By Ali Regah
Introduction
The horn of Africa is one of the water insecure regions in the world. The only available water sources are those found within ancient rocks and below the ground aquifers. Rainfall is higher in the highland of Ethiopia compared to the lowland and availability of perennial rivers are limited. Climate change-induced droughts have reduced the herd size for pastoralists and many were forced to adopt a negative coping mechanism for survival. The population is growing with higher rates and access for farmland are reducing.
The government of Ethiopia is promoting agriculture and few years back there was a surplus harvest of wheat in Jigjiga and its surrounding areas. The action has increased demand for farmland, more people rented a plot of land and irrigation started next to available surface water sources including Jigjiga dam. As the agricultural demand for land, overgrazing and deforestation increases, the water holding capacity of the soil decreases and erosion increases. This leads to increased siltation and filling of major rainwater harvesting structures. (Zerga et al., 2018).As runoff increase and soil water holding capacity decrease, the expectation of recharge for aquifer will dimension. Experts recommend, constructing rainwater harvesting structures upstream to hold surface runoff as long term solutions to sustain water in these aquifers. (Stevanović Z., Kebede S., 2020).
Jigjiga dam was constructed over nearly forty years ago for 1) for flood control, 2) water sources for irrigation and domestic use and for aquifer recharging (Gebremedhin, Weldu and Bajgo, 2018). The support the last, A rig “Halco Drill” was purchased as part of the Jigjiga dam construction project. Even though I haven’t seen a proof, there was information indicating several boreholes were drilled and filled with aggregated within the dam before it was filled with water to allow fast recharge of the aquifer. As witnessed, the dam has played, more than its objectives. it was the only available all year round water source for people in and around Jigjiga town.
Climate change can be blamed for this disaster unfolding but it can be a multi-dimensional problem as detailed below. Other factors including an increase in water demand, siltation, poor management of the water catchment and many more are some of the main issues to analyses in depth. This piece of work is intended to stimulate more expert discussion and attract the attention researchers, government officials and other interested parties to look the matter in depth.
Importance of the Dam and Possible Consequences
As mentioned above, the Jigjiga earth dam has prevented extreme flooding for the town, was a major source of water for both rural people living in adjacent villages and Jijiga town in particular. In addition, the dam has played a greater role in recharging shallow groundwater aquifer supplying water for Jigjiga town and the Jarar valley. Thus, further and urgent monitoring is required in the boreholes drilled within a few kilometers from the dam and mainly those drilled in downstream. There are boreholes supplying water for Jigjiga University and this might be the first few boreholes which will get dry.
The worst comes, when the few available surface water harvesting structures “Birkas” depletes and both humans and livestock from surrounding villages require water. The matter can’t be underestimated and urgent preparedness action is required to supply water Feb to April 2020 focusing on the rural communities depending on Gu 2020 performance.
Possible major causes of drying?
Rainfall:
As mentioned above, different researchers confirmed the national rainfall data have not changed significantly in the last five decades. However, a recent study shows the meteorological station in the low lands areas including Jigjiga, has shown a reduction of rainfall from 1982 onwards (Hurni, Tato and Zeleke, 2005). The Jigjiga dam depends mainly on rainwater to replenish the annual water losses. In 2019, Jigjiga has received the one of the best rains in recent years and if the rain alone was to be the cause, this dry up would have happened not this year but other drier years. Thus, it indicates there are other causes which need to be studied together with rain performance over the last 30 years. The opportunity is Jigjiga’s rainfall data is available within the Jigjiga Meteorology Agency and this can be easily retrieved.
Siltation and catchment management
Understanding, monitoring and managing of the catchment area activities is a critical step to ensure long term sustainability of surface water dams and their contribution to groundwater recharge (Mugabe et al., 2011). In another study conducted in the highland of Ethiopia concludes a higher correlation between human activities and surface runoff causing soil erosion (Hurni, Tato and Zeleke, 2005). In recent years, due to the introduction of wheat cultivation and the use of technologies to harvest “combiners”, the demand for farmland has increased. You might see from the sky as you fly out of Jigjiga, the land prepared for cultivation has increased compared to few years back. This results increased in soil erosion and all upstream flooding will bring a huge amount of silt to the dam. The level of silt can be easily measured as the dam is equipped with a water volume measuring unit. I, personally, presume this might be one of the topmost reasons why the dam dried in the middle of the rainy season.
Groundwater Abstraction:
The dam plays a crucial role in replenishing the groundwater in Jarar Valley. The population of jigjiga town and demand for water has increased. There is no, as my knowledge, a proper groundwater modelling that was conducted to understand recharge versus discharge of these valuable groundwater sources. It can be assumed hydrogeologically, the dam is contributing a lot to sustaining water from these shallow wells. More drilling and pumping is happening only to cover up for political campaigning and please communities with a painkiller.
It wouldn’t be long to see a dramatic reduction in yield and drying of several boreholes in Jarar valley mainly in upstream areas. The Makelle town aquifer which dried within a few months is the best recent example to learn from. “prevention is better than cure” is an English proverb that suites here well. Understanding the problem in-depth and investing resources will save millions of dollars and saves lives in the future. This can be a call for the leadership to take drastic action and understand the importance of knowledge and invest in research. The water situation in the Somali region and beyond, need to be studied well and implement recommendations. If not, the worst is yet to come!
Conclusions:
Dams that depend on rainfall have a finite water source and they are vulnerable for poor water management coming from lack of understanding and awareness. As detailed above, conducting a groundwater modeling led by expert from Addis Ababa University and the region can clearly and scientifically define what needs to be done in the long run. We should not mix the issue, the Harumaya dams and the Jigjiga dam which have similarities and differences. The amount of runoff in Jarar valley is huge and it might require different attention to use as an alternative water source.
The Jigjiga dam is one of the few dams in the region and needs extra attention. For short term, i) we need to consider desilting the dam without damaging the structure, ii) manage the upstream human activity causing increased soil erosion, iii) check if there are any structural damages and leakages happening and iv) conduct a detail research led by experts in the field.
Ali Regah
WASH Coordinator
Oxfam , Hargeisa , Somaliland
Email: [email protected]
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References:
- Gebremedhin, Y., Weldu, T. and Bajgo, A. (2018). Analysis of Factors Affecting the Sustainability of Elbahi Micro-Dam Catchment, Near Jigjiga Town, Ethiopia Somali Regional State, Ethiopia. International Journal of Environmental Sciences & Natural Resources, [online] 15(5). Available at: https://www.researchgate.net/publication/332781940_Department_of_Natural_Resources_Management [Accessed 14 Jan. 2020].
- Girmay, F., Gebreselassie, G. and Bajigo, A. (2018). Climate Change Risk Management and Coping Strategies for Sustainable Camel Production in the Case of Somali Region, Ethiopia. Journal of Biotechnology Research, (9), pp.66-75.
- Hurni, H., Tato, K. and Zeleke, G. (2005). The Implications of Changes in Population, Land Use, and Land Management for Surface Runoff in the Upper Nile Basin Area of Ethiopia. Mountain Research and Development, 25(2), pp.147-154.
- Bookmetrix.com. (2020). Jurassic Carbonate Aquifer—The Most Valuable Fresh Water Resource at the Horn of Africa – Bookmetrix Analysis. [online] Available at: http://www.bookmetrix.com/detail/chapter/9db55749-ade0-4120-8a20-4d1b4071cf70#downloads [Accessed 12 Jan. 2020].
- Mugabe, F., Chitata, T., Kashaigili, J. and Chagonda, I. (2011). Modelling the effect of rainfall variability, land use change and increased reservoir abstraction on surface water resources in semi-arid southern Zimbabwe. Physics and Chemistry of the Earth, Parts A/B/C, 36(14-15), pp.1025-1032.
- Tolera, M., Chung, I. and Chang, S. (2018). Evaluation of the Climate Forecast System Reanalysis Weather Data for Watershed Modeling in Upper Awash Basin, Ethiopia. Water, 10(6), p.725.
- Zerga, B., Bikila Workineh, B., Teketay, D. and Woldetsadik, M. (2018). Rangeland Degradation and Rehabilitation Efforts in the Somali National Regional State, Eastern Ethiopia: A Review. International Journal of Innovative Research and Development, 7(5).
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