Environmental implications of changes in the levels of lakes in the Ethiopian Rift since 1970

Ayenew, Tenalem

doi:10.1007/s10113-004-0083-x

Cited by 104 publications

(119 citation statements)

References 7 publications

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“…The fluctuation of the lake's water is in response to the changes in the surface-and sub-surface components of the lake's water balance. The expansion extent and hydrochemical characteristics of the lake have been well documented by different researchers [1][2][3][4][5][6][7][8][11][12][13][14][15][16][17][18] The expansion of Lake Basaka, owing to its poor water quality, is threatening the socio-economics and environment of the region significantly [10]. Different study reports [7,10,19,20] indicated that the lake's expansion is affecting the irrigation development, pastoralism, infrastructure, and the ecosystem of the region (see Figure 1d,e).…”

Section: Introductionmentioning

confidence: 90%

“…2. Water transmission loss from Awash River because of its increased water level after the construction of Koka Dam, located some 152 km upstream [2,5,14]. The water losses and recharges, according to Ayenew et al [5], are facilitated by the presence of active terminal faults in the region [7], favorable geologic factors, and the availability of water.…”

Section: Potential Sources/causes Of Groundwater Fluxmentioning

confidence: 99%

“…Most of the closed-basin type Main Ethiopian Rift Valley (MERV) lakes are experiencing water level and salinity fluctuations [1][2][3][4][5][6][7][8][9][10], mostly shrinkages in size. Lake Basaka is found to be unique compared to the terminal lakes within the MERV region due to the fact that the water is expanding at a very fast rate and is not usable for irrigation or drinking purposes [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…However, Water 2017, 9, 797 3 of 19 the possible sources/causes for GW flux to the lake are not fully identified yet, except for views and suggestions. Most of the previous scholars generally relate it to increased GW recharge upstream due to the establishment of irrigation schemes [3][4][5]9,14,16], and others are relating it to leakage from the Awash River [2,5,14] and lake neotectonisim [4,5,11,16,22]. No comprehensive and critical research has been done so far regarding the possible causes/sources of GW flux to the lake.…”

Section: Introductionmentioning

confidence: 99%

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Delineating the Drainage Structure and Sources of Groundwater Flux for Lake Basaka, Central Rift Valley Region of Ethiopia

Dinka

2017

Water

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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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Section: Introductionmentioning

confidence: 90%

Section: Potential Sources/causes Of Groundwater Fluxmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Delineating the Drainage Structure and Sources of Groundwater Flux for Lake Basaka, Central Rift Valley Region of Ethiopia

Dinka

2017

Water

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“…Over the past few years, several researchers have studied the long-term water balance of Lake Hawassa, such as Gebreegiziabher [10], Ayenew [13], Deganovsky and Getahun [14], WWDSE [11], Ayenew and Gebreegiziabher [15], Gebremichael [16], and Shewangizaw [17]. Land use/cover changes have also been studied by Wagesho et al [18], and WWDSE [11].…”

Section: Introductionmentioning

confidence: 99%

Linkage between Water Level Dynamics and Climate Variability: The Case of Lake Hawassa Hydrology and ENSO Phenomena

Belete

Diekkrüger

Roehrig

2017

Climate

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Lake Hawassa is a topographically closed lake in the Central Main Ethiopian Rift Valley. The water level of this lake has been reported to dramatically rise without falling back to the original level. The cause of this rise is not yet sufficiently investigated and subjected to this study. This study argues that the general variability in the lake level and its resultant rise has significant linkage to the temperature variability at the Pacific Ocean. The linkage between water level dynamics and climate variability was analyzed through the application of diverse statistical techniques. It comprises the Mann-Kendall trend analysis to test monotonic variations over time; sequential regime shift index (RSI) to detect significant shifts in the mean values of time-series records of lake level; and coherence analysis to investigate the linear relationship between ENSO index and records of local hydrology. Despite the multiple rises and falls, the results of the trend analysis revealed that the lake level experienced a significant resultant upward trend with Mann-Kendall τ values of 0.558, 0.629, and 0.545 (at α = 0.05 and p < 0.01%) for monthly maximum, average and minimum values respectively. The sequential regime shift evidenced that most of the significant shifts coincide with the occurrences of ENSO events. Generally, the lake level tends to be high during El Niño and low during La Niña episodes. The typical examples are the coincidence of extreme historical maximum lake level to the strongest El Niño event of the century that occurred in 1997/98 and the lowest lake level record in the year 1975 with a strong La Niña year. The coincidence of climate regime shift in the Pacific Ocean in 1976/77 with an equivalent regime shift in the lake level is an additional confirmation for the possible climate-hydrology linkage. The likely involvement of anthropogenic factors (at least in modifying the effect of climate) is justified by the interplay between the non-trending rainfall and potential evapotranspiration and trending streamflow. The coherence analysis between 492 pairs of monthly step datasets of 3.4ENSO index and lake level changes is also found to have a significant linear relationship over frequencies ranging from 0.13 to 0.14 cycles/month or 1.56 to 1.68 cycles/year. This corresponds to a dominant average periodicity (coincident cycle) of about 7.4 months which is thought to be related to the time span of the two rainy season in the locality.

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Performance assessment of smallholder irrigation in the central rift valley of ethiopia

Halsema

Lencha

Assefa

et al. 2011

Irrigation and Drainage

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The recent increase in smallholder irrigation schemes in the Central Rift Valley of Ethiopia has been associated with the overexploitation of water resources, while the economic viability of these schemes has been questioned. This paper assesses water use efficiencies of the Haleku Irrigation Scheme and quantifies improvement scenarios. The viability of these scenarios is discussed, taking into account the socio-economic performance of the Haleku Irrigation Scheme and the nearby Dodicha Irrigation Scheme -that feature similar settings but contrasting socio-economic performance.The irrigation efficiency of Haleku is 35%, but conveyance losses and application efficiencies vary widely across the scheme. Scenario results indicate scope for improvement and reduced water abstraction. Yields and economic returns of irrigated crops were higher in Haleku than in Dodicha, but yields are still lower than attainable yields. Any strategy to increase irrigation efficiency will have to include a programme to improve crop productivity and economic returns.Considering the over-abstraction of water resources, the poor irrigation performance of Haleku and the disappointing socioeconomic performance of both Haleku and Dodicha suggest that policy should focus on improving existing schemes in the Central Rift Valley instead of further developing new ones. Copyright # 2011 John Wiley & Sons, Ltd. RÉ SUMÉ L'augmentation récente des périmètres irrigués à petite échelle dans la vallée centrale du Rift, en É thiopie a été associée à la surexploitation des ressources en eau, tandis que la viabilité économique de ces emménagements a été mise en doute. Cette étude évalue l'efficacité de l'utilisation d'eau du système irrigué de Haleku et quantifie les scénarios d'amélioration. La viabilité de ces scénarios est discutée en tenant compte des performances socio-économiques de l'aménagement de Haleku et de celles du système irrigué de Dodicha. Les deux sont géographiquement proches, présentent des caractéristiques physiques similaires, mais diffèrent par les performances socio-économiques. L'efficacité de l'irrigation de Haleku est de 35%, mais les pertes de transport et efficacité de l'application varient considérablement au sein du périmètre. Les scénarios appliqués indiquent des possibilités d'amélioration et de réduction des prélèvements d'eau. Les rendements et la rentabilité économique des cultures irriguées sont plus élevés à Haleku qu'à Dodicha, mais les rendements sont toujours inférieurs aux rendements réalisables. Toute stratégie visant à accroître l'efficacité d'irrigation devra inclure un programme de l'amélioration de la productivité des cultures et la rentabilité économique.Compte tenu de la surexploitation des ressources en eau, la performance médiocre de l'irrigation à Haleku et la performance décevante socio-économique des deux emménagements Haleku et Dodicha, il est suggéré que la politique devrait se concentrer

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Environmental implications of changes in the levels of lakes in the Ethiopian Rift since 1970

Cited by 104 publications

References 7 publications

Delineating the Drainage Structure and Sources of Groundwater Flux for Lake Basaka, Central Rift Valley Region of Ethiopia

Delineating the Drainage Structure and Sources of Groundwater Flux for Lake Basaka, Central Rift Valley Region of Ethiopia

Linkage between Water Level Dynamics and Climate Variability: The Case of Lake Hawassa Hydrology and ENSO Phenomena

Performance assessment of smallholder irrigation in the central rift valley of ethiopia

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