On the total freshwater storage deficit of Ethiopia

As it receives one of the highest rainfall amount in the continent and the region,  Ethiopia is the water tower for the greater horn of Africa and the Nile. Because of its small-holder and traditional based  agrarian economy, but recurrent drought is the main development challenge. In the last decades, hydrologists developed  many drought indexes based on various hydrological and meteorological components like rainfall, evapotranspiration, and runoff to provide indexes for decision making. some of these are: Drought Severity Index (PDSI) (Palmer, 1965), Crop Moisture Index (CMI) (Palmer, 1968), Standardized Precipitation Index (SPI) (McKee et al., 1993), and Surface Water Supply Index (SWSI) (Shafer and Dezman, 1982). There are already  some efforts  to  understand the pattern of rainfall in the region,  mainly from the long term climate change perspective, and the findings are mixed.

The total available freshwater is the residual of all the hydrological fluxes. Hence, it is the integrated indicator of the water budget system of a basin.  On the contrary,  it  is the most difficult component to measure, if obtained with huge efforts, it is very specific and point information. NASA’s Gravity Recovery and Climate Experiment (GRACE) mission (Tapley et al., 2004) provides an independent satellite observation of change of the total water storage. Recently this data has been used to estimate the total water deficit of large basin, and it is evaluated positively. Here, I analyzed GRACE data to understand the total water storage of the Ethiopia. The objectives are:1. to estimate the long term water storage mean at monthly time steps; 2. to estimate the total water deficit of each months ("drought event" if longer than the months ); 3. to calculate the total water status according to the GRACE observation for the last one decade.Here are some results, and hoping to detail the methodology and extend the results in the near future. 

Fig 1: The long term mean monthly total water storage distribution of Ethiopia according to GRACE observation.

Fig 2: the long term monthly mean storage deficit maps of Ethiopia as observed from GRACE

Fig: Time series storage deficit (below zero ) at national level . At national scale, the water storage over the long term trend is more or less at constant level

 Fig 4: the time series storage deficit at four location in the country 

To be continued…..

References 

Palmer, W.C. Meteorological Drought; U.S. Department of Commerce, Weather Bureau: Washington, DC, USA, 1965. 

Shafer, B.A.; Dezman, L. Development of a Surface Water Supply Index (SWSI) to assess the severity of drought conditions in snowpack runoff Areas. In Proceedings of the Western Snow Conference, Reno, NV, USA, 19–23 April 1982. 

McKee, T.B., Doesken, N.J., Kleist, J., 1993. The relationship of drought frequency and duration to time scales. In: Proceedings of the 8th Conference on Applied Climatology, American Meteorological Society, Anaheim, CA, Boston, MA, 17–22 January, pp. 179–184.

Tapley, B. D., S. Bettadpur, J. C. Ries, P. F. Thompson, and M. M. Watkins (2004), GRACE measurements of mass variability in the Earth system, Science, 305(5683), 503–505, doi:10.1126/science.1099192.

Drought in Ethiopia

According to different sources such as relief web , news24, and European commission for humanitarianism aid,  in this year, there has been a drought in Ethiopia, particularly in the Easter and Southeastern part of the  country.  I have been closely following the news in this regards, and some of the News  shows the level of severity on human is  really shocking. I am  deeply sadden.  For a glimpse view  on the nature of the drought is documented by this aljazeera video.  According to the European commission for humanitarianism aid  Easter Tigray, Wollo, Shewa, Arsi, Harerghe and Somalia areas are at risk. FEWS (http://www.fews.net/east-africa/ethiopia) presented the spatial distribution of the famine food insecurity of the few  previous months and short term forecast estimation is shown in the following map.

The first thing is first! We need to help those people at risk. We need to feed those poor peasants suffered by this unpleasant evil, famine, and save their  life. Most of the time, Ethiopian farmers are very dogmatic and religious to such natural disasters, and  they mask their suffers and agonies.  By the time  the drought is discovered, it could be already late and the risk on human life could be very high. Worse than that, most of the time, all governments of Ethiopia has been always reckless about the situation , and they only worries about their power and refrain from accepting the fact. There,  it takes another time to nationally accept the problem and act for the solution. IT is ok to play the political game, but HUMAN FIRST please!
Secondly, if the rainfall is short to provide the peoples' demand, we have to look for other option. For instance,  for those pastoral areas, the government could have  invest to drill some walls and supply water for animals. For pastoralist,  few sites of water walls could serve large communities.

Fourthly, if not possible to maintain most the incoming rainfall into the blue water system, the next strategy is to make an effort to infiltrate the rainfall into the soil and store it in the form of what is called green water. So all the land management activities such as terrace and conservation tillages helps to infiltrate the rainfall.  In a region where there is high potential evapotranspiration, the water will leave back to the atmosphere. If we don't use this stored water, it will leave as evaporation which is from bare land and which is non-productive.  However, all the idea of the use of green water means that the return has to be through the plants in the form of transpiration, after producing the biomass instead of just evaporation from the bar lands. Hence, our land has to be covered in all the vegetations and increase the availability of the green water.  In other words, our technology has and understanding of this transpiration need to clearly outline important crops (local climate adapted species ) so as to increase the water efficiency.    SHIFT the transfer (cycle) from evaporative loss to useful transpiration!
Lastly, there has to be forecasting and prediction of those events. We know drought (famine) more than any country in this whole world. On the contrary, we are the least to develop the strategies and methods to  forecast (predict). We don't have to say "the cause is El Nino effect" for every year's drought. The fact that the drought is happening almost in every two years specifically in this region, this reason does not convinced me at all. We really need to work what is exactly happening in the regional climate circulation and,  be able to forecast  the subsequent effect on the hydrological  cycle of the region!   


Huge number of animal is dying in some part of Afar and Somalia regions, and hence, life of the people  depends on animal, pastoralist, are at high risks. Now the drought extends to the small land holding farmers in the above mentioned area.  As reported from the News that the cause of the drought is  rainfall shortage. Drought is essentially natural, and happens in different part of the world. It is unavoidable!  However, how we react to the drought is what matters and what makes difference. The point is what has to be done and what strategies has to be designed to reduce the impacts of drought?

Thirdly, in semi-arid region, the focus has to be on water productivity, not on land productivity. The first step is to make an effort that the income water, rain, into the blue water system (small pond and natural and artificial lake). If we have water storage that we can supplement the rainfed agriculture, then, for sure, with all the degraded soil productivity, the farmers will have enough food production. INCREASE the accessibility of  BLUE WATER for the farmers so as to increase  water productivity! Blessed are those invest in the irrigation projects!