. The proposed link canal passes through the districts of Karur, Tiruchirappalli, Pudukkottai, Sivaganga and Virudhunagar. The link canal terminates at Gundar river in Tiruchuli taluk of Virudhunagar district at latitude 90 38' N and longitude 780 08' E. The total length of the link canal is about 256.820 Km. The important rivers crossed by the link canal alignment are NapiliAr, Ariyar, Koraiyar, Vallar, Virisalar, Manimuttar, SaruganiAr, Uppar, Vaigai and Gridhamalnadi. The command area under the link canal project is spread over Karur, Tiruchchirappalli, Pudukkottai, Sivaganga, Ramanathapuram, Detailed Project Report of Cauvery (Kattalai) - Vaigai - Gundar Link Project Virudhunagar and Thoothukudi districts of Tamil Nadu. The whole project area falls between latitudes 90 12' N & 10o 58' N and longitudes 780 13 ' E & 790 12' E in Tamil Nadu State. The index map of the link project showing rivers, basin boundary, district boundary, important towns, off take, link alignment, out fall, existing and proposed command areas etc. is appended at Plate 1.3 in Vol. IV. 2.2 Topography of the basin, reservoir and command area The Cauvery (Kattalai)-Vaigai-Gundar link canal passes through Tirumanimuttar sub-basin of Cauvery basin, basin area of the streams between Cauvery and Vaigai, Vaigai basin and basin area of the streams between Vaigai and Vaippar. The link canal off takes from the existing Kattalai barrage on Cauvery. The proposed command area under the link canal falls in the Tirumanimuttar sub-basins of Cauvery basin, basin area of the streams between Cauvery and Vaigai, Vaigai basin and basin area of the streams between Vaigai and Vaippar. The topography of these sub-basins/basins is described briefly in the following paragraphs: 2.2.1 Cauvery basin The Cauvery river is one of the major rivers of the Peninsular India extending over an area of 81,155 km2 in the states of Kerala, Karnataka and Tamil Nadu. It rises in the Coorg district of Karnataka at an elevation of about 1340 m and falls in the Bay of Bengal in Tamil Nadu traversing a distance of about 800 km in the south-east direction. In size it ranks fourth, next to Godavari, Mahanadi and Krishna in the Peninsular India. The basin lies between longitudes 750 30' E & 790 45' E and latitudes 100 05' N and 130 30' N. It is bounded in the west by the Western Ghats, in the east and south by the Eastern Ghats and in the North by the ridges separating it from the Krishna and Pennar basins. The percentage of catchment area of the Cauvery basin in the States of Kerala, Karnataka and Tamil Nadu are 3.5, 42.2 and 54.3 respectively. The principle tributaries of the Cauvery are Harangi, Hemavathi, Shimsha, Arkavathi, Lakshmanathirtha, Kabini and Suvarnavathi in Karnataka and 36 Chapter 2: Physical Features Bhavani, Noyil and Amaravathi in Tamil Nadu. The Cauvery basin can be broadly divided in to three main physiographic regions viz. (i) the Western Ghats (ii) the plateau of Karnataka and (iii) the delta. The Cauvery basin is taken to comprise 16 sub-basins for the purposes of NWDA studies. These are (1) Upper Cauvery (2) Kabini (3) Suvarnavathy (4) Shimsha (5) Arkavathi (6) Middle Cauvery (7) Palar (8) Chinnar (9) Bhavani (10) Noyil (11) Amaravathi (12) Tirumanimuttar (13) Ponnanaiar (14) Upper Coleroon (15) Lower Coleroon (16) Cauvery delta. The Cauvery basin map is appended at Plate 2.1. 2.2.1.1 Tirumanimuttar sub-basin of Cauvery basin The Tirumanimuttar sub-basin comprises the catchment of Cauvery river below Mettur dam on both sides upto Upper Anicut including the sub- catchments of Sarabhanganadi, Tirumanimuttar, Pungar and Ayyar but excluding the catchment of Bhavani, Noyil and Amaravathi rivers. The sub- basin lies between north latitudes 100 36' 10" and 110 55' 50" and east longitudes 770 27' 30" and 780 41' 35". The independent catchment area of Tirumanimuttar sub-basin is 8429 km2 and the catchment area of Cauvery river upto Kattalai barrage is 63,694 km2. The sub-basin lies in Salem, Namakkal, Tiruchirappalli, Karur, Erode and Dindigul districts of Tamil Nadu. The Tirumanimuttar sub-basin lies in the uplands at elevation ranging from 100 to 300 meters, excluding the Yercaud hill region. The height of the Shevaroya hills situated in Yercaud taluk range from 1220 to 1463 meters. The Kollimalai and few isolated hills and ridges are strewn over the taluks of Namakkal and Rasipuram. The catchment of Tirumanimuttar sub-basin can be classified as ‘Rectangular Type’ based on the shape and stream pattern. It has an average length of about 130 km from north – west to south – east and an average width of 100 km from north-east to south-west. This sub-basin is mainly commanded by the Mettur canals, Kattalai canals, Kalingarayan channel and part of Lower Bhawani Project canal and Salem – Tiruchi channels. 37 Detailed Project Report of Cauvery (Kattalai) - Vaigai - Gundar Link Project 2.2.2 Basin area of streams between Cauvery and Vaigai The basin area covered by the streams between Cauvery and Vaigai comprises the catchment of 7 small to medium streams viz. Agniyaru, Ambuliyaru, Vellar, Koluvanaru, Pambar, Manimuttar and Kottakaraiaru draining independently with their outfall in the Bay of Bengal. Vellar, and Manimuttar rivers with their tributaries are the important streams in this basin area. The basin area lies between latitudes 090 36'& 100 44' N and longitudes 780 07'&790 27' E. It is bounded on the north and west by the Cauvery basin, on the south by the Vaigai basin and on the east by the Bay of Bengal. The river Vellar raises in the Velamalai near Marungapuri in Tiruchirappalli district and the river Manimuttar raises in the Perumalai (839 m), Alagarmalai (830m) and Karanandamalai (912 m) in the Madurai district. The lengths of these two rivers from the origin to the outfall are about 136 km and 150 km respectively. The catchment area of the basin is 10,040 km2 covering parts of Madurai, Dindugal, Tiruchirappalli, Thanjavur, Pudukkottai, Sivaganga and Ramanathapuram districts of Tamil Nadu. Except for a few hillocks in the extreme west, the basin is almost flat, gently sloping from about 200 m elevation in the west to the sea level in the east. The eastern part of the basin is comparatively wider which gradually narrows down towards the western side. The maximum width of the basin in the eastern portion is about 130 km and the minimum width in the western side is about 30 km. The vellar and Manimuttar, which are the main rivers of this basin have average bed slope of 1 in 210 and 1 in 180 respectively. Most of the rivers in this basin are flowing in the south east direction. The basin map of streams between Cauvery and Vaigai is appended at Plate 2.2. 2.2.3 Vaigai basin The river Vaigai rises in the western slopes of the Varushanad hills near Kottimalai in Periyakulam taluk of Theni district in Tamil Nadu State and flows in a northerly and north easterly direction upto the confluence with Varahanadi and flows through the Madurai and Ramanathapuram districts and falls into the Bay of Bengal close to the Palk Strait. During its course, the river travels over a distance of about 258 km. Suruliarnadi, Varahanadi, 38 Chapter 2: Physical Features Manjalar and Marudhanadi are its principal tributaries. The basin area lies between latitudes 090 18'N & 100 19' N and longitudes 770 10' E & 790 01' E. The catchment area of the basin is 7741 Km2 and covers parts of Theni, Madurai, Dindigul, Sivaganga, Virudhunagar and Ramanathapuram districts of Tamil Nadu State. The shape of the catchment of the Vaigai basin is like an arch with eastern side little longer than western side. The western periphery of the basin lies in the Southern part of the Western Ghats. The part of the basin from the foot hills upto sea slopes south easterly and the terrain is of undulating plains with stray hillocks. The Vaigai basin map is appended at Plate 2.3. 2.2.4 Basin area of streams between the Vaigai and Vaippar The basin area comprises the catchments of all streams between Vaigai and Vaippar, draining independently and falling into the Bay of Bengal.