Development of an ecologically sustainable strategy for growth of urban areas & conservation of nature as an integral part of urban development
· Define the region of urban growth & evaluate it for carrying capacities & ecological footprints
· Propose sustainable future development of the urban area
· Favouring dependence on local resources, & charting growth based on their availability
· Develop a proactive control & land use allotment system
Land is the platform on which terrestrial beings survive & thrive. Humans have developed a complex social order based on resources generated directly or indirectly from land. Since the last century, human settlement pattern is shifting towards increased urbanization. An urban region is an area of intensive human activity. Ecological footprint of such a region exceeds many times its physical area, since the density of humans usually far exceeds the carrying capacity of the region. It results in a large stress on surrounding regions. In order to maintain an ecologically sustainable development for urban areas, future growth must be directed based on natural resource availability & conservation.
Ahmedabad is located in the centre of Gujarat State, spreading in the Sabarmati basin on both banks of the river. It forms a vital transport & trade link to the vast landlocked areas in the north & east. Historically too, Ahmedabad was the main trading hub for goods shipped to & from India via the port of Cambay. Under the British rule, it became home to numerous textile mills, being known as “Manchester of the East”. Today, it is a major industrial & trade hub, having about 25% of the total industries in the state.
The city is unable to meet its resource needs by itself, depending on an intensive transport & infrastructure network to sustain itself. Its ecological footprint for civic amenities extends up to Mahi River for sourcing water & Gulf of Khambhat for disposing wastes into the sea. While residents of Ahmedabad may benefit from a compact urban community, they unknowingly play hosts to high indirect costs borne by civic authorities & uninvited costs to residents of the surrounding regions, along with destruction of ecology.
4.1.1. Climate: The region experiences a semi-arid climate. The mean maximum & mean minimum range of 40ºC & 11ºC respectively. The average annual rainfall is 700mm & rainy days are 30 to 45.
4.1.2. Topography: The region is generally flat with the exception of a few sand-hills & a series of sections cut by rivers flowing across the region. The chief feature is river Sabarmati, dividing the city into two different regions. The western part is resource poor while the eastern part is resource rich.
4.1.3. Surface Water & Drainage: The region is divided into two distinct parts by the Sabarmati River. The western region is poorly drained due to absence of any major rivers. The eastern region is well-drained since it falls in the Sabarmati River basin. The drainage is primarily through sheet flow, & leads to formation of lakes where undulations disallow drainage into the nearby river.
4.1.4. Groundwater: The groundwater recharge potential is high due to sandy well-drained soil character. Inadequate rainwater recharge in the urban areas is leading to depletion in water levels over the last few decades. Groundwater is found at a depth ranging from 10 to 120 metres in the area. Groundwater in the City, Sanand & Daskroi talukas has been categorized as Over-exploited (>100% of annual recharge is utilized).
Water Supply for Ahmedabad City
Due to Dharoi Dam upstream, Sabarmati has fallen short of providing water supply requirement to the city & acts only as a sewage disposal channel. Ahmedabad depends highly on groundwater, with 658 MLD coming from various bore-wells of the municipality. The groundwater level has fallen to more than 90m & the city faces issues of high TDS & soil salinity.
4.1.5. Soils: The western side of the river has less fertile soils while the eastern part has more fertile soils. The soil depth varies from 45-90 cm & irrigation potential of the area varies from unsuitable to high. The soils range from deep sandy with good drainage to loamy in character.
4.1.6. Ecology: The region is characterized by human induced ecosystems, dominated by agriculture. The typical forest type is arid scrub forest, but there are no natural forests in the area. The only natural wildlife areas in the region are Thol & Nal Sarovar lakes where migratory birds breed in winter. Riparian zones are subjected to development pressure like sand mining for construction, river bed agriculture, industrial effluent drainage, etc.
Geology: Bedrock layers, faults, aquifer system, catchments, denudation & deposition
Topography: Slope, drainage, relief, watersheds, floodplains & water logging areas
Soils: Depth, texture, moisture, erosion, porosity, salinity, sodicity, mineral composition
Climate: Temperature regime, rainfall, humidity, wind regime
Humanity is leaning towards increasing urbanization. Dense pockets of human activity draw resources from surrounding regions & deplete them. Such irresponsible usage of resources is not sustainable in the long run, and affects the quality of life over time.
Allocation of resources in a sustainable manner will allow better utilization and future security. Applying the same premise to urban areas, it is necessary to direct their future growth based on locally available natural resources.