The May Ayni is a river of the Nile basin. Rising in the mountains of Dogu’a Tembien in northern Ethiopia, it flows southwestward to empty finally in the Giba and Tekezé River.[1]
| May Ayni | |
|---|---|
  May Ayni River in Dogu’a Tembien | |
| Etymology | “Spring” in Tigrinya language |
| Location | |
| Country | Ethiopia |
| Region | Tigray Region |
| District (woreda) | Dogu’a Tembien |
| Physical characteristics | |
| Source | |
| • location | Ra’isot in Ayninbirkekin municipality |
| • elevation | 2,298 m (7,539 ft) |
| Mouth | Afedena River |
• location | Near Afedena in Addi Azmera municipality |
• coordinates | 13°38′49″N 39°18′11″E / 13.647°N 39.303°E |
• elevation | 1,995 m (6,545 ft) |
| Length | 6 km (3.7 mi) |
| Width | |
| • average | 5 m (16 ft) |
| Basin features | |
| Progression | Afedena→ Hurura→ Giba→ Tekezé→ Atbarah→ Nile→ Mediterranean Sea |
| River system | Seasonal river |
| Topography | Mountains and deep gorges |
Characteristics
editIt is a confined ephemeral river, locally meandering in its narrow alluvial plain, with an average slope gradient of 51 metres per kilometre. With its tributaries, the river has cut a deep gorge.[2]
Flash floods and flood buffering
editRunoff mostly happens 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 often have a 50 to 100 times larger discharge than the preceding baseflow.[2] The magnitude of floods in this river has, however, been decreased due to interventions in the catchment. On steep slopes, exclosures have been established; the dense vegetation largely contributes to enhanced infiltration, less flooding and better baseflow.[3] Physical conservation structures such as stone bunds[4][5] and check dams also intercept runoff.[6][7]
Boulders and pebbles in the river bed
editBoulders 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.[8]
- Amba Aradam Formation
- Mekelle Dolerite
- Antalo Limestone
- Quaternary freshwater tufa[9]
See also
editReferences
edit- ^ Jacob, M. and colleagues (2019). Geo-trekking map of Dogu'a Tembien (1:50,000). In: Geo-trekking in Ethiopia's Tropical Mountains - The Dogu'a Tembien District. SpringerNature. ISBN 978-3-030-04954-6.
- ^ a b Amanuel Zenebe, and colleagues (2019). The Giba, Tanqwa and Tsaliet rivers in the headwaters of the Tekezze basin. In: Geo-trekking in Ethiopia's Tropical Mountains - The Dogu'a Tembien District. SpringerNature. doi:10.1007/978-3-030-04955-3_14. ISBN 978-3-030-04954-6.
- ^ Descheemaeker, K. and colleagues (2006). "Runoff on slopes with restoring vegetation: A case study from the Tigray highlands, Ethiopia". Journal of Hydrology. 331 (1–2): 219–241. doi:10.1016/j.still.2006.07.011. hdl:1854/LU-378900.
- ^ Nyssen, Jan; Poesen, Jean; Gebremichael, Desta; Vancampenhout, Karen; d'Aes, Margo; Yihdego, Gebremedhin; Govers, Gerard; Leirs, Herwig; Moeyersons, Jan; Naudts, Jozef; Haregeweyn, Nigussie; Haile, Mitiku; Deckers, Jozef (2007). "Interdisciplinary on-site evaluation of stone bunds to control soil erosion on cropland in Northern Ethiopia". Soil and Tillage Research. 94 (1): 151–163. doi:10.1016/j.still.2006.07.011. hdl:1854/LU-378900.
- ^ Gebeyehu Taye and colleagues (2015). "Evolution of the effectiveness of stone bunds and trenches in reducing runoff and soil loss in the semi-arid Ethiopian highlands". Zeitschrift für Geomorphologie. 59 (4): 477–493. doi:10.1127/zfg/2015/0166.
- ^ Nyssen, J.; Veyret-Picot, M.; Poesen, J.; Moeyersons, J.; Haile, Mitiku; Deckers, J.; Govers, G. (2004). "The effectiveness of loose rock check dams for gully control in Tigray, Northern Ethiopia". Soil Use and Management. 20: 55–64. doi:10.1111/j.1475-2743.2004.tb00337.x.
- ^ Etefa Guyassa and colleagues (2017). "Effects of check dams on runoff characteristics along gully reaches, the case of Northern Ethiopia". Journal of Hydrology. 545 (1): 299–309. doi:10.1016/j.jhydrol.2016.12.019. hdl:1854/LU-8518957.
- ^ Sembroni, A.; Molin, P.; Dramis, F. (2019). Regional geology of the Dogu'a Tembien massif. In: Geo-trekking in Ethiopia's Tropical Mountains — The Dogu'a Tembien District. SpringerNature. ISBN 978-3-030-04954-6.
- ^ Moeyersons, J. and colleagues (2006). "Age and backfill/overfill stratigraphy of two tufa dams, Tigray Highlands, Ethiopia: Evidence for Late Pleistocene and Holocene wet conditions". Palaeogeography, Palaeoclimatology, Palaeoecology. 230 (1–2): 162–178. Bibcode:2006PPP...230..165M. doi:10.1016/j.palaeo.2005.07.013.