Five - point guidelines for urban development with groundwater dimension



Guideline 3
Ensuring enough room for water: 'Catch water where it falls'
Retaining water helps prevent flooding. In the areas around the main rivers measures to improve the safety can go hand in hand with habitat creation. Raising the water storage capacity by lowering the ground level of the river fore lands and / or moving the dikes further back offer further opportunities for nature development. Widening ditches and watercourses and raising the drainage level can further increase the water storage capacity. Rainwater, for example, can be infiltrated into the soil instead of being drained away as quickly as possible to the sewer, while planting woodlands and less intensive drainage of agriculture land help to hold water in the soil for longer. A beneficial effect of giving water more room is the greater opportunity it presents to make use of natural filtration and water purification processes. Natural water systems have the ability to remove the nutrients from surface water; nitrogen compounds are broken down and phosphate is fixed. As an added bonus of retaining water, natural treatment can in future play a more important role because area-based measures will continue to be necessary, despite a stronger focus on tackling pollution at source.

Guideline 4
Controlling Excessive Subsurface Contaminants Load And Ensuring Sufficient Clean water - now and in future
  1. Defining source protection zone for priority control of surface contaminants load. Water pollution problems can be partially minimised or controlled by delineating source protection zones around major groundwater catchment areas at regular intervals and eliminating pollution within these zones.

  2. Reducing contaminants load in selective areas, especially where aquifer is highly vulnerable, by appropriate planning provisions or mitigation measures. To moderate the subsurface contamination to acceptable levels by considering the vulnerability of local aquifers to pollution, land use planning to reduce potential pollution sources, and selecting controls over effluent discharges and other existing pollution sources.

  3. Planning waste water treatment / landfill disposal sites taking account of groundwater interests and impacts.
Guideline 5
Institutional Framework and Social Dimension
To improve groundwater management, a strong institutional framework is prerequisite, and the ideal framework would include legislation:
  1. To provide clear definition of water use rights (separate from land ownership) through granting of licences and levying of charges for groundwater exploitation in a specified manner.

  2. To prescribe that the discharge of liquid effluents to the ground, the land disposal of solid-wastes, and other potentially polluting activities need legal consent / or planning approval.
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.
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