Transitional Territories

Composition
The city of Gdańsk is located in the Delta of the Vistula River by one of the river’s mouth, in the coast of the Baltic Sea. Therefore the potential flooding event in the city can originate from three different directions, namely the sea, the Vistula River and the creeks in the moraine hills as Gdańsk is situated on a hilly and on a low-lying terrace1.

In the past, the city experienced severe flood events mostly caused by ice jams on the Vistula River1. One of them triggered the creation of a new mouth of the Vistula River (Śmiała Vistula)2. Since the end of the 19th century, there were no ice jam floods in Gdańsk because the Dead Vistula was separated from the main river by storm barriers and locks1.

Today the city is threatened by the events of high sea water level and storm surges in the Baltic Sea, which cause flooding due to backwater effect. Storm surges lead to extremely high sea water level at rivers mouths, which might be transmitted upstream via rivers by backwater effect3.  In Gdańsk, most of the land prone to flooding from the sea is used for industrial and port activities.


Alteration
The dynamics of rivers is strongly correlated with sediment transport, which, next to sedimentation and erosion, is an important factor shaping the riverine landscapes1. A substantial amount of sediment is concentrated in estuaries as the sediment load is transported from inland sources by rivers and also from the sea by tidal currents2.

The sediments in estuaries are often contaminated by pollution from the surrounding soil and ground, and thus they change the ecological quality of waterways3.

Flood events pose a real risk in the areas of high concentration of pollutants, such as industrial areas, as they can cause a release and spread of the compounds present in the sediment back to the water body4. To reduce the risk of flooding, waterways are maintained by dredging, which also suspends deposited sediment2.


Limit
The coastal flooding within the Baltic Sea basin originates from storm surges which mainly depend on the amount of water flowing into the Baltic Sea from the North Sea leading to variations in water level1. The frequency of storm surges which exceed the cautionary level (around 0.7m above mean sea level) is currently rising, the annual number of storms escalated from two in the mid-twentieth century to six in the 2000s2. Storm surges may affect not only coastal areas but also landscapes inland, especially fluvial plains, as the seawater flows into the river system.

Additionally, the climate change triggers sea level rise which is another factor increasing the vulnerability of coastal areas to inundation. As stated by Hunter (2010) the rising sea level is a predominant agent of the increase in the frequency of storm surges3. Paprotny and Terefenko (2017) assessed the relation between the sea level rise and the exposure of the land, population and buildings to inundation in the Polish coastal zone1.

The land would be endangered even with a small change in the sea level, whereas the number of endangered people and buildings noticeably soars when the mean sea level change is higher than one meter.

Composition
The riverscape is composed of out of a set of geomorphological elements, created by the processes of terraforming and erasure over time. These dual processes manifest the fluidity of riverine territories through the fixation of their elements of movement, the particles of sand and clay.

The composition map shows the geomorphological characteristics related to the migrational patterns of the IJssel. Amongst the most important terraforming elements are river dunes and fluvial deposits of clay in the floodplains. Erasure is characterized through the meander gully patterns and worn-down crevasse gullies (Geologische Dienst Nederland, 2020). In relation to the current river, as can be seen in the ‘cut-outs’, the influence the IJssel used to have on the surrounding territory in its natural form exceeds its current streambed immensely.  Many spatial elements of the riverine patterns are still visible in the landscape today.


Alteration
As is explained in the composition, a natural river system migrates laterally through the territory. The section on top shows this movement over time, in which sediment on the outside bend of the meandering river is eroded, while new land is formed on the inside. The exposed material is blown onto river dunes by the west by south-western winds, creating an ever changing riverscape.

Most sediment carried in the riverine system is moving downstream from its origins in the Swiss Alps. Due to the creation of weirs, locks and hydropower plants (mostly in Switzerland and Germany) the carrying capacity of sediment in the longitudinal direction is largely eliminated, depleting the Dutch rivers of new sediment.

On the temporal scale, the section at the bottom, the processes of normalisation and straightjacketing are shown. Through the creation of straight rivers and hard embankments, lateral movement is limited. The addition of groins into the riverscape has further eliminated the terraforming and erasure processes, which combined with the normalisation has led to scouring of the riverbeds.

Limit
Through the continuous human interference in the riverine system, the dual processes of terraforming and erasure, or sedimentation and erosion, have effectively been eliminated. The spatio-temporal diagram to the right shows on the vertical axis the timeline of taking space from the rivers, the total amount which is taken from all Rhine related streambeds in the Netherlands (Hooijer et al., 2002).

Interesting is the recent example of the Room for the River project, which has started a reversed pattern giving more space to the river. All in all, over two thirds of space was taken from the rivers in the past 170 years, an immense amount. The spatial characteristics of these practices are the straightened riverbanks, and dikes and rigid embankments alongside those.

The straightjacketing has, in combination with the addition of groins to ensure a clear river channel to benefit navigation, led to the continuous scouring of the riverbed, as is shown in the bottom of the diagram. Since 1901, the riverbed near Lobith, where the Rhine enters the Netherlands, scoured almost 2 meters. Firstly, this means more water is needed to connect the river to the floodplain level of the surrounding territory, causing a territorial disconnection. Secondly, the subsurface scouring has different rates in relation to the soil characteristics and possible underground infrastructure, leading to underwater levees and ponds hindering shipping during low water levels.

The proposition put forward in the diagram is that the typical Dutch landscape of levees and embankments is the manifestation of a completely anthropogenic river system, rigid through the interference of infrastructure. This depletion of natural processes now poses problems through long-term side effects on the territory. Are the solutions to this to be found in even more engineered scenarios, or is reversing the system towards natural processes more beneficial?

Composition
The Baltic Sea is one of the youngest seas in the world, therefore the coastal processes that form the Sea are dynamic and still ongoing. The first stage of the Baltic Sea was formed by the melting glacier that created the Baltic Ice lake. The glacier activity left different sediments, mainly sandy clay, gravel, rocks, and pebble that can be found inland from the current coastline (Aboltins, 2010, 67-74)

As the water level fluctuated and decreased, different stages of the Baltic Sea were formed, from which the latest was the Littorina Sea 2500 years ago. This stage corresponds with the Holocene period in the Quaternary epoch, that by wind and long-shore sediment flow created aeolian and marine sand sediments. The Littorina Sea retreat also formed lagoon lakes and marshes in the low-lying areas, in which peat and lake sediment is created. (Nikodemus et. al, 2018, 61-80, 179-181; Atlas, 2014).

However, the longshore sediment flow is still active nowadays, bringing in the Gulf more sand sediment from the Easter Baltic sediment flow. The coastal erosion processes that are increased by the wind and sea level changes are persistently changing the coastline. Thus, anthropogenic activities, such as building ports and excess sediment dumping from the ports, as well as indiscreet coastal protection are influencing this natural process, causing alterations in the sediment flow and increasing erosion (Eberhards, 2004,4-8) .


Alteration
The transgressions and retreat of Baltic Ice lake and Littorina Sea have left visible changes in the topography of the coastal landscape. Different heights in the topography can be traced to the dynamic processes that happened over thousands of years. However, the coastal formation is still happening also nowadays. (Atlas, 2014; Aboltins, 2010, 67-74)

The current dynamic coastal processes can be divided into two major influential processes – accumulative and eroding coasts. In accumulative coasts marine sand sediments brought to the beach by long-shore sediment flow are translated over the old dunes, forming new dunes. In contrast, the erosion coast has minimal beach area and the wave fluctuations erode the old sand dunes. The sand from the eroding dunes supplement the long-shore sediment flow and are transported away along the flow. (Atlas, 2014; Nikodemus et. al, 2018, 136-142)

This natural erosion process is altered by coastal protection infrastructure, that is created using concrete rip-rap blocks, rocks and debris. With continuous erosion, the pieces of debris are detached from the coast and mixed in the natural sand and rock sediments, creating a new, anthropogenic layer of sediment that flows together with the natural sand and pebble sediments.


Limit
From the perspective of urbanization, coastal erosion puts pressure on the existing infrastructure and human habitation along the Wester coastline of the Gulf of Riga. Although in most areas the erosion affects natural areas with low or non-existent urbanization, in several villages and urban areas multiple buildings, roads and other infrastructure elements are in risk to be lost or severely damaged by the erosion. It is projected that till 2060 the coastline could retreat by up to 100 m in several areas (Vadlinijas, 2014; Lapinskis, 2019)

The guidelines for mitigating the risk of coastline erosion (Vadlinijas, 2014) suggests to not interfere in the natural processes in cases where it does not oppose risk to human habitations. However, in Roja, Mersrags, Engure and Riga, the damage to the existing infrastructure is caused by the erosion that is created by distraction of long-shore sediment flow by port piers (Eberhards, 2004,7-8) . From the perspective of erosion as a natural process, the existing urbanization and port infrastructure on the coast can be viewed as a limit to the natural process, because the coastal protection infrastructure limits and distracts the natural process.

Therefore, it can be concluded that the anthropogenic limits of coastal erosion are not only the endangered buildings and infrastructure of the coast, but also the man-made port structures that both limits and creates the erosion.

Composition
The oldest Norwegian settlements were located at the coastline (Møller 1987).   Since historic settlement, coastal communities have relied heavily on the ocean for food, trade, transport and livelihood (Gee 2019). Human-sea relations have developed since then, embedding into local culture and heritage (MEA 2003). At present, the vast majority of the Finnmark population resides at the coast (Eurostat 2020). Their dependency on marine resources is reflected in Norway’s main industry sectors: oil and gas, aquaculture, hydropower and shipping (Plecher 2019).

Aside from a dependency on the ocean’s resources, the agglomeration of human settlement on the coast could be explained by the topography of the land. A characteristic typology of the Finnmark coast is the ‘strandflat’, roughly translated as ‘beach flat’. The strandflat is a low and wide bedrock plane, eroded and partially submerged. Inland, sudden steep cliffs outline the flats. Providing a surface suitable for human settlement and occupation, yet one that limits inland expansion. As such, coastal communities in Finnmark expand along the coast and are often positioned on hillsides oriented to the water.


Alteration
Just as on land, the settlement, occupation and inhabitation of marine space is defined by the topos. The tools of a woodman are fitted to the forest and the tools of the miner are shaped to handle rock. Reeds are long and sturdy to emerge from the shallow riverbed and lilies are flat-leafed in order to stay afloat on the water surface.  In exactly the same way, the morphology, positioning and operability of an oil rig varies for different depths, soil types and environmental conditions. The same goes for other forms of marine urbanisation.

Evidence of this can be found when comparing forms of urbanisation as a response to both bathymetry and topography. I will do this at the coast of Hammerfest, where urban land and urban sea come together. The mapped forms of urbanisation are: i) occupation (sea/land use), ii) inhabitation (density) and iii) settlement (architectural form).


Limit
As stated before, Nordic settlements were historically always positioned in approximation of the coastline. However, since the first settlement in 8000 B.C. the coastline has shifted alternately seaward then inland due to changing sea levels in the Holocene time period. Interestingly, archaeological research has provided evidence that the average altitude of prehistoric settlements shifted along with the shoreline displacement during that time, maintaining an average altitude of 4.8 meters above sea level (Møller 1987).

When the sea level rises, it affects the coastline in three dimensions. In the y-axis, the coastline changes in elevation. In the x-axis, the coastline shifts seaward or inland. Behind this two- dimensional plane lies the topography and bathymetry. The coastline cuts the soil and divides it into topography and bathymetry. When the sea level rises that division rises as well. What was once considered topography, is now, submerged, bathymetry. This translation forms the third dimension. Along the z-axis, the morphology of the coastline changes as it cuts through a different topography.

Composition
Southeast England’s Landscape Characteristics

The English coastline is known for its cliffs that  surround the islands of the United Kingdom. In particular the southeast coastline, where the white chalk cliffs are located. Apart from these high cliffs, lower areas that have risks of flooding can be found on the southeast coast. These different terrain types cause issues along the coastline that are in need of management.

Four types of coastal management are implemented in England by DEFRA (2001). For the coast of southeast England, only three are used. Currently, the most used type of management is hold the line management, where the current coastline is maintained in its current state with the use of coastal measures. Natural protection, but also sea walls, embankments and timber constructions are used to prevent coastal erosion. Other management types are no active intervention, where the current natural protection is sufficient, and managed realignment, where the coastline is moved backwards and can cause conflicts between urban environments and natural environments.

The use of these different management types is a way to manage the terrain types that can be found in the area. These terrain types all erode in a different pace and are, therefore, in need of different measures and management types (Boardman, 1990; Neal et al, 2019).


Alteration
Anthropogenic Landscape Alterations

The goal of managing the coastline is primarily to maintain the urban environment, however, it is also important to maintain the natural cliff environments as these coastal cliffs are a home to a great biodiversity unaffected by the anthropocene landscape in the coastal zones of England. The coastal management types, also called shoreline management plans (SMP) in the UK, each focus on maintaining either the urban environment or the natural environment, with an exeption of managed realignment, which focuses on maintaining both environments. For many locations, maintaining both environments would be an ideal outcome of shoreline management.

The management plans can be distinguished by their function. No active intervention and managed realignment have the function of limited intervention with natural processes, while management strategies such as hold the line and advance the line are prevention strategies that intervene with the current natural processes. The prevention methods are then distinguished by the location of these measures. Where hold the line strategies focus on prevention measures along the current coastline, the advance the line strategy moves the coastline further in sea and uses coastal measures that should be located in at sea to create this distance from the current coastline. These prevention measures have positive effects towards the erosion as they are able to limit the hydraulic action to a certain amount. However, most prevention measures interfere with the natural processes in such a way that the sediment quantity and transport is negatively impacted, causing erosion issues including sediment quality and quantity in other, nearby, locations along the coastline (Brown et al, 2011).

The erosion in the southeast of England is currently only limited through the use of coastal protection measures within the hold the line strategy. If these protection measures are removed in a managed realignment strategy, the land will erode naturally in locations where the soil resistance is weak. The limits of this erosion will be defined by the transition in land to strong resistance soils that are naturally resistant to the effects that cause erosion (Masselink & Russel, 2013).


Limit
Endurance of SMPs in relation to Erosion Effects

The shoreline management plans (SMPs) such as hold the line, managed realignment, advance the line and no active intervention all have a different impact on the spatio-temporal scales. Plans such as advance the line and hold the line are active on the spatial scale as these are plans to maintain the current coastal environments as they are and do not have adaptive characteristics in the temporal scale. The distance of these plans is defined by the erosion distance the measures are able to prevent, the temporal scale is defined by the time the coastal measure is in operation. This time of use is for most coastal measures around 30 to 50 years (DEFRA, 2001).

The no active intervention management plan works for a certain erosion distance where the urban environment is still unaffected. After a certain period of time this distance has overlapped with the urban environment and creates an environment with a negative livability.

The managed realignment management plan is an adaptive plan as it follows the path of erosion and creates an urban environment that keeps changing position to avoid risks and vulnerabilities. This relocation happens parallel to the erosion rate of the soils that exist in a location. This means that for each location this pattern will differentiate.

In locations for sandy soils, the need for adaptive management plans are most needed as the erosion rate is significantly higher than other soils. However, the erosion rates of both chalk and clay still require management plans. This is the case for all of southeast England as hard rock soils can only be found in the northern part of the United Kingdom.

Composition
The Seine is an anthropogenic river: its entire watershed is under the control and management of humans. This control is apparent through the alterations made to the river basin impacting the fluvial dynamics and the adjacent riverine territory. While remnants of a non-altered water body can be read through topographic information - notably through the traces of the dynamic meanders, the river has been forced into a static channel to best serve and protect human occupation. In the last 200+ years, the Seine River and its tributaries have undergone aggressive modifications on the longitudinal, lateral, and vertical axis: the river channel has been narrowed, its course straightened, and has been equipped with various engineering works such as locks, weirs, and reservoirs to regulate discharge and water levels1… Today, the processes of terraforming, erosion, translation, and flux are, for the most part, provoked and accentuated by humans. The river has little agency in its formation and all embedded-forces that would counteract the possibility for human activity to prosper are either controlled or reversed. The river today serves the primary utilitarian purpose of navigation both of goods coming from overseas as well as for internal traffic pertaining primarily to mineral movements for construction purposes. The river also serves as a cooling agent for industrial and nuclear riverine activity, and as a secondary hydro-electrical production source. All functions of the river have been operationalized.

Alteration
The anthropogenic utilization of the river has resulted in noticeable alterations in the profile of the Seine. As seen from these sections, the river has been significantly deepened to facilitate navigation. The river has been channelized and its banks stabilized (artificialized), particularly in floodplains that have been equipped with dikes and levees. The presence of locks and weirds have caused the modification of river flow often impacting the morphology of the river as well. Various naturally forming islands have been leveled or attached to the banks to favor a direct channel and minimized the otherwise in-born dynamic changes. Through various engineering structures, water levels are intended to be kept at a fixed value +- 35 cm with minimal river discharge variations. While these interventions have significantly altered the riverscape, they highlight a dissociation between its applied function and the naturally-occurring functional processes which unfold in the river. This is exemplified by the yearly repeated dredging activities to erase the formation of sandbars and sediment accumulation. These interventions have altered the hydrological functioning of the river which in turn has impacted its ecological dynamic. The river’s fish population has largely fluctuated through the ages as interventions on the river channel and varying water quality (and chemical composition) have disturbed their habitats and spawning grounds.

Limit
The process of anthropogenic river-scape transformations exemplifies a will to alter systems that are not fundamentally understood as they require repeated engineering interventions highlighting their limits. Anthropogenic control has been exercised massively on the channel and riverbed of the Seine and its tributaries. These interventions have been incremental and begun in the 1800s when the city of Paris was rapidly industrializing. The Seine has, for the most part, been channelized downstream of the city of Paris to ensure minimal variations in the river channel. In 1910, Paris experienced the largest flood event in its collective memory with the Seine’s water level exceeding 8 m above typical height. The city halted for several weeks as boulevards and basements were underwater. Although not fatal the disasters caused much damage to structures and infrastructures in the city.  From then on, large scale reservoirs were constructed upstream of the Parisian metropole to ensure flood protection and low-water discharge in times of heavy rainfall and winter floods. Undergone engineering solutions of the 20th Century seem to still not suffice as rain periods have intensified in the last decades. Currently, a fifth water catchment infrastructure system is underway: la Grande Bassée. Today the river is under the control of the Minister of Ecology and the VNF (Voies Navigable de France) is the administrative branch in charge of managing all navigable waterbodies functioning in the country – highlighting the main perceived function of the river as a mobility channel.

Composition
The Supervolcano Eruption

About 74,000 years ago, The Toba Caldera was formed through a process of volcanic tectonic explosive followed by a pattern of continuous ring-fractures. Next, the collapse of the volcano’s body (flare-up) happened due to the vacuumness in the magma chamber (UNESCO, 2018). Afterwards, the rain water fulfilled the caldera and formed the largest volcanic lake in the world with 240 km3 of fresh water.

Besides, this volcanic activity continued with the several cone volcanoes formed along the western edge of the caldera (Sibandang-Pardepur Mountain, Pusik Buhit Mountain, and Sipiso-Piso Mountain). The island of Samosir in the center of this caldera was formed afterwards since about 33,000 years ago, along by a resurgent doming to achieve a new equilibrium post-supervolcano eruption. This supervolcano eruption formed geothermal nodes that are found within this area and a unique landscape trail.

Alteration
Dynamic Landscape

Lake Formation
Moedjodo et al. (2006) concluded that Lake Toba formation was not because of a single event, but a combination and complex events. It was a result of series events that is illustrated by Figure 5 and influenced by Sumatra Fault starting about 1.3 million years ago.

Samosir Resurgent
The dynamics of the Samosir island process resulted in an en-echelon fracture pattern in the eastern part of the island, lake cliffs, and the accumulation of thick lacustrine sediment (Aldiss & Gazali, 1984). Until now this island has been uplifted and ‘tipped’ + 700 m from its original position, tilted to the west.

The Rock Type
The types of the rocks were classified based on their formation. Most of the region is formed with sedimentary rock with low to nonexistent porosity. As a result, the water is hard to be infiltrated by the soil, hence numerous fault lines are spreaded over the area to allow water flow into the soil. In addition, some areas along the lake have igneous rock type instead with high bearing capacity that is suitable for building construction. But, the rock type within the samosir island is different from any other part of the region, which is Non-Clastic Sedimentary Rock that has low to medium bearing capacity. This is also the reason why in this area traditional buildings with local material for the construction such as wood.


Limit
Landscape Vulnerabilities

Due to the location of Sumatera Island which has two main faults along the island (Mentawai Fault and Sumatran Fault), a mountain range – called Barisan Mountain that transversely spread the island causes the area to have high risk of natural disaster such as earthquake and landslides. Moreover, intensive agriculture and land cover change from forestry to productive landscape also created pressures on soil quality as it is illustrated within the critical zone area and flooding in the coastal areas nearby the adjacent sea.

Composition
Additions and Subtractions

Since the first plan for the Hydropower dam on the Xingu river in the 1970s, which would divert the natural flow of water from the area known as Volta Grande do Xingu, there have been continuous revisions to the project in order to reduce the impact that its reservoir would inflict (Ascselrad, 2009, Nascimento, 2017).

The technology known as “continuous water flow dam” was decided as the least impacting on the territory since it reduced in 80% reservoir surface area from the previous projects.

This was seen as a technological advancement by government bodies and major communication outlets, but the impacts of such a massive enterprise still affected thousands of people directly and indirectly around the construction and flooding areas. Around 20.0000 people were displaced (Ascselrad, 2009, Pezzuti, 2018) and resettled in urban peripheries, completely disassociated from cultural natural processes by the river.


Alteration
Replaced Systems

During the planning and construction of the dam complex. little or no attention was given to the implications of these constructed barriers would have on natural processes of fauna displacement as well as the movement and territorial range of indigenous practices (Pezzuti, 2018). The “stabilization of nature” for operationalization purposes has affected landscape systems in a variety of ways.


Limit
Damming Lives

These landscape manipulations have imposed physical barriers to the territory and the social and natural systems, directly affecting its ecology. In the Volta Grande do Xingu life has been completely affected by the change in course of the river, destabilizing its natural processes caused by prolonged periods of intentional drought. The two formal indigenous territories of the Juruna people; Arara and Paquiçamba, have been closed off from the rest of the Xingu basin indigenous populations as well as the rest of the amazon region itself by engineered systems of river transposition that dictate and control passage from lower to upper Xingu River.