Liviu Giosan

Last updated
Liviu Giosan
Giosan liviu.jpg
Born1968 (age 5556)
Alma mater University of Bucharest, State University of New York at Stony Brook
Scientific career
Fields Geosciences
Institutions

Liviu Giosan (born 1968) is a Romanian marine geologist studying the interactions between climate, landscapes and humans. In the public sphere, he initiated "Ad Astra", an association of scientists from Romania and Romanian diaspora, [1] and has been actively involved in efforts to reform Romania's post-communist science and academia. [2]

Contents

Career

Studying the sediment transfer system through rivers into and inside the ocean, he focuses especially on river deltas and has worked in the Danube, Indus, Ebro, Mackenzie among other regions. His work includes contributions reported on by National Geographic [3] on the so-called "Noah's Flood" or the Black Sea deluge hypothesis, New York Times, [4] [5] on the collapse of the ancient urban Indus Valley civilisation and the long term impact of deforestation on the Danube Delta and the Black Sea, BBC [6] on the drowning of river deltas under human-induced climate changes.

Giosan started his career studying the Danube delta. This work led to a classification of deltas highlighting the constructive role of waves and to the discovery of an asymmetric (polygenetic) end-member. These advances, together with novel ideas on river mouth morphodynamics, inspired approaches to numerically model river delta evolution and architecture. After producing the first accurate evolution model of the Danube Delta, Giosan explored the dramatic effects of early deforestation on the Danube and Black Sea as a type example of how humans have unintentionally affected the coastal ocean for millennia. Together with colleagues spanning disciplines from paleogenetics to engineering, he linked the rapid growth of the Danube delta in the last 2000 years to deforestation that started under the Roman Empire and accelerated during the Ottoman Empire's expansion in Europe. Paleo-DNA preserved in sediments indicated the ecosystem of the whole Black Sea has changed following the deforestation as Danube brought in more nutrients and silica from eroding soils. The magnitude of these changes for a continental-size system such as the Danube-Black Sea is a prime argument for an early Anthropocene epoch.

In 2003, after discovering of a large submarine extension of the Indus delta, Giosan and his colleagues started to explore the Holocene history of the Indus River and its ancient urban Indus Valley civilisation. Their analyses of landscape and human settlement dynamics along the Indus and its tributaries offered ample field-based support for a climatic theory of the Indus Civilization collapse. Landscape semi-fossilization as the Indian monsoon declined and aridity increased demonstrates that floods became erratic and less extensive making inundation agriculture less sustainable. Their studies also showed that the Ghaggar-Hakra, a former Indus tributary or a river flowing between the Indus and the Ganges watersheds and the most likely candidate for Sarasvati River of mythical fame, retracted its reach toward the foothills of the Himalaya. That region continued to be populated by the Indus people long after the collapse of their cities. Further work by Giosan's team in peninsular India highlighted the regional character of the impact of such climate changes: while the Indus civilization collapsed under the monsoon decline, people of the peninsula expanded agriculture to cope with aridity. In interviews, [7] [8] Giosan compared the ancient Indus collapse to the present dependence on fossil fuels and introduced the term "Goldilocks civilization" to underline their non-sustainable character.

In 2014, together with other leading deltaic researchers, he examined the global health of river deltas showing that these vast coastal lowlands cannot withstand the predicted rise in sea level for the next century and calling for maintenance and reconstruction measures. [9] Using again Danube delta as an example, Giosan and his colleagues showed that the expansion of a shallow channel network used for fishing in the mid 20th century had beneficial effects by trapping sediments on the delta plain and counteracting sea level rise effects. [10] This channelization of the delta plain, which mimics natural deltas in their youth, emerged as one of the methods for delta reconstruction.

Public life

In 2000, Giosan initiated and co-founded "Ad Astra", an association of academics dedicated to the reform of science and education in post-communist Romania. Occasionally he publishes analyses and OpEd texts in the Romanian media such as România Curată, Adevărul , or România Liberă .

Related Research Articles

<span class="mw-page-title-main">Indus River</span> River in Asia

The Indus is a transboundary river of Asia and a trans-Himalayan river of South and Central Asia. The 3,120 km (1,940 mi) river rises in mountain springs northeast of Mount Kailash in Western Tibet, flows northwest through the disputed region of Kashmir, bends sharply to the left after the Nanga Parbat massif, and flows south-by-southwest through Pakistan, before emptying into the Arabian Sea near the port city of Karachi.

<span class="mw-page-title-main">Geography of Romania</span>

With an area of 238,397 km2 (92,046 sq mi), Romania is the twelfth-largest country in Europe. It is a Balkan country located at the crossroads of Eastern and Southeast Europe. It's bordered on the Black Sea, the country is halfway between the equator and the North Pole and equidistant from the westernmost part of Europe—the Atlantic Coast—and the most easterly—the Ural Mountains. Romania has 3,195 kilometres (1,985 mi) of border. Moldova and Ukraine lie to the east, Bulgaria to the south, and Serbia and Hungary to the west by the Pannonian Plain. In the southeast, 245 kilometres (152 mi) of sea coastline provide an important outlet to the Black Sea and the Atlantic Ocean.

<span class="mw-page-title-main">Thar Desert</span> Large arid region in India and Pakistan

The Thar Desert, also known as the Great Indian Desert, is an arid region in the north-western part of the Indian subcontinent that covers an area of 200,000 km2 (77,000 sq mi) in India and Pakistan. It is the world's 18th-largest desert, and the world's 9th-largest hot subtropical desert.

<span class="mw-page-title-main">Sarasvati River</span> River mentioned in the Vedas and ancient Indian epics

The Sarasvati River is a mythologized and deified ancient river first mentioned in the Rigveda and later in Vedic and post-Vedic texts. It played an important role in the Vedic religion, appearing in all but the fourth book of the Rigveda.

<span class="mw-page-title-main">Levee</span> Ridge or wall to hold back water

A levee, dike, dyke, embankment, floodbank, or stop bank is a structure used to keep the course of rivers from changing and to protect against flooding of the area adjoining the river or coast. It is usually earthen and often runs parallel to the course of a river in its floodplain or along low-lying coastlines.

<span class="mw-page-title-main">Indus Valley Civilisation</span> Bronze Age civilisation in South Asia

The Indus Valley Civilisation (IVC), also known as the Indus Civilisation, was a Bronze Age civilisation in the northwestern regions of South Asia, lasting from 3300 BCE to 1300 BCE, and in its mature form from 2600 BCE to 1900 BCE. Together with ancient Egypt and Mesopotamia, it was one of three early civilisations of the Near East and South Asia, and of the three, the most widespread, its sites spanning an area from much of modern day Pakistan, to northwestern India and northeast Afghanistan. The civilisation flourished both in the alluvial plain of the Indus River, which flows through the length of Pakistan, and along a system of perennial monsoon-fed rivers that once coursed in the vicinity of the Ghaggar-Hakra, a seasonal river in northwest India and eastern Pakistan.

<span class="mw-page-title-main">Danube Delta</span> River delta in Europe

The Danube Delta is the second largest river delta in Europe, after the Volga Delta, and is the best preserved on the continent. The greater part of the Danube Delta lies in Romania, with a small part in Ukraine. Its approximate surface area is 4,152 square kilometres, of which 3,446 km2 (1,331 sq mi) is in Romania. With the lagoons of Razim–Sinoe, located south of the main delta, the total area of the Danube Delta is 5,165 km2 (1,994 sq mi). The Razim–Sinoe lagoon complex is geologically and ecologically related to the delta proper; the combined territory is listed as a World Heritage Site.

<span class="mw-page-title-main">River delta</span> Silt deposition landform at the mouth of a river

A river delta is a landform shaped like a triangle, created by the deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs at a river mouth, when it enters an ocean, sea, estuary, lake, reservoir, or another river that cannot carry away the supplied sediment. It is so named because its triangle shape resembles the uppercase Greek letter delta, Δ. The size and shape of a delta are controlled by the balance between watershed processes that supply sediment, and receiving basin processes that redistribute, sequester, and export that sediment. The size, geometry, and location of the receiving basin also plays an important role in delta evolution.

<span class="mw-page-title-main">Anthropocene</span> Proposed geologic epoch for present time

The Anthropocene ( ) is the common name for a proposed geological epoch, dating from the commencement of significant human impact on Earth up to the present day. It affects Earth's geology, landscape, limnology, ecosystems and climate. The effects of human activities on Earth can be seen for example in biodiversity loss and climate change. Various start dates for the Anthropocene have been proposed, ranging from the beginning of the Neolithic Revolution, to as recently as the 1960s as a starting date. The biologist Eugene F. Stoermer is credited with first coining and using the term anthropocene informally in the 1980s; Paul J. Crutzen re-invented and popularized the term.

<span class="mw-page-title-main">Sedimentation</span> Tendency for particles in suspension to settle down

Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to the forces acting on them: these forces can be due to gravity, centrifugal acceleration, or electromagnetism. Settling is the falling of suspended particles through the liquid, whereas sedimentation is the final result of the settling process.

<span class="mw-page-title-main">Black Sea deluge hypothesis</span> Hypothetical flood scenario

The Black Sea deluge is the best known of three hypothetical flood scenarios proposed for the Late Quaternary history of the Black Sea. One other flood scenario proposes a rapid, even catastrophic, rise in sea level of the Black Sea.

<span class="mw-page-title-main">Chautang</span> River in India

The Chautang is a seasonal river, originating in the Sivalik Hills, in the Indian state of Haryana. The Chautang River is a tributary of the Sarsuti river which in turn is a tributary of the Ghaggar river.

<span class="mw-page-title-main">Ghaggar-Hakra River</span> Intermittent river in India and Pakistan

The Ghaggar-Hakra River is an intermittent river in India and Pakistan that flows only during the monsoon season. The river is known as Ghaggar before the Ottu barrage at 29.4875°N 74.8925°E, and as Hakra downstream of the barrage in the Thar Desert. In pre-Harappan times the Ghaggar was a tributary of the Sutlej. It is still connected to this paleochannel of the Sutlej, and possibly the Yamuna, which ended in the Nara River, presently a delta channel of the Indus River joining the sea via Sir Creek.

<span class="mw-page-title-main">Sulina branch</span> One of three distributaries of the Danube River

The Sulina branch is a distributary of the river Danube that contributes to forming the Danube Delta.

Romania's landscape is almost evenly divided among mountains, hills, and plains. These varied relief forms spread rather symmetrically from the Carpathian Mountains, which reach elevations of more than 2,400 metres, to the Danube Delta, which is just a few metres above sea level.

<span class="mw-page-title-main">Danube</span> Second-longest river in Europe

The Danube is the second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest south into the Black Sea. A large and historically important river, it was once a frontier of the Roman Empire. In the 21st century, it connects ten European countries, running through their territories or marking a border. Originating in Germany, the Danube flows southeast for 2,850 km (1,770 mi), passing through or bordering Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova, and Ukraine. Among the many cities on the river are four national capitals: Vienna, Bratislava, Budapest, and Belgrade. Its drainage basin amounts to 817,000 km2 (315,000 sq mi) and extends into nine more countries.

<span class="mw-page-title-main">Nara Canal</span> Canal in Pakistan

The Nara Canal is a deepened delta channel of the Indus River in Sindh province, Pakistan. It was built as an excavated channel stemming off the left bank of the Indus River to join the course of the old Nara River, a tributary c.q. paleochannel of the Indus which received water from the Ghaggar-Hakra until the Hakra dried-up, early 2nd millennium BCE.

<span class="mw-page-title-main">Land loss</span>

Land loss is the term typically used to refer to the conversion of coastal land to open water by natural processes and human activities. The term land loss includes coastal erosion. It is a much broader term than coastal erosion because land loss also includes land converted to open water around the edges of estuaries and interior bays and lakes and by subsidence of coastal plain wetlands. The most important causes of land loss in coastal plains are erosion, inadequate sediment supply to beaches and wetlands, subsidence, and global sea level rise. The mixture of processes responsible for most of the land loss will vary according to the specific part of a coastal plain being examined. The definition of land loss does not include the loss of coastal lands to agricultural use, urbanization, or other development.

Many river systems are shaped by human activity and through anthropogenic forces. The process of human influence on nature, including rivers, is stated with the beginning of the Anthropocene, which has replaced the Holocene. This long-term impact is analyzed and explained by a wide range of sciences and stands in an interdisciplinary context. The natural water cycle and stream flow is globally influenced and linked to global interconnections. Rivers are an essential component of the terrestrial realm and have been a preferable location for human settlements during history. River is the main expression used for river channels themselves, riparian zones, floodplains and terraces, adjoining uplands dissected by lower channels and river deltas.

<span class="mw-page-title-main">Sedimentation enhancing strategy</span> Environmental management projects aiming to restore land-building processes in deltas

Sedimentation enhancing strategies are environmental management projects aiming to restore and facilitate land-building processes in deltas. Sediment availability and deposition are important because deltas naturally subside and therefore need sediment accumulation to maintain their elevation, particularly considering increasing rates of sea-level rise. Sedimentation enhancing strategies aim to increase sedimentation on the delta plain primarily by restoring the exchange of water and sediments between rivers and low-lying delta plains. Sedimentation enhancing strategies can be applied to encourage land elevation gain to offset sea-level rise. Interest in sedimentation enhancing strategies has recently increased due to their ability to raise land elevation, which is important for the long-term sustainability of deltas.

References

  1. Enserink, Martin (2008-11-21). "Reaching for the Stars in Romania". Science. 322 (5905): 1183–1185. doi:10.1126/science.322.5905.1183. ISSN   0036-8075.
  2. Nature - Scientists in Romania and Bulgaria are having the best and the worst of times.
  3. National Geographic - "Noah's Flood" Not Rooted in Reality, After All?
  4. The New York Times - An Ancient Civilization, Upended by Climate Change
  5. The New York Times - From Ancient Deforestation, a Delta Is Born
  6. "Major deltas 'could be drowned'", BBC
  7. Oceanus - Climate Change Spurred Fall of Ancient Culture
  8. Schultz, Colin (2013). "Climates, Landscapes, and Civilizations". Eos, Transactions American Geophysical Union. 94 (40): 355–356. Bibcode:2013EOSTr..94..355S. doi: 10.1002/2013EO400014 . S2CID   128544603.
  9. Giosan, L., Syvitski, J.P.M., Constantinescu, S., Day, J., 2014, Protect the World’s Deltas, Nature, 516: 31-33. doi : 10.1038/516031a
  10. Giosan, Liviu; Constantinescu, Stefan; Filip, Florin; Deng, Bing (2013). "Maintenance of large deltas through channelization: Nature vs. humans in the Danube delta". Anthropocene. 1: 35–45. doi:10.1016/j.ancene.2013.09.001. ISSN   2213-3054.