CITY STORM WATER DRAINAGE SYSTEM -Revisiting fundamentals

Please visit my web page "Urban Tenets" at https://urbantenets.nl/

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SITUATION

No matter how well you plan Storm Water Drainage System, it often fails as it has so many missed variables, scores of design and operational dependencies, aging infrastructure and multitude of agencies to put blame on, later on.

TREND

Storm water and Urban Flood used to be two different things, but their boundaries have started to get blurred, as rainfall events are getting more unpredictable and severe due to climate change and as normal rainfall events have frequently started causing sticky urban floods that is not easily dissipated.

POSSIBLE MEANS TO DEAL WITH SITUATION

There are only couple of ways you can deal with storm water inundation and urban flood events, i.e. either move the city elsewhere OR tame the nature through uphill dams and artificial mega wetlands at outskirts OR brace the city with flood barriers OR capture and store part of runoff water allowing as much water to percolate if water table permits OR make way for water and allow storm water and floods to pass through city while assuring minimum impact and damage.

CHALLENGES

Temporal rainfall data of whatever time period used in modeling is primarily historic data, there is no consideration for future rainfall event modeling considering climate change, increasingly aggressive weather events being witnessed every passing year.

Historic Flood data doesn't consider cause and effect of flood due to slow or sometimes radical temporal change in built form and landscape of city.

Expanding cities, increasing paved areas, shrinking greens and disappearing urban waterbodies are changing the overall runoff coefficient of city converting normal rainfall event into disastrous situations and unmanaged events.

OPTIMAL SOLUTION

Instead or in addition to regular storm water network if you plan or redevelop your city as well as design buildings to allow periodic Inundation and water retention and absorption, that will be less destructive and less overwhelming then flash floods due to heavy downpour and in case of actual flood events.

It's important to keep reiterating that Multicriteria based assessment, design and scenario modeling is of utmost importance for planning any urban core infrastructure, be it SWD, SWM, Water Supply or Power Distribution.

#urbanplanning #smartcity #stormwatermanagement #sustainability #future #water #flood #swale #LID #zerowaste #urban #cityplanning #townplnaning #municipality #municipalcorporation

Thoughts on Complete Street Design

Please visit my web page "Urban Tenets" at https://urbantenets.nl/

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A lush green street, a canopy street, aesthetic avenue, rich boulevard and a street equipped to handle and harvest storm water in every part of city has been a distant dream here. Is it too difficult a dream to achieve. There are few reasons for same. A preconceived RoW template mindset which leaves very little earth or scope within RoW for landscape Architects to play with, transport modeling software only being limited to carriageway design and not the complete RoW, lack of synergy between approach of transport planning, storm water management, landscape architecture and street lighting leading to complete absence of collective vision. It cannot be solved professionally as by that time each one is rigid and wise enough to exclude most of above tasks from their respective scope of work.  Unless a transport planner will care for trees or a landscape architect will care to understand what goes into engineering of road or a water expert will have affinity and knowledge of ecology until then we won't get to experience a complete street. It has to start with education not from the desk of multi disciplinary team sitting in office. Above mentioned subjects to be made compulsory in each others curriculum for few semesters not just to teach them the technicalities but to help them sensitize about each others domain, to gain/give respect to each other and garner natural affinity about others subject so that end user could experience a complete street.

Lets restore the lifeline of city called River! #LetsRestoreRiver

Riverfront development as a tool for ecological revival.

River-edge development is about confronting the centuries of neglect towards lifeline of city called river.

It is about restoring the natural dignity of river while making some commercial sense out of it.

That riverfront was anyway thriving ecologically before city invaded the river edge.

River edge development is just an effort to restore the past equilibrium.

[Post by- Anoop Jha]

A Portrait In Mirror

Mirror, A subject of art itself - Fluid and Subjective!

Post-calamity socio-physical reconstruction: Untapped potential of urban planning!

It’s high time they should care for heritage values of shattered settlements.

Contemporary planning response : A wake-up call!! 

Any Natural calamity, An Earthquake, A Tsunami, A Flood or A Hurricane strangles the life of community and leaves a physical and emotional mark behind! Damage which is irreversible, but still people gather their spirit and strength and try to reconstruct that which has been shattered, their home, their neighborhood, their community, their village, their city, sometimes on their own sometimes hand in hand with community, with the support of government and with the aid and good wishes from around the world. It’s a collective effort of those who care to rebuild, those who feel responsibility to reconstruct, everyone contributes their bit!

A relevant question to ask here is that what an urban planner, an architect, an urban designer, a conservationist or a policy maker can do to restore the faith, hope and dignity of that community, How they can better contribute in the socio-physical reconstruction after an unforeseen natural calamity which physically shatters the settlement, a settlement which might have evolved in course of centuries whether it’s a village or a small town or a metropolitan city. Of course such situations demand a quick immediate response, a fast solution, a resettlement plan, a re-construction effort, a physical master plan to absorb and protect the affected population as quickly as possible; an infrastructure fast and techno-economically optimized enough to be viable. But in this race of providing the immediate comfort and amenities to the affected population we usually tend to forget or sometimes purposefully ignore the very basic need of community, the settlement itself, the fabric of settlement with which community has intimately remained attached throughout its life, probably they have grown together help shaping each other and hence the highly emotional bonding of community and settlement cannot be ignored neither its legacy of heritage value and learning.

In a neighborhood or community affected or devastated by natural calamity, an individual is not just bothered about his or her own loss, their own damaged house, but they are subconsciously also moved by the loss of others in the community and their very own settlement and neighborhood which has been shattered heavily. Their memories of growing in that neighborhood, those winding streets, their facades and architecture, their community spaces, those lingering familiarities and so on. We can try to reconstruct the original face of settlement if the damage is low and concealable, but sometimes they feel it’s better to reconstruct the settlement in adjacent open lands if the physical damage is much, this phenomenon is more noticeable and even more a point of concern in the rural or small urban communities. Usually physical planning response form the government and planners after a natural calamity in most of the cases is generally a super-optimized techno-economic solution, an efficient physical infrastructure, fast paced architecture, but surprisingly lacking in emotional response and nativeness in terms of architecture, lacking in regional impression and heritage values of planning, alienated from urban/ rural design principles and practices of the region, a shear absence of conservationist inputs and above all lack of human touch. Outcome seems an efficient but emotionless physical planning response which can and are being radially justified in the name of constrained resources and urgency of demanded action. Image above speaks for itself!

Though a much needed temporary relief, imagine the emotional and functional pain this new mechanical re-settlement master plan causes to the inhabitants in longer course of time through its totally alienated new physical planning environment, fabric and architecture, by continually reminding them of the disaster which occurred in past, due to its ever-present imposed unfamiliar environment. Imaging the continual struggle to adapt to this new imposed “efficient but rigid” neighborhood plan which has no relation whatsoever to the original form and architecture of the village or town which was devastated in earthquake or else and the loaded feeling of never to return to a spatial experience in their lifetime which even vaguely resembles to their original neighborhood or to a locality with its regional character! Imaging the loss to the future generation who is going to grow up in these reconstructed integrated prefab concrete township or villages with identical kind of off the shelf household unit next to the fading ruins of their devastated ancestral village and who will never know how it is like to live in the vibrant settlements were their parents, their grandparents and their ancestors used to live!

It’s high time that the legacy of heritage planning values, unique and integral to specific regions need to be acknowledged and incorporated in the post disaster reconstruction efforts specially in physical planning of the settlement which will have a long term beneficial effect. Even the communities in crying need of immediate physical reconstruction support, in a post-natural-disaster environment, need a physical planning solution with a “human touch”! 

What are the urban planning challenges today?

Inferences from review of JNNURM CDP & Appraisal Reports!

Following sectoral list of “Urban Planning Challenges” have been compiled based on data extracted and analyzed from JNNURM Comprehensive Development Plan (CDP) for selected cities of India and its appraisal reports. Though these aspects are generalized and somewhat overlapping across most of the urban nodes of Indian sub-continent, lessons and inferences can be equally valuable and applicable for other cities across the world to considerable extent. It’s just an effort to have a consolidated perspective and understanding of future urban challenges, you can further suggest additional planning constraints and challenges to the list!

Comprehensive list of Urban Planning Challenges-

INSTITUTIONAL 

Functional overlap

Jurisdictional overlap

Issues of convergence and coordination

POLICY     

Lack of stakeholder consultations or under-participation

Disaster management issues

Governance issues

Delegation of functions to the new ULB

Prioritizationof action and projects alienated from problems and vision

Matters of resource sharing with neighboring states

ECONOMIC

Lack of value-add sectors

Expansion of informal sector

Continued influx of low skill manpower from neighboring states in some cases

Expanding un-organized sector

Lower work participation rates of women at some places

SOCIAL     

Issues of urban sociology in a multi-ethnic city

Social unrest,

Civil disobedience,

Public safety,

Unemployment,

MUNICIPAL FINANCE   

Unstructured financial profile of urban local bodies

Long-term financial viability of municipal finances

Capital investment requirement

High level of dependency on state government grants

Un-assessed properties for property tax base

Tax rates not being revised regularly

Irregular flow of specific grants

Irregular servicing of debt

PROPERTY 

Low coverage of properties by taxation

Low collection efficiency,

Inefficient user charge

SLUMS & URBAN POOR       

Security of tenure

Quality of housing

Access to infrastructure

Rehabilitation and resettlement

Problem of sanitation

Community toilets

Inadequate night shelters and security

High density with poor infrastructure

Issue of ‘unapproved slums’

PLANNING 

Infrastructure deficits

Unplanned growth

Constraint on growth in city areas due to natural or environmental constraints

Increasing gap between demand and supply

Inadequacies in the basic services in unauthorized clusters

Encroachment,

Non-confirming land use

Missing link between physical and fiscal planning

Protecting, conserving and managing heritage resources

Skewed spatial density distribution

TRANSPORT

Limited road space

Shortage of public transport system

Regional traffic through the city

Inadequate management of streetlights

Problems of roads and transport during festival season

Congestion in the old city areas

Lack of facilities for NMV

Rapid increase in vehicles

Lack of land use transport integration

Inadequate facilities for physically challenged, pedestrians

Inadequate parking

Multiplicity of agencies

Missinguser interface

WATER     

Nonrevenue water

Leakages

Losses in distribution network and transmission main

Inequitable Distribution

Obsolete distribution system 

High energy cost in water production and Distribution

Ground water pollution

Water supply Vs storage capacity gap

Ground water depletion

Problems of water supply on specific festival days

O&Mproblems

Unequal intra-city distribution

Inefficient network hydraulics,

Old and dilapidated networks

Pricing and cost recovery

High pollution in distribution network

River/ Sea odor

Lack or failure of river action plans

SEWAGE   

Limited sewerage treatment facility,

Release of untreated municipal waste into rivers

Release of untreated waste into natural drains and open grounds

Disposal of industrial effluent into the city rivers,

Soft soil condition

Storm water management

DRAINAGE 

Frequent floods

Lack of proper drainage system

Silting

Uncontrolled solid waste dumping causing blockage,

Stagnation of water & waste water runoff

Backflow of water from the river system

Flooding during monsoon season

SOLID WASTE MANAGEMENT (SWM)

Absence of effective primary collection mechanism

Inadequacy of waste dumping sites

Lack of scientific waste disposal

Continued use of open dustbins

Un-segregated waste disposal

Land availability for sanitary dump sites

Issue of industrial slag

HEALTH CARE    

Inadequate bed strength

Ill-equipped and inadequate operation theatre in some government hospitals

Ill-equipped corporation dispensaries and health posts

Unsafe hospital waste disposal practice

ENVIRONMENTAL

Depletion and pollution of water resources,

Degradation of forest cover

Deteriorating air quality

High incidence of environmental health problems

NATURAL  

Earthquake

Fire

Possibility of epidemic events

JNNURM CDP & Appraisal Report Source: http://jnnurm.nic.in/citywise-cdp.html. 

Said to be the most photographed in the world…

Golden Gate Bridge

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Changing landscape of rural architecture

While scrolling, zooming in to google earth or something you find satellite image of villages across the world very fascinating very different from the urban settlement, it’s almost enchanting to look at their wonderful spatial patterns, their distributed uniformity, their hierarchical cohesiveness in terms of architecture, spatial arrangement and surprisingly it all evolved without any development blueprint, without an preconceived vision, without any kind of architectural bylaws at least in the case of India, but with long sustainable past, at least it was the case decades back and beyond.

Now today when you look at the same villages of India you will find usually two sets of clusters in most of the cases, one organically evolved village settlement with impression of time, with wonderful lively streets, with hierarchy of spaces, driven by family needs, scalable with demand, a symbol of community effort and cohesion, built by local materials, crafted by passionate local hands, using indigenous skills, planned by intuition, nourished by centuries of experience, in the guidance of wise old people, architecture by personal choice and collective regional aesthetics.

Though many of them are financially weak, but they usually have a place they can call home unlike urban poor.

The other distinct set of cluster you will see in the adjacent part of village, which is either a result of recently accumulated wealth by the young generation of villagers who live in metropolitan cities of India for better livelihood opportunities and who bring wealth to their village along with new architectural exposure and experiences, new construction techniques and remote aesthetics of cities when back home. It is architecture in transition from traditional to contemporary from thatch-&-mud to brick-&-mortar and may be its need of time as well, but little confusing at the same time. This new strikingly different grid iron pattern of recently developed cluster of village can also be a result of some development efforts by government, not so surprisingly way different an architecture and planning from the traditional settlement and sentiments. An imagination of planners and architects sitting thousand miles away with their own perception and impression of what an ideal village should be, while being most cost effective replicable, scalable and with speedy construction possibilities, neat and clean imported village with all the amenities. Hundreds of thousands of house arrays being constructed throughout the countries, apparently job done! Similar is the case of several villages and outskirts of cities across the world. 

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It’s good idea to provide shelter to poor rural inhabitants, but their traditional architecture and planning needs and sentiments cannot and should not be ignored. It doesn’t cost much to incorporate century old traditional planning and aesthetic of the rural settlement of different regions in the contemporary rural architecture and planning solutions which need to be tailored for specific regions, it’s just demands a little more  communication and careful investigation as well as understanding of spoken and unspoken lifestyle and perceptual needs of rural communities. 

Planner’s Dilemma – A case of developing nation.

Choked Public Drain, Whose fault? 

Repeatedly choked public drains, is it due to under capacity drainage Infrastructure, an unplanned network, inadequately planned disposal system, underestimated growth, unexpected demand, immigration externalities, over exploitation of resources, lack of vision, out dated technology, inefficient management, uneducated population, citizens with low or no sense of public responsibility, lack of willingness, lack of database for timely assessment, no early warning system, underreported occurrence, over hyped issues,  diverted attention, prevalence of corruption, discrete tax structure for usage of public infrastructure, lack of maintenance, insufficient funds, absence of relevant law, loophole in policies, or may be implementation failure?

Drainage/ sewage disposal issue is just an example to illustrate; there are innumerable examples and issues like this in an urban setting whether its inadequate water supply, transport chaos, interrupted and poor power supply etc, and innumerable reason for the each of these issues.  It’s a very common phenomenon in towns and metropolitan cities of developing nations, but what’s the solution.

After some time of tolerance people start losing their patience due to public infrastructure system failure like this, then some hue and cry, some demonstration, followed by media coverage, then suddenly public agencies wake up, some blame game, then some investigation committee, followed by months long survey, then few months of compilation, then some kind of outcome and recommendations, by that time people already start losing their interest in the subject, by that time there are  other hyped issues to deal with, and this show goes on. Somewhere in this cycle of events planner or some planning consultancy firm gets introduced to assess the situation and resolve the issue. Do you wonder how much or how little a planner can help to resolve the situation at least bringing down the scale of chaos.

Do you see how many vulnerable points can be there in the value chain of any system as we saw in the blocked drain example? More the number of elements more the chances of failure of system.  A system with a long operational or value chain can only work efficiently, if all the possible elements of interest work efficiently individually and cohesively together as well. When an urban planner or similar is approached by public/ private agency to resolve such development or redevelopment issues, they expect an out of box magical solution. Planners can of course suggest a wonderful infrastructure solution at some reasonable cost; they can propose some implementation and regulatory strategies as well, but one has to understand that a “multifaceted urban issue” needs an “inclusive solution”. Planners need to be empowered to have a say on any or rather every element which might affect the proper functioning of any urban or regional system, even if it’s an aspect which is tangential to the core system but which can impact the system in future. Planners have to address or at least talk about each and every tangential aspect of any core issue while suggesting a solution blueprint for development redevelopment projects. For example, one might argue how a drainage problem can be related to education of citizen, they can always say while problem like this demands infrastructure solution why to talk about education? Let’s consider this.  No matter how well you plan the infrastructure, if there are uneducated users, infrastructure is not going to work as the way it was perceived and planned. Even simply being educated is not enough, there has to be education with a sense of responsibility, a sense of citizenship.

What a planner can do in this situation for example. A planner has to talk about the relevance of educated citizens in proper functioning of the public infrastructure in its strategy report; he can go to the extent proposing restructuring of school curriculum, so that users become responsible enough toward public infrastructure while they are still in school. suppose If people are educated and responsible as well but still not using public infrastructure as intended there might be flaw in signage design or placement, planners need to talk about that in its development report, they might need to talk about the role of education through technological infusion to masses through different communication channels before they are about to introduce a new technology in public domain along with ways of infusion. Similarly they need to propose some short to long term strategic inputs for all the ancillary aspects revolving around the core public system or infrastructure issue no matter how distinct they appear.

Disposal on the go - For a cleaner city you deserve.

Disposal at the source of generation- Case of Travel generated waste!!

Environmentally responsible
waste management 

Some of us occasionally of habitually buy and carry a plastic pack of chips, a paper wrapped snack, a can of coke, a bottle of juice, a paper mug of coffee, fruits and so on in our car or other vehicles while traveling in city, and disposing those paper, plastic, metal or organic residues in a responsible ways becomes an issue. Depending on the Education level, economic exposure, existence of local transport and environment laws, pro activeness of implementation measures, people’s behavior vary in a cityscape across the region, across the cities of world. Even within a particular city people show different level of responsible behavior depending on economic profile of zone, surveillance and enforcement level.

In many cities of developing countries people tend to pollute the city roads and transit routes by dumping such food waste and byproducts from their vehicle irrespective of occupants education and economic level even in presence of such laws to prevent them, due to lack of willingness to keep their cities clean or lack of enforcement measures or absence of sensible waste disposal infrastructure. Garbage bins if provided are either so scarce in numbers, so inaccessibly located, are in utter unhygienic conditions, surrounded by mounds of open dumped waste, either overflowing of underutilized, that people even if they make up their mind to act in environmentally responsible ways they immediately lose their interest to do so.

In this particular kind of waste generation scenario which emerges on the go should have a “disposal mechanism on the go” itself. Garbage generated within vehicle should be disposed off from vehicle only at pre-identified locations, why to carry it everywhere you go, why to keep garbage in your car just because you couldn’t get the time for weeks to dispose it off on foot to some disposal bin located somewhere. Why not to stop them throwing garbage on road by providing them hygienic garbage bins approachable from within the car along the transit routes, at places where traffic is bound to be slow, somewhere near toll plaza ticket counter, somewhere near the parking entrance, in some of dedicated service lanes of the city etc. 

All the Planning Effort goes in vain if not implemented and maintained well.

Why we plan something which we can't maintain!!

Or rather why we can't also plan how to maintain the same infrastructure while we are busy preparing city blueprint and master plan. 

Infrastructure without stringent maintenance measures is like .."a plan for how to waste the precious resources in efficient way".    

An efficient infrastructure if not maintained well, leads to speedy wastage of fine resources

Blue Infrastructure strategies for Green Infrastructure

Water and related infrastructure collectively plays a vital role in wellbeing of city. Urban quality of a city can be accessed on the attention given to its water resources by the city planners and authority which includes conservation measures, utilization strategies and quality of water resources.  Quality of Water is the scale on which urban health can be measured. Water has its whole spectrum of influence from drinking water to sanitation to micro climate to green cover and varies in scale and operation from pond to river to sea and flood. Conserving and creating and managing blue infrastructure of city is the way towards greener infrastructure  and sustainable future

Integrated Infrastructure for Sustainable Urban Planning

By - Anoop Jha

Integrated infrastructure is the key to sustainable infrastructure planning. Planning at Urban or Township scale involves an intricate system of utility infrastructure like power, water, sewage, drainage, HVAC. All these utilities and services need to co-exist together while every system plays a crucial role in proper function of city as a whole. 

Integrated decentralization for planning

Integration and decentralization both have their own advantages. Integration has some fundamental befits like - optimized resource, saved time, centralized supervisory and partial control, possibility of automation, less manpower requirement, wastage control, resource efficiency etc. while decentralization presents its own set of benefits like- better management and control, output efficiency, better understanding of the system, better control, modular unitisation, replication, last mile value addition etc. but for a sustainable urban infrastructure planning a hybrid these two systems should be used which we can call “Integrated decentralization”. It would advantages both the systems fused together for best results and optimization.  

Perception of space – a function (f) of day and night

Dramatic shift in Perception of Space during Day and Night.

Day and Night, an ever existent inseparable phenomenon, it’s an external influence on the perception of space, architecture and built form, an environmental influence which alter the experience of space in dramatic way, but we pay very little attention on such a wonderful aspect of such powerful influence while planning an urban setting, or while designing interior of a building. 

In day sun light is ambient and almost omnipresent when it comes to outdoor urban setting with an interplay of light and shadow, but mostly the experience of any specific outdoor space is more or less uniform and little monotonous throughout the day, while night provides infinite possibilities to create, mould, play with space, volume and ambiance outdoor as well as indoors using variety of light sources. Volume of space is directly proportional to intensity of light source, sources of artificial light give a totally different perception on a dark night compared to day time since the space that we perceive and experience in night time. In this case the bright perceived space slowly merges into the  dark sphere of night. Hence night provides ample scope of creating user experience in an urban setting and its responsibility of planners, and architects  and landscape architects to plan and design lighting of public spaces as well interiors of a building with an aim to provide a unique experience of end use in night period. 

Definition of “Per Capita Consumption” need to be modefied - Water Sector

By- Anoop Jha

Apparently “per capita consumption” figure is used in financials, estimates and projections of every project, and DPRs across the country and across the sectors, but apparently age old definition (Per Capita Demand in litres per day per head) and formula of “per capita consumption” seem to be flawed and vague. Let’s consider Water Sector for example.

There are few reasons for this apparently flawed 

First, this formula invariably assumes that all the water is being consumed at household, institutional or community level for some useful purpose, but that is not the fact. The fact is “the collective water losses at household and institutional level are huge in any given community, settlement, or housing society”, leaking taps, pipes due to “lack of maintenance and willingness to maintain” and water wastage related to casual behavior of users “due to lack of education and sense of responsibility”  are a regular phenomenon of almost every household. Planning bodies and Policy makers have to understand that unless they stop these water losses or unless they change the definition from  “Per capita Consumption” incorporating the water losses, there demand estimates, future projections, projects cost estimates, will inevitably  be vague and skewed,

Some interesting extract from the discussion on “India Water Portal” (indiawaterportal.org) on the similar subject are as follows-

Link: http://www.indiawaterportal.org/ask/5409

“ When the norm for a large city is 250 lpcd, it doesn’t mean the residents actually get or use 250 lpcd. A large city has many other water needs such as public use in offices, railways stations, commercial places, for fire fighting, public horticulture, etc. All these are distributed over the population and indicated as per capita use” - Chetan Pandit

“The norms do not take in to account the climate. No distinction is made between Delhi that has a huge water requirement for desert coolers in summer and a bath twice a day is not a luxury; Pune that uses some coolers but not as common as Delhi and usually bath once a day is enough; and Copenhagen where the maximum summer temperature in 17 C and most of the time it is below 10 C” -Chetan Pandit

“Water consumption is affected by various factors which are variable and hence it is difficult to precisely assess the demand of public. There are empirical formulas available for estimating a fair value of domestic consumption for design of water supply systems. However, Indian Standard (BIS):1172-1993 is the basis of 135 litres/capita/day. This 135 litres/capita/person includes drinking (5 litres/capita/day), Cooking (5), Bathing (55), Washing of clothes (20), Washing of Utensils (10), Washing & Cleaning of house (10) and flushing of toilets (30 litres/capita/day)” - J.Harsha

Second, basis, thumbrules, lifestyle, requirement and related values for arriving at “standard per capita water consumption” in different urban areas changes in courses of time and cahnge as per seasonal variation which need to be accounted for calculation per standard water consumption” Standards need to be revised after a certain time interval.

“Details of present norms for water consumption are available in CPHEEO Manual on Water Supply and Treatment and Per capita water supply in selected urban centers of India is available at Water Supply, Sanitation and Solid Waste Management in Urban Areas by National Institute of Urban Affairs, 2005”

Third, accuracy of standard per capita water consumption figure is directly proportional to the size of sample (no. of household) surveyed, which may vary from agency to agency which prepares the report. Larger the sample more realistic the results would be. There should be Policy norms for minimum size of sample to be surveyed and heterogeneity of the sample.