Building the Foundation for a National Approach to Climate Change
Adaptation in Namibia.
GIS-Based and Gender-Specific
Climate Risk Assessment
Decision Making Tool Development
Triple E Systems Inc., USA
Asmerom M. Gilau
Felix B. Dayo
Lijalem Z. Abraham
Lisho C. Mundia
July 19, 2011
Africa Adaptation Project
Namibia
Africa Adaptation Programme; Supporting Intergrated and Comprehensive
Approaches to Climate Change Adaptation in Africa.
Overview of
Drought and Flooding Risk map
Development
SELECTION OF METROLOGICAL
STATIONS
• Total number of meteo stations = 1408
• Data Available for 225 stations
• Out of which, only 167 stations have data of
starting year before 1961
• Out of which 43 stations selected for SPI Analysis
that meet SPI criteria for drought an flooding risk
mapping
43 Selected Metrological Stations
No.
RFSta_GIS_Name
RFSta_Short_Name
LAT
LON
1
Walvis Bay Radio & RN Erf 1497
Walvis Bay Pellcan Point
-22.95
14.5
2
Swakopmund HaweAmt (H130) Block 1
Swakopmund
-22.683
14.533
3
Awogobibtal on 344
Awagobibtal
-19.65
17.867
RF_Class
0-50
more than 600
550-600
450-500
4
Gaub (Ghaub) 47 (H043)
Gaub
-19.467
17.75
5
Karasburg P, Erf 386 (H342)
Karasburg
-28.017
18.75
6
Nimmerrust 350
Nimmerrust
-27.533
19.55
7
Davignab Suid 286 (H336)
Davignab Suid
-27.533
19.817
8
Gellap Ost 3
Gellap Ost
-26.45
18.083
9
Naos 79
Naos
-27.133
19.033
10
Morgenzon Suid No.1 on 219
Morgenzon Suid
-26.15
19.4
11
Eindpaal 195
Eindpaa
-25.367
19.15
12
Aranos P, Erf 2 (H258:Araohab)
Aranos
-24.15
19.117
13
Gomchanas Ost 125
Gomchanas Ost
-23.9
18.283
14
Khorixas P., Erf 15
Khorixas
-20.367
14.967
15
Leonardville P, Erf 115
Leonard Ville
-23.5
18.783
16
Westfalenhof 23
Westefa Ilenhof
-22.267
16.417
17
Windhoek Waterworks Erf 5505
Windhoek Met. Hq.
-22.55
17.083
18
Erora Ost 12 Farm 6, now 139 (H146)
Erora Ost
-22.017
16.5
19
Wilhelmstal 8
Wilhelmstal
-21.917
16.317
20
Eremutua 23
Eremutua
-20.9
15.783
21
Binsenheim on 85
Binsenheim
-22.783
17.383
22
Omateva 113
Omateva
-22.267
18.15
23
Steinhausen 212 P (H226)
Steinhausen
-21.817
18.233
24
Otjikururume 213
Otjikururume
-21.117
17.217
25
Kalidona (Karidona) 277
Kalidona
-21.283
18.05
26
Erundu R (H077)
Erundu
-20.65
16.417
27
Hohenfels 153
Hohenfeis
-20.7
16.85
28
Halali N C
Halali
-19.033
16.467
29
Rehoboth Mission (H003)
Rehoboth
-17.883
15.067
30
Ondangwa AFB
Ondangwa
-17.883
15.95
31
Arbeidsgenot 409 Ph 06731-81103
Arbeidsgenot
-19.567
16.917
32
Una 139
Una
-20
17.383
33
Oshivelo P
Oshivelo
-18.617
17.167
34
Chaontsas 292
Choantsas
-18.867
18.133
35
Koukuas 1056
Koukuas
-18.9
18.3
36
Otavi PO Erf 431
Otavi
-19.633
17.333
37
Tsumeb P/PO Erf 5 (H038)
Tsumeb
-19.233
17.717
38
Tondoro R C M
Tondoro
-17.783
18.8
39
Rundu Town PO Erf 114
Rundu
-17.917
19.75
40
Warmbad M/P (H347) Erf 137
Warmbad
-28.45
18.733
41
Aus P, Erf 15 (H281)
Aus
-26.667
16.267
42
Kuren Kuru Rhenish/F.M.
Kuren Kuru
-17.633
18.617
43
Katima Mulilo Farm I (ENOK)
Katima Mulilo
-17.483
24.25
550-600
!(
!(
!(
!(
!(
more than 600
!(
550-600
500-550
500-550
!(
100-150
!( !(
!(
450-500
!(
!(
!(
550-600
!(
500-550
!(
!(
150-200
400-450
!(
!(
!(
!(
200-250
350-400
!(
!(
250-300
!( !(
!(
300-350
!(
300-350
!(
Average Annual Rainfall
CLASS
!(
250-300
!(
!(
!(
0-50
0-50
!(
100-150
200-250
350-400
!(
150-200
!(
200-250
50-100
250-300
150-200
400-450
!(
300-350
350-400
!(
400-450
!(
!(
450-500
100-150
450-500
50-100
!(
!( !(
500-550
!(
550-600
!(
> 600
0-50
500-550
50-100
>600
Selected Stations Map with Station
Names
Kuren Kuru Rhenish/F.M.
!(
more than 600
450-500
Rehoboth Mission (H003)Ondangwa AFB
550-600
!(
!(
!(
!(
Tondoro R C M
Rundu Town PO Erf 114
Katima Mulilo Farm I (ENOK)
more than 600
!(
550-600
500-550
500-550
Oshivelo P
!(
Chaontsas 292Koukuas 1056
!( !(
Tsumeb P/PO Erf 5 (H038)
!( Gaub (Ghaub) 47 (H043)
Arbeidsgenot 409 Ph 06731-81103Otavi PO Erf 431
!( !( !( !( Awogobibtal on 344
!(
Halali N C
450-500
500-550
!(
!(
550-600
Una 139
400-450
Khorixas P., Erf 15
Erundu R (H077)Hohenfels 153
!(
!(
Eremutua 23
!(
350-400
!(
Otjikururume 213
Kalidona (Karidona) 277
!(
Steinhausen 212 P (H226)
Wilhelmstal 8
!( 139 (H146)
!( !( Erora Ost 12 Farm 6, now
Westfalenhof 23
Omateva 113
!(
!(
Windhoek Waterworks Erf 5505
Swakopmund HaweAmt (H130) Block!(1
Binsenheim on 85
!( Walvis Bay Radio & RN Erf 1497
!(
!(
300-350
Average Annual Rainfall
CLASS
250-300
0-50
!(
200-250
!(
Leonardville P, Erf 115
Gomchanas Ost 125
!(
Aranos P, Erf 2 (H258:Araohab)
0-50
100-150
150-200
200-250
50-100
250-300
150-200
!(
!(
Aus P, Erf 15 (H281)
!(
Gellap Ost 3
Eindpaal 195
300-350
!(
Morgenzon Suid No.1 on 219
350-400
400-450
450-500
100-150
!(
Naos 79
Nimmerrust 350
Davignab Suid 286 (H336)
!( !(
!(
0-50
!(
Karasburg P, Erf 386 (H342)
Warmbad M/P (H347) Erf 137
50-100
500-550
550-600
> 600
Filling Missing Data
• Missing Values of stations were filled by using
correlation analysis of stations data
• Data of a station were correlated with data of
neighboring stations
• Correlations with highest accuracy, i.e, 𝑅2 ≈ 1,
were selected
• Based on the correlation equation, the missing
data of the station were filled
SPI CALCULATION
• SPI Values of each station were calculated
base on the historical records of Rainfall
• Total Monthly RF values of years 1960-2009
were fed to the SPI model
• SPI values were calculated as:
SPI 3
3 months
SPI 6
6 months
SPI 9
9 months
SPI 12
12 months
RESULTS OF THE ANALYSIS
Sample SPI Result for Two Stations
Walvis Bay Pellcan Point
Spi1 Spi3 Spi6 Spi9
0-50
1960
1960
1960
1960
1960
Spi12
Swakopmund
Spi1
Spi3 Spi6 Spi9
0-50
1
2
3
4
5
0.67
0.54
0.43
1.34
1
-99
-99
-0.06
0.27
0.33
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
1960 6
1960 7
1960 8
1960 9
1960 10
1960 11
1960 12
1961 1
1.43
2
1.1
0.91
1.05
1.04
0.91
0.67
1.11
1.13
1.32
0.54
0.42
0.55
0.59
0.17
0.33
0.42
0.55
1.01
0.93
1.08
0.22
-0.13
-99
-99
-99
0.28
0.35
0.46
0.91
0.53
-99
-99
-99
-99
-99
-99
0.23
0.14
1960
1960
1960
1960
1960
Spi12
1
2
3
4
5
-0.09
-0.13
-0.11
0.78
0.86
-99
-99
-0.77
-0.25
-0.02
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
-99
1960 6
1960 7
1960 8
1960 9
1960 10
1960 11
1960 12
1961 1
1.23
1.34
1
0.47
0.6
0.23
0.41
-0.29
0.84
1.06
1.14
0.17
-0.17
-0.41
-0.35
-0.59
-0.07
0.04
0.26
0.7
0.8
0.73
-0.6
-0.81
-99
-99
-99
-0.15
-0.05
0.09
0.45
0.08
-99
-99
-99
-99
-99
-99
-0.31
-0.38
│
│
│
│
│
│
│
│
│
│
│
│
│
│
│
│
2009
7
2
0.6
-0.54
-0.66
-0.81
2009
7
1.34
0.17
-1
-1.48
-1.48
2009
8
1.1
0.75
-0.47
-0.66
-0.73
2009
8
1
0.29
-0.91
-1.48
-1.48
2009
9
0.91
0.54
-0.17
-0.75
-0.81
2009
9
0.47
0.17
-0.6
-1.49
-1.48
2009 10
0.67
0.06
-0.29
-0.75
-0.81
2009 10
0.6
-0.17
-0.75
-1.21
-1.48
2009 11
0.91
0.17
-0.11
-0.75
-0.81
2009 11
0.23
-0.41
-0.83
-1.1
-1.48
2009 12
0.91
0.23
-0.17
-0.54
-0.83
2009 12
0.41
-0.35
-0.6
-1.34
-1.69
SPI Result …
SPI Legend Guide
< -2
Exceptionally Dry
-1.99 to -1.6
Extremely Dry
JUL07_DT_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
Severely Dry
-1.29 to - 0.80
Moderately dry
-1.29 to - 0.80
-0.79 to -0.51
Abnormally Dry
+0.51 to +0.79
-0.5 to + 0.5
Near Normal
+0.51 to +0.79
Abnormally Wet
-1.59 to -1.30
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+0.80 to + 1.29
Moderately Wet
+1.30 to +1.59
Severely Wet
+1.6 to +1.99
Extremely Wet
> +2
Exceptionally Wet
+1.30 to +1.59
+1.6 to +1.99
> +2
RISK MAPS BASED
ON
MOST FREQUESNT WET AND DRY
SPI VALUES
MOST FREQUESNT WET AND DRY SPI
VALUES
• Based on the analysis of the SPI results
Feb 1974 – has the most frequent wet SPI value
for most of the selected station
Jan 1995 – has the most frequent dry SPI value
for most of the selected stations
Feb74_W_SPI-3
Feb74_W_SPI-6
MAPS OF THE
WETTEST
SEASON
JUL07_DT_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
-1.29 to - 0.80
+0.51 to +0.79
Feb74_W_SPI-9
Feb74_W_SPI-12
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+1.30 to +1.59
+1.6 to +1.99
> +2
Jan95_D_SPI3
Jan95_D_SPI6
MAPS OF THE
DRIEST SEASON
JUL07_DT_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
Jan95_D_SPI9
Jan95_D_SPI12
-1.29 to - 0.80
+0.51 to +0.79
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+1.30 to +1.59
+1.6 to +1.99
> +2
RISK MAPS BASED ON HISTORICAL
DROUGHT AND FLOODING YEARS
SPI Maps For Historically Drought and
Flooding Years
• From literatures and historical records, the years
shown in the table had shown to have had
highest drought and flood levels in Namibia
Drought
May
Sep
Nov/Aug
Jul
1992
1996
2002
2003
2007
Flooding
Feb
Mar
Mar
Mar
Feb
Mar
Apr
Mar
1989
2003
2004
2006
2007
2008
2009
2011
SPI Maps
Drought and Flooding Years….
• Among those, 3 different years from each
category selected for SPI mapping of 3, 6, and
9 months
Drought
May
Aug
Jul
1996
2003
2007
Flooding
Mar
Feb
Apr
2006
2007
2009
• SPI results for drought and flooding
were consistent with highest historical records.
Drought Maps
May 1996 Drought for SPI 3, 6, 9
JUL07_DT_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
-1.29 to - 0.80
+0.51 to +0.79
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+1.30 to +1.59
+1.6 to +1.99
> +2
Drought Maps
Aug 2003 Drought for SPI 3, 6, 9
JUL07_DT_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
-1.29 to - 0.80
+0.51 to +0.79
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+1.30 to +1.59
+1.6 to +1.99
> +2
Drought Maps
Jul 2007 Drought for SPI 3, 6, 9
JUL07_DT_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
-1.29 to - 0.80
+0.51 to +0.79
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+1.30 to +1.59
+1.6 to +1.99
> +2
Detailed Map - JUL 2007_SPI 9
Drought
JUL07_DT_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
-1.29 to - 0.80
+0.51 to +0.79
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+1.30 to +1.59
+1.6 to +1.99
> +2
Areal Coverage Affected by 2007 Drought
Areal Coverage JUL07_DT_SPI9
SPI
Category
Areal Coverage (%)
< -2
Exceptionally Dry
0.06
-1.99 to -1.6
Extremely Dry
11.97
-1.59 to -1.30
Severely Dry
22.34
-1.29 to - 0.80
Moderately dry
31.42
-0.79 to -0.51
Abnormally Dry
13.15
-0.5 to + 0.5
Near Normal
20.51
+0.51 to +0.79
Abnormally Wet
0.30
+0.80 to + 1.29
Moderately Wet
0.21
+1.30 to +1.59
Severely Wet
0.04
+1.6 to +1.99
Extremely Wet
0.00
> +2
Exceptionally Wet
0.00
Flooding Maps
Mar 2006 Flood for SPI 3, 6, 9
JUL07_DT_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
-1.29 to - 0.80
+0.51 to +0.79
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+1.30 to +1.59
+1.6 to +1.99
> +2
Flooding Maps
Feb 2007 Flood for SPI 3, 6, 9
JUL07_DT_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
-1.29 to - 0.80
+0.51 to +0.79
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+1.30 to +1.59
+1.6 to +1.99
> +2
Flooding Maps
Apr 2009 Flood for SPI 3, 6, 9
JUL07_DT_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
-1.29 to - 0.80
+0.51 to +0.79
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+1.30 to +1.59
+1.6 to +1.99
> +2
Detailed Map – Apr 2009_SPI 9
Flood
APR09_FL_SPI9
< -2
-1.99 to -1.6
-1.59 to -1.30
-1.29 to - 0.80
+0.51 to +0.79
-0.5 to + 0.5
+0.51 to +0.79
+0.80 to + 1.29
+1.30 to +1.59
+1.6 to +1.99
> +2
Areal Coverage Affected by 2009 Flooding
Areal Coverage APR09_FL_SPI9
SPI
Category
Areal Coverage (%)
< -2
Exceptionally Dry
0.38
-1.99 to -1.6
Extremely Dry
0.27
-1.59 to -1.30
Severely Dry
0.34
-1.29 to - 0.80
Moderately dry
1.46
-0.79 to -0.51
Abnormally Dry
2.11
-0.5 to + 0.5
Near Normal
15.16
+0.51 to +0.79
Abnormally Wet
15.34
+0.80 to + 1.29
Moderately Wet
40.43
+1.30 to +1.59
Severely Wet
19.86
+1.6 to +1.99
Extremely Wet
4.00
> +2
Exceptionally Wet
0.65
Potential Flooding Areas
• For potential flooding areas, SPI charts were
prepared for the years from 1961 to 2009
• The flooding areas selected and the
corresponding representative stations are
shown in the following table
• April and May are chosen because these are
rainy season months and taking spi3 or 6,
higher can capture all season variations
Potential Flooding Areas …
Potential Flooding
Area
Representative Selected
Meteo Station Month
SPIs
Marintal Town
- Gomchanas Ost
April
3, 6,,9, 12
Oshakati Areas
- Ondangwa
- Rehoboth
April
3, 6,,9, 12
Zambezi River
Catchment
- Katima Mulilo
April
3, 6,,9, 12
Kavango River
Catchment
- Kuren Kuru
- Tondoro
- Rundu
May
3, 6,,9, 13
Sample Potential Flooding Areas …
SPI FOR STATIONS NEAR POTENTIAL FLOODING AREAS - OSHAKATI
SPI-12 APRIL 1961-2009, ONDANGWA 400-450mm
2009
2006
2003
2000
1997
1994
YEAR
1991
1988
1985
1982
1979
1976
1973
1970
1967
1964
1961
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
SPI
0.5
1.0
1.5
2.0
2.5
3.0
N.B. The title is to stress the 2009 flooding. The graph contains drought and flooding.
Potential Flooding Areas …
SPI FOR STATIONS NEAR POTENTIAL FLOODING AREAS - MARINTAL TOWN
SPI-12 APRIL 1961-2009, GOMCHANAS OST 200-250mm
2009
2006
2003
2000
1997
1994
1991
YEAR
1988
1985
1982
1979
1976
1973
1970
1967
1964
1961
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
SPI
0.5
1.0
1.5
2.0
2.5
3.0
Potential Flooding Areas …
YEAR
SPI FOR STATIONS NEAR POTENTIAL FLOODING AREAS - ZAMBEZI RIVER
CATCHMENT
SPI-6 APRIL 1961-2009, KATIMA MULILO >600mm
2009
2006
2003
2000
1997
1994
1991
1988
1985
1982
1979
1976
1973
1970
1967
1964
1961
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
SPI
0.5
1.0
1.5
2.0
2.5
3.0
Potential Flooding Areas …
SPI FOR STATIONS NEAR POTENTIAL FLOODING AREAS - KAVANGO RIVER
CATCHMENT
SPI-12 MAY 1961-2009, RUNDU 500-550mm
2009
2006
2003
2000
1997
1994
YEAR
1991
1988
1985
1982
1979
1976
1973
1970
1967
1964
1961
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
SPI
0.5
1.0
1.5
2.0
2.5
3.0
NEXT STEPS (Max 2 Weeks)
1. We are calculating the probability of
recurrence of drought and flooding so
that decision-makers could prepare to
mitigate impacts
2. We are also determining population
affected by drought and flooding by
region
NEXT STEPS (Max 2 Weeks)
3. Report writing and refining
The End