Five - point guidelines for urban development with groundwater dimension

Urban Groundwater Supply Management: Objectives, Problems and Mitigation Measures
Objectives	Problems experienced	Targets	Mitigation Measures
1. Maintain groundwater supply	Declining in well yields due to falling watertable	Constrain groundwater levels	Redistribute/reduce abstraction (includes mainsleakage reduction) Increase urban recharge
2. Safeguard groundwater quality	Unacceptable water quality for potable uses Excessive treatment costs Secondary quality nuisance effects	Moderate subsurface contaminant load	Restrict contaminant loading by identified sources, especially on vulnerableaquifers Restrict density of residential develop-ment in vulnerable areas Selective control of industrial effluents Zone land for different uses Control landfill location and design Separate waste disposal from groundwater supply spatially
	Increasing salinity due to river water intrusion Induced contamination	Constrain groundwater levels	Redistribute and/or reduce abstraction Modify depths of water supply boreholes
	Contaminants mobilized from contaminated land by rising water table	Constrain groundwater levels	Increase abstraction of shallow polluted groundwater for non-sensitive uses Reduce urban recharge

Urban Groundwater Problems And Management Requirements
Underlying Cause	Resultant Problems Groundwater	Management Requirements
1. Inadequately controlled groundwater abstraction	Over abstraction of good quality resources within city limits Over abstraction of good quality resource around city periphery (competition between urban supply and agricultural irrigation)	Reserve good, deeper groundwater for sensitive uses and encourage use of shallow, poor groundwater for no sensitive uses Reserve good groundwater for potable supply and substitute treated waste water or shallow, poor groundwater for irrigation
2. Excessive subsurface contaminant load	Contaminant of municipal water supply boreholes / well fieldsGeneral widespread contamination of groundwater	Define source protection zones for priority control of surface contaminant load Reduce contamination load in selective areas, especially where aquifer is highly vulnerable, by appropriate planning provisions or mitigation measures Plan waste water treatment / landfill disposal sites taking account of groundwater interests and impacts
3. Excess urban infiltration	Rising water table beneath city causing: Basement flooding Malfunction of on-site sanitation units Reversal of aquifer flow directions (with contamination of per urban wellfields by polluted urban groundwater)	Reduce urban infiltration by: Control of mains leakage Reducing seepage from on-site sanitation unit by mains sewerageinstallation Increase abstraction of shallow (polluted) groundwater for nonsensitiveuses

Conclusion
Groundwater is not only essential for a supply of drinking water, and for nature and agriculture; it also makes an important contribution to creating a pleasant and attractive living environment, one with recreational value. For this reason we need to take more account of the opportunities offered by water when designing new urban areas and infrastructure. We should 'go with the flow 'of natural processes more in urban planning and designing the land use to improve the living environment. For good management, only that portion of the overall recharge should be abstracted which is not needed by the ecology, ensuring protection of groundwater from all contamination, developing new principles in urban water resource assessment and management with minimum anthropogenic impacts. Opinion should be selected with changing effectiveness and performances of water-uses, based on a stepwise process of generating detailed scientific information packages on hydro-geological characteristics of the groundwater flow field and the contaminants dynamics under natural and stressed conditions.

References

1. Delhi 1999- A Fact Sheet, NCRPB, New Delhi.
2. Carrying Capacity Based Developmental Planning of NCR (1995), NEERI, Nagpur.
3. Foster S, R.A.Hirata, 'Groundwater Pollution Risk Assessment- A Methodology using Available Data', Lima, Peru: WHO/PAHO/PACEPIS.
4. P.S.Datta,'Groundwater Situations in Delhi: Red Alert' (1999), NRL/IARI publication.
5. P.S.Datta, S.K. Tyagi,'Groundwater intermixing model and recharge conditions in Delhi area as derived fron Oxygen- 18 and Deuterium', Sub-Surface Water Hydrology,(1995), Kluwar Academic Publication, Netherlands.
6. P.S.Datta,'Stable Isotopic Investigation for Groundwater Management and Sustainable Environment: A case Study of Delhi Region'(1997), NRL/IARI publication.