Water management problems in the Ethiopian rift: Challenges for development

Ayenew, Tenalem

doi:10.1016/j.jafrearsci.2006.05.010

Cited by 103 publications

(79 citation statements)

References 22 publications

(43 reference statements)

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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: 86%

“…Various research reports [3,6,7,9,14,16] indicated that the GW contribution to Lake Basaka is more than 50% of the total inflow. Recent studies [7,9] quantified the amount of GW contribution in different hydrologic years (1970 up to 2010) using a conceptual water balance model.…”

Section: Introductionmentioning

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: 86%

Section: Introductionmentioning

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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“…Hydrologically, these gullies are important features that facilitate fast transfer of surface water into the aquifer and then to the lake. Field evidences also indicate the positive role of newly formed gullies that act as conduit to ground water inflow from the elevated areas to Lake Hawassa [69]. Unfortunately, these gullies developed in a region of the catchment which was not monitored using stream discharge gauges.…”

Section: Interaction Of Geomorphological Processes With Lake Hydrologymentioning

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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Understanding the relative impacts of natural processes and human activities on the hydrology of the Central Rift Valley lakes, East Africa

2015

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Significant changes have been observed in the hydrology of Central Rift Valley (CRV) lakes in Ethiopia, East Africa as a result of both natural processes and human activities during the past three decades. This study applied an integrated approach (remote sensing, hydrologic modelling, and statistical analysis) to understand the relative effects of natural processes and human activities over a sparsely gauged CRV basin. Lake storage estimates were calculated from a hydrologic model constructed without inputs from human impacts such as water abstraction and compared with satellite‐based (observed) lake storage measurements to characterize the magnitude of human‐induced impacts. A non‐parametric Mann–Kendall test was used to detect the presence of climatic trends (e.g. a decreasing or increasing trends in precipitation), while the Standard Precipitation Index (SPI) analysis was used to assess the long‐term, inter‐annual climate variability within the basin. Results indicate human activities (e.g. abstraction) significantly contributed to the changes in the hydrology of the lakes, while no statistically significant climatic trend was seen in the basin, however inter‐annual natural climate variability, extreme dryness, and prolonged drought has negatively affected the lakes. The relative contributions of natural and human‐induced impacts on the lakes were quantified and evaluated by comparing hydrographs of the CRV lakes. Lake Abiyata has lost ~6.5 m in total lake height between 1985 and 2006, 70% (~4.5 m) of the loss has been attributed to human‐induced causes, whereas the remaining 30% is related to natural climate variability. The relative impact analysis utilized in this study could potentially be used to better plan and create effective water‐management practices in the basin and demonstrates the utility of this integrated methodology for similar studies assessing the relative natural and human‐induced impacts on lakes in data sparse areas. Copyright © 2015 John Wiley & Sons, Ltd.

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Water management problems in the Ethiopian rift: Challenges for development

Cited by 103 publications

References 22 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

Understanding the relative impacts of natural processes and human activities on the hydrology of the Central Rift Valley lakes, East Africa

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