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Hydro meteorological Impactassessment for Bega 2012 overdifferent catchments.
February 1, 2013
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Background
Objectives
Major river catchments of Ethiopia
Methods
Results Summary
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Water supply interest are concernedwith the total amount of wateravailability.
Water demand management practice
Managing and Forecasting the inflowand discharge rates
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To assess the impact of Bega 2012 onwater resources in the differentcatchments of the country.
To assess the impact of Bega 2012weather on Reservoirs, Dams andirrigation schemes.
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Thornthwaite introduced the concept of theprecipitation effectiveness index , which iscomputed from the monthly values of rainfall andevaporation. The evaporation is computedempirically from mean monthly air temperature.
In assessing the effectiveness of rainfall, in
terms of water availability relationships betweenthe rainfall and air temperature has been workedout in terms of moisture indices.
Where, R = monthly rainfall in mm;
T = temperature in C
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Index Status Symbol
< than 16 Dry
1631 Semi-Dry
32 63 Sub-humid
64
128 Humid
> than 128 Wet
0
16
32
64
128
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Aridity status for Bega 2012 at different basins
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Distribution of Heavy fall days exceeding 30mmrainfall during Bega 2012 over main river basins.
STATION Heavyfall(mm)
ADET 37.1
ADWA 38.0
ARBA MINCH 30.5
ARJO 36.2
AYKEL 56.0
BLATE 37.0
BUI 32.0CHAGINI 39.1
DANGILA 38.6
DEBARK 38.1DEBRE TABOR 30.0DOLLO-MENA 77.1
GAMBELLA 44.8
GINNIR 30.0
JINKA(BAKO) 38.2
KIBREMENGIST 46.4
LARE 61.5
MOYALE 34.1
NEDJO 30.6NEKEMTE 44.4
TEPPI 79.0
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....
STATION HEAVYFALL(mm)
GOLOLCHA 34.7
TEPPI 32.1
GINNIR 30.0
CHIRA 30.0
STATION HEAVYFALL(mm)
JIJIGA 30.1
MAJI 39
METEHARA 31.6
SIRINKA 45.3
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98
100
102
104
106
108
110
112
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
WaterLevel(m)
Month
Koka
2005
20062007
2008
2009
2010
2011
20122013
Mean
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2502
2504
2506
2508
2510
2512
2514
2516
2518
2520
2522
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Wat
erlevel(m)
Month
Melka Wakena
200520062007200820092010
201120122013Mean
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2212
2213
2214
2215
2216
2217
2218
2219
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Wa
terLevel(m)
Month
Fincha
20062007200820092010
201120122013Mean
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1783
1784
1784
1785
1785
1786
1786
1787
1787
1788
1788
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
WaterLevel(m)
Month
Tana Beles
20052006200720082009
2010201120122013Mean
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1645
1650
1655
1660
1665
1670
1675
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Waterlevel(m)
Month
GilGel Gibe 1
20052006200720082009
2010201120122013Mean
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1020
1040
1060
1080
1100
1120
1140
1160
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Waterlevel(m)
Month
Tekeze
2008
2009
2010
2011
2012
2013
Mean
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Seasonal mean of Bega 2012
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In October and November over western half of Abay,Baro Akob, southern half of Omo Gibe and central Rift
Valley, upper and middle parts of Genale Dawa and pocketareas of lower Tekeze were experienced in wet condition. In the rest parts of eastern Abay, most parts of Tekeze,
middle Wabishebele and middle Omogibe and Rift valleycatchments were performed humid to semi humid
condition. Awash, eastern Abay, upper Omo Gibe and Rift Valley andsome parts of upper and lower Wabishebele the drycondition were observed in October and November.
In December and January the dry Bega condition weredominated over all basins except lower Omo Gibe andsouth eastern parts of Baro Akobo.
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During October some stations reported heavy falls thatexceed 30 mm for 1 to 4 heavy fall days over mostcatchments. The maximum heavy fall days was reportedover Genale Dawa basin at Kibremengist station.
In November many stations reported heavy falls for oneday except Awash and Wabishebele catchments, and inthe rest two Bega months some station also reportedheavy fall over Wabishebele, Awash, Baro Akobo, OmoGibe and Genale Dawa for one day for each basins.
In general during Bega 2012 except Genale dawa basin the
upper and middle parts of all catchments were dominatedunder dry and semi dry condition.
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Hydro meteorological outlook for Belg2013 Over different Basins
February 1 , 2013
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Outline of Presentation
Objectives Selected analogue Year
Methods Results Summary
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Objectives To indicate the impact of climate outlook
of Belg 2013 on water resources in thedifferent catchments of the country.
To indicate the impact of climate outlookof Belg 2013 on Reservoirs, Dams andirrigation schemes.
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For the coming season the selected analogueyear 1778, 2005, 2007,1980,1995 and 2003were compared based on probabilisticseasonal forecast for Belg 2013 and viewedout on catchments based map usinggeostatistical kriging method. Among whichthe year 2007, 2005 and1778 are the best
analogue year that can enlighten the Ariditystatus in the coming Belg season.
Selected analogue Year
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MethodsThornthwaite introduced the concept of the
precipitation effectiveness index , which iscomputed from the monthly values of rainfalland evaporation. The evaporation is computedempirically from mean monthly air temperature.
In assessing the effectiveness of rainfall, interms of water availability relationships betweenthe rainfall and air temperature has beenworked out in terms of moisture indices.
Where, R = monthly rainfall in mm;T = temperature in C
F b
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February
M h
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March
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April
M
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May
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Seasonal mean of Belg for each analogue year
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For the coming Belg season in the first month Februarywill be performed humid to semi humid condition oversome parts of the upper catchments of many basins.
In March wet condition will be observed over EasternBaro Akobo, upper Wabishebele, upper Genale Dawa,OmoGibe and some parts of upper Rift valley willexpected to be wet condition.
During April and May the wet condition will bedominated over wide areas of southern and westernbasins of the country respectively.
The coming Belg 2013 Omo Gibe and Wabishebele damswill have a better chance to get some amount of water.
However it should be noted that Belg rain has smallcontribution for surface runoff.
It is important those catchments which will be in wetcondition to compensate the loss of water due toevaporation over irrigation schemes, hydro-electric
dams and drinking water purposes.
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Thank you