Nethravathi River – Water Supply Scheme in Dakshina Kannada District
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Available online at www.sciencedirect.com ScienceDirect Aquatic Procedia 4 ( 2015 ) 625 – 632 INTERNATIONAL CONFERENCE ON WATER RESOURCES, COASTAL AND OCEAN ENGINEERING (ICWRCOE 2015) Nethravathi River - Water Supply Scheme in Dakshina Kannada District - A Case Study H C Chinnagiri Gowda1 , Girisha K 2 , Chandan C Gowda3 1Department of Civil Engineering, Government Polytechnic, Bantwal, 574211, India 2Minor Irrigation Department, Mangalore, 575001, India 3Researcher, Department,of Civil Engineering, University of Minho, Guimaraes, 4800-058 Portugal Abstract Water is essential for all living beings. It is a major concern to provide water to all. It is a challenge to supply water to all major cities in Dakshina Kannada district, Karnataka, India. Nethravathi River is one of the major sources of water in the region which yields about 1240TMC per year. Nethravathi River has its origins in Western Ghats of Karnataka flowing to a length of 126 Km and joins Arabian Sea. In Dakshina Kannada district all major cities face water scarcity in summer season even after getting an average annual rainfall of 3.75 – 4.25 m. It is a major challenge to the district administration for providing required water to the people during summer season in spite of plenty of water available during monsoon. This paper highlights in giving solution to this issue after studying various parameters like geographical structure, rainfall data and climate, study of catchment area, storage methods, water demand and water supply schemes available in the region. An attempt has been made to suggest for supplying the water to the cities in Dakshina Kannada district by increasing the storage capacity on the upstream side of the river to get water round the clock. © 20152015 The The Authors. Authors. Published Published by by Elsevier Elsevier B.V. B.V. This is an open access article under the CC BY-NC-ND license (Peerhttp://creativecommons.org/licenses/by-nc-nd/4.0/-review under responsibility of organizing committee). of ICWRCOE 2015. Peer-review under responsibility of organizing committee of ICWRCOE 2015 Keywords: Nethravathi; Dakshina Kannada; water scarcity; water supply 1. Introduction The Nethravathi river basin is a part of Dakshina Kannada and it plays a key role not only in the district’s economic development but also in the historic and cultural identity of the people. The river basin caters to approximately 50% of district population and about 60 % of the agricultural area. Water is essential for all living * H C Chinnagiri Gowda. Tel.: +91-9448466919. E-mail address:[email protected] 2214-241X © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of organizing committee of ICWRCOE 2015 doi: 10.1016/j.aqpro.2015.02.081 626 H.C. Chinnagiri Gowda et al. / Aquatic Procedia 4 ( 2015 ) 625 – 632 beings. It is a major concern to provide water to all. It is a challenge to supply water to all major cities in Dakshina Kannada district, Karnataka, India. The study focuses on the basic geography of the basin, rainfall, water availability, present water utilization and demand, etc. 1.1. Dakshina Kannada district Dakshina Kannada district is an emerging district in all respects such as financial, education, information technology, fisheries, etc., with about 4859 sq. kms area and a population of 20,89,649 (2011 census). The district suffers scarcity of water during summer even after getting heavy rainfall during monsoon. Mangalore is the capital city of this district having an about 200 sq. km area and a population 7, 84,569 (2011 census). Other towns such as Subramanya, Dharmastala, Belthangadi, Uppinangadi, Puttur, Bantwal, etc., are economically upcoming cities. Dakshina Kannada district is having a coastal length of about 40 kms and nestles between Arabian sea in west and western Ghats in the east. Dakshina Kannada is surrounded by Kerala in the south and Udupi in the north. The district is famous through its natural beauty by sceneries, beaches, river back water, harbor, kudru (small island in river), historic places like temples, basadis, churches, mosque, well developed education institutions, etc. The major rivers in this district are Nethravathi, Phalguni(Gurupura), Nandini and Shambhavi which joins Arabian sea and other rivers Payaswini and Shiriya which flows to Kerala state and joins sea. Dakshina Kannada normally experiences three seasons every year namely summer, monsoon and winter. In summer season the temperature may vary from 25° to 38° C in the month of February to May, in monsoon season the district gets heavy rain about 4000mm during June to September and the winter season from October to January. In monsoon season the rivers are flooded, in winter they experience a lean flow and dries up in summer. This district faces scarcity of water in summer season. 1.2. Nethravathi River The Nethravathi River has its origins at Bangrabalige valley, Yelaneeru Ghat in Kudremukh in Chikkamagaluru district of Karnataka. This river flows through the famous pilgrimage place Dharmasthala and is considered as one of the holy Rivers of Karnataka. After being joined by a number of small tributaries, it debounches into the Arabian Sea near Mangalore. The main tributaries of this river are Kumaradhara, Mrithyunjaya (Charmadi hole), Kapila (shishila) river, Aniyoor river and Somavathi (Laila) river. Kumaradhara is a major river which joins Nethravathi River near Uppinangadi which originates near Bisle ghat after merging of Giri hole and Adda hole. The major tributaries of this river are Kaniyoor River and Gundya (Kempu hole) river. Fig.1. (a) Origin to Arabian sea River Path; (b) Catchment area. H.C. Chinnagiri Gowda et al. / Aquatic Procedia 4 ( 2015 ) 625 – 632 627 2. Nethravathi River Basin A river basin is an ideal analytical unit for water supply and demand studies. Most of the data required for water demand estimation is collected and policy decisions taken at the administrative boundary level based on this. The Nethravathi is a major river of the district Dakshina Kannada, having a drainage area of about 3,432 sq. km. Dakshina Kannada receives an average rainfall of 3750-4250 mm annually. Nethravathi River flows from its origin at 13°06´10´´N 75°25´08´´E at an elevation of 975 m and flowing along Dharmastala, Uppinangadi, Bantwal, Thumbe, Mangalore to Arabian sea at 12°50´36´´N 74°49´45´´E about 126 km length through its path many tributaries joins to this river which increases its discharge capacity. The major tributary of this river is Kumaradhara River flows from its origin at 12°42´00´´N 75°43´13´´E at an elevation of 715 m about 67 km before it joins Nethravathi river at Uppinangadi 12°50´20´´N 75°14´32´´E. Kumaradhara River is also a major river in Dakshina Kannada district flows through the famous pilgrimage place Kukke Subramanya and is considered as one of the holy rivers of Karnataka. It merges with Gundya River flows from its origin at 12°51´31´´N 75°42´45´´E at an elevation of 730 m about 55 km before joining Kumaradhara river near Ulippu 12°44´38´´N 75°24´23´´E. Fig.2. (a) Flow in Nethravathi during monsoon; (b) Flow in Nethravathi picture 2. Fig.3. (a) Flow in Adda Hole; (b) River Cross Section Kumaradhara. 628 H.C. Chinnagiri Gowda et al. / Aquatic Procedia 4 ( 2015 ) 625 – 632 Fig.4. (a) Flow in Adda Hole; (b) Kempu Hole River Cross Section 2.1 Water flow and Rainfall Most of the rain falls within 4-5 months in the monsoon period, the average rainfall in the four months June to September of the south- west monsoon is about 3450 mm. The rest of the eight months receive on average about 550 mm of rainfall. Capturing the abundant south-west monsoon for beneficial utilization in the other period is an enormous task. The river is flooded in monsoon season and has a lean flow in summer which is due to percolated water from the Western Ghats. The flow in this river is measured in two water discharge measuring stations located at Uppinangadi and Panemangalore. The discharge measured at Uppinangadi discharge measuring station and the average rainfall detail of last 5 years of Dakshina Kannada district is shown in fig 5(a) & (b). Fig 5. (a) Water discharge data 1996-2010; (b) Rainfall data 2.2 Water Demand Rapid population growth across the district is resulting in increase of the water demand. From 2011 census data, district’s population has increased by about 35%, while the urban area population has increased by about 50%. Population projections suggest that water demand will continue to rise. Although many innovative urban water conservation programs have reduced per capita uses, population growth has increased the urban water demands approximately double in the last two decades. Steadily rising population and increasing water demands in the Nethravathi river region will inevitably result in increasingly costly, controversial and unavoidable trade-off choices to be made by water managers, politicians and other constituents. The present water demand of major towns of Dakshina Kannada district are collected from respective department and based on the population from 2011 census the future water demand considering 100% population growth and 135 lpcd calculated are summarized in table 1. H.C. Chinnagiri Gowda et al. / Aquatic Procedia 4 ( 2015 ) 625 – 632 629 Table 1. Water Demand Calculation. City/Town Present Water Future Water Demand in MLD Demand in MLD Mangalore 160.00 211.83 Bantwal 5.45 31.29 Puttur 8.57 16.43 Belthangadi 1.60 3.99 Subramanya 3.00 6.00 Dharmastala 4.00 8.00 Uppinangadi 2.00 4.00 2.3 Present Water Utilization Water from Nethravathi River and its tributaries is mainly used for drinking, agriculture and industrial purpose.