Very poor pasture conditions likely to persist through early spring

Chris Funk

This is yet another post about the low short/Deyr rains in East Africa, but today’s focus is on the very poor pastoral conditions in southeastern Ethiopia, northeastern Kenya, and Somalia. This blog is motivated by the extremely low NDVI values, discussed in a recent alert by FEWS NET as well as an email from my friend John McGrath at OXFAM who forwarded me an email from his colleague James Firebrace, who is reporting some severe outbreaks of acute malnutrition and water shortages in eastern Somaliland. After analyzing the available remote sensing data, I find such reports plausible, given the cumulative January-November NDVI record, and would suggest we pay very close attention to food security conditions in this area.

I was already planning to write this post when I arrived at work this morning, before I read John’s email. My concerns were motivated by the very large observed NDVI anomalies combined with the fact that the full impact of the October/November dryness may not be fully registered by the current vegetation.  There is a large degree of persistence and predictability in the NDVI record, and we wrote a paper on this back in 2006 that included a target application on exactly the region under stress now. NDVI tends to lag behind rainfall, so the current poor rainfall could lead to further drying. Even without more drying, it is unlikely (but possible) that the region will see much relief until spring 2017.

Figure 1 shows the most recent MODIS land surface temperature and NDVI anomalies. Many pastoral areas are very warm, which may indicate low levels of soil moisture, and satellite-observed vegetation levels are near or below historic lows in many areas.

 

Figure 1. MODIS Land Surface Temperature and NDVI anomalies for the 1st dekad of November 2016.
Figure 1. MODIS Land Surface Temperature and NDVI anomalies for the 1st dekad of November 2016.

These conditions appear related to long term persistent dryness in the region, as indicated by Standardized Precipitation Index values for the last dekad, month, 2 months, 3 months and 6 months (Figure 2).

Figure 2. Standardized Precipitation Index values calculated from the 1st dekad of November 2016. From earlywarning.usgs.gov.
Figure 2. Standardized Precipitation Index values calculated from the 1st dekad of November 2016. From earlywarning.usgs.gov.

Convergent evidence for water stress and poor water availability for cattle, goats and camels is provided by the FEWS NET waterpoint viewer. Figure 3 shows the current assessment – much of northeastern Kenya and southeastern Ethiopia is under alert or near-dry conditions.

Figure 3. USGS Waterpoint conditions as of early November 2016.

Figure 3. USGS Waterpoint conditions as of early November 2016.

We can look at stressed regions using time series of MODIS Normalized Difference Vegetation Index (NDVI) data. MODIS NDVI measures vegetative health at very high resolution (250m). Figure 4 shows time series of NDVI from far eastern Ethiopia. One year, 2003, was less green. Two recent very poor years 2009/2010 and 2010/2011 were actually greener. By early November, most years have already reached or passed the maximum NDVI value. Typical behavior is for the vegetation to senesce and dry from this point forward.

Figure 4. Somaliland NDVI time series.
Figure 4. Somaliland NDVI time series.

Figures 4, 3, 2 and 1 provide convergent evidence support John McGrath’s concern about very dry conditions in far eastern Ethiopia. This year looks way drier than most recent years.  In terms of long term moisture stress and poor pastoral conditions, it is very concerning that both January-to-early November NOAA CPC RFE2 rainfall totals and January-to-early November NDVI averages indicate very poor conditions (Figure 5). I am not an expert on pastoral early warning, but I believe this kind of repeated aridity can weaken herds and reduce their milk production.

Figure 5. Scatterplot showing 2003-2016 Jan-Nov RFE2 rainfall totals and average eMODIS NDVI for Somaliland.
Figure 5. Scatterplot showing 2003-2016 Jan-Nov RFE2 rainfall totals and average eMODIS NDVI for Somaliland.

Focusing on the same type of target – the anticipated average NDVI conditions between the second dekad of November and the last dekad of March, we find that simple regressions between the Jan-Nov1 NDVI (as shown in Figure 5) and Nov2-March NDVI have a reasonable R2 (~0.4). We can use this simple regression to project a plausible ‘what-if’ scenario for the rest of the dry season. This result is shown in Figure 6.

Figure 6. Somaliland NDVI projections.
Figure 6. Somaliland NDVI projections.

What this figure is telling us is that its quite likely that unless an unseasonal storm drops a lot of water in Somaliland, further browning of the vegetation is likely, as we saw in 2009/2010 and 2010/11. These seasons also appear to be the closest analogs, based on our projected Nov 2016-March 2017 ‘forecast’.

We next carry out a similar analysis for the Mandera region of NE Kenya (Figure 7). Once again, we see historically low levels of NDVI, drier than in 2010. Here, we do seem to be earlier in the season, and there seem to be more years that had a late December recovery.

Figure 7. NDVI time series for the Mandera region of NE Kenya.
Figure 7. NDVI time series for the Mandera region of NE Kenya.

Applying our same ‘forecast’ strategy, i.e. predicting Nov 2016-March 2017 NDVI based on January-November 2016 NDVI (R2=0.4), gives us the results shown in Figure 8. Here the forecast is more modest – a simple continuance of current historic low levels. The analog years based on this analysis might be 2005/2006 and 2010/2011. The USGS waterpoint analysis (Figure 3) provides a strong level of convergence on dryness in this area, and barring an unseasonal upturn in the rains, which has happened before, poor pastoral conditions seem likely to continue, based on the data analyzed here.

Figure 8. Projection of Nov 2016-March 2017 NDVI for Mandera.
Figure 8. Projection of Nov 2016-March 2017 NDVI for Mandera.

We conclude by presenting a new experimental Potential EvapoTranspiration (PET)  forecast, produced by Daniel McEvoy (DRI) and Shrad Shukla (CHG). This forecast (Figure 9) shows the median CFSv2 ensemble forecast over East Africa. The CFSv2 is a sophisticated coupled ocean-atmosphere model used for seasonal forecasts. The total number of ensemble members is 28. They were initialized at an interval of 5 days starting October 8th, 2016 through November 7, 2016.  According to this figure the PET outlook appears to be mostly within normal range (standardized anomaly of -0.44 to 0.44) over the drought regions (Kenya and Somalia).

Figure 9. PET forecasts for Eastern Africa. Kindly provided by Daniel McEvoy (DRI) and Shrad Shukla (CHG).
Figure 9. PET forecasts for Eastern Africa. Kindly provided by Daniel McEvoy (DRI) and Shrad Shukla (CHG).

Putting this all together, we can say that there is lots of evidence that pastoral areas in eastern Ethiopia, NE Kenya, and Somalia appear to have experienced very low rainfall, and that this has resulted in very low NDVI values, both at present and over the January-November time frame (Fig. 6, 8). The poor pasture conditions associated with these low NDVI values appears associated with very warm air temperatures (Figure 1) and water point estimates that appear to be almost dry in many places (Figure 3). The cumulative low NDVI values of the current Jan-Nov season appear to be very low, likely to persist, and similar to seasons like 2009/2010 and 2010/2011.  PET forecasts appear normal, but normal behavior for this region is associated with senescence and NDVI declines in most cases.

Setting aside the outlook for spring 2017 rains, we can look at FEWS NET assessments from January of 2010 and 2011 as possible indicators of where we might be in a few months (a, b, c). We at the CHG are not qualified to do food security assessments, but it does seem safe to say that the current pastoral conditions are very poor in many places, and unlikely to improve until spring. This may mean continued reductions in herd health and pastoral livelihoods. Close monitoring and assessment seems warranted.

 

 

4 thoughts on “Very poor pasture conditions likely to persist through early spring”

  1. Thanks Chris. I should say that our information about the humanitarian situation in Somaliland is still second hand and from a single source and therefore we would welcome corroboration. However, in conjunction with your warnings about dryness, the vegetation index, water holes etc we feel it is right to be concerned. The information passed on to us is that the rains have completely failed in the eastern regions of Somaliland, in the Sanaar (Sanaag) region in particular, and people – those who are able to – have been migrating out southwards to near Bohotle on the Ethiopia border, and south-east to Garowe in Puntland, and the single source has said that these movements might number perhaps 300,000 people. As I say, more information would be most welcome and let’s hope that things are not so bad. John Magrath.

  2. Thanks John. Yes let’s hope that the problems are quite isolated. Corroboration from ground reports seems critical at this point. Our ability to monitor from space certainly has many limits, which is why the humans involved in humanitarian relief are so incredibly important. The two week weather forecast suggest a chance for some relief, so we can hope for that as well.

  3. Hi Chris: an update: we’ve had lots of information in since and today (17 November) the Somaliland Government appealed for urgent humanitarian assistance, and this report came out: http://reliefweb.int/sites/reliefweb.int/files/resources/161117_consequences_of_drought_1.pdf which concludes
    “The worsening and expanded drought, poor Deyr rains in October and poor prospects for the remainder of the season is likely to further worsen food insecurity countrywide to the point where isolated areas could descend into profound need on a scale not seen since the end of famine in early 2012. The humanitarian situation is likely to continue to worsen until the start of the spring/Gu rains in April 2017. Further displacement and increased risk of protection violations and conflict, as well as the return of Somalis from Kenya and Yemen, add additional burden and accentuate the immediate life-saving humanitarian needs, while reversing some of the gains in recovery so far. To avoid the escalation of the
    crisis, the Somalia HCT is urgently appealing for funding to enable response activities through the end of 2016 and for timely and robust support for the 2017 HRP”.

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