Crop monitoring in Eritrea

Transcription

1 JRC SCIENTIFIC AND POLICY REPORTS Crop monitoring in Eritrea Abundant rainfall in Eritrea generated a satisfactory crop development in the Kremti season Ana Pérez-Hoyos, François Kayitakire and Felix Rembold October 2014 Rainfall anomalies the third dekad of July compared to the historical average. Source: ECMWF 1

2 1. BACKGROUND Eritrea covers about km 2 of which livestock-related activities occupies 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 for livelihood rendering them vulnerable to climate variability (OCHA, 2014). There are three distinct rainy seasons in Eritrea: Bahri rains from December to February in the eastern coastal lowlands, Azmera rains between March and May in the highlands (Debub and Maekel zobes) and the Kremti rains from June to September over the whole country apart from the coastal plain. The Kremti crops form the basis of the main annual harvest. This report provides a rapid overview of the meteorological and vegetation conditions of the Kremti season, focussing on cultivated areas due to its importance for agricultural production (see Figure 1). Major crops that grow during the Kremti 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 aboveaverage vegetation conditions and no major concerns for the 2014 Kremti season in Eritrea. Moreover, the abundant and well distributed rains throughout the season could ensure the first good harvest in years. Harvesting is expected to start normally at the beginning of November with a good production forecast in the main agricultural areas. 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 The Kremti rainy season in Eritrea had a timely onset and a normal to late end. So far, it has been characterized by abundant and well-distributed amounts of rains, providing favourable conditions for the maturation and harvesting of crops. Favourable levels of rainfall were concentrated in the main agricultural zobas (Gash Barka, Debub, Maekel and Anseba). According to the rainfall estimates by the European Centre for Medium-Range Weather Forecasts (ECMWF), the season started on time with rains around 10 mm at the beginning of June in Central Highlands (zobas of Debub, Maekel and Gash Barka) and in the Western Moist Lowlands (south of Gash Barka). Figure 2. Ten-daily rainfall anomalies (mm) compared to the last 5 years average ( ). Data source: EC-JRC, based on ECMWF model. Rainfalls have generally been higher than the average of the last 5 years almost everywhere in July, with the exception of some negative anomalies (around -10 and -25 mm) recorded in some reduced areas in 3

4 Maekel and Debub zobas, but with negligible impact on vegetation (see section 4). The 3 rd dekad of July shows wetter-than-usual conditions (exceeding heavy rains from 10 to 100 mm on the long-term average) over Gash Barka, Debub and Maekel and Anseba. The amount of rains and its temporal distribution do not indicate any risk of damaging floods contrary to last year s patterns. The overall situation in terms of rainfalls in August is satisfactory, and in general the differences with the long term rainfall average indicate above normal conditions, mainly in the 3 rd dekad of August where rainfall around 100 mm was reached in several sub-zobas of Gash Barka (La elay Gash), Maekel (Berik and Serejeqa) and Anseba (Adi Tekeliezan). The good rains of the season continued until the end of September and most of the area concerned with the Kremti season received more rains than normal. At the beginning of September, rainfall was still normal and slightly above, with values between 40 and 80 mm in Gash Barka and over the Central Highlands. Even though rainfall decreased gradually during the second and third dekads of the month, as expected, rainfall around 10 mm was still recorded in the 3 rd dekad of September. Hence, the end of the season was normal and a priori, the grain-filling phase for the main cereals is not expected to suffer from low soil moisture nor from excessive humidity. 3. VEGETATION ANALYSIS Figure 4 shows the Normalized Difference Vegetation Index (NDVI) from July to September The season is generally characterized by positive anomalies due to the favourable impact of the rainfall, mainly in cropland areas of central and western parts of the country. Only some pocket areas of below average vegetation condition were located in Ohmajer and La elay Gash (Gash Barka zoba) during July and in the second dekad of August. However, these areas show a normal recovery of vegetation (see profiles in section 4) during September that mitigates the possible early negative conditions. The vegetation status, compared to the long-term average, is good in August due to the effect of the abundant rainfall of July and even better in September where almost all of the cropland areas show a betterthan-average situation and no area of concern is identified. The vegetation index values indicate higher yields than in the previous years although the index cannot directly measure the final yield, which is affected by many other factors like crop management and harvest conditions. These positive anomalies detected by the remote sensing images are in agreement with the field reports by the Eritrean Ministry of Information ( 4

5 Crop Monitoring in Eritrea Kremti Season 2014 Figure 3. Monthly vegetation conditions (NDVI) compared to the historical average ( ). Data source: METOP- NDVI. 4. TEMPORAL ANALYSIS OF NDVI AND RAINFALL ESTIMATES PROFILES AT ZOBA LEVEL Figure 4 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 allows detecting possible seasonal anomalies of the current year as compared to the long-term average. These profiles all show a similar pattern. Rainfall in June is slightly above normal, which generally causes NDVI curves to be somewhat superior to the long-term average. Then, in the third dekad of July the clearly upper-average rainfall (around 30 or 40 mm superior) originates an above-normal vegetation development until the end of the season due to the continuous precipitation during August and September. 5

6 In Gash Barka and Anseba zobas where most of communal agriculture is located, performance of cropland was better than average over the last 14 years due to high amounts of rainfalls in July, with values higher than 50 mm over the long-term average in Geleb, Gonei and Omhajer. Moreover, these sub-zobas present a secondary rainfall peak reached in the second dekad of August, which benefits the continuity of the vegetation growth until the end of the season (i.e. Halhal). For example, the good condition shown by the Mensura profile is also confirmed by the farmers that indicated that the good preparation of land together with the rainfall led their crops to be in good condition at the end of September (Ministry of Information, 2014, North Red Sea 4.2 Maekel 4.3 Debub Figure 4. Profiles of vegetation index (NDVI) and rainfall estimates for the Kremti season. The graphs compare the current season with the historical average. 6

7 4.4 Anseba 4.5 Gash Barka Figure 4 (ctd). Profiles of vegetation index (NDVI) and rainfall estimates for the Kremti season. The graphs compare the current season with the historical average. 7

8 Figure 4 (ctd). Profiles of vegetation index (NDVI) and rainfall estimates for the Kremti season. The graphs compare the current season with the historical average. REFERENCES Ministry of Information, OCHA,

9 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. 9