Scientific registration n° : 77 Symposium n° : 15 Presentation : poster
Kuwait Desert Soil Properties And Genesis Genèse et propriétés des sols du désert du Koweit ABDAL M. S., M.K.SULEIMAN
Aridland Agriculture Department Kuwait Institute for Scientific Research P.O.Box 24885, Safat 13109, Kuwait
INTRODUCTION
Kuwait's environment is characterized by scanty and infrequent rainfall (100 mm/yr) high rates of evaporation evaporation (35.5 mm/day mm/day in July), and extreme temperature temperature variations throughout throughout the the year. The summer temperature temperature is very hot (over 40-50oC), while the winter is cool to mild with a mean temperature of 12.7 oC. Kuwait covers an area of 2 o about 17600 km at the north-eastern north-eastern corner of the the Arabian peninsula, peninsula, between 28 30 N and 30o 05 N in latitude and between 46 o 33 E and 48 o 35 longitude in addition to ten offshore islands. In the desert of Kuwait, the sediments, flora, and fauna, are integrated in harmony with the natural processes processes of the area. The most crucial soil forming forming factors existing over the years in this desert have been the aeolian processes. processes. These processes have have been impacted by wind erosion and have been influenced by the topography of the location or site. The nature of the parent parent material and the types types and quantities of native native plants, at each site location have also affected the soil forming processes, and have likewise influenced the extent to which the wind has caused erosion. erosion. Aeolian processes are activated activated or reflected by frequent sandstorms and dust-storms and accumulations of various types of aeolian sediments. Most of the the northern part of the country has has been blanketed blanketed by deflation, to lag gravels gravels that protect the underlying finer sediments sediments from wind action. The western and southern parts of the country have been covered mostly with vegetated sand sheets that have deteriorated significantly, due to excessive uncontrolled human activities (Khalaf et. al., 1984). SURFACE GEOLOGY OF KUWAIT
The land surface of Kuwait is flat and slopes gradually north-eastward with an average gradient of about about 2 m/km. Kuwait's desert can be divided divided into four four physiographic provinces provinces:: Al-Dibdib Al-Dibdibba ba gravelly gravelly plain; plain; southern southern desert flat; coastal coastal flat; and coastal coastal hills (Khalaf et al., 1984). The surface of Kuwait is carved into a clastic deposit sequence, which is locally called the Kuwait Group, and ranges in age from Miocene to recent (Owen & Nasr 1958; Milton 1965; 1965; Fuchs et al., 1968; 1968; Khalaf et al., 1984). 1984). The Kuwaiti desert is covered covered by several types of recent surface surface sediments (Khalaf et al., 1984). 1984). These are: aeolian deposits; residual deposits; playa deposits; desert plain deposits; slope deposits; and coastal deposits. 1
Aeolian sand deposits are the most frequent and cover many parts of the surface of Kuwait. Gypcrete is very abundant in the north where it has developed from gypsum precipitation in the upper horizon of the sand gravel deposits of the Al-Dibdibba formation. Calcrete and silcrete are more dominant in the south where they cap several isolated hills, e.g. Warah, Burgan and several hills in the Al-Wafra area. Fig. 1 is a simplified map of the distribution of the main types of recent surface sediments in Kuwait. SOIL CLASSIFICATION
Four great soil groups have been recognized in Kuwait. These include: desert soil consisting of four units (sandy desert hardpan soils (A1), gypsiferous (A2), gravelly saline (A3), gravelly gypsiferous saline and saline gypsiferous soils (A4); desert regosol lutygrade - sandy desert (B1), and desert dune soils (B2); lithosols - escarpment (C1); and alluvial - hydromorphic saline alluvial soils (D1) and recent alluvial soils (D2) (Al Nakshabandi & El-Mansy, 1984). The first two groups were formed under arid climatic conditions, and therefore, are sandy in texture and contain very low organic matter, and have considerable amount of cemented calcareous subsoil. The third group has a coarser texture, provides better drainage, and lacks the hardpan or cemented calcareous layer. The fourth group is found along the seashore; they are young, saline and gypsiferous. These alluvial soils should not be classified as hydromorphic as Ergun (1969) stated, because they are affected by tidal action and do not have a well developed profile. Also, they cannot be classified as solonchak, as suggested by Halwagy and Halwagy (1974), because solonchak and hydromorphic belong to the intrazonal order of soils, which have well developed profile (Foth and Tork, 1972). They can, however, be classified as saline alluvial deposits, belonging to the azonal order. Soil depth, drainability, consistency of substrata, and salinity, of the four great soil groups, are all shown in Table 1. More soil series were recognized by SCET - Cooperation in a survey conducted in 1970. Khalaf et al. (1984) recognized the following deposits on recent soil deposits of Kuwait: 1. Aeolian; (a) sand sheets, (b) sand dune, (c) sand drifts and (d) Aeolian Wadi Fill. 2. Residual; (a) residual gravels and (b) duricrust. 3. Playa. 4. Desert plain. 5. Alluvial fans and slope. 6. Coastal dunes; (a) coastal plain, (b) coastal dunes, (c) sabkha and (d) beach and tidal flat. SOIL CHARACTERISTICS
A hardpan calcareous layer (locally called gatch) is found throughout the Kuwaiti desert at various depths. It is a consolidated calcareous sandy matrix with high silica content, which is slightly gypsiferous. In a study of soil and gatches in Kuwait desert, Yamane (1970) found that all gatches were slightly alkaline. The major primary minerals 2
were sodic plagioclase and orthoclase, with major clay minerals of montmorillonite and vermiculite. Chemical composition, grain size distribution, and the mineralogical constituents of gatches are given by Yamane (1970). Such layers can restrict plant root penetration and deep water percolation when they are strongly consolidated, which therefore leads to the formation of local shallow water tables. The infiltration rate of Kuwait desert soil is generally high and therefore classified as excessive, it ranges from 15-100 cm/hr.(Riley and Abdal, 1989). Permeability co-efficient or hydraulic conductivity studies for the upper 50 cm was measured to average to 1.56 meter per day (Al-Nakshabandi et al., 1983). Because of the extreme climatic soil limitations, low rainfall, sandy texture of the soil, wind erosion and the problem of hardpan, the productivity of Kuwait soil is potentially low (Ergun 1969; SCET-Cooperation 1970; Ueda and Ueda 1968). With the exception of the alluvial soil, most virgin soils in Kuwait are unaffected by salinity. The irrigation of crops on shallow gatch cultivated areas often hinders the percolation of gravitational water and, with time the level of salinity increases to an alarming levels, restricting plant growth (Abdal and Al-Ajmi, 1991 and Razzaque and Abdal, 1991).
REFERENCES
Abdal, M., and D. Al-Ajmi. 1991. Demography and Geography of Kuwait. Kuwait Oil Fire Symposium. Harvard University, August 8, 1991. Abdal, M., and D. Kater. 1993. Preparation of Medium and Long-Term Master Plan for Greenery Development and Environmental Enhancement. SPP-8, KISR. Al-Nakshabandi, G. A., M. Sartawi, and S. Al-Kudsi. 1983. Efficient Use of Irrigation Water for Cash Crops Production Under a Protected Soil Surface in Kuwait. Kuwait Institute for Scientific Research, Report No. KISR 904. Kuwait. Al-Nakshabandi, G. A., and H. El-Mansy. 1987. A Review of Soil Survey Work in Kuwait. Technical Report. KISR. Kuwait. Ergun, H. N. 1969. Reconnaissance Soil Survey. Report to the Government of Kuwait. FAO/KU/TF 17. Foth, H. D., and L. M. Turk. 1972. Fundamentals of Soil Science, 5th ed. New York: John Wiley and Sons, Inc. Fuchs, F., T. E. Gatinger, and H. F. Holzer. 1968. Explanatory Text to the Synoptic Geologic Map of Kuwait. Geological Survey of Austria, Vienna. pp.1-87. Halwagy, R., and L. M. Halwagy. 1974. Ecological Studies on the Desert of Kuwait. In: The Physical Environment Journal, University of Kuwait (Science) 1:75-85. Khalaf, F. I., I. M. Gharib and M. Z. Al-Hashash. 1984. Types and Characteristics of the Recent Surface Deposits of Kuwait, Arabian Gulf. Journal of Arid Environments 7:9-33. Khalaf, F.I. 1989. Desertification and Aeolian Processes in the Kuwait Desert. Journal of Arid Environments, 16:125-145. Khalaf, F.I. 1990. Occurrence of Phreatic Dolocrete Within Tertiary Clastic Deposits of Kuwait, Arabian Gulf. Sediment Geol., 68:223-239. Milton, D. I. 1965. Geology of the Arabian Peninsula, Kuwait. U. S. Geological Survey, professional paper, 560-F.7 pp. 3
Owen, R. M., and S. N. Nasr. 1958. Stratisgraphy of the Kuwaiti Basra Area. In: Habitats of Oil, A Symposium. American Association of Petroleum Geologists, pp.1252-1278. Societe Centrale pour I'Equipment du Territoire Cooperation. 1970. Soil Survey and Classification of Kuwait. Report submitted to the Ministry of Public Works. Government of Kuwait. Ueda, H., and T. Ueda. 1968. The Preliminary Study on Agriculture in Kuwait. A report, Arid Zone Agriculture Division, Kuwait Institute for Scientific Research, Kuwait. Yamane, I. 1970. Studies on Soils and Gatches of the Desert in Kuwait. Kuwait Institute for Scientific Research, Report No. KISR 03, Kuwait. Kuwait. U. S. Geological Survey, professional paper, 560-F.7 pp. Owen, R. M., and S. N. Nasr. 1958. Stratisgraphy of the Kuwaiti Basra Area. In: Habitats of Oil, A Symposium. American Association of Petroleum Geologists, pp.1252-1278. Societe Centrale pour I'Equipment du Territoire Cooperation. 1970. Soil Survey and Classification of Kuwait. Report submitted to the Ministry of Public Works. Government of Kuwait. Ueda, H., and T. Ueda. 1968. The Preliminary Study on Agriculture in Kuwait. A report, Arid Zone Agriculture Division, Kuwait Institute for Scientific Research, Kuwait. Yamane, I. 1970. Studies on Soils and Gatches of the Desert in Kuwait. Kuwait Institute for Scientific Research, Report No. KISR 03, Kuwait.
Table 1: Depth, Drainage, Consistency of the Substrata, and Degree of Salinity of the Four Great Soil Groups in Kuwait Soil Group
Depth
Drainage
Consistency of Salinity Substrata Desert Very shallow Moderately well Moderately hard Non-affected to deep to imperfect to very hard Desert regosol Deep Somewhat Soft to slightly Non-affected integrade excessive to well hard Lithosol Very shallow Excessive Excessively hard Non-affected to shallow to very hard Alluvial Deep to Imperfect to poor Slightly hard to Moderately shallow very hard strongly affected Keyword : Calcretized, fluvial, aeolian, regosol, alluvial, sheet wash. Mots clés : calcarisé, fluvial, eolien, regosol, alluvial
4
