All metro cities/urban centres in India are experiencing a period of unprecedented and rapid urbanisation:
- Among the impacts of this rapid population increase has been accelerated hard covering of surface, encroachment and pollution of drainage, impairment and loss of the lake system which was built by the early settlers manage city' water supply.
- It is prudent to note that the original cascading lake system built in various parts of INDIA, was a large-scale example of successful rainwater harnessing.
- It is likely that in the future, demand for water by the residents of urban cities outstrip the supply from concerned water bodies.
Rainwater harvesting has been envisaged as a new and alternative water source to meet the drinking and non-drinking water needs of the city. The development of large-scale rainwater harvesting may deliver other benefits to city's residents such as improved amenity and urban liveability, creation and greening of open spaces, as well as enhancement of biodiversity and environmental health.
Our Approach for Rain Water Harvesting Implementation
CWD uses sophisticated rainfall-runoff modelling methodologies for 100% capture of the rainfall-runoff generated from any catchment. We develop customized RWH solutions based on each site and requirement. Statistical methodologies such as knee-of-the-curve analysis is adopted to arrive at the optimum cost-benefit analysis of the RWH system to be implemented.
Rainwater Harvesting is performed at three levels of intervention based on the feasibility and client requirement as explained below:
- Direct Bore well Recharge: Harvested rainwater will be conveyed to recharge the groundwater aquifers through recharge pits, bore wells, shafts or inverted boreholes.
- Reuse for Houses: The rainwater collected from rooftop of buildings are collected and stored in storage tanks. This water can be filtered and pumped to overhead tanks for all domestic water consumption purposes.
- Recharge of soak pits: All the excessive surplus water can be used for recharging the unconfined aquifers through soak pits.
Hydrogeological studies help in identification & characterization of aquifers, assessment of quality and quantity of groundwater source and also to identify the suitable locations for tapping ground water to overcome the scarcity of fresh water requirements and allied activities.
Hydrogeological investigation involves collection, analysis, and interpretation of subsurface & groundwater data.
Our Approach for Implementing Hydrological Studies
We conduct hydrological investigation procedures in compliance with the Gazette Notification dated 24th Sep 2020 - The guidelines issued by the Central Ground Water Authority to regulate and control ground water extraction in India.
- Existing literature and data pertaining to study area collected during the site survey shall be reviewed for knowing the complexity of the terrain.
- Hydro meteorological data like rainfall, groundwater levels, ground water quality, aquifer characteristics, geology, soils collected shall be analysed before carrying out the field investigations.
- The total water demand for the project has to be ascertained and the actual availability at present is to be calculated to plan for future development.
- Rainfall and groundwater fluctuation data of long term (at least for 10 years) of nearby rain gauging and observation wells will be analysed for trend and the same has to be correlated for estimating their interrelation and sustainability of source.
- For the field tests, flow modelling will be carried out to assess the divergent and convergent flow conditions to assess the nature of subsurface water.
- Isogram maps of various parameters, groundwater level and groundwater table maps of the study shall be generated, using GIS techniques and are to be correlated with each other to identify critical conditions, if any.
Design of Water Distribution System
The purpose of the water distribution network is to convey wholesome (treated) drinking water to the consumers
Water distribution system usually accounts for 40 to 70% of the capital cost of the water supply system, depending upon the lengths of streets and roads to be covered in the project area. As such, proper design and layout of the network is of great importance.
DISTRICT METERING AREAS
District Metered Areas (DMAs, also called sectorization) is one of the most promising methods of improving the water supply qualitatively and quantitatively.
The importance of DMA division is justified by:
- Better monitoring. Smaller regions can be monitored better than a large unified network. By separating the network into zones, the manager of a water system can directly detect and localize the area which has water loss problems.
- Uniform pressure across the Water Distribution Network( WDN). It has been proven that pressure is one of the most critical parameters affecting pipe failures and thus water loss.
Water Audit Systems
Why do we need to conduct Water & Energy Audit Systems?
Water audits are primarily tools used for controlling water loss. A water audit is followed by an intervention to identify the losses and implement solutions and an evaluation of the intervention measures and the need for further improvement.
A Case study of Water Consumption at a typical 'Cement Plant' includes provides the following insights on the different processes that consume water like equipment's cooling, Gas Conditioning Tower/Down comers, Coal Yards, Limestone yards and for domestic needs as well:
- The plant usually requires a minimum amount of water per day for smooth functioning. The water distribution network used for transporting water to various places of requirement will be studied and areas of unscientific water usage, excess usage, water loses will be studied to determine the efficiency of the existing system.
- Flow measurements can be recorded using Ultrasonic flow meters at the source and consumption defining locations to arrive at the Water balance sheet of the water distribution network.
- Unaccounted water loss will be noted from various cooling systems of the plant.
- Engineering Solutions like refurbishing of the existing cooling systems, water proofing of the retaining structures, installation of side stream filters to increase cycles of concentration thereby efficiency, replacement of scaled pipes with new ones to reduce wastage and energy consumption/pumping cost can be suggested to improve the Water Use Efficiency at the Plant.
Lift Irrigation Schemes
Which agricultural lands require Lift Irrigation systems?
Lift Irrigation systems are designed where the gravity flow of water by canals or river is not available or used.
Agriculture & allied sectors roughly account for about 80 per cent of the current water use in India with Irrigated areas accounts for nearly 48.8 per cent of the 140 million hectares (mha) of agricultural land in India. As such, India has many ongoing Lift Irrigation Projects to enable food security in India.
The technical approach to designing Lift Irrigation Projects:
- Lift Irrigation Projects primarily are designed to carry water by means of pumps from the water source to the main delivery chamber, which is situated at the top most point in the command area.
- Subsequently, they will be designed to distribute this water to the field of the beneficiary farmers by means of a suitable and efficient distribution.
Lake & River Rejuvenation - Restoration
Lakes are important part of any urban ecosystem. These water bodies, whether man-made or natural, fresh water or brackish play a very vital role in maintaining environmental sustainability, from being a source of drinking water, recharging groundwater, acting as sponges to control flooding, supporting biodiversity and providing livelihoods.
Rapid urbanization demanding for land in many parts of the India, including Bengaluru, has posed a serious threat to natural resources around urban areas.
“It shall be the duty of every citizen of India, to protect and improve the natural environment including forests, lakes, rivers and wild life, and to have compassion for living creatures” (Article 51A -Constitution of India)
CWD's expertise in Hydrology and Hydraulic Modeling makes for a holistic analysis for the restoration of Lake-River Chain Systems:
- Watershed Delineation using SRTM DEM elevations to analyse the catchment behaviour.
- Profiling of Surface water lakes for quantification of extreme precipitation.
- Profiling of Surface water lakes for quantification of extreme precipitation.
- Reducing the phenomenon of urban floods by connecting the neighbouring lakes horizontally through 'Rajakaluves'.
- Replenishing the ground water by connecting the lakes to the ground water channels vertically through recharge shafts.
- Revival of Storm Water Drains by construction of eco-friendly Vegetative Swales
- Project Monitoring and Maintenance through a cloud-based productivity enhancement application technology.
- Study of Sewage Treatment Plants around the Catchment, Identification of Sources of Contamination - Separation of sewage from storm water
- Engage Community at all levels and ultimately hand over the maintenance and upkeep of the lake chain system.
Flood Frequency Analysis
Flood frequency analysis is a technique used by hydrologists to predict flow values corresponding to specific return periods or probabilities along a river/lake.
The application of statistical frequency curves to floods was first introduced by Gumbel.
CWD uses various statistical tools to arrive at the necessary inferences. These include:
- Site visit and investigation at the core area/plot area and other relevant catchments around study area.
- Study of the local drainage (streams/nallahs/creeks/tanks/ponds etc.) in the project area and buffer area through Survey of India (SoI) Topo Sheet/remote sensing data and field visits.
- Review and analysis of rainfall information to arrive at required design storm scenarios
- Estimation of peak rainfall intensity for different durations for various return periods.
- Estimation of flood hydrographs considering historical as well as design rainfall to suggest complete scheme for storm water drainage of project and its adjoining areas including diversion of existing nallahs/streams, if any. In case short interval observed rainfall, runoff data would be not available then the standard regional approaches will be used for design flood estimation.
- Estimation and routing of design flood hydrograph through the drainage system of concerned catchments considering appropriate boundary conditions including pre-project scenario as well as post-project scenario for suggesting Safe Grade Elevation for the plant.
- Infiltration model studies with recommendation on type of rain water harvesting systems depending on ground water table and their soil permeability characteristics.
- Flood modelling studies covering the detailed information related to highest flood levels in and around the project site with recommendations on proposed filled finished ground levels for project site.
Design of Water Utilities for Plotted Development
TWMS makes sure that with scientifically engineered RWH system, groundwater table is always recharged.
Properly designed RWH, WTP, STP and Greywater System ensures reduction of water usage there by reducing the monthly water bill and most importantly dependence on potentially contaminated tanker water. This water security is for long-term future with cost savings at various stages.
Total Water Management Solution (TWMS®) for developing the site as a residential neighborhood with 100% water security.
Multi-fold objectives of TWMS can be summarized as below:
- Providing effective rain water harvesting solutions (RWH) that captures nearly 100 % of runoff generated from the annual rainfall at the site.
- Depending upon the site, the RWH design will focus on recharging the groundwater table directly or filling up the fresh water tank for direct use.
- Water Treatment Plant (WTP) will be designed based on the IS10500 lab test results to give residents best potable water with adequate hardness and free of any contamination.
- Biogas plants for Organic & Kitchen Waste
- Packaged MBR (Membrane Bio-Reactor) Sewage Treatment Plant (STP) is the most sophisticated STP technology available that gives consistent Odor, color and pathogen free treated water.
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