5.7.3 Water Balancing
After assessing the availability and requirement both in terms of the quality and quantity a comparison can be made to determine the surplus/shortage at any given time as shown in Table 5.4 in an assumed situation.

Table 5.4: Water Balance

Availability of water		Requirement of water		Surplus/ shortage mgd
Quality	Quantity mgd	Quality	Quantity mgd
A	55.7	A	63.4	-7.7
B	32.5	B	33.0	-0.5
C	18.5	C	20.5	-2.0
D	12.6	D	10.1	+2.5

Such data should be collected for all the months, individually, round the year, and should be compared accordingly to know the difference between availabilities and requirements in different parts of the year. This will indicate and requirement and possibility of management through storage of extra water, its treatment and supply in lean months.

5.7.4 Water quantity management
The water balance exercise discussed above gives the idea of availability and requirement of water, qualitatively and quantitatively. The area under consideration may be deficient in some quality water and surplus in some other quality. In order to meet the requirement of the water for various purposes not only for the present but also for future it is necessary to look into management measures. Some of the measures are discussed hereunder. From the water quality which stands extra, if the surplus amount can be treated to meet the deficiency of some other quality and the treatment cost is economic, it may serve the purpose.

In some situations there may be locational difference in the availability and requirement, i.e., the required quality and quantity of water is available at some distance from the place of requirement. In such cases suitable water transportation arrangements are to be made, e.g., through canals, pipe line transport, etc. It would be advisible to compare such transportation cost with the cost of treatment of water of other quality in required quantity to required quality, if available nearby.

If the water is to be brought from outside the area, it would be necessary to locate the sources of water and the quality of water available therein and then examine the various options for transporting and treating the water so as to make it available at the place of requirement economically.

As mentioned in Table 5.3 reclamation of abandoned quarries may be achieved by different processes generated through different research activities. Mention may be made of aquifer regeneration (Ghosh 2000a&c), revegetation (Ghosh & Ghosh 1993, Ghosh et al., 1993, Singh & Ghosh, 1996, and Ghosh, 1999a), formation of surface water storages (Ghosh and Ghosh 1994) as some of the best ways of water resource management.

Augmentation of water quantity in mining complexes can be done by taking the following actions.
* By producing green cover on mined out areas at the earliest (Ghosh 1999a).
* By storing water in underground openings in the abandoned underground mines (Saxena, 1999).
* By regenerating aquifers while backfilling the opencast mining areas (Ghosh 2000c).
*By forming surface water storages in reclaimed opencast mining areas (Nelson et al., 1982).
* Reactivating water table in subsided areas by suitably plugging the cracks.
* Rain water harvesting (Vishwanath, 2001).
Optimum development of water resources can be achieved by the conjunctive use of surface and ground waters. Ground water recharge occurs in nature by seepage from canals and reservoirs and return flow from irrigation. It can be augmented by artificial methods such as spreading of pumped out mine water or storm water in ponds or basins Fig.5.5a, recharge pits recharge Fig. 5.5b, wells Fig. 5.5c and shafts. Even pumped-out mine-water may be poured (after due consideration of its quality) in goaves (Saxena, 1999) at proper distance (not to generate more pumping-requirement at the excavation site) or, may be poured in abandoned quarries to form a surface water storage or may be used for other purposes on the surface to curtail pumping requirements for those purposes (Fig.5.6) (Ghosh & Ghosh 1994). Nelson et al. (1982, pp.1.3-3) have proposed mine-cut lakes and has mentioned that such lakes may be of equal or better economic or public use as compared to pre-mining land-use.

The usable capacity of the ground water reservoir can be developed by planned extraction of ground water during periods of low precipitation while subsequent replenishment can be made during periods of surplus surface supply. Such a coordinated operation of surface and ground water supplies is possible if there is sufficient ground water storage to meet the requirements for regulation of local and imported water supplies and if the aquifers possess sufficient transmissibility to permit the movement of recharged water to the area of extraction. Also, the underground storage is free of losses due to evaporation etc. The lesser danger of destruction of ground water reservoir structures and wide dispersion of outlet facilities in earthquake areas, in places liable for atomic attacks, etc. make ground water basins of inestimable value as an emergency supply. Large ground water reservoirs thus developed not only meet the deficiencies of the surface supplies in seasons of drought but also supplement these to a large extent. These conjunctive operations result in a more economic yield as they provide more water at a lower average cost. The benefits accruing from the conjunctive use of water sources are being listed below.

1. Formation of a large-subsurface storage at a relatively lower cost and safe against any risk of dam failures or pollution.
2. Provides water supplies during a series of drought years while a surface storage can at the most tide over one such year.
3. Provides efficient water use from well-spaced wells due to smaller surface distribution system than a canal irrigation scheme.
4. Water table can be controlled by pumping from wells and prevent water logging in canal-irrigated areas. This can reduce land subsidence due to reduced ground water levels particularly in confined aquifers.