|
|
|
Five - point guidelines for urban development with groundwater dimension
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.
- 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.
- 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.
- 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.
- 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.
- Raising storage capacity in the river basin through habitat creation, landscaping and establishing outdoor recreation areas.
|
|
|