High resolution radar satellite images as task force system in extremely active morphologic areas? By Jörn Kohlus, State Service for the National Park Wadden Sea, Tönning
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Stones in the National Park Wadden Sea Schleswig-Holstein - OpenArch Conference, Albersdorf 2013
1. 1
Stones in the National Park Wadden Sea Schleswig-
Holstein ? High resolution radar satellite images as
task force system in extremely active morphologic
areas.
General meeting
Jörn Kohlus
Landesbetrieb für Küstenschutz,
Meeresschutz und Nationalpark
Tönning (Germany)
Landesbetrieb für
Küstenschutz,
Nationalpark und Meeresschutz
3. 3
The Wadden Sea
• The Wadden Sea is a part of three European Nations:
Starting in the west at Den Helder in The Netherlands,
eastward in Germany along the Lower Saxony coast,
turning to north at the mouth of the Elbe until
Esbjerg in Denmark
• The landscape is characterized by a belt of
barrier islands, big tidal flats, rest of ice age material
and flat marsh land along the coast
3
4. 4
• Total area of NP 4,415 km²
• Coastline of mainland
and islands: 460 km
• Inhabited areas are excluded
• National Park established in 1985
• Marine habitats like salt marshes,
extended tidal areas, open sea,
sand banks, beaches and dunes
• UNESCO Biosphere Reserve
since 1990
• World Heritage Site since 2009
Facts and Figures:
19. 3 terbs, badly to recognize
double structure of ditches
(14th and 17th century)
simple systems of
ditches (14th century)
TerrarSAR Composite (2013) archeologic structures
19
20. Description Sediments Rouphness Signal
fine and middle sand
with wave ripples
fine and middle sand wave ripples, high high, differences in
polarization
surf region with shell
detritus
shell detritus flat area, low high
marine mud mud flat, wet middle low
wet fine sand fine sand flat, wet low
water, no waves water flat, wet very low
organic material peat, gyttia flat, wet middle
small stripes of peat,
fossil plants and
mussels
gyttia, mussels stripes, mostly lower
than
8 cm
middle
TSX as like radarsat - 2 could be used to
observe archaeological sides in the wadden
sea
In the Wadden Sea archeological surveys have to be done „just
in time“ and the work is difficult
TSX is qualified for observation
2011
2013
I am geographer, working in the stuff of the authoritie for the nationl park of schleswig holstein waddensea. My job are today european data networks and remote sensing.
since eight years my work on remote sensing meets the work of archeologists. So far, it seems simple to answer with "yes" when Rüdiger ask me to talk about my work in the area of the national park of Wadden Sea. Later he told me, that a central keyword of your meeting is "stone" - since that moment I Understand my presentation as a dare. Because the Wadden Sea perhaps could be named as home of mud and worms.
This biggest Wadden Sea Area of the earth is part of 3 …. And in the area of Schleswig-Holstein it becomes protected as a national park since 1985.
This national park, some kilometers westward from here is the biggest national park of Germany and it became part of the world heritage area European Wadden Sea. This mostly Holocene formed area get it's respect as "once in the world" - better earth, as area of undisturbed geo- morphological processes and dynamics in the largest coherent tidal flat system world wide. Also as a place of mostly undisturbed ecological processes and - here clearly limited to the climatic and geographic situation, it's role for biodiversity. If it would be a criteria of World Heritage, we also could have find respect as Europeans biggest area of rare stones. So your keyword made me a little bit nervous .
We could find stones in the Wadden Sea: Mostly at deep places, streams which erode Tertiary ice age material. Next to islands, builded around a nucleus of ice age material, we could also find stone. In the long time of rising sea level old land was eroded or sink down in the sea. Today we find this old land as part of the sea bottom and we could go to some of this place while low water. Here you see old megalith graves near the island Föhr. This stones have been moved by humans, but at least, they are natural and indigenous.
Also this stone is recently eroded at a cliff of Sylt - but most stones, exactly like this are imported later than 19th century as material for coastal protection.
But typical for this thousands of square kilometers are micro-stones, called sand, mud or sometimes clay. In some of this areas Stone could be find: Neolithic instruments made of flint. If you could accept bricks as stone - I am geographer, for me both photos show human formed hard substrate. Bricks are next to pottery the most common hard substrate in the Wadden Sea. At least nearly any stone, bricks like pottery in The Wadden Sea could be seen as a sign for human activity. And not a least, morphologic harder substrate like clay and peat – both mostly tell us about human being in today Wadden Sea.
Where stones could be disposed naturally and where they will disposed by man? To answer we have to follow landscapes history. Sorry, what I show now is more pedagogical than science. Here you see the most extended boarders of Saale and Weichsel Glacial.<K> Also later big parts of the Northsea have been Land, Britain was connected to the main land.<K> When the ice smelt down the sea level rise and deeper place are flooded. <K>, stone instruments can be find.<KLICK> Since 6000 B. P. there will be something like a Wadden Sea, barrier Islands take place <K>, riparian forest with softwoods grow, artifacts of Neolithic settlements can be find. But most of artefacts are out of medieval settlements, when the Wadden Sea was a swampy area far away from the sea.
This map by the Regional State Service for Archaeology shows all recognized landmarks and salvaged findings in the North Frisian Wadden Sea Area. Red areas are rests of settlements and field structures. As I told, we find Neolithic instruments, but much more pottery of roman time and pottery like field structures early middle age and the 17 th century.
Here we see the change caused by surges in the 14 th century. But 200 to 250 years later, there was a new increase of surges. Again big areas got lost. It was not one big event, but the horror of 1634 can be found in a lot of tales. This was not only triggered by nature. Nothing at least, the “thirty years war” has reduced the number of people, destroyed infrastructure and financial resources.
I am working for the national-park-administration, so my central view is not artifacts of settlements. Our problem is to monitor seagrass, oyster banks, algae, changes of sediments in a big and difficult but very variable area. Traveling and working at the ground or with the help of ships is expensive and slow. Remote sensing from air borne platforms or space seems to be an alternative. Daytime is limited and clouds, we have a lot. Half the time our area of interest is covered by water – here on the way to a mussel-bank before low tide. And mud could be dangerous and makes walking and working very slow .
Working with optical data from satellites is difficult by clouds and limited by daytime. So remote sensing by radar seems to be charming in cause it is independent from daylight and clouds, so that we mainly have only to look for the tidal situation. The knowledge about the use of radar signals in Wadden areas is limited. What we know is, that we could not identify the most of our targets only by radar. Our concept is to combine radar and optical signals with maps, created by in-situ measurements and flights.
On high resolution radar images of TerrarSarX we could recognize parallel lines on the sand banks next to mud flats. And we could find those structures since 2013 also on those images of another new satellite system – RadarSat 2.
If you go into the field – or mud - you will see something like this. Comparing different states of erosion, I could create a schema. For us, working on remote sensing, it is for interest, that those structures are as small or smaler than the resolution of the signals.
Structures like this are known by field survives. Also our colleagues from the State Service for Archeology analyzed our air borne photos made for mussel monitoring since around ten years.
We could understand this structures by comparing it to well preserved Landscapes on islands and especially the marshes on the peninsula of Eiderstedt. Here we see the structure of fields and a drainage system. Perhaps looking like this old marsh land in Eiderstedt Peninsula Also we see rests – the bases - of terps. They are not looking different from recently used terps today.
At another place northern of Pellworm island we could follow this structure on the bottom of the sea. Two ditches, sometimes crossed by other elements. What we recognized was an old lane. The crossing lines were newer, they might be ditches of the 17th century. So I made a draft to give you an idea of the situation in the 14th century. Perhaps the wooden elements in the center of the photo are rests of a bridge