I concur with Rizal.

You can also employ both Structural flood mitigation measures

i. Construction of dams for the purpose of river regulation;

ii. Construction of flood protection dykes as a short term measure;

iii. Construction of drainage channels;

OR Non structural flood mitigation measures

i. Undertaking river training works;

ii. Undertaking soil conservation measures;

iii. Establishment of early warning system;

iv. Assessment of climatic time series (climatic variability and climate change);

v. Study of the catchment characteristics;

vi. Floodplain mapping; and

vii. Proper delineation of the floodplain.

Maybe you can make some like a water retention, biopori, and etc. Or another way you can do reboitation.

Or if your country have a lot of money. You can make "multi-function tunnel" like in malaysia. Or you can make some

Dykes and buy some pumps.

I concur with Rizal.

You can also employ both Structural flood mitigation measures

i. Construction of dams for the purpose of river regulation;

ii. Construction of flood protection dykes as a short term measure;

iii. Construction of drainage channels;

OR Non structural flood mitigation measures

i. Undertaking river training works;

ii. Undertaking soil conservation measures;

iii. Establishment of early warning system;

iv. Assessment of climatic time series (climatic variability and climate change);

v. Study of the catchment characteristics;

vi. Floodplain mapping; and

vii. Proper delineation of the floodplain.

you can also deploy water sensitive urban design to help reduce run-off in urban areas. These are things like grass swales, pavements which reduces runoff and allows filteration into the ground water.

Also in Australia there is alot of work on designing rain water tanks for the city environment to capture rain water as a resource rather than letting it go to waste.

Hi,

It is quite difficult to answer your question without knowing exactly the hydrological and hydraulic situation. Nevertheless I would first sugest to create retention areas (polders) so that minor events will not create flooding situations. This mesure should, in my opnion, also be complemented with a flood forecasting system that will warn population for larger events.

Hope this could help a little bit.

BR

Christophe

Hi,

There are lot of solutions and really you have to know a bit of local situation, I can suggest not a single solution but some literature where you can look in and search if this is reasonable for your situation. I believe these book should be in your university library or national library architectural section:

- Land&Scape series: Waterscpaes. Using plant systems to treat wastewater; by H. Izembart and B. Le Boudec (EDitorial Gustavo Gilli, sa) 2003

- Basics. Ladscape architecture. Ecological design by N. Rottle; K. Yocom (AVA publishing, sa) 2010

- Water Sensitive Urban design. Principles and inspirations... by group of authors (Jovis) 2011

- Low impact development a design manual for urban areas (University of Arcansas) 2010

- Ecological Urbanism by M. Mostafavi with G.Doherty (Harvard University; lars Muller publishers) 2010/2011

-Water urbanisms by group of authors (Uitgeverij SUN and authors, Amsterdam) 2008

I hope this could help for beginning,

take care,

Ilze

Think retention and infiltration around your low-lying city, but also what ecosystem services that this could provide for local land managers (i.e. farmers). The two should go hand in hand, because engineered solutions usually just get blown out. If there is an incentive for people to benefit from using the flood waters, then they will manage it, and this is the key to success. For example, developers started buying up rice paddy lands in Nepal(I believe it was Nepal, I may be wrong about the location) and flooding occurred. Nepal then protected at least some rice fields, and the fact that some farmers lifestyles were subsequently protected makes the flood protection more sustainable.

In addition to the drainage improvements and flood control structures mentioned above, you can consider making some modifications to the structures in the flood hazard area to make them more resistant to damage when flooding occurs. Some of the things you can do include:

-Elevating existing structures or building new structures so that the living/usable area is above the flood level; alternatively, using the first floor only for non-living uses such as storage and parking

-Building openings into walls so that water is allowed to enter the building when it floods--this allows hydrostatic forces to equalize and minimizes the potential for structural damage, though increases the potential for damage to the contents inside the building (you can use flood damage-resistant materials to help minimize damage)

-Using flood barriers to prevent water from entering a building, either by strengthening a structure's walls and adding shields over doors and windows or by building a floodwall around the structure

FEMA offers a lot of guidance about protecting individual buildings from floods. FEMA 312 is the Homeowner's Guide to Retrofitting (available here: http://www.fema.gov/library/viewRecord.do?id=1420) and offers an overview of flood mitigation techniques. FEMA 259 (available here: http://www.fema.gov/library/viewRecord.do?id=1645) goes into additional technical detail about protecting individual structures. The National Flood Insurance Program Technical Bulletin Series (available here: http://www.fema.gov/plan/prevent/floodplain/techbul.shtm) offer information about specific mitigation techniques within the parameters of the US's National Flood Insurance Program.

Flexible foundations on an up and down direction with floating technology underneath so as the water rises the city does too and is anchored in a vertical axis.

Cheers

I agree with Timmy Selles's opinion that we should discuss how we can make and live urban cities in flooding sites with in nature. For example, last summer in Seoul, South korea, Woomyun-mountain was a landslide due to foolding and over-developing like as park or apartment followed by slope.

Prevention of flood is not a good idea. Most of the time preventive measures such as embankments interrupt natural flow of water. It may create most devastating and intense flooding for the neighbor community. Now it is the time to accept floods with minimum losses and sufferings. Flood risk reduction might be the main concerns not flood prevention.

Provide safe passage to drain out flood water and use rain water harvesting technique to preserve it.

Initially I would have clarified the hydrology. Then I will try to define the boundaries of the areas that I want to protect. I will make the estimation of my possibility and will decide can I took up the entire area at once. If the restrictions are defined, it has to graduate priorities. For such designated areas would be protected it has to clarified his relief, and in the same time I would not underestimate the importance of other unprotected areas. An important step is also clarifying the geology of the priority areas and have in mind the filtration process as a possible factor which can compromise a traditional defense. If this option is accepted, will need a good hydraulic assessment. In the case of the appropriateness of such protection more filtration or poor material for local prevention equipment, or just a bad hydraulic conditions (low speed, small hydraulic gradiuent, large and expensive equipment, inability to build and bank consolidation) is good to consider the possibility of using new materials and technology. These materials or technologies have to be consistent with the climate conditions. It should not be underestimated and the drainage network must be suitably combined with other facilities. If these measures are ineffective is better to make deployment of adequate water amount retention facilities.Naturally it is very important to have well selected team.

Urban flooding occurs due to faulty design of drainage network. Some flooding is usually tolerated, e.g., for a total of 10 minutes in two years, or a similar criterion. This is because preventing all flooding is expensive. But if flooding occurs several times in a single year, the drainage network is underdesigned. Backwater computation from the outlet of the network can identify where the design changes are to be made. The design changes normally required are increased cross sections. This involves land acquisition, which can be expensive in cities.

There is no general solution for the prevention of low lying city from flooding. Every terrain / catchment needs flood prevention analysis for proper solution. You need 2D hydrodynamic analysis. At the end, this may require building of embankment.

I think Fredrick Mutua give the the complete answer.

I think you should have large partition walls which would protect the structure. Moreover you should have put barrages around the river. Have rain water harvesting systems which would help you. You should have a look on the barrages.

The flow of rainwater towards the stream is greatly affected. As it is a low lying area, rain water harvesting system for recharge won't work. As suggested by Sri. Ayodele, 2 D hydrodynamic analysis can give an idea about the flow. Could you give more information on this aspect

To use the urban parks as sinks, to avoid the excessive use of the asphalt and the cement. To create sinks areas..

In Kerala, India, due to high population density, the availability of land is becoming scarce. Also there is no proper urban planning and this led to the existence of railway station, bus station and commercial establishments all exist in the flood plain itself. The lack of drainage facility, sewerage facility have made the problem worse.

Wetlands in urban area can be used as reservoir that can retain excess flood water and minimize the adverse effect of flood.

From the google map image it appears that Thampanoor and East Fort are nearly adjacent, and although the information content of google maps in inadequate, there does not appear to be any surface drainage system. In somewhat similar circumstances a large drainage tunnel provided the most cost effective solution (San Antonio River Tunnel, San Antonio, Texas). The trick there was to be able to bore the tunnel far enough down that it did not endanger the subsurface infrastructure or building foundations (in San Antonio this was 30 to 45 meters).

Planing growth of building and control infar-structure not block way of water.

There are reservoir,swamp or marsh, for restore riain when flood and drain when no critical

Thank you for all the answers.

Regarding Mr. George Perry's answer, it may kindly be noted that the site is a low lying area where ground water level is more and the construction of such drainage tunnel in such place is very costly. I think such work may not be possible in a developing country. Is it feasible for a developing country?

It is Gregory Perry. The project I referred to was the least costly of half a dozen alternatives. As part of a pair of tunnels the San Pedro Creek and the San Antonio River Tunnels were completed and operational in the mid 1990's. Another tunnel project with conditions similar to Thiruvananthapuram city, India (low swampy area behind a protective barrier) proved the cheapest of 5 alternatives and is awaiting funding.

I think the lessons from Netherlands could be of a great help. The situation seems to be somehow similar in these two locations.

Primarily, you have to check and find out whether ANY measures are currently present. If they are there, try to check on the adequacy and try to improve the situation. If there are no facilities, conduct an investigation of the area and design an appropriate drainage system to ensure the floods are managed. Such proposals/action should be economically viable as the the cost of a proper drainage system should be able to offset the losses incurred to commerce every time the area is flooded.

The site below contains a flash that illustrates various protection schemes. I hope it can help,

http://ees.as.uky.edu/sites/default/files/elearning/module12swf.swf

Regards, Amro

Creating a flood plain above the city may help but if the embancment fails this could create a worse problem. This hapened in Québec a few years ago. The ensuing flash flood destroyed most of the buildings.

The use of fibers or polymers can help increase the flow of water through canals and drains (by reducing turbulence) thereby improving your drainage. Proper dosing would minimise your flooding problem providing you do have drainage canals.

An interesting and a very economic approach to tackle the problem is that to dig distribution of square-shaped ditches in an ingenuous way along flood prone areas. These ditches will cause the flooded water to store in. Further we could use this water to cultivate nearby areas when it needs.

Past flood history has to be thoruoughly studied and the direction of flow has to be diverted through weirs..

I think the best ways are to make diversion canals, make check dams, dams construction etc. Before this the water delineation modelling must be done and as per the analysis and to the most prone areas the necessary steps can be taken..

in ARCGIS is possible to make the maps and show the areas. Is necessary to include in your research the anthropic factors, like the type of houses, economy, the relationship with environment and management of the wastes. Many researches forget this factors and presents their studies without it.

First of all do modelling in ARC GIS and as per the analysis where the flood prone areas are identified from water delineation process. You can identify the need of check dams, else construction of diversion canals can be studied and approach and recommendation can be made in accordance

If its because of rainfall than we can have a porous manhole to be constructed in lowland area so that it takes the water directly to the outlet.......

Taking a view on some flooding in Europe: (1) restricting building in flood plains, (2) creating optional floodplains upstream that can act as buffer, (3) modifying transport and energy links such that they resilient and not increasing damage.

Flood, a natural occurence, can be minimised in plains, among other methods, by scooping grounds at reasonable intervals, but far away from buildings, to create retarding basins.

Broadly speaking, there is no direct answer as to "how to prevent flooding in a low lying urban city" as it needs thorough analysis and design measures. In fact, we have a separate project here in Colombo, Sri Lanka to address the problem of frequent flooding (Colombo is also a low-lying city, located at near sea level).

Urban flooding can have several causes such as; poor physical planning when developing lowlands, inadequate detention/retention areas and unauthorized filling of the same, blocking of drains and culverts by debris and increasing hard-to-forecast rainfall patterns.

I though to share some of the mitigatory methods, according to my experience in working in the same project I mentioned earlier.

1. Rehabilitating existing canal network by; reconstructing canal banks and culverts and realigning them to accommodate increased flow according to hydraulic principles

2. Constructing new (or dredging existing) detention/retentions areas such as ponds and lakes

3. Constructing micro-tunnels to divert flow to the sea

4. Constructing pumping stations to pump and discharge water from lowlands where gravity flow does not take place or is inefficient due to shallow gradients

5. Implementing real-time flood forecasting mechanisms by using flow/precipitation gauges, forecasting models and public warning system

I think there is no unique answer to the problem. However you should follow some procedures:

1. You need to study the city from topographic point of view.

2. study the current situation from the point of view of flood arrival to the city.

3. study the existing protection schemes (if any) and see if they are adequate.

4. suggest solutions (structural and non-structural) measures.

You may need some software to analysis the situation like:

- SMADA for rainfall analysis.

- WMS for stream network analysis and watershed delineation.

- HEC-HMS for flood predictions.

- HEC-RAS for flood wave propagation together with WMS for delineation of inundation areas.

You can study scenarios of flood protections using these models to come up with the best scenario.

This paper can provide you with some advice but not all:

https://www.researchgate.net/publication/230641649_SIMULATION_OF_URBAN_FLOODING_BY_DIFFUSIVE_WAVE_MODEL_JEDDAH_FLOOD_2009_CASE_STUDY?ev=prf_pub

https://www.researchgate.net/publication/235788496_Simulation_of_Urban_Flooding_by_Diffusive_Wave_Model

https://www.researchgate.net/publication/235935206_Geomatics_Technologies_in_the_City_(gtc_paper_2011)

good luck, Amro

Article SIMULATION OF URBAN FLOODING BY DIFFUSIVE WAVE MODEL: JEDDAH...

Data Simulation of Urban Flooding by Diffusive Wave Model

Data Geomatics Technologies in the City (gtc paper 2011)

Thank you for the valuable information.

Also let me know whether the said models are freely available

The best long-term solution is the zoning of wetlands and incentives for relocation depending on the type of land use.

All other solutions, sooner or later show their problems. Dykes disrupt, channels suffer deposition, dams show to be insufficient and expensive......

Policies bonds and cost for relocation of inappropriate areas, in two or three generations are definitive solutions, leaving areas of flooding to less noble activities.

These models are free:

- SMADA for rainfall analysis.

https://ucf-rainfall.pbworks.com/w/page/49689488/SMADA%20Software%20and%20SMADA%20Files

- HEC-HMS for flood predictions.

http://www.hec.usace.army.mil/software/hec-hms/downloads.aspx

- HEC-RAS

http://www.hec.usace.army.mil/software/hec-ras/downloads.aspx

-WMS is not free and I do not know if there is a similar free program.

Read the book Flood Risk Simulation, chapter two.

By constructing buffer storages/dam in the upstream and creating more obstructions.

Sorry guys everyone, but I think that they forget the most important. "THE TRUTH" for whom PROBABLY will benefit from the actions against floods.

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I have worked in the works for flood containment project, I have worked in the works to reduce the intensity of floods and have worked in zoning plans. And with my experience and the experience thousands of engineers who have worked on projects of all types, I and most the others we can say with clarity what you really should do is enlighten people of all that is right and wrong in each of the possible alternatives.

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Until the 70s major works were "sold" to the people as definitive solutions, and as the weather is variable and unpredictable, and also the worst flood is one that has not yet occurred, large communities had the surprise to know that the final solutions do not were as definitive as well.

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After this time begins with the concepts of reducing flood waves, this more "modern" concepts are presented to the people as more "politically correct" or "sustainable". Also "sell" an idea that everyone taking part, collecting water from their roofs, waterproofing or not deforesting certain areas, we will be back to natural and risk situations and damage disappear like a charm. What you see below is the natural and sustainable is often flooding people's homes.

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Finally, zoning often removes people from danger area and place them in areas far of resources for the survival of the population, creating another risk, the risk of not surviving even during the time that there is no flooding.

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Engineering solutions, antiquated or modern, are described there for everyone, but the difficulty of choice is not due to technical parameters.

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There is no technician with engineering or socio-economical, able to define what is the best solution, because unless the solution is taken to prevent flooding in the house that only technical, he will never know clearly what is best for others .

I'm not saying that we should stay in immobility, I am saying that we should before choosing any project, it is better to show the TRUTH of each option.

Each solution is more appropriate to each reality

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If we deal with, willing even with a small risk to invest in large projects not to change anything in your way of life, large dams, canals, polders systems and large pumping stations affluent communities can give them the best solution.

If we deal with communities where space is abundant, urban mobility is common and culturally accepted, zoning and removal of hazardous area may seem ideal.

Finally, if we treat with poor communities in the construction of major works is heavy on the budget and any withdrawal of the next risk area may represent a heavy loss in quality of life, any mitigation work to prevent the loss of life and large losses in the equity, will be the ideal action.

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All those who will benefit from a work and pay a cost for it to be fully aware of the problems, costs and limitations of each solution. No use demonizing the solutions of the "big engineering" or ridicule small mitigation measures without explaining who does not know the limitations of these and suffer from one form or another its effects.

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I live in a city in 1941 by a flood that hydrological calculations had a return period of 300 to 500 years there. No one died drowned and only property damage occurred, the city center was 1m to 3m high water (there were deaths from waterborne diseases, lack of food and other deaths by isolating poor structure derived by civil defense). As the philosophy of the time made up the great works in the 60s that currently protects for even bigger than the floods occurred, are 68 kilometers of dikes, 14 floodgates sealing , 19 pump houses, 83 large pumps and 2,647 meters in reinforced concrete wall (built between 1971 and 1974) and three meters high over the same dimension buried to prevent subsoil seepage.

As was to be expected statistically, after the flood of 1941 was not a flood with such intensity, that is, it took 72 years and such a violent full not yet occurred. This concrete wall shall enter the ancient port city and the center of it, creating a visual uneasiness in the city center.

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Well, spent 41 years building the wall begins to be a part of the population (around 10%) a desire to remove an existing protection. The wall holds because the majority of the population believes that the existing wall should not remove it mere aesthetic reasons and the wall is already built, it is not removed, but nowadays there is the possibility of not build it and spend money on other priorities, this proportion may change completely.

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As at the time of construction of the wall, Brazil was a military dictatorship, two interesting events occurred; technical project was implemented without the slightest political discussion (the technique occurred) and the poorest people living in the lower areas, and would the main beneficiaries during construction were removed from areas that would be protected, all to make way for residential and commercial property with greater purchasing power, or those who were outside the protection system remain exactly where they were.

.

Conclusion: The solution was the work of a technical protection, but nothing political solution!

.

Japanese have a very efficient way of preventing flooding of low lying areas. All should adopt that.

In India's coastal regions the river flooding is compounded by potential storm surge flooding. Since your city is on the Arabian Sea (all the below publications can be downloaded from my researchgate-profile:

Fritz, H.M, C.D. Blount, F.B. Albusaidi, A.H.M. Al-Harthy (2010). Cyclone Gonu Storm Surge in Oman, Estuarine Coastal and Shelf Sciences, 86(1):102–106, doi:10.1016/j.ecss.2009.10.019.

Likewise on the Bay of Bengal Cyclones are more predominant:

Fritz, H.M., Blount, C.D., Thwin, S., Thu, M.K., Chan, N. (2009). Cyclone Nargis storm surge in Myanmar, Nature Geoscience 2(7):448-449, doi:10.1038/ngeo558.

Fritz, H.M. (2009). After the storm, Nature Geoscience 2(7):528-528, doi:10.1038/ngeo568.

Then in the US we have the paramount example and struggle with New Orleans with everything from levees, to coastal barriers, to pump stations:

Fritz, H.M., C. Blount, R. Sokoloski, J. Singleton, A. Fuggle, B.G. McAdoo, A. Moore, C. Grass, B. Tate (2008). Hurricane Katrina Storm Surge Reconnaissance, J. Geotechnical and Geoenvironmental Engrg., ASCE, 134(5):644-656, doi:10.1061/(ASCE)1090-0241(2008)134:5(644).

Fritz, H.M., C. Blount, R. Sokoloski, J. Singleton, A. Fuggle, B.G. McAdoo, A. Moore, C. Grass, B. Tate (2007). Hurricane Katrina Storm Surge Distribution and Field Observations on the Mississippi Barrier Islands, Estuarine, Coastal and Shelf Sciences, 74(1-2):12-20, doi:10.1016/j.ecss.2007.03.015.

Applying LID(Low Impact Development) or Building a reservoir for storing a flooding.

Sheela,

1. You may want explore the services and products of this company in rergards to

Flood Control Wall Systems (removable). The Invisible Flood Control Wall (IFCW™) is a removable flood wall that is erected before a flood event occurs. After the flood, the wall is easily demounted and stored. The IFCW™ is in extensive use, with hundreds of installations across the United States and has been analyzed and accepted for use by the United States Army Corps of Engineers, with installations on many Corps of Engineers projects. Flood Control America is the industry leader and a pioneer of removable flood barrier systems in the United States.

http://floodcontrolam.com

2. The link is a research paper in regards to this problems and potential design solutions from a source in Taiwan; RAINWATER UTILIZATION TO REDUCE

FLOODING IN LOW-LYING AREAS OF TAIPEI CITY, TAIWAN by Andrew Lo

http://jmst.ntou.edu.tw/marine/20-6/657-661.pdf

3. Another research from UK;

Reducing flood vulnerability of urban lowland areas by R.E. De Graaf*

http://web.sbe.hw.ac.uk/staffprofiles/bdgsa/11th_International_Conference_on_Urban_Drainage_CD/ICUD08/pdfs/149.pdf

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The images obtained from Google Earth and Figure 1colocada by Houghton, seems surprising because only Thampanoor and East Fort areas presents this problem. According to information I collected the average rainfall in the city is 3100mm/ano a monsoon climate, therefore easily have become very heavy rains.

.

If the abovementioned areas are not down the level of the rest of the city, there is a problem logically located macrodrainage and this should be resolved by rebuilding the drainages that may have been disrupted by new works, such as the airport which is just across the sea and cited locations.

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The first thing to be considered here is the history of flooding and verify that the drainage network were not partially blocked by works in recent years (eg expansion of the airport).

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The following papers may help,

https://www.researchgate.net/publication/235935206_Geomatics_Technologies_in_the_City_(gtc_paper_2011)?ev=prf_pub

https://www.researchgate.net/publication/230641649_SIMULATION_OF_URBAN_FLOODING_BY_DIFFUSIVE_WAVE_MODEL_JEDDAH_FLOOD_2009_CASE_STUDY

https://www.researchgate.net/publication/235788496_Simulation_of_Urban_Flooding_by_Diffusive_Wave_Model

Data Geomatics Technologies in the City (gtc paper 2011)

Article SIMULATION OF URBAN FLOODING BY DIFFUSIVE WAVE MODEL: JEDDAH...

Data Simulation of Urban Flooding by Diffusive Wave Model

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Dear Aria.

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Care with citing articles. In the last mentioned Hydrographs are presented with and without specific capture for systems having hysteresis curves, not Hydrograph for pure storage systems (see Applied Hydrology, Chow, Maidment and Mays).

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I.e. not looked at the rest of the text, but I think if there are inconsistencies in the basic or read the entire text.

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