Crop monitoring in Eritrea

Transcription

1 JRC TECHNICAL REPORTS Crop monitoring in Eritrea Unfavourable crop prospects in the main producing areas of western lowlands and central highlands Ana Pérez-Hoyos, François Kayitakire and Felix Rembold October 2015 NDVI anomalies of August compared to the historical average. Source: SPOT-VGT 1

2 1. INTRODUCTION Eritrea covers about km 2 of which livestock-related activities occupy 56% of the area, whereas cultivated rain-fed land covers 5% of the territory. The country s economy largely depends on subsistence agriculture, with two thirds of the population engaged in subsistence farming and pastoralism rendering them vulnerable to climate variability. There are typically three rainy seasons in Eritrea: Bahri rains from December to February in the eastern coastal lowlands (North and South Read Sea zobas), Azmera rains between March and May in the highlands (Debub and Maekel zobas) and the Kiremit rains from June to September over the whole country apart from the coastal plain. The Kiremit crops form the basis of the main annual harvest whereas the Bahri season is important in the pastoral areas along the Red Sea coast. This report provides a rapid overview of the meteorological and vegetation conditions of the Kiremit season, focussing on cultivated areas due to its importance for agricultural production (see Figure 1). Major crops that grow during the Kiremit season include wheat, barley and teff grown in the highlands, short-cycle sorghum and pearl millet at lower altitudes, maize at intermediate altitudes and sesame mainly located in Gash Barka zoba (see calendar on Figure 1). The analyses, based on satellite imagery and meteorological data, presented in this report indicate belowaverage rainfall in July and the first half of August, resulting in poor crop growth at the beginning of the season. Despite a slight improvement of rainfall in September, the uneven distribution in the previous months has negatively affected crop development and jeopardised the 2015 main harvest. Figure 1. Cropland and herbaceous land cover in Eritrea and FAO-GIEWS crop calendar for main cereal crops. Source: JRC crop mask (v2.2) and FAO-GIEWS. 2

3 2. PRECIPITATION ANALYSIS According to the rainfall estimates by the European Centre for Medium-Range Weather Forecasts (ECMWF), the present Kiremit season is characterized by an erratic rainfall distribution, with drier than average conditions compared to the period Similar conditions are observed in other areas in the Horn Africa, for instance in Sitti and southern Afar in Ethiopia (FEWSNET, 2015), and they might be related to the El Niño phenomenon which is expected to affect rainfall patterns until early Figure 2. Ten-daily rainfall anomalies (mm) compared to the last 7 years average ( ). Data source: EC- JRC, based on ECMWF model. The present rainy season started on time with rains around 10 and 20 mm at the beginning of June in the Central Highlands (zobas of Debub, Maekel and east Gash Barka) and in the Western Moisture Lowlands (south of Gash Barka). Rainfall conditions were normal in June (see Figure 1) in most parts of the country with the exception of some small pockets in Maekel and Debub zobas (Figure 2) that showed small negative anomalies (around -10 and -25 mm). The Kiremit rains performance declined in the second and third dekads of July. Particularly, large negative anomalies (more than 50 mm) were recorded in the main agricultural areas in the Central Highlands. The 3

4 monthly total rainfall for July 2015 is the 7 th driest in the last 26 years (since 1989) for Debub and Anseba zobas (Figure 3). Similar to July condition, the beginning of August (1 st dekad) showed a below normal rainfall. On the contrary, the scarce rainfall was followed by a very intensive rainfall in Maekel zoba, making this month the wettest one since 1989 (Figure 3). From mid-august, Gash Barka and Anseba have experienced enhanced rainfall. September marks the end of the Kiremit season, with almost no rainfall after the second dekad. Rainfall in this month improved in some areas and the situation was even above normal in some pockets of Anseba. Figure 3. Ranking of total ECMWF rainfall against the 26 years for a selection of regions for Top) July 2015 (Gash Barka, Anseba and Debub), Bottom) for August 2015 (Gash Barka, Maekel and Debub). 3. VEGETATION ANALYSIS Figure 4 shows the Normalized Difference Vegetation Index (NDVI) from July to September 2015 compared to its respective long-term average ( ), according to SPOT-VEGETATION/ProbaV data. Generally, the season is characterized by negative anomalies due to the dry spell in July. The lack of rainfall in July resulted in abnormal vegetation conditions in the southwestern part of Eritrea, indicating either stressed crops at the very beginning of the growing season or delays in planting. From July onwards, most of the productive areas of the country show a clear deterioration of vegetation conditions and poor production. The main areas of concern are located in the sub-zobas of La elay Gash, Malqui, Mensura, Tesseny and Ohmajer in Gash Barka zoba, Adil Kuala in Debub zoba and Gala Nefhi in Maekel Zoba. In August the situation remained problematic in most parts of the Central Highlands and even got worse. Negative NDVI anomalies covered the most part of the agricultural areas of Gash Barka and Debub. Even 4

5 if rainfall in September was slightly better, the crops had not recovered the development delay at the end of the month. A few sub-zobas were showing positive NDVI anomalies. Figure 4. Monthly vegetation conditions (NDVI) compared to the historical average ( ). Data source: SPOT- VEGETATION/Proba V. 4. TEMPORAL ANALYSIS OF NDVI AND RAINFALL ESTIMATES PROFILES AT ZOBA LEVEL Figure 5 shows combined graphs for NDVI and rainfall for the main agricultural sub-zobas in Eritrea. The figures also show both NDVI and rainfall long-term average, which allow detecting possible seasonal anomalies. The temporal NDVI profiles indicate that the season started normally in most places, except in Adi Kual (Debub), Mensura and Omhajer (Gash Barka) where the season onset was delayed for one to two dekads. The NDVI profiles show a better performance in Anseba, compared to other parts of Eritrea, and even some sub-zobas in the eastern part (i.e. Elebered or Halahal) present a normal or above normal vegetation development during the major part of the season. 5

6 In Maekel, after below average rainfall in mid-july, rainfall in the first dekad of August (Gala Nefhi) and the first dekad of September (Serejeqa) has been much above normal, leading to more favorable growing conditions. Nevertheless, the situation has not always reversed, and the areas most affected by the dry spells remain below average (i.e. Gala Nefhi). Crop performance in Gash Barka is clearly below average. The impact of below average rainfall in July and part of August is observed in both the mechanized (i.e. Ohmajer) and the traditional areas (i.e. La elay). In all sub-zobas the vegetation index profiles indicate poor crop conditions and delays in the development that will translate into a sharp reduction in production of the main cereals. Pastures must be badly affected too. The area account for a large share of cereal production, especially for supplying non agricultural regions. The impact on food security is expected to be strongly felt not only in Bash Barka but also in other areas. 4.1 Maekel 4.2 Debub Figure 5. Profiles of vegetation index (NDVI) and rainfall estimates for the Kiremit season. The graphs compare the current season with the historical average (LTA=Long Term Average). 6

7 4.3 Anseba 4.4 Gash Barka Figure 5 (ctd). Profiles of vegetation index (NDVI) and rainfall estimates for the Kiremit season. The graphs compare the current season with the historical average (LTA= Long Term Average). REFERENCES Ethiopia Food Security Alert, September 23, FEWSNET. 7

8 z As the Commission s in-house science service, the Joint Research Centre s mission is to provide EU policies with independent, evidence-based scientific and technical support throughout the whole policy cycle. Working in close cooperation with policy Directorates-General, the JRC addresses key societal challenges while stimulating innovation through developing new standards, methods and tools, and sharing and transferring its know-how to the Member States and international community. Key policy areas include: environment and climate change; energy and transport; agriculture and food security; health and consumer protection; information society and digital agenda; safety and security including nuclear; all supported through a cross-cutting and multi-disciplinary approach. 8