Contrasting water management techniques in Tunisia: towards sustainable agricultural use     

Jennifer Hill  Wendy Woodland 《The Geographical journal》2003,169(4):342-357

Tunisia is a marginal country hydrologically and it has adopted a number of distinctive methods of water management for agriculture. The central region supports modern dam irrigation, whilst traditional rainwater harvesting is practiced in the south. These contrasting techniques are described and evaluated in terms of sustainability using empirical field data and secondary literature for two study sites. Research focuses primarily on the physical environment, but socio-cultural and economic viability are also examined. Analysis indicates that traditional water management advantageously partitions the continuum dividing hazards and resources through subtle manipulation of the environment. A potentially hazardous environment is rendered secure by resourceful water management based on community action and cumulative knowledge. This practice minimizes community dependency and local economic imbalance. With dam irrigation, carrying capacity is established more forcibly by centralized control in order to place society within world markets. An almost total break from environmental variability is made in the short term, but this can lead to disequilibrium over longer durations. Additionally, the spatial and social distributions of development are uneven. In Tunisia, maintenance of traditional methods can reduce the negative impacts caused by modern programmes and support their positive characteristics. A mix of both methods offers a foundation to sustainable water supply in the new millennium.  相似文献   

Néotectonique affectant les dépôts marins tyrrhéniens du littoral sud-est tunisien : implications pour les variations du niveau marin     

Samir Bouaziz  Younes Jedoui  Éric Barrier  Jacques Angelier 《Comptes Rendus Geoscience》2003,335(2):247-254

Pleistocene marine deposits of so-called Tyrrhenian age in southeastern Tunisia include two lithostratigraphic units of Last Interglacial (marine isotopic substage 5e). The lower unit culminates at about +3 m above the sea level; the upper unit with Strombus bubonius culminates at +5 m. Brittle deformations affected the upper unit. The analysis of fault-slip data sets reveals a post-Tyrrhenian N020°E trending compression, consistent with joint patterns. This event induced limited vertical movements, showing that at the northeastern edge of the Saharan Platform, the coastal area of the southern Tunisia remained relatively stable since at least the Last Interglacial.  相似文献   

Sedimentation, depositional environment and diagenesis of Eocene biosiliceous deposits in Gafsa basin (southern Tunisia)     

Mohsen Henchiri   《Journal of African Earth Sciences》2007,49(4-5):187-200

The sedimentary rocks of the Metlaoui Formation in the Gafsa basin (southern Tunisia), which may be grouped in three units: the basal (Thèlja), middle (Chouabine) and upper unit (Kef Eddour), provide a record of preserved sedimentary, authigenic and biological processes. This paper presents the findings of sedimentological investigations of the biosiliceous deposits of the middle unit. This unit contains either well-preserved (Opal-A) or diagenetically altered (Opal-CT, clinoptilolite, quartz and even clays) diatom frustules. Such diagenetic changes are commonly described in marine and lacustrine biosiliceous deposits. The fossil content of theses diatomaceous layers implies shallow-marine conditions.The opal-rich sediments, and the associated facies record the transgressive transitions associated with high organic productivity, probably enhanced by seasonal input of nutrients, and high sea level stands, and a close association with stratified water column conditions. The formation of bedded diatomaceous sediments is known to require either high organic productivity or anoxic conditions in bottom/intermediate water, and eventually both processes. The initial organic content of the biogenic deposits was impoverished in early stages of sedimentation and diagenesis. A large part of the organic matter could have been destroyed during early diagenetic processes and from further oxidation in outcrops.  相似文献   

Silicification of sulphate evaporites and their carbonate replacements in Eocene marine sediments, Tunisia: two diagenetic trends   总被引：1，自引：0，他引：1  

MOHSEN HENCHIRI  NAJET SLIM-S'HIMI 《Sedimentology》2006,53(5):1135-1159

Samples of chert nodules, diagenetic carbonates and evaporites (gypsum/anhydrite) collected from the gypsiferous limestones of the Kef Eddour Member (Ypressian‐Priabonian) near Metlaoui and Sehib (Tunisia) show selective silicification with great variety in the silicified by‐products. Based on δ¹³C values, which support an organic origin for the carbon, carbonates replaced evaporites microbially through bacterial sulphate reduction. Observations and results suggest two scenarios for chert formation that are related to the rate and timing of diagenetic carbonate replacement of the evaporites (anhydrite/gypsum). In the absence of early diagenetic carbonate phases, silica with δ¹⁸O values from +25 to +28·6‰ [standard mean ocean water (SMOW)] replaced the outer parts of anhydrite nodules at pH < 9. In contrast, pore‐fluid pH values > 9 in the innermost parts of the anhydrite nodules prevented silica precipitation. The record of this chemical barrier is preserved in the microquartz rims and geode features that formed in the inner parts of the nodules after dissolution of the anhydrite nucleus. The microbial diagenetic replacement of evaporites (bacterial sulphate reduction) by carbonates (calcite, aragonite and dolomite) favoured silica replacement of carbonates rather than evaporites. Silica, with δ¹⁸O signature of +21 to +26‰ (SMOW), replaced carbonates on a volume‐for‐volume basis, yielding a more siliceous groundmass, and accounting for 90–95% of the nodules. The relatively higher δ¹⁸O values of quartz replacing anhydrite can be explained by a diagenetic fluid in equilibrium with mixed (meteoric/marine) to marine water. The lower δ¹⁸O values of the quartz that replaced the diagenetic carbonates are ascribed to flushing by meteoric water in a later diagenetic stage. The silica supply for chert formation could be derived from the reworked bio‐siliceous deposits (diatomites) to the west of the basin [vestiges of an opal‐CT precursor undetectable by X‐ray diffraction (XRD) were revealed by δ²⁹Si magic‐angle‐spinning nuclear magnetic resonance investigations], diagenesis of the extraformational and overlying clay‐rich beds (the host limestones are clay‐poor as shown by XRD measurements), and minor volcanogenic and hydrothermal contributions during early diagenetic stages.  相似文献   

Un Pachyerymnoceras arabique dans le Callovien supérieur du Dahar (Sud tunisien), nouvel élément de datation du membre Ghomrassène (formation Tataouine) ; corrélations avec l'Arabie Saoudite et le Moyen-Orient     

Raymond Enay  Khaled El Asmi  Mohamed Soussi  Charles Mangold  Pierre Hantzpergue 《Comptes Rendus Geoscience》2002,334(16):1157

The first ammonite discovered at the base of the Ghomrassène Member of the Tataouine Formation belongs to a species of Pachyerymnoceras from the Latest Callovian (Solidum Zone) of the Arabian province. The underlying Krechem el Miit Member is also dated Late Callovian, with a fauna of Pachyerymnoceras from the Lower Athleta Zone in Algeria. The associated faunas (echinids, brachiopods) are the same, as well as the faunas of the overlying Ksar Haddada Member, which is dated also Late Callovian, referring to the brachiopods faunal succession in Saudi Arabia. Correlations with other areas in Tunisia, Saudi Arabia and Middle East underline the same sedimentary evolution during a second-order transgressive half-cycle. To cite this article: R. Enay et al., C. R. Geoscience 334 (2002) 1157–1167.

Résumé

La première ammonite découverte à la base du membre Ghomrassène de la formation Tataouine est un Pachyerymnoceras de la partie supérieure du Callovien supérieur (Zone à Solidum) de la province arabique. Le membre Krechem el Miit sous-jacent est aussi daté du Callovien supérieur par des Pachyerymnoceras connus dans la partie inférieure de la Zone à Athleta en Algérie. La faune associée (échinides, brachiopodes) est la même que celle du membre Ksar Haddada sus-jacent, daté également du Callovien supérieur par référence à la succession des brachiopodes en Arabie Saoudite. Les corrélations avec les autres régions de Tunisie, l'Arabie Saoudite et le Moyen-Orient mettent en évidence une même évolution sédimentaire au cours d'un demi-cycle transgressif de deuxième ordre. Pour citer cet article : R. Enay et al., C. R. Geoscience 334 (2002) 1157–1167.  相似文献   

A water balance approach for quantifying subsurface exchange fluxes and associated errors in hill reservoirs in semiarid regions          下载免费PDF全文

Maroua Bouteffeha  Cécile Dages  Rachida Bouhlila  Jérôme Molenat 《水文研究》2015,29(7):1861-1872

Hill reservoirs are rain water‐harvesting structures that have been increasingly adopted in arid and semi‐arid regions, such as North Africa, to capture and conserve runoff water and for use as alternative water resources in agricultural development. Currently, process‐based information on reservoir hydrology is needed to improve reservoir management practices. The study aims to develop an approach to estimate the reservoir–subsurface exchange flux and its associated error at the annual, monthly, and intra‐monthly time scales to better understand the hydrological functioning and dynamics of hill reservoirs. This approach is based on a hydrological water balance of the hill reservoir by considering all water input and output fluxes and their associated errors. The results demonstrate the ability and relevance of the approach in estimating the net reservoir–subsurface exchange flux and its error estimations at various time scales. Its application on the Kamech catchment (Northern Tunisia) for the 2009–2012 period demonstrates that the net reservoir–subsurface exchange flux is positive, i.e. the infiltration from the hill reservoir to the aquifer dominates over the discharge from the aquifer to the reservoir. Moreover, reservoir–subsurface exchange constitutes the main output component in the water balance. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Structuring and evolution of Neogene transcurrent basins in the Tellian foreland domain, north-eastern Tunisia     

Fetheddine Melki  Taher Zouaghi  Salah Harrab  Antonio Casas Sainz  Mourad Bdir  Fouad Zargouni 《Journal of Geodynamics》2011,52(1):57-69

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Incorporating elevation in rainfall interpolation in Tunisia using geostatistical methods     

Haifa Feki  Mohamed Slimani  Christophe Cudennec 《水文科学杂志》2013,58(7):1294-1314

Abstract

This paper compares the performance of three geostatistical algorithms, which integrate elevation as an auxiliary variable: kriging with external drift (KED); kriging combined with regression, called regression kriging (RK) or kriging after detrending; and co-kriging (CK). These three methods differ by the way by in which the secondary information is introduced into the prediction procedure. They are applied to improve the prediction of the monthly average rainfall observations measured at 106 climatic stations in Tunisia over an area of 164 150 km² using the elevation as the auxiliary variable. The experimental sample semivariograms, residual semivariograms and cross-variograms are constructed and fitted to estimate the rainfall levels and the estimation variance at the nodes of a square grid of 20 km?×?20 km resolution and to develop corresponding contour maps. Contour diagrams for KED and RK were similar and exhibited a pattern corresponding more closely to local topographic features when (a) the network is sparse and (b) the rainfall–elevation correlation is poor, while CK showed a smooth zonal pattern. Smaller prediction variances are obtained for the RK algorithm. The cross-validation showed that the RMSE obtained for CK gave better results than for KED or RK.

Editor D. Koutsoyiannis; Associate editor C. Onof

Citation Feki, H., Slimani, M., and Cudennec, C., 2012. Incorporating elevation in rainfall interpolation in Tunisia using geostatistical methods. Hydrological Sciences Journal, 57 (7), 1294–1314.  相似文献   

Geochemical constraints on the genesis of the Pb–Zn deposit of Jalta (northern Tunisia): Implications for timing of mineralization,sources of metals and relationship to the Neogene volcanism     

《Chemie der Erde / Geochemistry》2014,74(4):601-613

The occurrence of Pb–Zn deposits of Jalta district (northern Tunisia) as open space fillings and cements and breccia in the contact zones between Triassic dolostones and Miocene conglomerates along or near major faults provides evidence of the relationship between the mineralization and tectonic processes. Pb isotopes in galena from the deposits yielded average ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios of 18.821, 15.676 and 38.837, respectively, implying a well-mixed multi-source upper crustal reservoir of metals. Magmatism and compressional tectonism during the Alpine orogeny favored Pb–Zn mineralization in the Jalta district. The enrichment in Pb, Zn, Cd and Co of the Triassic carbonates and enrichments in Pb, Zn and Cd in Triassic clayey shales is associated with hydrothermal alteration around faults. Alunite in the deposit has δ³⁴S values (−2.5 to −1.5‰ VCDT), which could have been formed at and above the water table in a kind of steam-heated environment, where fluids containing H₂S mixed with fluids containing K and Al. The H₂S could have been produced by TSR of sulfates at high temperature at depth and then leaked upward through deep-seated faults, whereas the K and Al could have been acid-leached from Miocene volcanic rocks.  相似文献   

Middle Triassic (Anisian-Ladinian) Tejra red beds and Late Triassic (Carnian) carbonate sedimentary records of southern Tunisia,Saharan Platform: Biostratigraphy,sedimentology and implication on regional stratigraphic correlations     

《Marine and Petroleum Geology》2017

The “red beds” of the Triassic succession outcropping at Tejra-Medenine (southern Tunisia, Saharan Platform) have yielded rich fossil assemblages of both freshwater and brackish-marine invertebrates and vertebrates. The new discovered fauna indicates an Anisian-Lower Ladinian age for the Tejra section. Its lowermost part is considered as equivalent of Ouled Chebbi Formation, while the medium and upper parts are considered as equivalent of the Kirchaou Formation. Both sedimentological characteristics and fossil assemblages indicate the increasing marine influences within the middle part of the section and the migration of brackish and freshwater fauna into the lacustrine/playa environment at the top. The marine fauna-rich interval of the Tejra section correlates well with the well-known Myophoria-rich carbonate stratigraphic marker confirming the Middle Triassic (Ladinian) major transgression well recorded eastward in the Tunisian Jeffara basin and in Libya. The use of this Ladinian stratigraphic event in addition to the Carnian carbonate transgressive events of the Jeffara escarpment outcrops was of great help for regional lithostratigraphic correlations between the Triassic outcropping series and those currently buried in Ghadames and Berkine basins. The age of the sandstones of “Trias Argilo-Gréseux Inférieur” (TAGI) which forms the main oil and gas reservoir in the Saharan domain is attributed to the Anisian-Carnian and considered as coeval of Ouled Chebbi and Kirchaou Formations of the Dahar escarpment. An updated synthetic stratigraphic chart is proposed for the Triassic of Saharan Platform domain on the basis of the compilation of the new obtained results and the subsurface data taken from published literature.  相似文献