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National Seminar on Rainwater Harvesting and Water Management 11-12 Nov. 2006, Nagpur 85. Large Water Storage Structures and Rain Water Harvesting Structures- Limitations and Efficacy *R. S. Goel **Jay Narayan Vyas ***V. B. Patel ****Aditya Sharma ABSTRACT This paper critically examines the controversies of large vs small dams and focuses on limitations and efficacy of large water storage versus small dams and rain water harvesting structures. Important conclusions of significant studies have been interwoven regarding comparative evaporation, submergence, seismic & hydrologic safety as well as the benefits and cost aspects of large dams versus RWH schemes and small dams. Basic objectives and drivers of Interlinking of Rivers (ILR) are also summarised. Few NGOs and self styled non-professional environmentalists leave no stone unturned to oppose almost each water storage dam, hydel plant and continue fighting tooth and nail against vitally needed inter-linking of rivers, perhaps also siphon off foreign funds mainly to garner awards, fame and monopoly. They are generally ignorant of even basic facts and intricate ‘dose response functions’ of complicated environmental processes and techniques of water resources and hydro power development due to no professional background. Such persons repeatedly use media to create fantasies and tirade against water storage projects on many shifting grounds. In every sector other than water and power, specialists like doctors, surgeons, economists, space & atomic scientists etc. are considered competent but any ‘Tom’, ‘Dick’ and ‘Harry’ claims to be expert to oppose large dams, hydel projects and inter-basin transfer of water projects. Supreme Court’s admission of PIL by NCCL against NBA and Prime Minister’s direction for vigilance inquiries against NBA due to siphoning of foreign funds and over 200 FIR’s for stopping R&R works are matters of alarming concerns. Even though such presentation cannot be an exhaustive treatise; nevertheless, authors hope that the policy planners, administrators, professionals, media, NGOs and public at large should understand basic facts to avoid street fights and social tensions almost every where now in India, due to breaking down of water and power supplies. Key words- large dams, water harvesting, run of river projects, interlinking of rivers, relation of forest & water. *Chairman, Indian Water Resources Society, Gandhinagar Centre, Convenor, Coordination Committee, Water Related National Professional Societies, Chief Engineer, Narmada Tapi Basin Organisation, Central Water commission, Sector 10 A, Gandhinagar (Gujarat) – 382043 Fax- 079-23246115 E-mail - goelrscwc@yahoo.com **Former Minister for Narmada & Water Resources, Govt. of Gujarat, Chairman, Saket Projects Limited, Saket House, Panchsheel, Usmanpura, Ahmedabad 380013 Fax- 079- 27550452 E-mailmail@saketprojects.com ***Vice-President, Indian Water Resources Society & Former Chairman, Central Water Commission & Ex- officio Seccretary to Govt. of India, Co-chairman, Coordination Committee, Water Related National Professional Societies,128, Manekbaug Society, Ambawadi, Ahmedabad – 38 00 52 FAX- 079- 26764099 E-mail - vbpatel@multimantech.com ****Convenor, Indian Water Resources Society, Gandhinagar Centre, Deputy Director, Narmada Tapi Basin Organisation, Central Water commission, Sector 10 A, Gandhinagar 382043 FAX- 079-23246115 E-mail- cwcmon_gandhinagar@yahoo.co.in 488
INTRODUCTION Indian water sector is confronted with the controversies of inter-state disputes vs. integrated basin development, reliance on water-shed development vs. reservoir projects, government owned vs. private utilities and large vs. small projects. On one side, the technological advances in the fields of meteorology, hydrology, geology, seismology and the techniques of investigation, planning, construction and operation of the projects are making possible the optimisation of scarce national resources. On the other hand, a fear syndrome has been created against river valley and hydro projects by exaggerated likely or assumed adverse environmental impacts and by ignoring or suppressing their need and tremendous benefits by few non-credible NGOs like NBA and novelists self styled activists. As a result, many potential economic developmental activities, which could generate wealth and employment in India have been blocked in large cities, towns and villages due to acute shortage of water especially during the dry season. At the same time, fury of floods routinely continue to affect the economic activities causing large scale loss of life, properties and flora & fauna. Widely prevalent beliefs about the role of land use and its relation to hydrology must be critically examined in the light of scientific evidence. Simplistic views have created a mindset which not only links degradation with less forest but also rehabilitation & conservation with more forest. Most of the people imply the inevitable link between the absence of forests and ‘degradation’ of water resources. Same is the situation about relation to forestry, agro forestry and various hydrological elements; even though claims by enthusiastic agro foresters and nonprofessional ecologists are often not valid. When scrutinized, many of the mother statements relating to forestry and the environmental processes are seen to be either exaggerated or untenable. It is highly relevant and crucial to know what can be attached to these statements for the proper management of water resources and land use. This article presents basic facts on limitations and efficacy of large water storage versus small dams & popularly known as rain water harvesting structures and suggests serious examination of mother statements about relation of forests and hydrologic elements - Whether Forests increase rainfall, Forests increase runoff, Forests regulate flows, Forests reduce erosion, Forests reduce floods, Forests ‘sterilize’ water supplies and improve water quality and Agro forestry systems 489 increase productivity? CAN SMALL DAMS & RWH REPLACE LARGE DAMS? The former captures rain in-situ and supplements/conserves soil moisture for a longer period, whereas the latter holds the run-off in storages of surface waters and make it available through canals for irrigation. The former has a crucial role in treatment of catchment area and noncommand areas of irrigation schemes. It recharges ground water for use in local drinking water needs. Also, it provides soil moisture to replace may be one or two irrigation watering, in kharif season. Its main role therefore is important for the vast rainfed areas of the country, which will not be irrigated through surface storages even in ultimate stage of development. Small dams and RWHS successfully operate within a narrow band of meteorological phenomena of intensity, duration, antecedent rainfall, potential evaporation, infiltration capacity dictated by topography, geology, slope, vegetative cover etc. Its contribution in increase in productivity of cropped land is rather limited. It is also essential that adequate investigations & foundation testing, detailed hydrologic analysis, hydraulic & structural designs, proper construction supervision are given needed attention even for small water projects, check dams and rain water harvesting structures. Large number of incidences have been noticed for washing away of too many check dams within a year or two due to structural, hydrologic, seismic and hydraulic failures. Both therefore are considered as complementary and not adversarial. Sediment generation is reduced in the former case. Erosion and deposition in downstream will continues due to hydraulic phenomena. Dams hold bed load of sediment in the designed pockets. Economic analysis on dams accounts for such siltation. Peak flood is reduced for local watersheds but does not have significant impact on generation of floods. Available data shows that when numerous small projects are constructed to substitute a single large storage project the cost per unit storage, relative submergence and relative evaporation losses are invariably many times more. Evaporation loss would obviously be more because of larger water spread. Claims that only small size (or some claim only large) of dams be adopted are wrong. Only small dams can not capture required quantity of water. In each basin, even if one wants, all dams can’t be of only large or only
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National Seminar on Rainwater Harve
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once subsoil water starts draining
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The plantation process starts with
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DOLASANE , SANGAMNER RANGE I, SANGA
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Table 1. Present land use of waters
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the determination of specification
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Hydrological Parameters (mm) 140 12
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Drainage Engineering, 129(3): 184-1
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March to July, 2004 in the field si
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mm in 4 lph drip followed by 755.25
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Table 3 : Seasonal water use (mm) i
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pinnata) Aquatic plants are represe
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the base of the trench to assist dr
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SUDS (Sustainable Drainage Systems)
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Figure 3 : Cascade model of constru
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H eff = H R - H aq - H f ……..
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• Layers of gravel/media laid hor
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1.3 % annually, and the total energ
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Figure 1a. Schematic diagram of sol
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Figure 5. Cross-section of partitio
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Fig. 1 (a) - (d) : Water Level Soun
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farms and industries hope to get ad
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Geology of Area The area is a part
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ground water recharge, which includ
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Table - 3 : Salient features of the
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Table 2 : Tolerance limit for metal
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CASE STUDY The Salem Municipality i
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After analyzing the characteristic
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1. Ash Pond water recycling System
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Poly Electrolyte Dosing RAIN WATER
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Canteen Waste Garbo-drain Bar Scree
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SERVICE WATER FOR SPAYING COAL CRUS
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In coastal areas of Gujarat, the vi
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Water diversion Channel The work fo
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04. Natural Water harvesting at Sol
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Work Done Storage No. of Area No. o
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Conclusions The process of rainwate
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Infact, these are ‘lessons’ tha
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we get our act together and make wa
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One relatively easy means of storin
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Ground Water Conservation Technique
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