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Delineating the drainage structure and sources of groundwater flux for Lake Basaka, Central Rift Valley Region of Ethiopia

- Dinka, Megersa Olumana

  • Authors: Dinka, Megersa Olumana
  • Date: 2017
  • Subjects: Basaka Lake , Hydrologic models , Groundwater fluxes
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/260032 , uj:27371 , Citation: Dinka, M.O. 2017. Delineating the drainage structure and sources of groundwater flux for Lake Basaka, Central Rift Valley Region of Ethiopia. Water, 9:1-19. doi:10.3390/w9120797
  • Description: Abstract: As opposed to most of the other closed basin type rift valley lakes in Ethiopia, Lake Basaka is found to be expanding at an alarming rate. Different studies indicated that the expansion of the lake is challenging the socio-economics and environment of the region significantly. This study result and previous reports indicated that the lake’s expansion is mostly due to the increased groundwater (GW) flux to the lake. GW flux accounts for about 56% of the total inflow in recent periods (post 2000) and is found to be the dominant factor for the hydrodynamics and existence of the lake. The analysis of the drainage network for the area indicates the existence of a huge recharge area on the western and upstream side of the catchment. This catchment has no surface outlet; hence most of the incoming surface runoff recharges the GW system. The recharge area is the main source of GW flux to the lake. In addition to this, the likely sources/causes of GW flux to the lake could be: (i) an increase of GW recharge following the establishment of irrigation schemes in the region; (ii) subsurface inflow from far away due to rift system influence, and (iii) lake neotectonism. Overall, the lake’s expansion has damaging effect to the region, owing to its poor water quality; hence the identification of the real causes of GW flux and mitigation measures are very important for sustainable lake management. Therefore a comprehensive and detailed investigation of the parameters related to GW flux and the interaction of the lake with the GW system of the area is highly recommended.
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Lake Basaka expansion : challenges for the sustainability of Matahara irrigation scheme, Awash River Basin (Ethiopia)†

- Dinka, Megersa Olumana

  • Authors: Dinka, Megersa Olumana
  • Date: 2017
  • Subjects: Basaka Lake , Groundwater , Landsat
  • Language: English
  • Type: Articles
  • Identifier: http://hdl.handle.net/10210/241805 , uj:24926 , Citation: Dinka, M.O. 2017. Lake Basaka expansion : challenges for the sustainability of Matahara irrigation scheme, Awash River Basin (Ethiopia)†.
  • Description: Abstract: Matahara Sugar Estate (MSE), after nearly 60 years of irrigation, is experiencing effects of waterlogging and salinization in some fields. The problem is believed to be the result of the expansion of (saline and alkaline) Lake Basaka towards the plantation fields. The objective of this study was to determine the geometry of the lake (area and shape) in the past about a half century (1957-2015) from both Landsat images and local information and then assess its negative effects on MSE's soil and water quality. Monthly groundwater (GW) depth was monitored using piezometer tubes. Water and soil samples were collected from each of the piezometer location and analysed for important physico-chemical parameters. The results indicate that the lake expanded approximately 47.3 km2 in the past about a half century. The soil quality is found to be very poor in plantation sections with very shallow GW depth and severe salinity condition. The lake, as revealed by the results, is intruding into the groundwater system of MSE on the Abadir side. Assuming continuation of the past trends, the lake is expected to inundate parts of MSE in the next few years and hence, challenge the production and productivity of MSE significantly. The Lake has the potential to join Awash River, thereby impacting all downstream irrigation developments in the Basin and the livelihood of the people depending on the water resources. As the area is situated in the uppermost part of MER, other factors are expected to exacerbate its...
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Analysing the extent (size and shape) of Lake Basaka expansion (Main Ethiopian Rift Valley) using remote sensing and GIS

- Dinka, M.O.

Analysing decadal land usecover dynamics of the Lake Basaka catchment (Main Ethiopian Rift) using LANDSAT imagery and GIS

- Dinka, M.O.

Effect of land use/cover change on the regimes of surface runoff for Lake Basaka catchment

- Dinka, M.O.

  • Authors: Dinka, M.O.
  • Date: 2016
  • Subjects: Basaka Lake , curve number , Matahara
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/123398 , uj:20786 , Citation: Dinka, M.O. 2016. Effect of land use/cover change on the regimes of surface runoff for Lake Basaka catchment.
  • Description: Abstract: Lake Basaka is expanding at a very fast rate. An appropriate method of estimating the surface runoff from such dynamic catchment is extremely important to delineate sensitive areas to be protected and to develop suitable management measures. In this study, the surface (direct) runoff was estimated using SCS-CN model, assisted by remote sensing and GIS. The result indicated that Lake Basaka catchment showed significant variability (temporal and spatial) in runoff responses depending on the rainfall amount and distribution pattern and land use/cover change. The significant increase of surface runoff (runoff coefficient) was observed to occur after 1973, which is in line with the significant increment of lake level after that period. The reduction in vegetation cover also resulted in increase of runoff coefficient of the Lake catchment from 0.07 in 1960s to about 0.23 in 2000s.
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