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Ethiopian Early Warning System

Alert Flood Vulnerability and Risks in Ethiopia in 2007

Flood Prone Areas

Early Warning Special Report 02 July, 2007


BACKGROUND

The topography of Ethiopia includes both mountainous highland and lowland plains. Its mountainous parts are mainly located at central parts while the low land areas on its outmost borders. According to the National Meteorological Agency (NMA), the country consists of 11 river basins, namely Abay, Awash, Ayisha, Afar Denakil, Baro-Akobo, Central Rift valley, Genale-Dawa, Ogaden, Omo-Ghibe, Tekeze, and Wabishebele. (See the map below)

The drainage systems of the country originate from the central highlands that make their way down to the outlying lowlands. During the main rainy season that extends form June to September, the major rivers and their tributaries carry high level of discharges. From the past experiences it is well recognized that the country normally faces two types of floods; flash and river floods. Flash floods are the ones formed from excess rains falling on the upper parts of the river basin and runs to the lower parts with high concentration, speed and force. In mot areas such types of floods are sudden that do not give a lead-time to be

Early Warning Special Report 02 July, 2007 Page 1


recognized. Therefore, such floods often result in considerable losses of both human life and properties. If such type of flooding passes across areas with high concentration of human settlement and infrastructure, the damages become devastating. The 2006 incident that Dire-Daw City experienced is the most typical example of flash flooding. On the other hand, much of the flood disasters in Ethiopia are related to rivers that overflow and brust their banks and inundate the lowland plains. The 2006 flooding that have occurred in South Omo Zone of SNNP, Gode and Afder zones of Somali, and most parts of Gambella regions are the recent examples of river flooding. Flooding in some areas of the country, when the main rainy season has high amount and distribution as compare to usual seasonal patterns, is inevitable. Therefore, it is expected in localized areas of Humera in Tigray, around Lake Tana and Oromiya zone of Amhara, zones 1 and 3 of Afar, Gode, Afder and Liben zones of Somali, east and southwest Showa of Oromiya, South Omo zone of SNNPR, Gambella, Itang and Jikawo woredas of Gambella Regional State. Apart from these, flash flooding is common in many areas including Dire Dawa.



WEATHER OUTLOOK FOR KIREMT 2007 The National Meteorological Agency (NMA) has recently issued its weather outlook report for the current Kiremt season. The outlook indicates that the coming Kiremt rainy season will be analogous to the rain performances observed in the years 1970, 1978, 1995 and 2005. According to the report, weak to moderate La- Nina episode is the most likelihood scenario to happen during the current Kiremt season. If so, the most likely effects on Ethiopian weather will be wetter than normal conditions during the months of June, July, August and September 2007. In this regard, it is anticipated that wet Kremt will dominate in most of the Kiremt-rain-benefiting parts of the country. Therefore, the following features are expected to happen during this rainy season.

• Normal onset and cession, • High rains over central, southern, north and northwest Ethiopia, • Occasional heavy rains during July and August, and • Erratic rains to prevail over the southwest, northeast and eastern parts of the

country (See the map below for the details).

Tercile Rainfall Probability



According to the Agency, the likelihood of getting normal to above normal rainfall in most parts of the country is 70 - 80%. This occurrence is anticipated to increase the risk of flooding in flood prone areas and the scale is expected to be worse than the 2006 kiremt when nearly 700,000 people were affected, of which over 200,000 were displaced and more than 600 people lost their lives. Approximately 60,000 hectares of cropped land was destroyed or damaged and substantial loss of infrastructure occurred.

PERFORMANCE OF THE BELG SEASON’S RAIN (FEB 1 _ MAY 31, 2007) The over all seasonal cumulative amount of rainfall during Belg 2007 (January 1 – May 31, 2007) performed normal to above normal in most parts of the country with exceptions of northern half of Afar Regional State where rainfall deficit was so severe (see the map below).



START OF THE KIREMT RAIN AND FLOOD RISKS IN 2007

The Kiremt season in most parts of the country extends from June to September. The rainfall in June normally starts low in amount and gradually increases and extends from South and Western parts of the country to North with a break of four to five weeks between the end of the Belg and the start of the kiremt rains. However, this year's rain started early in June with no sufficient gap in between, merging into the kiremt in some parts of the country. On the other hand, as observed from satellite rainfall estimate for the first decade of June (see map below), except in the Western and North Western parts of the country, most areas received normal to above normal rains. This is also confirmed by station data from NMA. According to NMA, some parts of the country received heavy rainfall ranging from 30- 63mm in a day. Ijaji, Metema, Arsi Robe, Arbamich, Chora,, Arjo, Bulen, Majete and Nejo meteorological stations particularly received 102, 98, 62.2, 44.4, 40, 39.7, 39.2, 33.7 and 32.3mm of rain a day respectively.

Rainfall Estimate Difference Map for the First Dekade of June, 2007



The amount and intensity of the rain during the second and third decades of June continued with much more strength and area coverage. As a result, soil saturation levels became very high and increased fears of landslides and flash flooding. Such soil saturation as currently observed is also associated with high intensity of flooding, as the soil cannot absorb excess rainwater. Flooding has already taken place in South Omo, Gamo Gofa and Wolayita zones in SNNPR. In Humbo woreda of Wolayita, recent floods have affected a total of 6,768 people. Similarly, floods that occurred some two weeks ago displace 601 people in Abaya and 890 in Boke woredas of Gamo Gofa Zone. Crops and residential houses are inundated in both woredas. These occurrences are considered abnormal for this time of the year and are earlier than last year’s flooding commenced in August. As illustrated by the graphs below, hydrological forecasts from NMA indicate that the water levels in dams are expected to be higher than the same time last year. Traditionally flooding in the lower catchments of the dam occurs during the peak water levels of the Dams in August and September. This year, flooding is anticipated to occur earlier than usual with maximum water levels of the dams expected to be reached earlier than normal. Close monitoring and early management of the water levels in the dams is essential to mitigate the worst effects of last year. Incidences of malaria and water borne disease such as Acute Watery Diarrhoea (AWD) are also likely to increase with such heavy rainfall and will be further exacerbated by floods. Hence, preparedness is essential to intervene on time. THE NEED FOR URGENT PREPARDNESS TO MITIGATE THE EFFECTS OF THE FLOOD

In light of the need for effective preparedness in order to mitigate the severe impacts of floods such as those witnessed last year, the immediate commencement of flood contingency planning, and timely and adequate preparedness by all concerned is essential.



Mitigation activities such as early and appropriate dam management and early warning information dissemination to populations at risk are needed. Such preparedness activities as pre-positioning of food and non-food items are also essential particularly to those areas that would be inaccessible due to flooding. Government and humanitarian partners are urged to act urgently for preparedness and early response. The experience from the year 2006 flood in Gode and South Omo showed that mitigating the animal diseases during and after the flood could minimize the effect of flood on livestock. Flooding creates a favorable environment for infectious and vector borne diseases such as Blackleg, Anthrax and Foot Rot that will increase morbidity and mortality of livestock species. Moreover, feed assistance on the spot will be needed for livestock that may be trapped by flooding because the grazing areas will be inundated and it is very difficult to take them out. Therefore, adequate preparedness before the actual flood happens will protect the livelihood assets of the community.

Forecasts of Water Levels in the Major Dams in 2007

Lake Tana Koka Dam

1783.5

1784.0

1784.5

1785.0

1785.5

1786.0

1786.5

1787.0

1787.5

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

2005 2006 2007 Mean Expected 1783.5

1784.0

1784.5

1785.0

1785.5

1786.0

1786.5

1787.0

1787.5


2005 2006 2007 Mean Expected Early Warning Special Report 02 July, 2007 Page 7

Melka Wakena Dam Fincha Dam

2504.0

2506.0

2508.0

2510.0

2512.0

2514.0

2516.0

2518.0

2520.0

2522.0


2005 2006 2007 Mean Expected 2214.0

2214.5

2215.0

2215.5

2216.0

2216.5

2217.0

2217.5

2218.0

2218.5


2006 2007 Mean Expected

Gilgel-Gibe Dam

1645

1650

1655

1660

1665

1670

1675

1680


2005 2006 2007 Mean Expected

Early Warning System Special Report

Alert: Flood Vulnerability and Risk in Ethiopia in 2007

Prepared by The Early Warning Department of the Disaster Prevention and Preparedness Agency

in Collaboration with the Flood Task Force of the Early Warning Working Group

Tel. 251 11 515 8236 Email: [email protected] Web: http://www.dppc.gov.et


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