STUDY OF RAINFALL PATTERNS IN
(Comparison Between Meteorological Data & Estimated Data from FEWS.)
A term project prepared
by
IBRAHIM N.MOHAMMED
nourein@cc.usu.edu
CEE5440/CEE6440 G I S in
Water Resources
A Virtual Course Presented On-Line
Fall 2003
Table of Contents:-
·
Results
Introduction:-
The
AREA:
2.376 million sq km. Population: 38,114,160 (July 2003 est.)
Historically and up to
a very recent date the common belief in
Aims of the Paper:-
·
Analysis of
Isohyets of Rainfall Patterns in the Sudan Sudan
· Tracking The Rainfall lines During Autumn and Summer Seasons.
Objectives:-
·
Contribution to
find out the Best places for Rain Agriculture (Highly dependence in Sudan
·
Kind of Early
Warning for Draught ness
·
Reflection of
Isohyets upon Demography.(The Population of western Part of Sudan is mixed
between Farmers and Nomads so the movement of these tribes seeking water for
them selves and their herds cause fetal clashes)
Data Collection:-
Metrological Data had been collected from National
Council For Research-SUDAN during the (1941-1970) period of study through
different rain gage stations as presented below:
|
STATION_ID |
NAME |
LAT (deg) |
LONG (deg) |
|
12 |
EN
NAHUD |
13 |
28 |
|
22 |
|
5 |
32 |
|
30 |
GEDARIF |
14 |
35 |
|
35 |
NEW
HALFA |
15 |
36 |
|
36 |
|
20 |
37 |
|
54 |
WAU |
8 |
28 |
|
81 |
MALAKAL |
10 |
32 |
|
99 |
KADUGLI |
11 |
30 |
|
137 |
GENEINA |
13 |
22 |
|
141 |
EL
FASHIR |
14 |
25 |
|
145 |
|
13 |
30 |
|
154 |
KOSTI |
13 |
33 |
|
258 |
WAD MEDANI |
14 |
33 |
|
412 |
KASSALA |
15 |
36 |
|
615 |
|
16 |
33 |
|
653 |
GHAZALA
GAWAZAT |
11 |
26 |
|
874 |
ED
DAMAZIN |
12 |
34 |
|
5001 |
ABU
NAAMA |
13 |
34 |
|
5002 |
YAMBIO |
5 |
28 |
|
5003 |
|
18 |
34 |
|
5004 |
KARIMA |
19 |
32 |
|
5005 |
ABU
HAMAD |
20 |
33 |
The gage
stations are scattered upon the country….
The second source of Data was FEWS (Famine Early Warning Systems Network
(FEWS NET)
Which has tremendous information about Sudan (For more information here are the
links to learn more about Sudan and some detailed information about DEKEL Data
that I used for analysis)
METADATA FOR Sudan, Africa Rain Stations
(Contains
Detail information about DEKEL Data e.g. Identification Information, Spatial Reference …etc)
ADDS
(AFRICA DATA DISSEMINATION SERVICE)
(Contains Administrative, Agro-Climate Zones, Rainfall
Data…etc)
The gage stations are
scattered upon the country covering the population band in the middle of the
country:
|
STATION_ID |
NAME |
LAT (deg) |
LONG (deg) |
|
1 |
MANAQIL |
14.2500 |
33.0000 |
|
2 |
BARA |
13.7000 |
30.3700 |
|
3 |
SHABASHA |
14.1300 |
32.2300 |
|
4 |
ABU DELEIQ |
15.9200 |
33.8200 |
|
5 |
KAMLIN |
15.0800 |
33.1800 |
|
6 |
WAD NIMR |
14.5300 |
32.1300 |
|
7 |
ABGAR |
14.4800 |
32.0700 |
|
8 |
EL GETEINA |
14.8700 |
32.3700 |
|
11 |
ED DUEIM |
13.9800 |
32.3300 |
|
12 |
EN NAHUD |
12.7000 |
28.4300 |
|
22 |
|
4.8670 |
31.6000 |
|
30 |
GEDARIF |
14.0330 |
35.4000 |
|
41 |
GINAINA |
13.1500 |
22.3670 |
|
54 |
WAU |
7.7000 |
28.0170 |
|
107 |
ER RENK |
11.7500 |
32.7830 |
|
113 |
NYALA |
12.0670 |
24.8830 |
|
141 |
EL FASHIR |
13.6330 |
25.3330 |
|
145 |
|
13.1670 |
30.2330 |
|
154 |
KOSTI |
13.1670 |
32.6670 |
|
369 |
GHADAMBALIYA |
14.0330 |
34.9830 |
|
441 |
TOKAR |
18.4330 |
37.7330 |
|
615 |
|
15.6000 |
32.5500 |
|
644 |
EL DAEIN |
11.4500 |
26.1670 |
|
874 |
ED DAMAZIN |
11.8170 |
34.4000 |
|
1192 |
SENNAR |
13.5500 |
33.6170 |
Procedure:-
·
Invoke Arc Gis
and add the administrative shape file to depict Sudan
·
Use the 
(Add Data) button to add the data table "text
file or DBF file". This file should then appear in the table of
contents (source tab) of the active data frame, but not on the map, because the
system does not (yet) know how to interpret the data geographically.
·
Right click on
the table of contents entry for "text file or DBF file" and select
display XY data.
·
At the display
XY data dialog adjust the X field to long and Y field to lat. Click on Edit to
set the Coordinate System. Select a
predefined coordinate system and browse to Geographic Coordinate Systems/ Same
as Data frame coordinate system.
·
Preparation of
rain gage shape file. Convert the text file or DBF file events display to a
shape file. Right click on "text file or DBF events file" and
select Data/Export Data.
·
At the export
data dialog, click use the same coordinate system as the data frame (to convert
from latitude and longitude to same frame data coordinate) and specify the
output name.
·
Preparation of
Spatial Analyst. The calculations are done using Spatial Analyst.
First set the options of Spatial Analyst to cover the domain of interest.
·
Use
Spatial Analyst / Interpolate to raster / Inverse Distance weighted method /
choose the Z value the months from January up to December each time to get the
grid file for the specified month (Hint you may change the output cell size to
get the result).
(This procedure is the same as EX 3
for how to display text file)
Results:-
1- The Data is almost symmetrical as we seen below:
August is the Main month contributor to Rainfall in Sudan
2- The Rainfall Patterns during the whole year using
the two different sorts of Data:
·
PORT SUDAN
·
YAMBIO HAS EQUITARIOAL
CLIMATE.
·
FEWS DATA
HASN’T GOT STATION RECORDS (January) DURING PERIOD OF STUDY.
·
February IS THE
SECOND MONTH OF WINTER AND WE RELAIZE THAT THE AMONUT OF RAINS INCREASED IN
EXPANDED.
·
March IS STATRT
OF AUTUMN IN SOUTH.
·
April IS THE
MONTH OF AUTUMN IN SOUTH AND WE SEE THAT SOME PARTS FROM NORTH BEEN RAINED.
·
May PRECITATION
IS A VERY IMPORTANT FOR THE NORTHERN FARMERS BECAUSE OF USE IN AGRICULTURE.
·
June IS THE
LAST MONTH OF SUMMER.
·
July IS THE
START OF AUTUMN IN NORTHERN
SUDAN YAMBIO IN SOUTH
WESTERN PART OF SUDAN
·
August HAS THE
STAKE SHARE IN SUDAN’S PRECIPITAION, YAMBIO IN SOUTH WESTERN PART OF SUDAN HAS
240 mm AVERAGE RAINFALL.
·
September IS
THE END OF AUTUMN AND THE RAINFALL BEGAN TO GO BACK SOUTH.
·
October
RAINFALL IS MAINLY IN SOUTH AND SOUTH EAST.
· November RAINFALL IS MAINLY IN SOUTH AND NORTH AS MEDITERRANEAN CLIMTE.
·
December RAINFALL
IS MAINLY IN SOUTH AND NORTH WITH LESS AMOUNT FROM November.
3- Tracing of Rainfall lines during summer and
autumn using the two different sorts of Data:
Determination of Rainfall line during autumn (July,
August and September):
We realize that average Rainfall line starts with 30
mm in July at 12˚ 52́ 40˝ N and then increased to 40 mm in
August at 13˚ 29́ 43˝ N after that decreased to 20 mm in
September at 12˚ 53́ 37˝, this clearly reflects upon the people
moving towards and backwards at the Western part of Sudan
Summary and Conclusion:-
The annual rainfall
ranges form zero in the North of the country to more than 240mm in the extreme
South West of the Sudan.(it is 1500mm but for this paper and due to time period
stated just 1941-1970 we get 240mm). The isohyets are zonal (parallel to
latitude) up to 14˚ N after that the pattern changes to give a low
rainfall along the
The mean annual rainfall
is not a reliable measure of the rainfall unless accompanied by a measure of
the variation of rainfall around that mean. The standard deviation is usually
taken as good indication of the variability. The standard deviation is found to
increase with decreasing rainfall in this study.
The beginning of the
rainy season is of importance for many purposes (Agriculture, people,
animals…etc). The rainy season begins early in the South of the
|
Latitude˚ N |
2 |
4 |
6 |
8 |
10 |
12 |
14 |
16 |
|
Date |
1st March |
20th March |
10th April |
30th April |
18th May |
7th June |
27th June |
15th July |
The end of the rainy
season is not so well correlated with latitude. The length of the rainy season
increases as one goes South. It is 60 days at Kosti, 100 days at Abu Namma, 130
days at Kadugli, 160 days at Malakal, 200 days at
With Refer to NATIONAL
COUNCIL FOR RESERCH,
COUNCIL FOR SCIENTIFIC & TECHNOLOGICAL RESEARCH,
WATER RESOURCES IN