The Amblo is a river of the

Nile The Nile (also known as the Nile River or River Nile) is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa. It has historically been considered the List of river sy ...

basin. Rising in the mountains of

Dogu’a Tembien Dogu'a Tembien (, "Upper Tembien", sometimes transliterated as Degua Tembien or Dägʿa Tämben) is a districts of Ethiopia, woreda in Tigray Region, Ethiopia. It is named in part after the former province of Tembien Province, Tembien. Nowadays, ...

in northern

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

, it flows northward to empty finally in the Weri’i and

Tekezé River The Tekezé River (; , originally meaning "river" in Ge’ez; , also spelled Takkaze; ), is a major river in Ethiopia. For part of its course it forms a section of the westernmost border of Ethiopia and Eritrea. The river is also known as the Seti ...

Characteristics

It is a confined ephemeral bedrock river, with an average slope gradient of 63 metres per kilometre. With its tributaries, the river has cut a deep gorge.

Flash floods and flood buffering

Runoff mostly happens in the form of high runoff discharge events that occur in a very short period (called

flash floods A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, or tropical storm, or by meltwater from ice and snow. Flash fl ...

). These are related to the steep topography, often little vegetation cover and intense convective rainfall. The peaks of such flash floods have often a 50 to 100 times larger discharge than the preceding

baseflow Baseflow (also called drought flow, groundwater recession flow, low flow, low-water flow, low-water discharge and sustained or fair-weather runoff) is the portion of the streamflow that is sustained between precipitation events, fed to streams by d ...

. The magnitude of floods in this river has, however, been decreased due to interventions in the catchment. On steep slopes,

exclosure An exclosure, in an area being used extensively for grazing, is a limited area from which unwanted browsing (herbivory), browsing animals, such as domestic cattle or wildlife such as deer, are excluded by fencing or other means. Environmental ...

s have been established; the dense vegetation largely contributes to enhanced infiltration, less flooding and better

. Physical conservation structures such as stone bunds and

check dam A steel check dam A check dam is a small, sometimes temporary, dam constructed across a swale, drainage ditch, or waterway to counteract erosion by reducing water flow velocity. Check dams themselves are not a type of new technology; rather, t ...

s also intercept runoff.

Transhumance towards the gorge

Transhumance Transhumance is a type of pastoralism or Nomad, nomadism, a seasonal movement of livestock between fixed summer and winter pastures. In montane regions (''vertical transhumance''), it implies movement between higher pastures in summer and low ...

takes place in the summer rainy season, when the lands near the villages are occupied by crops. Young shepherds will take the village cattle down to the gorge and overnight in small caves. The gorges are particularly attractive as a transhumance destination zone, because there is water and good growth of semi-natural vegetation.

Boulders and pebbles in the river bed

Boulders and pebbles encountered in the river bed can originate from any location higher up in the catchment. In the uppermost stretches of the river, only rock fragments of the upper lithological units will be present in the river bed, whereas more downstream one may find a more comprehensive mix of all lithologies crossed by the river. From upstream to downstream, the following lithological units occur in the catchment. * Upper basalt * Interbedded lacustrine deposits * Lower basalt *

Amba Aradam Formation The Amba Aradam Formation is a Cretaceous sandstone formation in Ethiopia. It is up to 200 metres thick, for instance in the Degua Tembien district. As fossils are absent, the age of the Amba Aradam Formation was interpreted based on the age of as ...

Antalo Limestone The Antalo Limestone, also known as the Antalo Sequence, is a geological formation in Ethiopia. It is between 300 and 800 metres thick and comprises fossiliferous limestones and marls that were deposited in a reef. Marine microfossils have shown ...

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

freshwater

tufa Tufa is a variety of limestone formed when carbonate minerals precipitation (chemistry), precipitate out of water in ambient temperature, unheated rivers or lakes. hot spring, Geothermally heated hot springs sometimes produce similar (but less ...

Adigrat Sandstone The Adigrat Sandstone formation in north Ethiopia, in a wide array of reddish colours, comprises sandstones with coarse to fine grains, and locally conglomerates, silt- and claystones. Given the many lateritic palaeosols and locally fossil woo ...

Natural boundary

Along its course, this river passes through three municipalities and two woredas and constitutes two different borders. On the various parts: * In its upper course, between Addi Walka and

Arebay Arebay is a ''tabia'' or municipality in the Degua Tembien, Dogu'a Tembien district of the Tigray Region of Ethiopia organised around the Arebay mountain peaks (2799 m). The ''tabia'' centre is in Arebay village, located approximately 13 km ...

, in

* In its middle and lower course, between Addi Walka (

) and Tsigereda ( Kilte Awula’ilo) and

Trekking along the river

Trekking routes have been established across and along this river. The tracks are not marked on the ground but can be followed using downloaded .GPX files.Public GPS traces tagged with nyssen-jacob-frankl , OpenStreetMap
/ref> Trek T follows the upper and middle course of the river from a distance, giving good views on the gorge.

References

{{reflist Rivers of Ethiopia Dogu'a Tembien Tigray Region Nile basin