Imperial Journal of Interdisciplinary Research (IJIR) Vol-3, Issue-2, 2017 ISSN: 2454-1362, http://www.onlinejournal.in Impact Of Encroachment In Chennai B.Krishnakumari,P.Yadhavan, R.SriVignesh & K.M.Sathish Kumar Department of Civil Engineering, Panimalar Engineering College Poonamalle, Chennai, India Abstract: “A drop of water is worth more than a sack this water to percolate into the ground. Furthermore, of gold to a thirsty man” Chennai: In a clear we have already exploited about 80% of our ground indicator as to why Chennai is going thirsty, a report water and experts fear that any more extraction from from the public works department show how cities the ground could lead to salt water ingression growth over the years had eaten into precious water (movement of salt water into fresh water reservoirs bodies. A staggering 50 per cent of 19 major lakes due to a pressure gradient). located in and around Chennai have been encroached and there are close to 20,000 illegal structures! These encroachments have reduced lakes’ water spread area and acute water shortage in the region. The water bodies have become sites for residential houses and commercial structures and in some cases even been regularised. As a result, Chennai was compelled to draw its supply of drinking water from Veeranam taluk, which was hundreds of kilometres away from the city. In the name of development, the city has caused irreparable damage to lakes. Successive governments failed to address the issue showing high degree of insensitivity. It’s not just the lake, the catchment area is equally important. Keywords— Landuse, Encrachment, Waterbodies, Watershed, Landcover Fig 1. Chennai river basin I. Introduction The Chennai Metropolitan Area (CMS) has a The Chennai river Basin as shown in fig 1, which is size of 1,189 sq km and comprises of eight districts, situated between latitudes 12°40'N and 13°40'N and including the Chennai city district. The population has longitudes 79°10'E and 80°25'E at the north east increased from 5.8 million in 2001 to 8.9 million in corner of Tamilnadu.. Andhra Pradesh lies on it 2011 in CMA. Industrial developments and north; Palar River basin lies on west and south and establishments at Sholinganallur and Perugudi, Special the Bay of Bengal on the east were the main Economic Zone (SEZ) at Ennore and Nadambakkam boundaries of this basin. The total area of the basin is attracted many investors to Chennai. The city almost 7282 km². Out of that 5542 km² lies in Tamilnadu changed to a concrete jungle. The open areas decreased and the rest is in Andhra Pradesh listed in Table 1. drastically and the built up and paved areas, according to This basin group covers partly or fully 26 blocks of an analyses by IISC, increased from 29.53 per cent in Tiruthani, Thiruvallore, Saidapet, Tambaram, 1991 to 64.4 per cent in 2013.Furthermore, rapid Ponneri, Sriperumbudur, Arakonam, and Walajapet urbanization and industrialization has led to large taluks of Thiruvallore, Kanjeepuram, Chennai and scale encroachment into water bodies. Houses, Vellore districts. The major part of the basin area apartment complexes and buildings are built over comes under Thiruvallore and Chennai districts (fully lakes and eris, causing them to perish and obstructing covered) and only a few area covers Vellore and the flow of water. With real estate and land prices Kanjeepuram districts. Of the four rivers, the Adayar skyrocketing, people are scrambling to get their hands River carries the floodwater and drainage of Chennai on any piece of land, and often end up building on city and its environs. It does not have any direct areas where lakes used to exist not so long ago. This irrigation and carries only the flood discharge during is, incidentally, also one of the major reasons for the northeast monsoon period for few days. The severe flooding during the monsoons. Encroachment Cooum River serves as drainage and sewerage carrier into water bodies also severely reduces the potential within the Chennai city limit. Chennai River Basin is for groundwater recharge. Even though Chennai an interdependent river basin of Araniar, receives an average rainfall of 129cm, well above the Kosathalayar, Cooum and Adyar all rivers mostly national average, encroachment allows only 5% of flow from west to east with a man made artificial Imperial Journal of Interdisciplinary Research (IJIR) Page 1805 Imperial Journal of Interdisciplinary Research (IJIR) Vol-3, Issue-2, 2017 ISSN: 2454-1362, http://www.onlinejournal.in Buckingham canal runs from north to south. The river peaks and volumes even for short duration low Araniar and Kosathalayar originate from Andhra intensity rainfall. Due to their destructive effects, Pradesh whereas the Cooum and Adyar originate floods can significantly increase the expenses on from surplus courses of Cooum tank in Thiruvallore mitigation efforts. (14) Taluk and Chembarambakkam Tank in 2.Owing to massive concretisation of roads and Sriperumbudur Taluk. All these four rivers stretching unplanned constructions have flattened the natural from west to east and confluence with Bay of Bengal topography, almost 90 to 100 per cent of the in the East. The total command area in Chennai rainwater in both cities drains off into the stormwater Basin: is 1,31,665 hectares. There are 1,304 tanks by drains instead of being absorbed into the ground. The which 85,208 ha are irrigated. The storage capacity of Chennai suburbs have barely any stormwater drains the tanks is 410 mcm and the total capacity of the to boast of while those in the city also double as basin is 1069 mcm. carriers of sewage waste. Likewise, the British built the 400-kilometer-long Buckingham Canal, which TABLE I.Details of the area of the each sub Basin now serves as a drain and is heavily silted. Over 600 S.No. Name of the Sub Area of the Sub water bodies, wetland and lakes such as Velachery in Basin Basin in Sq. Km. Chennai have metamorphosed into IT parks, malls and residential areas, reducing the city’s natural 1 Araniar 763 holding ponds for water. (20) 2 Kosathalayar 3,240 3 Cooum 682 TABLE 2.Details of rainfall stations and 50 4 Adayar 857 years normal average rainfall. Total 5542 Coordinates Name of the RF S.No. SWM NEM Winter Summer Annual Station Latitude Longitude II. Source of water 1 Sholingar 13 07 00 79 26 00 445 391 31 84 952 2 Ramakrishnarajpet 13.167 79.439 362 320 13 79 773 3 Pallipet 13.336 79.442 404 361 19 111 895 1. A long sea coast with two tidal creeks – The Adyar 4 Minnal 13 05 00 79 33 00 445 398 361 91 959 Creek and Ennore Creek. 5 Arakonam 13 05 00 79 40 00 468 479 43 80 1070 6 Kesavaram 13 02 00 79 46 00 484 486 18 92 1080 2. The second largest lagoon in India – the Pulicat 7 Poondi 13 11 50 79 53 00 601 600 27 65 1292 8 Thiruvallore 13.135 79.911 424 545 46 73 1088 Lake. 9 Chembarambakkam 13 07 00 79 55 00 418 620 24 83 1145 3. Several other lakes, such as Redhills, 10 Sriperumbudur 12.967 79.792 418 547 36 66 1068 11 Tamaraipakkam Anicut 13 12 00 80 12 00 420 619 26 67 1131 Chembarambakkam, Poondi, Cholavaram and Porur. 12 Tambaram 12 55 00 80 07 00 513 809 22 80 1424 4. Many Estuaries and backwaters, such as the Adyar 13 Poonthamallee 13 02 00 80 07 00 408 702 49 64 1223 14 Sholavaram 13 14 00 80 10 00 438 733 26 91 1289 Estuary and Creek. 15 Meenambakkam 13 00 00 80 11 00 433 768 37 86 1324 16 Redhills 13 10 00 80 11 00 342 614 24 90 1070 5 .Weltands and Swamps – Pallikaranai, Oggian 17 Korattur Anicut 13 05 30 79 59 30 402 543 24 72 1041 Madugu, Madavaram and Ennore. 18 Ponneri 13 19 30 80 12 00 361 749 45 69 1223 19 Saidapet 13 03 00 80 14 00 405 759 52 70 1286 6. And a large number of smaller lakes, eris, ponds 20 Nungambakkam 13 04 00 80 15 00 363 750 43 60 1215 and several temple tanks. 21 Valliyur 13 12 50 79 59 15 409 720 30 103 1262 22 Athipet 13 15 38 80 17 00 328 750 42 56 1176 Chennai has fresh water reservoirs/lakes 23 Chepauk 13 04 00 80 16 00 378 622 26 86 1112 namely Poondi, Sholavaram, RedHills, Chembaramb 24 Tiruthani 13 09 20 70 32 40 456 466 44 82 1047 25 Thiruvetriyur * 13.133 80.283 355 707 56 14 1132 akkam, Veeranam to cater the daily needs of water 26 Tharamani * 12 59 30 80 14 55 489 789 41 58 1377 27 Kaveripakkam 12 54 00 79 29 00 431 927 33 80 1471 for chennai area.Chennai receives most of its water 28 Panappakkam 12 56 00 79 36 00 508 416 36 125 1085 from Poondi Lake (3,231 Mcft), Sholavaram 29 Thiruvalangadu * 13.167 79.75 534 651 42 56 1283 30 Pattabiramam * 13.12 80.11 490 572 48 57 1167 Lake (881 Mcft), Red HillsLake (3,300 Mcft) 31 Elavur 13 29 00 80 09 00 434 694 48 26 1202 Note: * These Rainfall Stations were installed during recent years, and average and Chembarambakkam Lake (3,645 Mcft).The has been arrived only for actiual years of data available. Veeranam Water Supply Project was implemented as - additional source of water to Chennai City.