Ab’aro is a river of the

Nile The Nile, , Bohairic , lg, Kiira , Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered the longest ...

basin. Rising in the mountains of Dogu’a Tembien in northern

Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...

, it flows northwestward to empty finally in Weri’i and

Tekezé River The Tekezé or Täkkäze River ( amh, ተከዜ, ti, ተከዘ; originally meaning "river" in Ge’ez, ), also spelled Takkaze, is a major river of Ethiopia. For part of its course it forms a section of the westernmost border of Ethiopia and Eri ...

Characteristics

Ab’aro is a confined ephemeral river in its upper part, whereas it widely

meander A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank) and deposits sediments on an inner, convex ba ...

s in the lower plains, with an average slope gradient of 60 metres per kilometre. Towards the footslope the river has cut a deep gorge (a cluse). Abaro Gorge

Flash floods

Runoff mostly occurs in the form of high runoff discharge events that occur in a very short period (called flash floods). 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. In contrast to neighbouring rivers such as

May Meqa May Meqa is a river of the Nile basin. Rising in the mountains of Dogu’a Tembien in northern Ethiopia, it flows northward to empty finally in Weri’i and Tekezé River. Characteristics It is a confined ephemeral river, locally meanderin ...

, May Shoate or Giraliwdo, the magnitude of floods in Ab’aro has not been decreased due to interventions in the catchment. 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, th ...

s that intercept runoff are absent. On the steep slopes,

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

s have not been established and there is no dense vegetation that could contribute to enhanced infiltration, less flooding or better

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 ...

. As such, it is one of the few catchments that could stand model for conditions before major human interventions for conservation started in the

Tigray region The Tigray Region, officially the Tigray National Regional State, is the northernmost regional state in Ethiopia. The Tigray Region is the homeland of the Tigrayan, Irob, and Kunama people. Its capital and largest city is Mekelle. Tigray ...

Lithology

From upstream to downstream, the following lithological units occur in the catchment. Abaro church

* Phonolite plugs * Upper basalt * Interbedded lacustrine deposits * Lower basalt * Amba Aradam Formation *

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 freshwater

tufa Tufa is a variety of limestone formed when carbonate minerals precipitate out of water in unheated rivers or lakes. Geothermally heated hot springs sometimes produce similar (but less porous) carbonate deposits, which are known as travertin ...

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 wood ...

Logically, in the uppermost stretches of the river, only the pebbles and boulders 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.

Natural boundary

During its course, this river passes through two woredas and constitutes their border for 2 kilometres. On the various parts: * Dogu’a Tembien to the southeast * Kola Tembien to the northwest

Transhumance towards Ab'aro

The valley bottoms in along middle Ab'aro have been identified as a transhumance destination zone.

Transhumance Transhumance is a type of pastoralism or 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 lower val ...

takes place in the summer rainy season, when the lands near the villages are occupied by crops. Young shepherds will take the village cattle 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.

Trekking along the river

A trekking routes winds across and along this river. The tracks are not marked on the ground but can be followed using downloaded .GPX files. Trek Gh2 roughly follows the river, partly occupying the track of an old road dating back to the time of the Italian occupation. In the rainy season, flash floods may occur and it is advised not to follow the river bed.

References

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