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Modern Structures During the last 100 years there has been considerable technological development, interalia, in the design and construction of water harvesting structures for various purposes. In areas where source of water is only rainfall, entire efforts of water conservation are to be concentrated on insitu rainfall.. Gully plugging , Contour bunding, Bench terracing and Gabbion structures are the common water conservation structures applicable in run off zone. They are also part of watershed improvement works. These measures are multipurpose, mutually complementary and conducive to soil and water conservation. They help to increase forestation and agriculture productivity. Gully Plugging : These are the smallest soil and water conservation structures built across gullies in hilly areas carrying drainage of tiny catchments during rainy season. These are built with locally available materials like stone boulders, earth, weathered rock brushwood etc. Sand bags or brickwork may also be used to strengthen the bund. Gully plugs may be chosen wherever there is local break in slope to permit accumulation of adequate water behind the bund. The height of individual plug depend upon land slope may be between 2 to 3 m above nala bed and progressively taper off on side slope. A number of gully plugs may be provided on the same gully or nala, one below the other at every hundred-meter separation. Contour Bunding : These are small structures earthen bunds built horizontally in parallel rows across the hill slope. These help in augmenting soil moisture and prevent erosion of topsoil. This technique is suitable in low rainfall area where monsoon runoff can be impounded by constructing bunds on the slopping ground all along the contour of equal elevation. The 434 flowing water is intercepted before it attains the erosive velocity by keeping suitable spacing between the bunds. The Spacing of between two contour bunds depends on the slope of the area and the permeability of the soil. Contour bunding is suitable on land with moderate slope without involving terracing.. Bench Terracing : Sloping land with surface gradient up to 8% having adequate soil cover can be leveled through bench terracing for bringing under cultivation. It helps in soil conservation and holding runoff water on terraced area for longer duration giving rise to increased infiltration recharge. The width of individual terrace should be fixed depending upon the slope of the land. The upland slope between two terraces should not be more than 1;10 and the terrace should be leveled. Gabbion Structure This kind of check dam commonly constructed across small streams to conserve stream flow with practically no submergence beyond stream course. Small bund across the stream is made by putting locally available boulder in a steel of mesh wires and anchored to the stream banks. The height of such structures is around 0.5 m and is normally used in the stream with width of less than 10.0 m. The excess water overflows this structure storing some water to serve as source at recharge. The silt content of stream water in due course and with growth of vegetation, the bund becomes quite impermeable and helps in retaining surface water runoff for sufficient time affect rain to recharge the ground water body.
Ground Water Conservation Techniques The water recharged into aquifer is immediately governed by natural ground water flow regime. It start seeping away due the steep water table gradient and transmissivity 0f the aquifer.As a result the water is not available for exploitation during the summer season.The aim is to conserve water for later use.The under ground bhandara has proved to be the most successful technique for improvement of sustenance of water supply source Ground Water Dams It is a sub-surface barrier across stream, which retards the base flow and stores water upstream below ground surface. The water level in upstream part of ground water dam rises saturating otherwise dry part of aquifer site where sub-surface dyke is proposed should have shallow impervious layer with wide valley and narrow outlet. After selection of site, a trench of 1-2 m wide is dug across the breadth of the stream down to impermeable bed. The trench may be filled with clay or brick / concrete wall up to 0.5 m below the ground level. These structures are preferred down stream of existing water supply structure to sustain availability during the summer. � � � 435 Sum Up The poor accessibility, adverse hydrogeological condition, higher cost of development and thin size of population etc are the factors not suiting to the state government norms, and also the ignorant attitude towards thinly populated poor people, are certain inhibiting factors for long term solutions to this problem. As a result these hilly areas remain perpetually under water scarcity for most part of the year. . In such situation, water scarcity can only be tackled by supply oriented management practices. While other measures of development of ground water are not found technoeconomic viable, the conservation of both surface water and ground water are the most appropriate option. The cost of construction of these structures is quite low as they can be built using the local materials and also not much scientific skill is required to execute them. References Hydrogeology of Maharashtra(1994), Central Ground Water Board,Ministry of water Resources,Faridabad PP 4-7 Jain,S.K.& Jain,P.K.(2001) Possibilities of Rain water Harvesting and Ground water Augmentation in Rajpura parliamentary constituency, MaharashtraPP 36-41 Manual of Artificial Recharge of Ground Water (1994),Central Ground Water Board,Ministry of water Resources,Faridabad PP112-117 Rain water Harvesting Techniques to Augment Ground water,(2003) Central Ground Water Board,Ministry of water Resources, Faridabad pp14-18
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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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Page 57 and 58: Geology of Area The area is a part
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Page 61 and 62: Table - 3 : Salient features of the
Page 69 and 70: eing 6.08, pH value of AB 3 and AB
Page 71 and 72: Table 2 : Tolerance limit for metal
Page 73 and 74: CASE STUDY The Salem Municipality i
Page 75 and 76: After analyzing the characteristic
Page 77 and 78: 1. Ash Pond water recycling System
Page 79 and 80: Poly Electrolyte Dosing RAIN WATER
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Page 89 and 90: 04. Natural Water harvesting at Sol
Page 91 and 92: Work Done Storage No. of Area No. o
Page 93 and 94: Conclusions The process of rainwate
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Page 125 and 126: echarging , A study of world wide f
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Page 133 and 134: The opinion of the public for the q
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Page 149 and 150: years. These beels can also be conv
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Page 153 and 154: contribute to increased fish produc
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Figure 1 : Map of Bangladesh showin
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end uses and the intentional manage
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INTRODUCTION Indian water sector is
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ut definitely they are not substitu
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having the height greater than 50m
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ain. There is no conducive evidence
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chase food self sufficiency as a go
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REPORTB OF WORLD COMMISION ON DAMS
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