9 The Land Resources of North East Nigeria A/blume1 The ...

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14" 10' 12° 10° 10° D.O.S.(L.R.)3064G Copyright reserved MILES 0 25 l i i i i 1_ MEAN ANNUAL RAINFALL TEXT MAP 3 SCALE 1:3,000,000 ___^^_ „Main Road -I 1 1— Railway + • + + + + ++ International Boundary 50 75 12° East of Greenwich l,M3mm-l,270mm 45-SOin Sices with atypical records Provisional boundaries 14° Based on data provided by the Nigerian Meteorological Service. Drawn and photographed by Directorate of Overseas Surveys, 1969. Printed by Ordnance Survey,
1 015 mm (40 in) and 890 mm (35 in) isohyets, roughly enclosed in a rectangle bounded by 10°- 13° longitude and 9°- ll° N. Within this rectangle lies a distinct isolated belt of 1 015 mm (40 in) m.a.r. about 30-50 km (20-30 mi) wide running from the Hawal - Gongola confluence to the Mandara range. In addition, smaller areas with a m.a.r. above 1 015 mm (40 in) and below 890 (35 in) also occur within the rectangle, associated with localised orographic effects. Where the presence of large atypical areas is suspected, but not fully substantiated, they are indicated by broken blue lines in Text Map 1. This feature is discussed further under eco-climatic zones. Mean Monthly Rainfall The extent and distribution of mean monthly rainfall is shown on Maps 4a and 4b. The monthly means range from 450 mm (18 in) to zero. The period November - February is virtually rainless over the greater part of the project area and the rains commence in March -April sweeping up from the southwest and west to reach their peak in August. From September onwards the rains retreat southwestwards and the annual northwest/southwest oscillation is clearly observable on the maps. (See pp. 18-42 for climatic maps and diagrams.) Distribution of Rainfall Figure 1 shows the distribution of the occurrence of annual rainfall for a restricted number of stations by (25 mm) 1 in integers and grouped 5 in (125 mm) units. Over the period examined it can be seen that low annual rains are atypical of the stations with a m.a.r. of more than 1 015 mm (40 in). Yola occupies an intermediate position with a wider scatter of records about the mean. In the northern group low rains occurred at Maiduguri in 6 years out of 40 and at Potiskum in 2 years out of 26. The lowest record occurred in the same year of drought, 1940, for both stations. The deviation from normal distributions indicated by the grouped histograms in Figure 1 should be noted and Figure 2 shows a range of typical rainfall patterns for selected stations. Twin-Peak Distributions The annual distribution of rainfall in twin peaks is well known in southern Nigeria and involves what is commonly termed the 'little dry season' in the month of August between twin peaks of rainfall in July and September (Ireland, 1962). This is associated with the double passage northward and southward of the ICTZ at the time when it usually reaches its most northerly position. There are indications that the feature occurs in the south and southwest of the project area, where the secondary minimum is July and not August (Kwojeffa is a marked exception). It appears to be confined to the rectangle between the 890- 1 015 mm (35-40 in) isohyets described under Mean Annual Rainfall, where, irrespective of total rain fall, there is a tendency for the predominance of August rainfall to be diminished with an additional tendency towards twin-peak distributions. TEMPERATURE Temperature records are available in the NMS Monthly Summary for four stations within our area, Maiduguri, Potiskum, Yola and Nguru. Fortunately there are some peripheral stations also recording temperature and Klinkenberg et al. (1963) give some figures for Gombe. From the restricted data available the broad trends of the temperature regime are shown on Text Maps 5a, 5b, 6a and 6b. Temperatures tend to be higher to the northeast and lower towards the southwest, with the marked exception of the Benue Valley which, particularly in the period December - March, experiences a higher temperature than the country immediately to the north. Excepting this, the area in general experiences the coolest temperatures in December - January, with monthly means falling to 20.0-22.5°C (68.0° - 72. 5°F). Night temperatures of the order of 8°C(46°F) are recorded during this period and, at high altitude, lower temperatures may be experienced. In the Benue Valley,minimum temperatures rarely fall below 13°C (55°F). Temperatures reach their maximum at the onset of the rains in April -May. In April itself mean maximum temperatures over most of the area are in excess of 39°C (102°F) while mean temperatures are of the order of 31°C (88°F). Maximum day temperatures of around 43°C (110°F) are not uncommon in the north and northeast. During the rains an intermediate regime with "lower and more uniform temperatures occurs. Throughout the area temperatures above the norm for the time of year are experienced in low-lying areas and enclosed valleys. 13
Page 1 and 2: 9 The Land Resources of North East
Page 3 and 4: ' -\* •ï /Ti' -»4, W 'JL "•
Page 5 and 6: THE LAND RESOURCES DIVISION The Lan
Page 7 and 8: LIST OF PLATES Frontispiece. Nomadi
Page 9 and 10: INTRODUCTION TO VOLUMES 1- 5
Page 11 and 12: HISTORY OF THE STUDY PREFACE TO VOL
Page 13 and 14: United States Agency for Internatio
Page 15 and 16: ACKNOWLEDGEMENTS PART 1. INTRODUCTI
Page 17 and 18: GENERAL CIRCULATION CLIMATE by P Tu
Page 19: MANGA PLAINS ' OMatsena ^ *^ / 10°
Page 23 and 24: Potential Evapotranspiration Discus
Page 26 and 27: Omm Oin l-25mm (O-l-lin) 25-50mm (l
Page 28 and 29: P 5-1 O 2- D.O.S. 3099 A Distributi
Page 31 and 32: 20 l°-22-5°C (68 l°-72-5°F) 22-
Page 33 and 34: D.O.S.(L.R.)3064M Copyright reserve
Page 35 and 36: MONTHLY ANALYSIS OF WIND DIRECTION
Page 37 and 38: Mean daily hours of bright sunshine
Page 39 and 40: mm in 300 12 -l Moist Period * Humi
Page 41 and 42: PHYSIOGRAPHY by M G Bawden The rang
Page 43 and 44: the more gentle Plateau slopes. In
Page 45 and 46: 10° ^rr: Outside project area /,/
Page 47 and 48: and the Gongola. They do not howeve
Page 49 and 50: en to DOS. 3099 F Geological Sectio
Page 51 and 52: spm,^ PLATE 1/1 Song. View from bas
Page 53 and 54: Group IV. Tertiary to Recent Volcan
Page 55 and 56: Type 17. Ancient alluvium (Chad) In
Page 57 and 58: GEOMORPHOLOGY by M G Bawden Over mo
Page 59 and 60: In some areas the Plateau is bounde
Page 61 and 62: apart. They have an asymmetrical cr
Page 63 and 64: Pediments are formed on Basement Co
Page 65 and 66: The characteristics of the sands fo
Page 67 and 68: 70 CO JS 5 o tl •o -t> co 0) * e
Page 69 and 70: TABLE 3 Mean monthly and mean annua
Page 71 and 72:
10° l4 'IT- 12° ,\ Mv / MILES 0 i
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The Yedseram and the Ngadda flow no
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Groundwater occurs in these igneous
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assess the recharge potential more
Page 79 and 80:
10" NgUTl D.O.S.(L.R.)3064Y Copyrig
Page 81 and 82:
Figure 7 Generalised soil pattern 0
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of clay becomes very small. In the
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Soils. Local alluvium is found thro
Page 87 and 88:
Two major groups of Ferruginous Tro
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capacity is below 30 meq. These soi
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Category (Map 3) Wd E Fn PI Fp Pc F
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degrees. In the Doksa Plain (Land S
Page 95 and 96:
Mapping Units Mapping Units Mapping
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30 meq per cent soil. Where limesto
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Soil unit (see footnote) 1 2 3 4 Cl
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This kind of soil is dominant throu
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Mapping Units Mapping Units EWe Map
Page 105 and 106:
The soils of the Bama and Ngelewa R
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The clay content of the soils is ne
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Soil patterns on sandy facies of Ch
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Most of the alluvial areas are repr
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American system and the Luvisols of
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^Ä~--«dß Ä'i;'?£^!&JE2 ^Js-j£
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direct impedence to root growth by
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Edaphic Factors LITHOSOLS DEEP, FRE
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The Species List * The species list
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1 APRORMOSIA/DETARIUM WOODLAND/TREE
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4 TERMINALIA spp./COMBRETUM spp. SH
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6 ACACIA HOCKII TREE AND SHRUB SAVA
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9 ANOGEISSUS/DETARIUM SAVANNA WOODL
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12 COMBRETUM spp. SHRUB SAVANNA Phy
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16 ANOGEISSÜS/ACACIA SEYAL SAVANNA
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SPECIES LIST Table 20 Community Num
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19 ANOGEISSUS WOODLAND/TREE SAVANNA
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22 ACACIA SENEGAL/COMBRETUM GLUTINO
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25 ADANSONIA PARKLAND Physiognomy F
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29 ZIZIPHÜS/ACACIA spp. TREE AND S
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33 LEPTADENIA SHRUB SAVANNA Physiog
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37 SOUTHERN ALLUVIAL COMPLEX 37a BO
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38 DEJI VALLEYS COMPLEX The plant c
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FAUNA by P J Aitchison and P E Glov
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available. Cattle, sheep and goats
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TABLE 27 Mammals recorded in the Sa
Page 157 and 158:
TABLE 31 Mammals recorded in the Gu
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POPULATION by P Tuley The distribut
Page 161 and 162:
COMMUNICATIONS by P Tuley The major
Page 163 and 164:
10* ETHNIC GROUPS 12* 14° TEXT MAP
Page 165 and 166:
14" 10" 10° . • * • • + •*
Page 167 and 168:
CHEVALIER M A CHRISTIAN C S and STE
Page 169 and 170:
GROVE A T 1958 The ancient erg of H
Page 171 and 172:
McKEOWN H P J MILLER R E JOHNSTON R
Page 173 and 174:
TOMLINSON P R 1965 Soils of norther
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