Ab'aro
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| Ab'aro | |
|---|---|
 The Ab’aro cluse cuts across an outcrop of Adigrat Sandstone | |
  Ab’aro River in Dogu’a Tembien | |
| Location | |
| Country | Ethiopia |
| Region | Tigray Region |
| District (woreda) | Dogu’a Tembien |
| Physical characteristics | |
| Source | Ab’aro rock church |
| • location | Atsa in Haddinnet municipality |
| • elevation | 2,340 m (7,680 ft) |
| Mouth | Agefet River |
• location | NE of Addeha |
• coordinates | 13°47′20″N 39°08′29″E / 13.7888°N 39.1414°E |
• elevation | 1,638 m (5,374 ft) |
| Length | 11.6 km (7.2 mi) |
| Width | |
| • average | 15 m (49 ft) |
| Basin features | |
| Progression | Agefet→ Tsaliet→ Wari→ Tekezé→ Atbarah→ Nile→ Mediterranean Sea |
| River system | Seasonal river |
| Landmarks | Ab’aro rock church, Kayeh Be'ati sandstone caves |
| Waterfalls | Rapids in Ab’aro cluse |
| Topography | Mountains, deep gorges and a sandy outwash plain |
The Ab’aro is a river of the Nile basin. Rising in the mountains of Dogu’a Tembien in northern Ethiopia, it flows northwestward to empty into the Weri’i, which is a tributary of Tekezé River.
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.[1] In contrast to neighbouring rivers such as May Meqa, 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[2][3] and check dams that intercept runoff[4][5] are absent. On the steep slopes, exclosures have not been established and there is no dense vegetation that could contribute to enhanced infiltration, less flooding or better baseflow.[6] 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.
Lithology
From upstream to downstream, the following lithological units occur in the catchment. [7]
- Phonolite plugs
- Upper basalt
- Interbedded lacustrine deposits
- Lower basalt
- Amba Aradam Formation
- Antalo Limestone
- Quaternary freshwater tufa[8]
- Adigrat Sandstone
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.[9] 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 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.[10]
