Depression Floor Research Articles

Laterite as a Potential Seepage Barrier From a Karst-Depression Tailings Impoundment

AbstractIn the absence of the necessary valley topography, karst depressions are sometimes used to construct conventional impoundments in order to contain tailings. Leakage is a primary concern for such impoundments. The purpose of the current study was to determine the characteristics and barrier performance of laterite mantling karst depressions, using, as an example, the Wujiwatang (WJWT) tailings impoundment, located in the Gejiu mining area, southwestern China. The geotechnical-hydrogeological properties, geochemistry, mineral compositions, and particle shapes of the laterite were investigated by geotechnical techniques, chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results showed that the laterite contained poorly sorted particles that covered a wide spectrum of grain sizes (<5 mm to <50 nm), and was unexpectedly categorized as silty clay or silt with a high liquid limit. The continuous gradation and small D90 value helped the laterite achieve saturated hydraulic conductivities in the range of <10–6 cm/s required for impoundment liners. The laterite beneath the tailings impoundment was finer-grained and had a lower permeability than that of the laterite on the depression walls within the same depression. Geochemically and mineralogically, the laterite was classified as true laterite and its major mineralogical constituents were gibbsite and goethite with chlorite occurring in trace amounts. The laterite was dominated by subspherolitic–spherolitic cohesionless grains (concretions) made up of Al, Fe, Ti, and Mn oxides and hydroxides. The laterite did not have plasticity indices in the clay range. Fortunately, slopewash prior to tailings containment selectively transported the finer oxide concretions to the depression floor, creating a natural low-permeability barrier for the WJWT tailings impoundment. This is undoubtedly important for the planning and design of future karst depression-type tailings impoundments around the world.

Land Evaluation of some Soils for El- Farafra Oasis, New Valley Governorate, Egypt تقییم بعض أراضی واحة الفرافرة بمحافظة الوادى الجدید - مصر

This work aims to identify the main physiographic units and their soil taxonomic ones as well as land evaluation for some promising areas of El- Farafra Oasis. The main materials and methods were Sentinel 2 image (2019), visual interpretation and digital elevation model (DEM) were used to produce physiographic soil map. The physiographic point of view, the landscapes include two units, i.e. plateau and depression floor. Eighteen profiles and seventy-two augers were dug to check the main physiographic mapping units in the studied area. Soil samples have been collected from the representative soil profiles for physical and chemical analysis. The main results pointed out that the El-Farafra oasis were classified into four capability classes, i.e. S2, S3, N1 and N2. The soils of S2 have moderate limitations for agricultural crops, whereas texture is the main limiting factor (18.55). The main limiting factors of soils of S3 are texture, soil depth and salinity (41.22 %). The soils of N1 (11.46 %), also the permanent not suitable of N2 (21.06 %) include rocky areas and very shallow soils. The cultivated area is about 7.7% of the total aforementioned area. The suitability for cultivation four main crops namely wheat, barley, sorghum and olive in the studied area are assessed. Olive was the most suitable to cultivation in these soils.

LAND AND WATER RESOURCES ASSESSMENT FOR SUSTAINABLE AGRICULTURAL DEVELOPMENT IN EL-KHARGA OASES BY USING REMOTE SENSING AND GEOGRAPHIC INFORMATION SYSTEM

El-Kharga Oases, New Valley governorate, Egypt was selected as a study area. It is located between latitudes 25o15ʽ and 26o05 ʽN. and longitudes 30o05 ʽ and 30o45 ʽE., having an area of 18813.8 km2. The aim of this investigation is to study the characteristics of soils and groundwater in this area for evaluating their capability and suitability for growing main crops using RS and GIS. The obtained geomorphic map showed that, the area comprises three distinct geomorphic units namely, high land (28.8%), plateau (39.3%) and depression floor (31.9%). The depression floor of various origin and almost flat areas is the main landforms and suitable units for developmental plans. The soils were classified up to sub great group level on the basis of Soil Survey Staff (2014). Land evaluation was conducted using a model depend on the bases of Sys & Verheye index and land suitability for irrigated agriculture. Accordingly, the current capability of the studied soils was classified as: fair (III) for about 45% from the studied area, poor IV (about 50%) and very poor N for the remaining area. By executing a suitable improvement practices, these classes could be developed to the following three potential capability classes; good (II), fair (III) and poor (IV). Also, soil suitability for growing specific field, vegetable and fruit crops were evaluated in the studied geomorphic units. The quality evaluation of ground water resources showed that, the pH values ranged from ultra-acid (3.47 north El-Kharga) to slightly alkaline (7.83 in Max Qibly). The salinity of ground water changed from 0.48 to 119 dS m-1 indicating non-saline to very extremely saline, TDS values varied from 307.2 to 71424 ppm (fresh, brackish, to extremely saline water). Total hardness varied from soft to very hard.

GEOMORPHOLOGY, CHARACTERISTICS AND MINERALOGY OF SOME SOILS IN EL-FARAFRA OASIS, NEW VALLEY GOVERNORATE, EGYPT

The studied area belongs to El-Farafra Oasis, New Valley Governorate. It is representing an area of about 372062 feddans. The aim of this work was to study the geomorphology, characteristics and mineralogy of some soils in El-Farafra Oasis, New Valley governorate, Egypt. Visual interpretation of 2 sentinel images and digital elevation model (DEM) were used to produce the geomorphic units and soil maps of the studied area. Two geomorphic units were identified namely plateau and depression floor. Eighty-two minipits and eighteen soil profiles were chosen to represent the main soil mapping units in the studied area. Soil samples were collected from the representative soil profiles for physical, chemical and mineralogical analysis. The results could be summarized as follows: X-ray diffraction analysis indicated that kaolinite is alternatively dominated in the studied soils (about 80 %) followed by smectite. Illite, interstratified minerals and chlorite are found as the lowest abundant clay minerals in these soils. The mineralogical composition of the sand fraction indicated that, the light fraction is composed almost entirely of quartz which constitutes about 95%. Feldspar minerals (orthoclase plagioclase and microcline) are detected in trace amounts. The presence of feldspars indicates that, the soils are young from the pedological point of views. Heavy minerals are generally dominated by opaque’s (about 55 %). Non-opaques are mainly dominated by pyroboles (pyroxenes + amphipoles) followed by ultra-stable minerals (zircon, rutile and tourmaline), Para metamorphic minerals (garnet, kyanite, staurolite, silimanite) and epidote. While the other minerals (biotite andalusite, glaucohite and apatite) are detected in less pronounced amounts. Distribution of the resistant minerals (biotite and amphipoles) weathering ratio, values indicate that, the soils are generally heterogeneous either due to their multi-origin or due to a subsequent variation along the course formation.

A Pedological Study on some Soils of Farafra Oasis, Egypt

Farafra Oasis is a natural depression which located in the Egypt western desert. The whole area is under hot arid circumstance. There, the lands conferred indications of promising agricultural expansion. Study of the landforms and soils related with them can give a general survey of soil attributes. The investigated landforms include; depression floor (Peni plain- Chalky plain-Sand sheets- Playa).Eight soil profiles were selected to represent the identified physiographic units according to the information obtained during the reconnaissance field survey and the pre-field interpretation. A total of 14 soil samples, representing the different soil horizons of the selected profiles were collected, air-dried, crushed to pass through a 2 mm sieve, and stored for physical and chemical analyses. The soils were classified as following : ((Calcisalids – Gypsisalids – Haplogypsids - Haplosalids – Calcigypsisalids - Quartzipsamment - Torryluvants – Torriorthents - Aquisalids- Gypsiargids -Torripsamment((. Gypsum and calcium accumulations were found in salinity condition in most of the investigated soil samples. The drainage problem and the groundwater presence are common in most of the depression. The challenge is to be knowing of the problems and to design a suitable management system of water and soil.

The role of pre-existing tectonic structures and magma chamber shape on the geometry of resurgent blocks: Analogue models

A set of analogue models has been carried out to understand the role of an asymmetric magma chamber on the resurgence-related deformation of a previously deformed crustal sector. The results are then compared with those of similar experiments, previously performed using a symmetric magma chamber. Two lines of experiments were performed to simulate resurgence in an area with a simple graben-like structure and resurgence in a caldera that collapsed within the previously generated graben-like structure. On the basis of commonly accepted scaling laws, we used dry-quartz sand to simulate the brittle behaviour of the crust and Newtonian silicone to simulate the ductile behaviour of the intruding magma. An asymmetric shape of the magma chamber was simulated by moulding the upper surface of the silicone. The resulting empty space was then filled with sand. The results of the asymmetric-resurgence experiments are similar to those obtained with symmetrically shaped silicone. In the sample with a simple graben-like structure, resurgence occurs through the formation of a discrete number of differentially displaced blocks. The most uplifted portion of the deformed depression floor is affected by newly formed, high-angle, inward-dipping reverse ring-faults. The least uplifted portion of the caldera is affected by normal faults with similar orientation, either newly formed or resulting from reactivation of the pre-existing graben faults. This asymmetric block resurgence is also observed in experiments performed with a previous caldera collapse. In this case, the caldera-collapse-related reverse ring-fault is completely erased along the shortened side, and enhances the effect of the extensional faults on the opposite side, so facilitating the intrusion of the silicone. The most uplifted sector, due to an asymmetrically shaped intrusion, is always in correspondence of the thickest overburden. These results suggest that the stress field induced by resurgence is likely dictated by the geometry of the intruding magma body, and the related deformation is partially controlled by pre-existing tectonic and/or volcano-tectonic structures.

SOIL CLASSIFICATION OF BAHARIYA OASIS USING REMOTE SENSING AND GIS TECHNIQUES

Bahariya Oasis is one of the most geologically important areas in the WesternDesert. It is also a promising location for agriculture expansion projects due to the plenty and good quality of ground water for agricultural activities. The objective of this work was to develop a soil classification map of this area using remote sensing and GIS techniques. Spot image, acquired in 2011 and digital elevation model (DEM) were used to develop physiographic units. Three main physiographic units were identified in the oasis, which are plains, depression floor with low, moderately high and high lands and pediment. Thirty one soil profiles were dug throughout the oasis to represent soil physiographic units. These profiles were described, and sampled. Soil samples were analyzed for the physical and chemical characteristics. Soils in the studied area were classified under 11 soil map units (SMUs), which are: 1. Sandy, siliceous, calcareous, thermic, Lithic Calcigypsids, 2. Sandy, siliceous, thermic, Lithic Haplogypsids, 3. Sandy, siliceous, thermic, Typic Haplogypsids, 4. Sandy, siliceous, thermic, Typic Aquisalids, 5. Sandy, siliceous, thermic, Typic Haplosalids, 6. Loamy, mixed, active, thermic, Typic Gypsiargids, 7. Sandy, siliceous, thermic, Typic Quartzipsamments, 8. Sandy, siliceous, thermic, Lithic Torripsamments, 9. Sandy, siliceous, thermic, Typic Torripsamments, 10. Loamy, mixed, super active, thermic, Typic Torrifluvents, and 11. Sandy skeletal, siliceous, thermic, Typic Torriorthents. Calcium, gypsum, and salt accumulations were found in most of the studied soils. Few accumulations of silicate clays were also observed in certain areas of the depression.

Assessment of optimum land use and water requirements for agricultural purpose in some soils South Paris Oasis, Western Desert, Egypt

The current work is aimed to realizing land suitability and water use efficiency and determining the optimum land use system. The main aims were to identify the physiographic futures and calculate the crop water requirements for specific crops. The study area was observed through a soil survey inventory in Paris Oasis, Western Desert, Egypt. Ten soil profiles plus a number of auger observations and mini pits were selected to represent the different mapping units. A fieldwork and morphological description were carried out, and soil samples were collected for demonstrating the physical and chemical soil properties. Based on satellite data that can integrate with GIS utility, field work, and laboratory analysis, the physiographic map was generated. The study found that the main land type units are plateaus, hills, dunes, and depression floor. Concerning the second aim, the main land qualities of different mapping units were rated and matched to obtain the current and potential land suitability using automated land evaluation system. This research concluded that the best crops adapted with the soil conditions and could be feasible for economic use are clover, wheat, beans, sugar beet, onions, maize, sunflower, tomato, potato, groundnut, pea, lentil, barley, sesame, and carrots. Crop water requirements were determined in variable rate according to the actual plant requirements using the aid of FAO–Cropwat model. Irrigation schedule and consumptive use of suitable crops were calculated and adopted. The crop water requirements for each selected crop were determined as follow: 828.0, 596.7, 410.3, 679.95, 409.52, 791.60, 712.2, 902.93, 456.55, 529.95, 231.4, 217.95, 303.93, 502.65, and 274.35 mm, respectively.

Assessing crop water requirements on the bases of land suitability of the soils South El Farafra Oasis, Western Desert, Egypt

The aims of this study are: (1) producing a geometrically corrected physiographic soil map scale 1:50,000 reduced to the attached map; (2) crop water requirements calculation for the suitable crops in this area. To fulfill the first aim, ten soil profiles were selected to represent the different mapping units. Morphological description was carried out and soil samples were collected for physical and chemical analysis. Based on the Enhanced Thematic Mapper Plus images and the geographic information system, coupled with the field work and laboratory analysis data, the physiographic soil map was produced. Satellite images interpretation indicated that the investigated area includes the main physiographic units are plateaus, hilland, mountain, and depression floor. With respect to the second aim, the main land qualities of the different mapping units and the crop requirement were rated and matched to obtain the current and potential land suitability using Automated Land Evaluation system. The most suitable crops for the studied area were: clover, wheat, beans, sugar beet, onions, maize, sunflower, tomato, potato, groundnut, pea, lentil, barley, sesame, and carrots. The crop water requirements for the selective crops were calculated using CROPWAT 8.0 for Windows program as: 781.80, 571.70, 383.20, 641.55, 395.45, 771.80, 693.90, 880.32, 432.00, 510.30, 205.05, 201.30, 284.20, 487.95, and 254.85 mm, respectively.

Geomorphological significance of Ontario Lacus on Titan: Integrated interpretation of Cassini VIMS, ISS and RADAR data and comparison with the Etosha Pan (Namibia)

Ontario Lacus is the largest lake of the whole southern hemisphere of Titan, Saturn’s major moon. It has been imaged twice by each of the Cassini imaging systems (Imaging Science Subsystem (ISS) in 2004 and 2005, Visual and Infrared Mapping Spectrometer (VIMS) in 2007 and 2009 and RADAR in 2009 and 2010). We compile a geomorphological map and derive a “hydrogeological” interpretation of Ontario Lacus, based on a joint analysis of ISS, VIMS and RADAR SAR datasets, along with the T49 altimetric profile acquired in December 2008. The morphologies observed on Ontario Lacus are compared to landforms of a semi-arid terrestrial analog, which resembles Titan’s lakes: the Etosha Pan, located in the Owambo Basin (Namibia). The Etosha Pan is a flat-floored depression formed by dissolution, under semi-arid conditions, of a surface evaporitic layer (calcretes) controlled by groundwater vertical motions. We infer that Ontario Lacus is an extremely flat and shallow depression lying in an alluvial plain surrounded by small mountain ranges under climatic conditions similar to those of terrestrial semi-arid regions. Channels are seen in the southern part of Ontario Lacus in VIMS and RADAR data, acquired at a 2-years time interval. Their constancy in location with time implies that the southern portion of the depression is probably not fully covered by a liquid layer at the time of the observations, and that they most probably run on the floor of the depression. A shallow layer of surface liquids, corresponding to the darkest portions of the RADAR images, would thus cover about 53% of the surface area of the depression, of which almost 70% is located in its northern part. These liquid-covered parts of the depression, where liquid ethane was previously identified, are interpreted as topographic lows where the “alkanofer” raises above the depression floor. The rest of the depression, and mostly its southern part, is interpreted as a flat and smooth exposed floor, likely composed of a thick and liquid-saturated coating of photon-absorbing materials in the infrared. This hypothesis could explain its dark appearance both in the infrared and radar data and the persistence of channels seen on the depression floor over the time. Shorelines are observed on the border of Ontario Lacus suggesting past high-stand levels of the alkanofer table. The analogy with the Etosha Pan suggests that Ontario Lacus’ depression developed at the expense of a soluble layer covering the region. Dissolution of this layer would be controlled by vertical motions of the alkanofer table over the time. During flooding events, liquid hydrocarbons covering the depression floor would dissolve the surface layer, increasing progressively the diameter of the depression on geological timescales. During drought episodes, liquid hydrocarbons of the underground alkanofer would evaporate, leading to crystallization of “evaporites” in the pores and at the surface of the substratum, and to the formation of the regional soluble layer. The presence of specific landforms (lunette dunes or evaporites) is compatible with such evaporitic regional settings. Alternatively, but not exclusively, the surface soluble layer might have formed by accumulation on the ground of soluble compounds formed in the atmosphere.

Use of satellite data and GIS for assessing the agricultural potentiality of the soils South Farafra Oasis, Western Desert, Egypt

Overpopulation and food security are the main global problems alert decision makers. In developing countries, such problem put extra pressure for horizontal expansion for agricultural development. The rapid sprawl of urbanized areas on the alluvial land of the River Nile and delta to accommodate the population growth has encouraged governmental and private sector for agricultural expansion in the desert. Unless there are reliable information and accurate studies for land and soil suitability, there will be a collapse of such investment. To evaluate the potential suitability of soil for agriculture development in areas of the western desert, satellite images, geographic information, and field survey including soil profiles and artesian water samples with laboratory analysis were integrated to classify the soils according their suitability for specific crop. The main land qualities of the different mapping units and the crop requirement were rated and matched to obtain the current and potential land suitability using Automated Land Evaluation System “ALES”. The study found that the main physiographic units are plateaus, hilland, mountain, and depression floor. But there are three limiting parameters for land suitability which are the lack of nutrient elements, wind erosion vulnerability, and soil texture. The study concluded that the best crops adapted with the soil conditions and could be feasible for economic use are: (1) native vegetation such as agol, sand trees, sammar, halfaa, bawaal, qordaob, bardi, and qortom; (2) filed crops such as onion, garlic, watermelon and wheat; and (3) fruits such as olive and date palms.

RELATIONSHIP BETWEEN LANDFORMS AND SOIL CHARACTERISTICS IN BAHARIYA OASIS, EGYPT

Bahariya Oasis is a natural depression located in the western desert of Egypt. The whole region is under hot arid condition. The images and GIS capabilities were used to generate soil maps. Six landforms were identified and soils availability of groundwater in the depression initiated cultivation of date palms and the associated industrial and economic activities. Due to abundant groundwater, the lands there gave indications of promising agricultural expansion. Study of the landforms and soils associated with them can give a general survey of soil characteristics. Landsat occupying are studied. The landforms include; plains, depression floor with low, moderately high and high lands, Mesa and plateau, and pediplains. Studying their morphological, chemical and physical characteristics, the soils were classified under the following taxa; Haplogypsids, Haplosalids, Calcisalids, Gypsisalids, Calcigypsisalids, Torriorthents and Torripsamments. Calcium and gypsum accumulations are found in saline soils in most of the soils. In the low lands, drainage may have serious problems. The presence of groundwater and the problem of drainage are common in most of the depressions. The challenge is to be aware of the problem and to design a proper and appropriate soil and water management system.

Landsat satellite imagery of the Qattara Depression area, Egypt

The Qattara Depression lies in the northern part of the Western Desert of Egypt at a distance of some tens of kilometers to the south of the Mediterranean Sea Coast. The depression in question is the largest one in the great Sahara extending across North Africa. It covers an area of some 19,000 km 2 at − 60 m level and the absolute level of its lowest point is about − 134 m. The depression extends for about 300 km in a roughly ENE-WSW direction, while its width is variable reaching to a maximum of about 145 km. Feasibility studies are currently carried out for the Qattara solar-hydro-electric project which aims at generating hydro-electric power by the drop of the Mediterranean Sea water into the depression after passing through a canal/tunnel system. Peak load electric power may be also generated by raising the water to the small hollow of Deir Kirayim, situated at a higher level near the depression, and allowing it to drop to a low level. For the purpose of assessing the regional criteria involved in the implementation of the project and the environmental impact of such implementation, the Qattara Depression and the surrounding area has been studied on a regional scale by the utilization of LANDSAT satellite imagery. The maps produced by the interpretation of the images in question include those of the geological and environmental units, structural lineations, drainage and vegetation cover. Lineation density and drainage density maps are derived by the computation of the structural lineation and drainage maps respectively. A map of groundwater conditions is worked out on the basis of the image interpretation, and the observations previously carried out on the groundwater aquifers in the Qattara Depression and the surrounding area. LANDSAT satellite image interpretation and computation are supported by intensive observations carried out in the field as well as chemical, petrological and mineralogical analyses of the samples collected. The LANDSAT satellite images proved to be of great importance in mapping the Qattara Depression floor which is hardly accessible to classical mapping, and especially in view of the large area which could be covered by imagery mapping in a reasonably short time compatible with the duration of the feasibility study. The special characters of the spaceborne multispectral imagery have been paramount in deciphering the major regional features of the investigated area. The overall synoptic picture of the regional setting of the geological and environmental units, faults, fractures and folds, drainage lines and plant cover in the large area studied has been clarified for the first time. It has been demonstrated that the Qattara Depression is actually constituted of several small depressions. The environmental impact of the project implementation has been visualized especially regarding the possible influence of the saline water on the fresh groundwater sources. The thick salt accumulation in the depression has been found to be of such extension as to increase the salinity of the Mediterranean Sea water stored in the depression following the implementation of the project. The lineation density map has been particularly of great help in the localization of sites subjected to intense crustal deformation, greater slope instability and run off surface water flooding.

Resurgent Volcano-Tectonic Depression of Oligocene Age, South-Central New Mexico

The Goodsight-Cedar Hills volcano-tectonic depression in south-central New Mexico formed concurrently with and following deposition of about 550 km 3 of Oligocene volcanic and volcaniclastic rocks. The depression is an asymmetric basin about 80 km long and 38 km wide. It is filled to a maximum depth of about 550 m by early rhyolitic ash-flow tuff, medial epiclastic strata derived partly from marginal raised rims (Bell Top Formation), and late basaltic andesite (Uvas Basalt). Much of the 295 km 3 of effusive rock was erupted from vents located near the center of the depression and from a major subsidence fracture zone along the eastern margin. Subsidence of the depression floor was noncatastrophic and approximately kept pace with basin filling, except along the eastern margin. Following eruption and broad, regional subsidence of the Uvas Basalt, the central floor of the depression was arched upward to form the Sierra de las Uvas dome and adjacent synclinal moat. The fault pattern of the dome and its association with known vents and the thickest part of the volcanic pile suggest that it formed by vertical movement of magma from an underlying chamber. Its development, following subsidence of the Uvas Basalt, suggests that it is essentially resurgent in origin. Although no postdoming volcanism is known, indirect evidence indicates that intrusion of silicic magma probably caused resurgence. It is clear that the Goodsight-Cedar Hills depression is not a resurgent cauldron of the classic Valles or Toba types. Rather, it appears to be a structure transitional in character between a cauldron and a fault trough. Subsidence apparently followed volcanism. Resurgence followed eruption of basaltic andesite rather than the usual ash-flow sequence, and the 10- to 12-m.y. history of the Goodsight-Cedar Hills depression is 5 to 6 times as long as other well-known resurgent cauldron cycles. Locally, deposition in the depression continued without interruption into early late Tertiary time, when extensional faulting occurred. The depression is elongated parallel to the late Tertiary Rio Grande Rift and may be a precursor of Basin and Range structure in the area. The late Tertiary fault pattern in the area indicates that earlier volcano-tectonic structures had important effects on the pattern of late Tertiary Basin and Range structures. Locally, late Tertiary faults were inherited from and duplicate the position of earlier subsidence faults or the synclinal moat. Elsewhere, the north-trending regional fault pattern was considerably modified by structural and litho-logic inhomogeneities of volcano-tectonic origin, particularly the Sierra de las Uvas dome and its buried intrusive masses.