Five – point guidelines for urban development with groundwater dimension

Five – point guidelines for urban development with groundwater dimension

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Venkatesh Dutta1, Suresh K. Rohilla2 & Dr. P. S. Datta3
1 School of Environment Management, Guru Gobind Singh Indraprastha University,
Kashmere Gate, Delhi – 110 006.
2 Project Officer, National Capital Region Planning Board,
Ministry of Urban Development, New Delhi.
3 Principal Scientist, Nuclear Research Lab. Indian Agricultural Research Institute (IARI)
Pusa Campus, New Delhi.

Abstract
Urban development has taken insufficient account of local hydrological and hydro-geological conditions. Groundwater is often degraded because of a lack of knowledge of the aquifer system and/or uncontrolled groundwater development. For socio-economic urban development and ensuring availability of potable water, scientific assessment of groundwater recharge characteristics over time and space, the extent of the groundwater pollution and impacts of over-exploitation on the resource base are very important factors. Modeling groundwater is difficult because of the inaccessibility of the plume below the ground surface and the heterogeneity of porous media. Groundwater moves very slowly, on the order of 1 cm per day, so it takes a long time for contamination to reach a drinking water aquifer. The residence time of the water in the surficial aquifer is likely to be on the order of decades, and deep aquifer waters are thousands of years old. So the good news is that it takes a long time to pollute an aquifer, but the bad news is that once the aquifer is contaminated, it will probably take a very long time for natural restoration. Further, due to heavy withdrawal of groundwater, the water table is constantly in motion adjusting its surface to achieve a balance between the recharge and outflow from the subsurface storage. In a general sense, the water table follows the topographic features of the surface superimposed with rate of pumpage and extraction. Urbanisation has had a profound effect on groundwater resources, which is inextricably linked with land use and waste disposal practices in a complex fashion The levels of contaminants in groundwater also varies spatially and temporally depending on hydrogeology of the groundwater flow field, recharge characteristics, surface run-off pattern, groundwater-surface water interaction in relation to land use changes and dynamics of the contaminants under natural and stressed conditions. This paper provides a framework for the proper and systematic consideration of the groundwater dimension in urban planning and management of groundwater resources in urban areas.

Introduction
Groundwater is an important source of clean drinking water in many areas, but sustainable management has not yet been established for many of these resources. The capacity for land to retain water is shrinking all over the world. Water is discharged at an ever-increasing rate as forests are felled and the land is drained and built up. And yet, changes are still being made to land use with little or no heed to the longer-term consequences and the impacts on downstream areas. Natural water bodies have become the repository of the wastes products of human activities. There is little natural water storage capacity left, resulting in flooding of low-lying areas during periods of very wet weather. By taking appropriate measure, new development can be built with water. In urban planning practice such measures have included reducing sewer overflows, improving the quality of treatment plant effluent and preventing falling water tables in areas around towns and cities. Concrete measures are possible for tackling the dispersal of pollution in water, in which both water management and spatial planning have an important role to play. Taking more account of water in urban and landscape design, a FIVE-POINT GUIDELINES for urban planning with groundwater dimension is proposed. These guidelines will allow water managers, spatial planners and environmental managers to communicate more knowledgeably with each other, and development can be planned and adapted in pursuit of environmental objectives to supplement policy measures for tackling groundwater related problems. This means more clean water in areas for agriculture, nature conservation and habitat creation water-based recreation, residential development, water storage and drinking water abstraction, coupled with measures to counter water loss and raise the amenity and recreational value of the landscape. The feasibility of using groundwater dimension in spatial planning and the practical changes and administrative and organisational requirements for developing the water system approach can be planned according to these five-point guidelines. The five-point system approach to developing spatial policy is a working method in which the mutual relations between changing land uses and the internal functional integrity of water system plays a central role. These principles should not be used in isolation but in combination to allow better coordination between the various decision-making processes.

Guideline 1
Use of `Hydrological Design Principles’ As A Basis for Making Spatial Planning Decisions or Design of Land Use Patterns.

  1. The Catchment Planning Approach This approach aims to assemble land uses or activities with compatible environmental requirements in each catchment area or drainage basin and to prevent peak discharges. This is achieved by allocating land use profiles to each catchment area and by taking measures to maintain or increase the water storage capacity within the catchment areas. In the catchment area management plans, attention is to be paid to both water quality and quantity aspects, which are to be managed with the ultimate goal of achieving an ecological balance with the landuse activities.
  2. The Location Approach This approach aims to order the various land uses and activities within each catchment area so that they affect each other as little as possible. Land uses that place greater demands on water quality are located upstream of more polluting ones, while locating more vulnerable uses in areas of groundwater seepage implies placing certain requirements on activities in the infiltration areas. Clean land use activities should be practised in the infiltration areas.
  3. The Buffering Approach This approach is used to allow land uses with incompatible environmental requirements to co-exist. A well-known example at the local level is the hydrological buffering of natural sites from surrounding agricultural land. This can be achieved through appropriate design and management measures, which can be relatively easy and quick to implement.

Guideline 2
Establishing An Integrated Approach To Land Use Activities, Groundwater Systems And The Environment.

  1. Water Storage, Habitat Creation and Natural Water Treatment combined with new Urban Development. In various places where the abstraction of drinking water causes damage to nature, water may be abstracted elsewhere instead. In some cases, groundwater abstraction should be stopped in favour of riverbank filtration. Water from the river can be pumped into the ground under the banks and later abstracted when it has been sufficiently filtered by passing through the sand and clay in the sub-soil.
  2. Raising storage capacity in the river basin through habitat creation, landscaping and establishing outdoor recreation areas.

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.