Cem (river)
The Cem, also known as the Cijevna, is a river that rises in Kelmend, Albania and after nearly half of its length crosses into Montenegro, where it flows into the River Morača near the capital Podgorica.
The Cem is fully formed at the confluence of its two tributaries the Vukël Cem and the Selcë Cem. It passes mostly through limestone terrain with many karstic formations. These features of the Cem's basin have their origin in the tectonic activity of the Alpine orogeny, which formed the Dinaric Alps. The terrain through which it flows in its course, is at an elevation of more than and can reach as low as. It passes through narrow valleys and steep canyons, where waterfalls are formed before it reaches the Zeta plain. As it approaches the Morača, the Cem area shifts from a continental climate to a Mediterranean one. The drainage basin of the Cem encompasses and is part of the Adriatic river basin.
The first cultural indicators of human settlement in the Cem river basin are from the late Copper Age and early Bronze Age. Illyrian tribes such as the Labeatae lived in the area in classical antiquity. In the following millennia, the area passed under the control of the Roman Empire and its eastern counterpart, Slavic principalities, the Republic of Venice and the Ottoman Empire. The Cem basin was the home of Albanian tribes such as Kelmendi, Hoti, Gruda and Triepshi until the 20th century. Today, the river is divided between Albania and Montenegro.
The Cem is one of the last free-flowing rivers in Europe. The river's basin is a source of very high biodiversity, and hundreds of plant and animal species live along its banks. Mammals include wild boars, brown bears and red foxes. The river's canyon is an Important Bird Area for species like the short-toed snake eagle and the Levant sparrowhawk. The marble trout is one of the 22 fish species in the river, which consistently ranks as one of the least polluted rivers in Albania and Montenegro. In the 21st century, it is threatened by industrialization, the installation of small hydropower stations and the effects of climate change in Europe.
Name
The Greek geographer Ptolemy was the first to mention the Cem as Kinna in ancient Greek. In Tabula Peutingeriana a location named Cinna in Latin is connected to the river. These two forms are considered to be written forms of a local, Illyrian name Cinua. Albanian Cem and medieval Slavic Cenva and Cemva ultimately stem from this original name of the river. The phonological evolution of Cinua to the Albanian Cem presupposes the Slavic second palatalization. Montenegrin– and also Bosniak and Serbian – Cijevna is derived from Serbo-Croatian cijev, but other toponyms preserve the older name Ćemovsko polje.Geography
The Cem originates in Kelmend, Malësi e Madhe, Albania and flows through the region of Malësia. The river has two tributaries: the Vukël Cem and the Selcë Cem, which join at the confluence of Tamarë. The Vukël Cem – the more important of the two in terms of water volume – rises at above sea level and flows for. It passes through a narrow canyon, a terrain which widens only near Kozhnja, where deposition has formed a small limestone valley. A creek called the Nikç Cem contributes to its volume in the rainy period. A small hydropower project has been built where the Cem i Nikçit passes through Kozhnja.The Selcë Cem rises at on Mount Bordolec near Lëpushë and flows for mostly through narrow limestone terrain until it reaches the valley of Tamarë. In its course it passes through the Gropat e Selcës karstic caves, the canyon of Gerrlla, long and deep, and the waterfall of Sllapi before reaching Dobrinjë.
The Cem then flows to the southwest for before crossing into Montenegro, near the village of Grabom. The Albania-Montenegro border crossing is located ca. west of Grabom. In Montenegro, the river flows through the villages of Tuzi for before it flows into the Morača, just south of Podgorica. The terrain through which the river flows in Montenegro is divided into two parts. Firstly, it forms a steep canyon and then slowly crosses into the Zeta plain, of which a part is called Ćemovsko polje after the river. On the plain, Špiro Mugoša Airport has been built between the Cem and the Ribnica to the east of Podgorica Airport. The land here has become more urbanized and industrialized.
The Cem canyon is long and has a depth of. It is the natural habitat of many animal, insect and plant species. The canyon starts at the Albania-Montenegro border and forms a distinct geomorphological formation that crosses into Ćemovsko polje just before the village of Dinosha.
Geology
The geomorphological features of the Cem basin have their origin in the tectonic activity of the Alpine orogeny, which has been forming the Dinaric Alps and its southern range, the Accursed Mountains since the Late Mesozoic and Cenozoic era. The Cem basin is in the High Karst Unit. In this sub-unit, tectonic activity lifts the landmasses vertically and carbonate rocks form a large part of the landscape, which is defined by fluvial processes like the deposition of carbonate sediments by the river caused by the flow of the river. As the Accursed Mountains have had glacial features, thus a high accumulation of water, the end of the Ice Age saw a general increase of the Cem's discharge, which in turn increased fluvial processes in the basin.An abundance of limestone has enabled the formation of uvalas, caves and other karst formations. However, water is retained in limestone, and so the denudation of geological formations is decreasing. The result of these interconnected processes is that the Cem flows mostly through elevated, vertical and steep terrain, which forms canyons and crosses into small valleys. In these places, such as in the valley of Tamara, non-carbonate rocks have caused horizontal erosion to occur. Then, the river exits high elevation areas and flows towards the Morača as the relief flattens and a polje is formed by karst processes.
Drainage basin
The drainage basin of the Cem is a part of the Adriatic river basin, along with other rivers that empty into Lake Skadar, a total area of. The river and its tributaries originate within the of the basin that are within the borders of Albania; are in Montenegro. To the north, it borders the basin of the Vermosh and to the east that of the Lëpushë. To the south, the Cem's basin ends near Bogë.The river flows from above to no more than. In Montenegro, waterfalls more than high are formed. Annual precipitation is about. The month with highest precipitation is November and the driest month is July. Snowfall can be observed as late as May. There is on average a 40-day period of annual snowfall and an accumulation average of.
The Cem has a continental climate in its upper part and a Mediterranean one as it reaches the Morača. The annual temperature averages 6.8-7 °C - January being the coldest month at -3 °C and July the hottest at 15.7-20 °C. Water temperatures range from 5 °C in the spring to 13 °C in the summer. There are three local winds that affect the Cem in Albania. The Murlani is a dry and cold northern and northeastern wind which blows towards the Adriatic, whereas the Shiroku and the Juga are humid and warm southern winds which are associated with rainy periods.
Discharge
The river's streamflow increases as tributaries and springs flow into it. Elevation and other morphological features also cause variations in its discharge. In general, the upper part of the Cem in Albania has a lower velocity and thus a lower streamflow than the flow of the Cem through the canyon in Montenegro, where the Cem's streamflow increases as it descends. When it reaches the Zeta plain, it slows again as it flows into the Morača.The Cem of Vukël contributes to the river. Measurements at Tamarë, where the confluence with Cem of Selcë is located, show an average discharge of. As the river passes into Montenegro near Grabom, karstic springs in at Dverbta and Brezhda increase its streamflow. After this point the average discharge through the canyon is, but as it crosses into the valley, it can drop below in the dry summer months. The maximal discharge rate of the river has been observed in May at.
Causes of the flow decrease include its use in the water supply network and environmental factors linked to climate change, which has led to a cyclical decrease of rainfall, groundwater and karstic springs water yield to the river. This trend of flow decrease was observed in the Trgaj measurement station near Dinosha, in 2019, where the summer flow was at a very low. As the Cem pours into the Morača, it can contribute up to to the total discharge of of that river into Lake Shkodra.
Ecosystem
The ecosystem of the Cem river basin is very biodiverse. The riparian zones of the Cem support hundreds of plant and animal species endemic to the region. Mammals include wild boars, brown bears, red foxes, brown hares, pine martens and the - until recently - endangered Eurasian otter. The total number of mammal species in the Cem valley has not yet been completely surveyed.Many bird species live on the banks of the Cem and the river's canyon is an Important Bird Area. Short-toed snake eagles, Levant sparrowhawks and the rock partridge use the canyon for breeding and nesting in the summer months. The Egyptian vulture, an endangered species - once very common in the Balkans - lived in the canyon until 1997, when it became extinct there as in many other areas in the Balkans. In Albania, 130 bird species in total have been identified along the Cem and its tributaries.
There are 22 species of fish in the river including endemic marble trout and eel. The height of the Cem above sea level affects flora distribution zones. At elevations between oak trees are common around Selcë and Vukël, but as elevation drops pomegranates become much more common. In the river basin about 40% of the total plant species found in Albania, have been identified. In the Cem canyon, 813 plant species have been identified, with a total of 959 in the wider canyon area. The canyon is host to a quarter of the total plant species of Montenegro.
A full identification of the flora of the Cem has yet to be completed. In 2018, the moss species Fissidens fontanus was identified for the first time in the part of the river in Montenegro, near Podgorica and in the nearby Sitnica river.