Mucilage Event in the Sea of Marmara

Today's post will be about a hot topic. Some abnormalities were observed on the Sea of Marmara, more specifically a slimy substance that was resembling saliva was floating on the surface of the sea. This substance is called Mucilage, it was most likely formed because of industrial waste, insufficient treatment levels, and overfishing. It is affecting the ecosystems in both under the sea surface and above it negatively. This topic was discussed briefly in my lectures, when I got more curious started searching about this, I found a TÜBİTAK research paper about the exact same event I was pretty shocked to find out the same thing happened 10 years ago. 

Eskihisar, Gebze 23 May 2021. Photo: Ersin Duman

   

October 2007, İzmit Bay

    Left: October 2007, Erdek Bey. Right: January 2008, Erdek Bey Underwater 

To understand how and why it is formed, a detailed scientific search must be made. It is made up of organic material; a carbohydrate-protein mixture. Although there are many factors that trigger the formation of mucilage, the main reason is the increase in the accumulation of organic matter in the environment by human-induced ways. The mucilage formed in our seas is thought to originate from complex organic substances such as carbohydrates found in the cell contents of phytoplankton (diatom and dinophlogellate species).

Müsilaj oluşumunda etkili olduğu düşünülen bazı fitoplankton türleri (a:Skelotonema costatum, b:Prorocentrum micans, c:Gonyaulax fragilis.) 

In summary, the mucilage phenomenon is the rapid increase in the concentrations of polysaccharide structures and hydrocarbons in sea water, which occur due to the death of certain overgrowing phytoplankton and/or bacterial species, their rapid decomposition and failure to settle to the bottom. This slimy structure covers the bodies of many fish and invertebrates (corals, sea anemones, sponges, mussels, crabs, etc.) and causes clogging of structures such as gills and holes, which they use for the continuation of their metabolic activities such as respiration, feeding and excretion. 

Due to climate change, surface water temperature is increasing every year. This affects the underwater oxygen level. Factors such as climate change, increasing human-induced pollution, excessive and unplanned fishing, unplanned coastal structuring, and increasing marine traffic cause both serious wear of the ecosystem and great economic losses.

Sources:

• https://www.bbc.com/turkce/haberler-turkiye-57293708
• https://sarkac.org/2021/05/deniz-salyasi-nedir/#
• ‌Tüfekçi V., Balkıs N., Polar Beken Ç., Ediger D., Mantıkçı M. (2010); Phytoplankton composition and environmental conditions of a mucilage event in the Sea of Marmara. https://doi.org/10.3906/biy-0812-1
• Integrated Coastal Zone Management Lecture Notes, Aslı Numanoğlu Genç

Flooding, Flood Structures and How These Structures Work

Today's topic is flooding, and how humans manage to control and manipulate water. This control mechanism is for preventing damage and making use of the excess water to be used in droughts. Environmental impacts of all types of structural and non-structural measures are to be assessed jointly in the long term in order to maintain sustainable development of land and water resources.

For rivers, the river streams join or separate because of the geological processes. A Watershed is the area of land that collects precipitation, there are areas where mostly drainage occurs too. These have a controllable ratio, but there are instances where this ratio may not be sustained. 

Source: https://bewaterfriendly.com/our-water/watersheds/

The wetland and overland areas that are seen in the figure may change with geological or hydrological alterations. This affects the settlements near the flow. Reasons may include; slopes on the side of the flow may not be steep. When the cannel over banks, this instance may lead to disasters. Solutions for this problem includes; Building Levees or earthen embankments on the sides of the river. 

Source: A Case Study of a Fluvial Deltaic Reservoir. (2018). ResearchGate.

Another solution is diversion canals; diverting water for purposes like irrigation, hydropower generation, and safety. To create a completely different path for the canal is not environmentally and economically achievable. So the canal is merged back into the original flow after taking a different path. So when the water levels rise, this canal transports the excess water to needed areas instead of it damaging the surrounding. 

Souce: Water Transport Structures(2021) FAO

Another solution; Dams. These infrastructures provide storage for excess water.  Each dam has a specific purpose, some may be full for most of the time to provide hydropower, irrigation... But Some dams are usually empty, when a big flood happens the storage fills up. If the reservoir is full then floodgates must be opened in order to let water through. 

The correct way for flood risk management is to determine the climate, geology, and other factors and designing the appropriate flood structure. These structures have negative effects as well so the design must be well thought. Since climate change is creating extreme situations(for example unnatural precipitation and drought.) and we need water resource management more than anything. 

Here are some related video's:

Sources:

• (Water Resources Engineering, Yanmaz A. Melih, 2018)
• (PDF) A Method to Integrate Geological Knowledge in Variogram Modeling of Facies: A Case Study of a Fluvial Deltaic Reservoir. (2018). ResearchGate. https://doi.org/10.4236\/ijg.2018.96021

• 8. Water Transport Structures(2021)   http://www.fao.org/fishery/static/FAO_Training/FAO_Training/General/x6708e/x6708e08.htm

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Best Civil Engineers on Earth: Beavers!

 Beavers are semiaquatic mammals, they build dams and lodges using tree lodges. Dams impound water and lodges serve as shelters. Their infrastructure creates wetlands used by many other species, and because of their effect on other organisms in the ecosystem, they are considered keystone species. They build dams across streams, in order to create a safe environment from predators. This is called a beaver lodge. These dammed streams provided food for water beetles and nymphs, and the ponds created have various types of fish. To conclude, these dams provide tremendous environmental benefits such as groundwater recharge, water quality, and other species benefit from these habitats as well.

An example for a beaver dam

A beaver dam is a dam made out of logs and mud. A dam is something that blocks or slows down the flow of water in a river or a stream. A good portion of these dams is very stable, they might be renovated by other beavers in order to be used since young male beavers have to create a new pond or find an empty one to re-use. 'Some beaver dams in California date back more than 1,000 years.'  

Some controversies about beavers; so these dams are apparently causing flooding and this wipes out land that farmers need. I think this is preventable damage since there maps for where beavers live and where they might build dams, I am no expert but I feel like it can easily be prevented if people were more mindful of these creatures' territory.  And I personally find it very odd to blame an animal's instinct for "damaging nature" when beavers ALMOST went instinct before some regulations came out about hunting beavers, In less than 200 years, the North American beaver went from 90 million to between 10-15 million. In Europe and Asia, just 1,200 beavers remained by 1900.

Anyways, thanks for reading, here are some cute beaver pictures:

Here are some nice videos related to the topic:

Sources:
https://www.treehugger.com/beaver-dams-can-last-centuries-map-shows-4867776
https://www.biophiliafoundation.org/beaver-dam-benefits/
https://www.theguardian.com/commentisfree/2017/aug/16/google-autocomplete-why-beavers-build-dams
https://www.nps.gov/articles/buildabeaverdam.htm#:~:text=What%20is%20a%20beaver%20dam,a%20river%20or%20a%20stream.

Aswan Dam: An example for Grout Curtain Application

In my Water Resources Engineering course, it was mentioned that before building a dam the foundation must be stable. The foundation must have less deformation under high loads, must have little to no permeability and seepage, increase shearing strength, and satisfy slope stability for the side hills. But regular foundation applications do not comply with the properties stated above. This is why grouting must be used. While I was searching videos about grouting, I came across this one:

In the video, the construction of the Aswan High Dam is being mentioned. This dam is very important for Egypt because of the drought problem and irrigation is now mostly provided by this dam. Periodic floods and droughts have affected Egypt since ancient times. The dam mitigated the effects of floods, such as those in 1964, 1973, and 1988. Navigation along the river has been improved, both upstream and downstream of the dam. 

Green irrigated land along the Nile amidst the desert

The base of the dam is nearly a wile wide and is the key to dam stability. As seen in the figure below, the dam has a core that must sit on the bedrock but in the region where the Aswan Dam is placed, bedrock is under 600 feet of silt and loose rock. So the most cost and time efficient solution was to transform a slice of the riverbed with a grout curtain. The workers drilled narrow holes lined with iron pipes into the sediment. Then the grout was pumped into the holes while the pipes were going up. This process was repeated hundreds of times until a grout wall was formed under the core. 

Source: 
(Water Resources Engineering, Yanmaz A. Melih, 2018)

Storm Surges

In this post, I will be writing about storm surges. For my Coastal Management course, we were assigned to watch some videos related to storm surges. While working on the course, I said might as well create a blog post about it.

A storm surge is not directly related to rain but is related to wind, basically, the sea level rises so much that it causes extreme flooding. This is an outcome of hurricanes mostly. 

Sea level usually changes because of the gravitational rotation of the moon, sun, and earth. When in line, the forces combine to create the highest of the high tides and lowest of the low tides, which are referred to as “spring tides.” These occur every 14-15 days, during the full and new moons. When the forces are perpendicular to each other, the variation between high and low tide is at its least since the forces are pulling the water in different directions. This is referred to as a “neap tide,” and it occurs during the first and last quarters of the moon.

Another effect on the sea-level rise is the wind, where the wind transfers its momentum into the water which causes water to crash into the shoreline with high momentum. So the speed of wind would be simply equal to the speed of the water. But speed varies a lot inside a storm, intensity, direction, and size change so it is extremely difficult to measure that. 

By tracking the sea level rise and collecting the timing, extent, and magnitude data to analyze it. Some sea walls as barrier structures might help and ease the damage, as for infrastructures they should also be designed keeping in mind the maximum flooding caused by precipitation values with the storm surge flooding values. According to the Panel on Climate Change, frequency and intensity may change in the future. And as for frequency, it may be decreasing. But the intensity, which is the wind speed and rainfall amount, is most likely increasing because of greenhouse warming. 

Here is a nice video about storm surges;

About Venus

So, in my previous posts, I mentioned Mars a lot. The reason behind this is that it is the best option for becoming our second home, and also we have the technology to travel through Mars and examine the needed properties. While doing research for my blog, I came across an article about how Venus went through global warming. And it sure does sound familiar. So today, I will briefly mention Venus and why it should be a warning sign for us. 

Venus has the same mass and same mass as Earth. It has a thick atmosphere. Its atmosphere contains greenhouse gas carbon dioxide and its clouds are made up of sulfuric acid. It rotates so slow that 1 year on Earth is equal to 2 days in Venus. It is the hottest planet we know, but it is not the closest planet to the Sun, its surface temperature is 460 degrees in Celcius. The best survival rate for a robot in Venus is 2 hours. 

Heres a brief video about Venus;

Data collected at NASA's Pioneer Mission to Venus has given some insight into Venus's past climate and geology. It is suggested that Venus had a very familiar climate and geology to ours, but its seas has evaporated because of its nearness to Sun. "As a result, the planet’s early ocean evaporated, water-vapor molecules were broken apart by ultraviolet radiation, and hydrogen escaped to space. With no water left on the surface, carbon dioxide built up in the atmosphere, leading to a so-called runaway greenhouse effect that created present conditions." 

Venus 700 million years ago and now. Credit: NASA.

Sources:

4https://climate.nasa.gov/news/2475/nasa-climate-modeling-suggests-venus-may-have-been-habitable/

https://www.space.com/venus-runaway-greenhouse-effect-earth-next.html

https://solarsystem.nasa.gov/planets/venus/overview/

Mars Might Have Water Encapsulated Inside It's Crater

In my previous posts, I mentioned Jezero Crater in Mars and its similarities with Lake Salda in Turkey. In this post, I will be writing about how Mars is extremely similar to our world, Earth. In those posts, it was briefly mentioned that Mars once had water on its surface. Today Mars is extremely dry at first glance, this creates many questions such as what happened to the water on Mars's surface? Is it possible that one day Earth may have a similar change? I think with further investigations to Mars it would be possible to answer these questions.  

There are some theories about where the water went such as a study that proposes that a combination of two mechanisms – the trapping of water in minerals in the planet’s crust and the loss of water to the atmosphere – can explain the observed deuterium-to-hydrogen signal within the Martian atmosphere. So water went nowhere, again a reference to the previous post about Jezero Crater, there was a moisturized section below the hard crust of Mars. Water is trapped in the crust, now another question might arise, why is the water encapsulated? This question will be answered when we have more data about the climate of Mars. 

Scientist have examined yet another crater that has extreme similarities with an Earth lake. "They also noted the presence of a distinct set of ridges that face upward toward the crater wall, which bear a striking resemblance to ridges on Earth that formed at the edges of glaciers. " 

A topographic map shows the raised ridges (dark yellow) and low-lying areas where water ponded (white). Credit: NASA/Boatwright et al./Brown University

For this reason, I think this is a very interesting topic when considering the world's climate is getting hotter by the day. Earth is very similar to Mars geologically, maybe they had similar climates. Maybe the data and information collected by the rovers would be somewhat beneficial for Earth's climate issues and how to prevent the Earth from becoming a dry crust with little to no life on it. 

Sources:

https://www.sciencedaily.com/releases/2021/03/210316132106.htm

https://www.jpl.nasa.gov/news/new-study-challenges-long-held-theory-of-fate-of-mars-water

https://www.universetoday.com/150726/a-lake-in-a-martian-crater-was-once-filled-by-glacial-runoff/

Understanding BIM and It's Implementation in Our Jobs

This weekend, I attended a BIM Education seminar by Saniye Öktem and a Revit seminar by Tolga Arçok. For the people who are interested in this kind of stuff, I wanted to mention some highlights from the seminar. In the beginning, the image below was presented and some important differences were asked.

 

The most important thing that caught my attention was the VR headsets, this technology is being used in some firms to examine the building by simply putting on the headset and wander inside the structure. There are some pretty interesting gadgets as well and the environment looks very diverse and safe. I think this model is a great example, and with the technology we use I think this image is not so far away from reality. 

BIM is a methodology that can enable safe, efficient, and sustainable construction site the image represents. Efficiency is obtained because every discipline can work with coordination in the same model. When exporting a model or data, there is no loss or misunderstanding because while using Revit, everything is assigned prior to it being included in the schedules. I think the construction process would be much more organized and revisions would decrease is BIM methodology is used. 

There are many software's and add-ins that can be used with Revit, most outstanding ones in my opinion is firstly Advanced Steel and Robot Structural Analysis. Aside from them a program I found very impressive and advanced was TestFit. In this program, the user assigns the map location and the program generates example models. The models can be imported to Revit or another modeling program and can be later on adjusted and improved but it was pretty impressive seeing software generating a whole model. Here is a youtube video explaining;

                                                        

Here is an article about BIM Methodology:

https://www.archdaily.com/957097/bim-methodology-for-the-creation-of-smart-buildings?ad_source=search&ad_medium=search_result_all                                                                                                                                                                                                                                                           

Using Numerical Methods to Examine Geotechnical Problems of Masonry Structures

Geotechnical analytical models are made for presenting the stress, deformation analysis, and settlement of the soil. The soil must be modeled in an advanced manner in order for the structural failure mechanisms to be observed. In this post, I am going to write about a research paper I found on the research gate that acknowledges and explains a model created using numerical analysis for geotechnical problem determination for the Abu Serga Church in Cairo, Egypt. Numerical and experimental analysis is used to characterize stress-strain analysis and subsoil deformation of the soft clay underneath the church. 

 

Abu Serga Church

The subsoil is composed of plastic silty clay layers mixed with fine to medium sand layers and the groundwater table is at 1.8 m depth. The geotechnical properties are summarized in the table given below;

Geotechnical Characterization of the soil layers underneath the Abu Serga Church

Church has a flood problem before a dam was constructed on the Nile River in 1971. But the floods caused loading and unloading of the subsoil for hundreds of years. the vertical effective stresses in the clay soil and its bearing capacity also changed with the rising and falling water table. Along with this problem, many cracks were observed on the superstructure of the church, because of the soil settlement and foundations movements undergoing a shear failure. A 3-dimensional model is implemented to analyze long-term creep deformations. To analyze the consolidation, a numerical model is produced based on assumptions, conditions, and simplifications. The main goal here is to find a suitable method for strengthening. 

Differential vertical displacement patterns in the bearing silty clay soil.

3D Finite Element discretization of the PLAXIS model and deformed generated mesh. 

References;

https://www.researchgate.net/publication/346041012_Numerical_Analysis_of_Geotechnical_Problems_of_Historic_Masonry_Structures

Building on a Site That Is "Pretty Much a Pool", What to Consider?

In this post, I will be writing about an off-the-grid getaway house that would ideally be located near Medellin, Colombia. But the soil study shows that the site is almost like a pool, having a high water table and thick layers of loose soil. These properties would provide little to no capacity for supporting heavy objects. The ground is made of silty sand, any design would be at risk for seismically-induced settlement dues to liquefication which would cause vertical settlement and lateral spreading. Also, there were some clays present on the site, and if this clay type is expansive then during rainy seasons, clayey soil would cause swelling which would cause an unwanted movement.

Project Site

The solution suggested was a floating slab- a flat layer of concrete resting on top of the soil, supported by vertical concrete piles beneath the outer edges. This solution has two problems;

1)It would damage the environment

2)Budget would be extremely high. 

When local geotechnical engineers were consulted, two alternatives popped up. The first one was deep foundation. This foundation type involves driving long piles into the ground to reach the more stable layers of earth below. Another solution was ground improvement, which would reduce the damage caused by liquefication.  This solution has many types; the first one would be the vibro-replacement stone column technique. Achieved by using a heavy vibrating weight to drill deep into the ground and create columns of compacted rock that support the earth around them. The second one would be deep soil mixing, achieved by using heavy equipment to mechanically combine weak soil and cementitious slurry.  At this point, the design process is continuing since these solutions are not perfectly sustainable or safe for the site. Further exploration is being done to develop the design.

Eco Shelter Rendering

Black and White Elevation Image

Source:

https://www.archdaily.com/585854/ask-arup-how-to-build-on-a-site-that-is-pretty-much-a-pool?ad_source=search&ad_medium=search_result_all

Impact Crater on Mars: Analyzing Its Morphology Using Slide2 and RS2

In my previous post, I mentioned the impact crater located on Mars. In this post, I will be talking about analyzing its morphology with software widely used by foundation engineers. This impact craters morphology is categorized as PPR (Peripheral Peak Ring). PPRs occur on craters having a diameter between 4 and 200 km when instabilities occur on the rim causing a crater deformation and a part of the rim to detach and slide into the crater. In the Department of Geoscience at the University of Calgary, there was a study to create a model for PPRS targeted to describe, characterize it. Jason Nycz, who was doing the research for this project, inversely modeled and analyzed the formation as a transversal block slide in Slide2 using the topographic inputs from DEM (Digital Elevation Models) and reasonable rock parameters. This research supplied much information about the strength parameters for the uppermost layers of the Martian crust. The model is created conditions and constraints (position, height, and shape of the crater) Three Phases of Modelling:

1. Modelling the crater before the PPR was formed. 

2. Detachment of the PPR from the crater rim, sliding laterally and downward toward the crater center. The result is an intermediate step in the formation of the PPR.

3. Transform the intermediate profile into the observed one.

Initial input model in Slide2

Slide2 model imported to RS2

Finite element analysis results in RS2

References:

https://www.rocscience.com/about/news-events/ocscience-goes-to-mars-using-slide2-and-rs2-to-advance-research-on-impact-crater-morphology

https://www.rocscience.com/documents/pdfs/rocnews/fall2011/Slope-Failure-Impact-Crater-on-Mars.pdf