Assessment of land degradation east of the Nile Delta, Egypt using remote sensing and GIS techniques

Arab J Geosci (2013) 6:2843–2853 DOI 10.1007/s12517-012-0553-2 ORIGINAL PAPER Assessment of land degradation east of the Nile Delta, Egypt using rem...
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Arab J Geosci (2013) 6:2843–2853 DOI 10.1007/s12517-012-0553-2

ORIGINAL PAPER

Assessment of land degradation east of the Nile Delta, Egypt using remote sensing and GIS techniques E. S. Mohamed & A. Belal & A. Saleh

Received: 25 October 2011 / Accepted: 27 February 2012 / Published online: 23 March 2012 # Saudi Society for Geosciences 2012

Abstract Land degradation is one of the most common issues in the eastern part of the Nile Delta area that threatens the ongoing agricultural activities and prohibits further reclamation expansions. The different degradation types and the associated risk assessment of some soils types of western Suez Canal region during the period from 1997 to 2010 is discussed. The assessment of the different degradation degrees in the investigated area has been carried out through integrating remote sensing, GIS and GLASOD approaches. Results revealed that the salinization, alkalization, soil compaction and water logging are the main types of land degradation in the area. The main causative factors of human induced land degradation types are; over irrigation, human intervention in natural drainage, improper time use of heavy machinery and the absence of conservation measurements. Low and moderately clay flats, gypsifferous flats, have high to very high risk in both salinization sodication and physical degradation. Values such as EC, ESP, and ground water level reach 104.0 dS/m, 176 % and 60 cm, respectively. These results will be of great help and be basic sources for the planners and decision makers in sustainable planning. The spatial land degradation model was developed based on integration between remote sensing data, geographic information system, soil characteristics and DEM. Keywords Nile Delta . Spatial land degradation model . Remote sensing . GIS . Soil map . Degradation risk

E. S. Mohamed (*) : A. Belal : A. Saleh National Authority for Remote Sensing and Space Sciences, 23 Joseph Tito Street, El-Nozha El-Gedida, Alf Maskan, PO Box 1564, Cairo, Egypt e-mail: [email protected]

Introduction With increasing demand for self-sufficiency of some agriculture products, the Egyptian government is working hardly towards reclaiming areas close to fresh water resources (e.g., East Nile Delta, North Sinai, etc.) that have potential crop yield rates. Land degradation in such areas hinders the governments' plans for agriculture expansion as well as contributes to the loss of production capacity (Varallyay 1987) of the ongoing agricultural activities. Better understanding of land degradation in terms of the processes causing the land to degrade and methods to reclaim such lands are important to minimize the areas affected and the number of people who might suffer the consequences. The main types of land degradation in the Nile Delta region are: salinity, sodicity, compaction, water logging, wind and water erosion (El Gabaly 1972; Gad and Abel Samei 2000; El Baroudy 2005). Soil degradation is a process that describes human-induced phenomena which lower the current and/or future capacity of the soil to support human life (Oldeman et al. 1991).Warren and Agnew (1988) showed that land degradation is the loss of resilience of land to climatic and land use change. Lal and Stewart (1990) reported that land degradation is the decline in soil quality caused through its misuse by human. According to USDA (2010), the soil temperature regime of the area could be defined as thermic and the soil moisture regime as torric, except for the soil that have high water table where the soil moisture regime could be considered as aquic. Coastal plains and Eolian plains are the main landscape of the investigated area. Clay flats, gypsiyferous flats, sand plain, sand sheet and basins are the main geomorphic units of the study area (Fig. 2) (Mohamed 2006). Conco (1987) revealed that the geological units of the investigated

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area are briefed into: Quaternary deposits of Nile silt, sabkha deposit, sand dunes, stabilized dunes and wadi deposits. The purpose of this study is to monitor the land degradation process through a duration of 13 years (from 1997 to 2010) in the Northeast Nile Delta using remote sensing and GIS techniques to evaluate the degradation risk in the different soil units of the area.

Materials and methods The study area is located to the northeastern part of the Nile Delta, south of EI-Salam canal and extends towards the northern edge of Ismailia Governorate. It is bounded by longitudes 32° 04′ 32″–32° 20′ 02″ E and latitudes 30° 45′ 00″–31° 20′ 00″ N (Fig. 1) with a total area of about 66,000 ha. According to the Egyptian Meteorological Authority (1996), the area receives a total annual rainfall of about 33.3 mm at Ismailia with the precipitation not equally distributed throughout the rainy season. The average annual mean temperature is 21.77 °C with a wide difference between summer and winter months. The study area is covered by one ETM + scene, Path/ Row 176/39. ENVI Software version 4.7 is used to elaborate preprocessing, processing, Normalized Difference Vegetation Index (NDVI) and classification of a satellite image dated 9-

Fig. 1 Location of the study area

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2010. Digital elevation model (DEM) of the study area has been generated from the elevation points (recorded during the field survey by GPS), about 64,000 points from Google Earth, and the vector contour lines using the ArcGIS 9.2 software. The field work is planned in five transects crossing the different geomorphic map units illustrated in Fig. 2. Morphological description of 23 soil profiles representing the different geomorphic units were carried out according to the field book for description and sampling soils of the USDA (2002). The laboratory analyses were carried out using the soil survey laboratory methods manual of the USDA (2004).The soil types are classified to the sub-great group level on the basis of the key to soil taxonomy of the USDA (2010). Based on the comparison between the data extracted from El NAhry (1997) and the current study, the degradation rate was assessed. The FAO (1979) methodology for assessing soil degradation is used, and the results are evaluated and confirmed with the geomorphic units. A spatial land degradation model is designed using spatial analysis tools to assess land degradation status. Severity level and causative factors were defined and described using the GLASOD approach (Oldeman et al. 1991).

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Fig. 2 Geomorphology of the study area

Results and discussion

of both the sea and the Nile River. It includes the following soil units:

Soils of the study area The soils of the study area include soil of the coastal and Aeolian plains. The classification of such soil types has been carried out through the American soil taxonomy of 2010 (Fig. 3). Soils of coastal plain The coastal plain which occupies the northern part of the study area is low lying, and it is affected by the interaction

Soils of clay flats This type of soils is represented by soil profiles 1, 2, 5, 7, 8, 10, 15 and 17 and is classified as Typic Haplosalids, Typic Aqusalids and Vertic Argigypsids. These soils are characterized by shallow to deep soil profiles fluctuating between 75 and 150 cm. The soil salinity values reveal that the electric conductivity (ECe) ranges from 3.6 to 60.8 dS/m. The exchangeable sodium percent ranges from 37 to 47 % with low to high CaCO3 content (0.9–25.3 %).The organic matter content ranges from 0.03 to 1.56 %.

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Fig. 3 Soil map of the study area

Soils of gysiferous flats This type of soil is represented by soil profiles 21 and 22 and is classified as Typic Haplogypsids. The soil is characterized by shallow to deep soil profiles (60– 90 cm), low to high salinity (0.3–16.6 dS/m), high exchangeable sodium percent (1.9–23.3 %) and low to high CaCO3 content (0.9–3.7 %) with very low organic matter content. Soils of lake bed This type of soils is represented by soil profiles 3, 9, 11, 12, 13 and 16 and is classified as Typic Haplosalids, Typic Aqusalids and Vertic Argigypsids. The soils of this landscape are characterized by shallow to deep soil profiles (60–130 cm), low to very high salinity (7.8–104.8 dS/m), exchangeable sodium percent (14.71–167.7 %) and low to high

CaCO3 content (0.9–24.4 %). Table 1 shows some chemical and physical analyses of the soil profiles in the study area. Soils of basins This type of soil is represented by soil profiles 4, 6 and 14 and is classified as Vertic Torrifluvents. The soil of this type is characterized by deep soil profiles (100–150 cm), low to slightly salinity (0.8–8.5 dS/m) and exchangeable sodium percent varies between 3.8 and 16.5 % and low to high CaCO3 content (0.5–18.4 %) with organic matter content ranging between 0.05 and 1.19 %. Soils of Aeolian plain Soils of Aeolian plain are represented by soil profiles 18, 19, and 20 and are classified to the sub-

Arab J Geosci (2013) 6:2843–2853 Table 1 Chemical and physical analysis of the soil profiles in the study area during the years 1997 to 2010

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Prof. no.

Mapping unit

EC (dS/M)

ESP (%)

1997

2010

1997

Bulk density (g/cm3)

Ground water depth (cm)

2010

1997

2010

1997

2010

9 10 1 5 17 22 19 21 20 18

LB HCF MCF LCF HGF LGF HSP MSP LSP SS

44.9 13.3 10.1 22 1.10 75 0.9 0.85 3.5 4.1

104 7.05 29 39.9 19.3 9.5 0.4 0.41 1.4 3.7

44.7 14.1 14.2 45 4.1 43.6 2.9 3 6.1 17.2

176.7 19.17 42.13 81.9 42.65 13.59 13.59 2.95 5.17 6.44

1.29 1.23 1.23 1.3 1.65 1.6 1.84 1.83 1.75 1.78

1.34 1.2 1.27 3.33 1.84 1.68 1.85 1.82 1.87 1.75

150 90 110 95 150 20 150 150 150 150

60 120 90 85 150 60 150 90 150 150

6 23 14 4

OB TB HDB LDB

13 17 8.45 30.35

8.17 3.16 0.54 2.4

13.5 24 18 45.9

17.3 17.9 4.6 11.89

1.25 1.8 1.4 1.37

1.29 1.9 1.3 1.24

100 160 100 110

130 150 100 150

great group level as Typic Torripsamments. The soils of this landscape are characterized by deep to very deep soil profiles (80–150 cm), low salinity (0.3–4.2 dS/m), exchangeable sodium percent fluctuate between 3.6 and 10.4 % and low CaCO3 content (0.9–1.8 %) with organic matter content ranging between 0.05 and 1.19 %.

Soil degradation Soil degradation (including degree, rate, causative factors and risk of degradation) was investigated for the different soil classes to assess salinization, alkalization, water logging and compaction in the studied areas. Four degradation

Table 2 Land degradation status in the different mapped units Prof. Map no. unit

Water Wind Salinity (s) Alkalinity (a) Compaction (c) Water logging (w) Degradation status erosion (Er) erosion (Ed) D

C

D

C

D

C

D

C

D

C

D

C

(Type, degree and causative factors)

9 10 1

LB N HCF N MCF N

– – –

N N N

– – –

SV S SV

LS LS LS

SV M SV

LS A A

S N S

A A

M S M

LS LS LS

(Cs 4L,Ca 4L (Pc2A, Pw3L) (Cs 2L, Ca 3 A)(Pw3 L) (Cs 4L,Ca 4 A, (Pc2A, Pw3A)

5 17 22 19 21 20 18 6 23 14 4

LCF HGF MGF HSP MSP LSP SS OB TB HDB LDB

– – – P P P P – – – –

N N N SV SV SV SV N N N N

– – – O O/A O A – – – –

SV SV M N N N N M N N N

LS A LS – – – – A – – –

SV SV S N N N N M M N S

A A A – – – – A A – A

S SV SV SV SV SV SV S SV S S

A A A A A A A A A A A

M M M N M N N S N S N

p LS LS – P – – A – A –

(Cs 4L, Ca 4 A), (Pc2, Pw3P) (Cs 4, Ca 4 A (Pc4 A, Pw3L) (Cs 4L, Ca 2A), (Pc4A, Pw3L) (Er 3 P) (Ed 4 O) (Pc 4 A) (Er 3 P) (Ed 4 O/A) (Pc 4 A Pw3P) (Er 3 P) (Ed 4O), (Pc4 A) (Er 3 P) (Ed 4A) (Pc 4 A) (Cs 3, Ca 3 A), (Pc2A, Pw2 A) (Ca3 A) and (Pc4 A) (Pc2 A, Pw2A) (Ca2 A) and (Pc2A)

N N N M M M M N N N N

D degree of present degradation, C causative factors, N none, S slight, M moderate, SV severe, A agricultural activities which includes improper management, improperly timed use of heavy machinery, improper use of water and absence of conservation measures, O other activities which includes absence of land cover and shortage of water, LS lake or sea seepage, p lack of protection measurements, e.g., concrete blocks, etc., Pc physical degradation / compaction, Pw physical degradation / water logging, Cs chemical degradation / salinization, Ca chemical degradation / alkalinity

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Fig. 4 Land degradation of the study area

degrees are recognized according to FAO 1979: none, slight, moderate and severe (Table 2 and Fig. 4). The soils of lake beds have severe degradation by salinity and alkalinity (as a chemical degradation) due to the high content of soil salinity that reached 104.8 dS/m. The ESP reached to 167.7 %, while compaction and water logging (as a physical degradation) were of slight and moderate degradation respectively. The soils of low clay flats and moderately clay flats have severe degradation of salinity and alkalinity (as a chemical degradation) due to the high content of soil salinity that

reached 60 dS/m. The ESP reached to 47 %. These soils have slight to moderate degradation of compaction and water logging types, respectively. The lake bed, low clay flats and moderately clay flats were of severe degradation due to the salinity of ground water and the seepage from Manzala Lake (El Nahry 1997; El Baroudy 2005). The soils of high clay flats have slight to moderate degradation of salinity and alkalinity types, respectively. These soils have moderate degradation of compaction and water logging types, respectively. Soils of gypsiferous flats

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Table 3 Land degradation rates of the investigated area Map. unit

Salinization

Alkalization

Compaction

Water logging

LB HCF MCF LCF HGF LGF HSP Msp

2 1 2 2 1 1 1 1

2 1 2 2 1 1 1 1

1 1 1 1 1 1 1 1

1 2 1 1 1 3 1 1

LSP SS OV TB HDB LDB

1 1 1 1 1 1

1 1 1 1 1 1

1 1 1 1 1 1

1 1 2 1 1 3

have none to moderate degradation of salinity and none to slight degradation of alkalinity, while it has slight to moderate degradation of compaction and moderate to severe degradation of water logging; the moderate type of compaction may

Fig. 5 Flowchart of the designed land degradation model

be due to improper management and timed use of heavy machinery. The soils of sand sheets and sand plains have severe degradation of water and wind erosion, but in the other units, water erosion and wind erosion were absent. These soils have no degradation of salinity and alkalinity types, respectively; on the other hand, compaction and water logging as a physical degradation in the soils of sand sheets were severe and none; the severe type of compaction may be due to high contents of calcium carbonate and low organic matter content. Soils of basins have none to moderate and moderate to severe degradation of salinity and alkalinity types, respectively. These soils have slight degradation of compaction and water logging types. Degradation rate The rate of land degradation was estimated by comparing the main land characteristics in 1997 and 2010 and degradation rates for each mapping unit shown in Table 1 and Table 3. Results show that the rate of salinization, alkalization, water logging and compaction are slight to moderate due to salinization ranging between 0.5 and 3 dS/m/year, alkalization ranging from 0.5 to 3 % per year and water table ranging from 1 to 3 cm/year .The annual increases of

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Fig. 6 Degradation degree of the study area

EC, ESP and bulk density reaches 1.15 dS/m, 1.04 % and 0.01 gm/cm3, respectively. The annual decrease of water table depth reaches 2.5 cm in the investigated area. The lake beds have a high degradation rate affected by the water table, while a moderate rate by salinity and alkalinity, respectively. Low clay flat and moderately clay flats have a moderate rate in both salinity and alkalinity and water table. Assessments of the degradation degree using spatial modeling techniques The work attempts to give insight in the use of RS and GIS to assess the degradation degrees. Spatial modeling and analysis have been made using Arc GIS 9.2 for identification of

areas that have high degrees of degradation. Some of the necessary components contributing to this operation are: (1) transforming features of electrical conductivity, exchangeable sodium percentage, bulk density and water logging to raster layers, (2) topography (slope and aspect), NDVI soil surface salinity maps with all raster layers been classified and (3) weightages that have been assigned as per the importance of a particular variable contributing to the degradation process. In this case, the highest weightage has been given to salinity, alkalinity and water logging factor and bulk density because these factors played an important role in the degradation process in the studied area. The second highest weightage has been given to NDVI, land use and slope because the large area is characterized with flats.

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The land degradation model revealed four degradation classes (Fig. 5 and Fig. 6), and these classes can be identified as follows: 1. Highly degraded class. This class occupies an area of about 25,425 ha representing 38.5 % of the total area. It is located in lake bed, low and moderately clay flats and gypsiferous flats that are characterized by EC >16 dS/m, ESP >15 %, bulk density >1.5 g/cm3 and ground water less than 100 cm. 2. Moderately degraded class.This class occupies an area of about 2,079 ha representing 3.15 % of the total area. It is located in moderately clay flats and gypsiferous flats that are characterized by EC ranges between 8 and 16 dS/m, ESP ranges between 10 and 15 % and ground water less than 100 cm. 3. Slightly degraded class. This class occupies an area of about 6,760 ha representing 10.25 % of the total area. It is located in high clay flats and decantation basin and some area in sand plain. 4. None degraded class. This class occupies an area of about 28,243 ha representing 42.7 % of the total area. It is located in overflow basin, sand sheets and sand plain that are characterized by very low salinity and alkalinity and very deep ground water.

Degradation risk and hazard assessment Soil, topographic and climatic factors are assigned for defining the natural vulnerability of salinization, sodication and physical degradation. The data of landscape, soils (i.e., soil depth, texture, EC and ESP) and the calculated climatic indices were used in calculating both soil and climatic rating factors for the determination of salinization, sodication and physical degradation risks, (Table 4 and Fig. 7). Field data indicate that the slope gradient in the study area ranges between 0.65 and 2.7 %, which has a slight effect on natural vulnerability. Thus, the topographic effect on the natural vulnerability was considered as 1.0 in different landforms. The climatic factor is calculated using four different formulas adapted to different degradation processes. Evapotranspiration and precipitation rates are included in these formulas. The obtained data reveal that low gypsiferous flats are characterized by very high risk in salinity, sodicity and physical degradation, while high gypsiferous flats are characterized by high degradation risk with salinization, sodication and physical degradation. Sand sheets have very high risk with physical degradation. Low clay flats are characterized by high risk with salinization and sodication while having moderate risk with physical degradation. Moderately clay flats have high risk with sodication and physical degradation while having moderate

Table 4 Salinization, sodication and physical degradation risks in the studied area Prof. no.

9 10 1 5 17 22 19 21 20 18 6 23 14 4

Mapping unit

LB HCF MCF LCF HGF LGF HSP MSP LSP SS OB TB HDB LDB

Salinizationa

Sodicationb

Physical degradationc

SR

CR

Risk

Class

SR

CR

Risk

Class

SR

CR

Risk

Class

3 1.5 2.5 1.5 1.5 3 0.1 2.5 0.1 0.1 1.3 0.1 0.7 1.5

0.35 0.02 0.55 1.39 1.41 0.05 0.04 0.01 0.07 0.03 0.04 0.04 0.01 0.03

1.04 0.04 1.39 2.1 2.12 0.14 0.00 0.01 0.01 0.00 0.05 0.00 0.01 0.04

2 1 2 3 3 4 1 1 1 1 1 1 1 1

3 1.5 2.5 1.5 1.5 3 0.1 2.5 0.1 0.1 1.3 0.1 0.7 1.5

0.03 0.03 0.9 1.4 1.41 1.41 0.04 0.07 0.07 0.03 0.04 0.04 0.03 0.03

0.09 0.04 2.25 2.1 2.12 4.23 0.00 0.18 0.01 0.00 0.05 0.00 0.02 0.04

1 1 3 3 3 4 1 1 1 1 1 1 1 1

0.53 0.19 0.52 0.3 0.51 1.0 0.13 0.41 0.13 0.55 0.3 0.4 0.3 0.13

5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6

3.0 1.1 2.9 1.7 2.9 5.6 0.7 2.3 0.7 3.1 1.7 2.3 1.7 0.7

3 2 3 2 3 4 1 3 1 4 2 3 2 1

a

Salinization: SR soil texture rating (coarse00.1, medium01 and fine01.5); in the case of shallow profiles, the used soil rating is 1, 2 and 3 for coarse, medium and fine texture, respectively; climatic rating CR0PET / (p + q) * 10 where p0annual precipitation (mm) and q0quantity of irrigation water used (mm). In the case of saline ground water the formula of CR0(PET / 1,000) * ECgw is used where ECgw is the ground water salinity

b

Sodication: the soil ratings used in both deep and shallow profiles are the same as those given for salinization. Climatic rating CR0PET / (p + q) * 10

c

Physical degradation: the soil rating SR0silt/clay ratio, climatic rating CR0∑(Pm)2 / (Pa)

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Fig. 7 Degradation risk in the studied area

risk by salinization. Moderately sand plains and turtle back have high risk by physical degradation. Lake beds have high risk with physical degradation and moderate risk with salinization. High clay flats and overflow basin have moderate risk with physical degradation.

Conclusion Remote sensing and GIS play an important role in elaborating the degradation degree. Soil salinity, alkalinity compaction and water logging are the main factors of degradation in the study area where arid climate and soil properties have

essential impacts on degradation hazards. Lake beds, clay flats and gypsiferous flats are subjected high risk of physical and chemical degradation. GIS is a very helpful tool to store, manipulate and quantitatively evaluate soil degradation. The soil degradation model was developed based on integration between remote sensing data, geographic information system, soil characteristics and DEM. Four land degradation classes have been obtained: high degradation class occupies areas about 38.5 % of the total area. Moderately degraded class occupies an area about 3.15 % of the total area. Slightly degraded class occupies an area of about 10.25 % of the total area and none degraded class occupies an area of about 42.7 % of the total area.

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References Conco Coral Egyptian General Petroleum Authority (1987). Geological map of Egypt, scale 1:50,000 Egyptian Meteorological Authority (1996). Climatic Atlas of Egypt. Published., Arab Republic of Egypt. Ministry of Transport El Baroudy AA (2005) Using remote sensing and GIS techniques for monitoring land degradation in some areas of Nile delta, PhD Thesis, Fac. of Agric., Tanta Univ., Egypt El Gabaly MM (1972) Reclamation and management of salt affected soils. Intern. Symp. on development in the field of salt affected soils, Cairo, Egypt. 40:14–34 El Nahry AH (1997) Using aerial photo techniques for soil mapping in some areas east of the Nile Delta. M.Sc. Thesis, Fac. Agric., Cairo Univ., Egypt FAO (1979) A provisional methodology for soil degradation assessment M-57 ISBN 92-5-100869-8. FAO, Rome, Italy Gad A, Abel Samei AG (2000) Study on desertification of irrigates arable lands in Egypt. (II- Salinization). Egypt J Soil Sci 40 (3):373–384 Lal R, Stewart BA (1990) Advances in soil science, soil degradation. Springer, New York, p 349

2853 Mohamed ES (2006) Optimum landuse planning for some newly reclaimed soils in west of Suez Canal area using remote sensing techniques. MSc. Thesis, Fac. of Agric., Zagazig, Univ., Egypt Oldeman LR, Hakkeling RTA, Sombroek WG (1991) World map of the status of human-induced soil degradation (GLASOD). 3 map sheets and explanatory note. UNEP, Nairobi, and ISRIC, Wageningen, The Netherlands USDA (2002) Field book for describing and sampling soils. National Resources Conservation Service (NRCS), United State Department of Agriculture. September 2002. Version 2 USDA (2004) Soil Survey Laboratory Methods Manual Soil Survey Investigation Report No. 42 Version 4.0 USDA (2010) Keys to soil taxonomy. United State Department of Agriculture, (NRCS), Eleventh Edition Varallyay G (1987) Conclusions on symposium: soil structure in fully mechanized cropping systems. Trans. XIII Congr. of the I.S.S.S., 13–20 August, 1986. Symposia papers. Vol. V, 328–329, Hamburg Warren A, Agnew C (1988) An assessment of desertification and land degradation in arid and semi arid areas. International Institute for Environment and Development paper No. 2, University College, London

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