Current Science

Vikram Soni ¹, Shashank Shekhar ², Diwan Singh ³

Affiliations
1 Jamia Millia Islamia University, New Delhi 110 025, IN
2 Department of Geology, University of Delhi, Delhi 110 007, IN
3 Natural Heritage First, B49A, Vasant Vihar, New Delhi 110 057, IN

Abstract

With an eye on all the natural functions of a river, the present article considers the flow of the river Yamuna in Delhi as an example of monsoon rivers in India. About 80% of the total virgin flow of Indian rivers is during the monsoon period and the remaining 20% is during the non-monsoon period. In case of the river Yamuna in Delhi, we find that at least 50% of the vir-gin monsoon (July to September) flow is required for transport of the full spectrum of soil particles in the river sediment. A similar flow is needed for adequate recharge of the floodplain aquifers along the river. For the non-monsoon period (October to June), at least 60% of the virgin flow is necessary to avoid growth of still-water algae and to support river biodi-versity. We conclude that about 50-60% of the virgin flow is necessary throughout the year to maintain the health of the river system.

Keywords

Algal Choking, Environmental Flow, Flushing Flow, Monsoon Rivers, Sediment Transport, Soil Particles.

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Vikram Soni ¹, Shashank Shekhar ², S. V. N. Rao ³, Suman Kumar ², Diwan Singh ⁴

Affiliations
1 Jamia Millia Islamia University, New Delhi 110 025, IN
2 Department of Geology, University of Delhi, Delhi 110 007, IN
3 Water and Power Consultancy Services (WAPCOS), Hyderabad 500 004, IN
4 Natural Heritage First, Vasant Vihar, New Delhi 110 057, IN

Abstract

Cities world over are facing drinking water problem. The planners are often over emphasizing on sourcing surface water from far off places. This will involve exorbitant cost and many a times diversion of river flow beyond the permissible limit. Obviously such river flow diversions will have adverse ecological consequences. In this context, the article reinvents traditional knowledge with sound scientific rigour. It argues for ecologically sustainable local solutions for meeting drinking water need of cities from flood plain of rivers. A case of river Yamuna in Delhi has been discussed to highlight the potential of flood plain aquifer as a drinking water source.

Keywords

River Floodplains, Quality Drinking Water.

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Aryaman Jain ¹, Shashank Shekhar ²

Affiliations
1 Delhi Technological University, Delhi 110 042, IN
2 Department of Geology, University of Delhi, Delhi 110 007, IN

Abstract

Urban agglomerations in India of late have started facing drinking and domestic water scarcity. The city state of Delhi has witnessed accelerated urbanization and an exponential growth in population. In this context, it is desired to locate sustainable groundwater resources in Delhi. This communication examines the northern stretch of the Yamuna floodplain system in Delhi with respect to source sustainability. An aquifer can sustain extensive exploitation only if it is replenished regularly. Though the river floodplain system gets recharged by monsoon flooding, the recharged water may not sustain the source aquifer until the end of summer. Thus before exploitation all floodplains have to be examined vis-à-vis regional groundwater dynamics. In this context it was found that the floodplain system in the northern stretch of River Yamuna receives considerable regional groundwater flow. Some of this also contributes to river flow. The present study has estimated regional groundwater flow in this aquifer stretch of the Yamuna river system as 10,513,460 m³/yr (~11 MCM/yr). Besides, the yearly baseflow contribution to the Yamuna in the study area has been estimated as 518,472 m³/yr (~0.5 MCM/yr).

Keywords

Baseflow, Flownets, Floodplain, Regional Groundwater Discharge, River System.

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Vikram Soni ¹, Shashank Shekhar ², Vikrant Jain ³

Affiliations
1 Jamia Millia Islamia University, New Delhi 110 025, IN
2 Department of Geology, University of Delhi, Delhi 110 007, IN
3 Discipline of Earth Sciences, IIT Gandhinagar, Gandhinagar 382 355, IN

Abstract

The present article highlights the need for a clear techno-legal definition of the river floodplains in India. In the context of environment protection, it reviews some of the recent judgements passed by the National Green Tribunal of India (NGT) pertaining to protection of the river floodplains. The inconsistency and differences in the legal arguments pertaining to the definition of river floodplains are highlighted. The geomorphic and hydraulic approach used for defining the floodplain of a river are discussed. It has emerged out from the discussions that the only abiding and faithful definition of the floodplain is its hydro-geomorphic character. This is manifested by sand, silt and clay and various geomorphic units associated with the depositional activity of the present day river.

Keywords

Embankment, Environment, Floodplain, Geomorphology, Hydrology, Hydro-Geomorphic, National Green Tribunal, Techno-Legal.

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Arkaprabha Sarkar ¹, Vicky Shankar ¹, Vimal Singh ¹, Iain Stewart ², Shashank Shekhar ¹, Vinayak Sinha ³

Affiliations
1 Department of Geology, Center of Advanced Studies, Chhatra Marg, University of Delhi, Delhi 110 007, IN
2 Royal Scientific Society, Amman 11941, Jordan, IN
3 Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research, Knowledge City, Sector 81, SAS Nagar, Manauli PO 140 306, IN

Abstract

With urbanization, cities are becoming new landscapes, significantly altering the properties, processes and pathways of previous natural environments. The natural critical zones that have existed for millennia are rapidly getting modified by the superimposition of the urban components to give rise to a new critical zone system, viz. the urban critical zone. The clogging and bypassing of the natural process pathways and the increasing demands of urban populations for ecosystem services put the native critical zone and the adjoining zones under stress. To elucidate this point, we present a case study on Delhi, the capital city of India, to demonstrate how the urban critical zone is unsustainable. We exemplify the increasing demand and supply gap of basic ecosystem services, such as clean air and water, that are essential to sustain life. In doing so, we redefine the limits of the critical zone in urban areas, recognizing that significant parts of cities are beyond the presently defined critical zone.

Keywords

Ecosystem Services, Natural Environments, Planetary Boundary Layer, Sustainable Development, Urban Critical Zone.

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