Water Demand for Baroda Urban Area

Large scale industrialization and urbanisation in Baroda has rendered the present water supply insufficient. This problem has been further compounded by surface and sub-surface water pollution. Water budget studies for the Baroda urban area have shown that the glaring present defecit in demand and supply will be even more acute in the year 2001.


Introduction
Baroda city, at present a large industrial centre, was in the recent past, a small university town. The only water supply was the Ajwa reservoir, built some 100 years ago to cater to the needs of 100,00-200,000 population. With rapid industrialization and urbanization, the synchronous population growth rendered this single water supply insufficient, forcing the authorities to look for alternative sources. Tube wells, bore wells, French wells in the Mahi river bed, were some of the other sources of water for urban as well as industrial consumption.
But all these sources together, are insufficient in the light of large scale surface and sub-surface water pollution. This study includes a calculation of the water budget for the present and future Baroda city. The present available water draft and water demand were calculated. The deficit in demand and supply is even more conspicuous in th~year 2001.

Available Water Draft
The calculations of total available water draft for the study area (714 sq. km.) were made based on proven methodology. Since groundwater is the main source of water, discussions about it have been considered in the beginning.

Groundwater
Groundwater is a renewable resource, subjected to periodic replenishment, primarily from precipitation. To have a measure of the quantum of such periodic increment to any groundwater body, it is necessary to obtain precise information on the hydrogeolocial framework of the reservoir, the groundwater conditions and the factors governing the recharge to and discharge from the groundwater system.
The Central Groundwater Board has cpnducted detailed inter-disciplinary and integrated studies on a large number of selected basins for determining the water balance situation. In view of the large variations in the geologic framework, lithological character of the wide range of rock units, hydrometeorological conditions, etc. the basins selected were typical of that region (Charlu and Dutt, 1982). These major studies were spread over various parts of the country and included, amongst others, the type areas of the peninsular hard rocks, the alluvial sediments of a part of the Sindhu-Ganga basin and the Rajasthan-Gujarat region.

Methodology
For carrying out groundwater development programmes in an effective manner, it is desirable to have an idea of available groundwater potential at any given point of time. Detailed methods are based on appreciation of the aquifer parameters, etc. obtained through long duration aquifer tests. However, in the absence of knowledge about these parameters in precise terms, importance is generally given to determine the replenishable component of recharge on an annual basis. The two approaches currently in vogue are (i) the water balance approach, and (ii) the water-table fluctuation / specific yield approach. For the study area, the water table fluctuation J specific yield approach is found most suitable.

Water Table Fluctuation I Specific Yield Approach
Groundwater levels rise due to rainfall or any other source of recharge. The rise during the monsoon period is, by and large, attributable to the increment to the groundwater body due to rainfall. In other words, the magnitude of the rise is in a way a measure of the recharge to the groundwater, which amongst other things is dependent on the specific yield of the formation material comprising the zone of saturation.
From this, periods of recharge and periods of groundwater discharge could be found out. Recharge due to rainfall could be made out from the general relation (after Charlu and Dutt, 1982) : where R = Recharge due to rainfall A =Area under evaluation (714 sq. km in the case of the study area), Sy = Specific yield of the aquifer. The specific yield value for different types of geological formations in the zones of fluctuations of water table area as below: i) Sandy alluvial areas : 12-18% ii) Silty alluvial areas : 6-12% ill) Granites : 3-4% iv) Basalt : 2-3% For the study area (i) is of relevance and hence can be used. h1 and h2 =Monsoon and pre-monsoon groundwater le\'els respectively. In the present case, a generalised 1.5 m can be assumed.

Groundwater Draft
The groundwater draft for all types of structures (tube wells, dug well, dug cum bore wells, etc.) has been calculated for the study area using the report given by the Group on the Estimation of Groundwater Resource and Irrigation Potential from Groundwater in Gujarat State (1986) (9) Considering the groundwater quality and population in the study area, wherein nearly 42% of the wells are polluted (where one or more water quality parameter exceeds the required limit), there has to be a drastic shortfall in the actual available pure drinking water in comparison to the calculated water draft.
From field observations, it has been seen that out of 500 dug wells in the study area, 166 are polluted; out of 2000bore wells, 600 are polluted; and out of 60 tube wells, 5 tube wells are polluted. Thus the actual and realistic water draft available is as follows: 140 L / Head / Day. 055 L / Head / Day. 015 L / Head / Day. 10% of total urban human, rural human and cattle requirements. Table 1 shows the overall water demand for the study area for the years 1981years , 1988years , 1991years and 2001 Rural (human) Cattle Industries

Agricultural Water Demand
The net irrigation water requirement for each district and taluka in Gujarat has been worked out by the Gujarat Water Resources Development Corporation. The data pertaining to the net irrigation water requirement in the study area (714 sq. km.) is 0.5 MCM / Year (GWRDC, 1981). This requirement would be reduced drastically with passage of time, as more and more agricultural land would fall prey to urbanisation or industrialization.
The future demand for water poses one of the biggest geo-environmental problems for the study area as : (i) the Mahi river bed at Fajalpur, which is a potential, futuristic, large-scale water supplier, is affected by tidal ingress and pollution, and (ii) the number of present tube-wells and dug wells which are currently polluted, do not constitute a future source for water, unless drastic measures are taken to stop pollution, and (ill) large-scale exploitation of ground-water would greatly reduce the potential in the light of erratic monsoons which are so common nowadays. year

References
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