Durch Mikrorelief-, Sediment-und pedo-hydrologische Untersuchungen konnte nachgewiesen werden, da... more Durch Mikrorelief-, Sediment-und pedo-hydrologische Untersuchungen konnte nachgewiesen werden, dass die Substrat-genese und -umformung, die Schicht-und Horizontkonstellation sowie einzelne Bodenmerkmale wie z.B. Textur, Humus-gehalt, Porosität, Mineral-und Salzgehalt einen bedeutenden Einfluss auf die Vitalität und das Überleben der Populus euphratica Bestände haben. Von der Tiefenlage feinerdereicher Horizonte hängt die Wasserspeicherfähigkeit, von der Mächtig-keit der Sandüberdeckung hängen der Verdunstungsschutz und die Wassertrans-fereigenschaften ab. Diese bestimmen die
Excessive withdrawal of water for farmland irrigation, and water losses from water reservoirs and... more Excessive withdrawal of water for farmland irrigation, and water losses from water reservoirs and channels, have caused water deficit problems along the Tarim River in Northwestern China. Especially, the lower reaches have been severely threatened since the 1950s, and are experiencing a drastic increase in the mineralisation of the river water. Additionally, large scale deposition of aeolian sand and dust is another major threat for the Tarim Riparian Ecosystem (TaRiEc). This development reached its “climax” with the desiccation of the Taitema Lake in 1972, and the “climax” was well expressed by severe degradation of the TaRiEc, which is in turn predominately characterized by the dying of Populus euphratica stands. All these developments led to the initiation of the “EcologicalWater Diversion Project” (EWDP). The main objective of this project is to ensure a constant water supply to the lower reaches of the Tarim River via the water transfer both from the Bosten Lake catchment and from Tarim’s upper and middle reaches. In this study, the processes and trends of the vegetation change during this period of intermittent water transfer were examined on the basis of remote sensing data. The results show that with the water transfer only some of the P. euphratica trees reached a more vital state. Common hypotheses about factors influencing the tree vitality under stressful conditions deal with the water level in the river, the groundwater level and the distance of the trees from the river. However, soil and sediment, as well as micro-relief conditions also play an important role and take influence on the vitality of the trees. The main objective of the present study was to analyse the features of soil and sediment concerning water passage and water storage processes in near surface and subsurface positions of the lower Tarim Riparian Ecosystem. For that purpose, 2010 and 2011 field and laboratory analyses of soil and sediment profiles were performed. Laboratory results comprise grain size measurements, pore size distribution, total organic content (TOC) and data from XRD-measurements on the soil’s mineral composition for all studied sites within the lower Tarim study area and for selected ecosystem types as well. These parameters allow conclusions about water storage and water passage conditions, which play a key role for water availability and water supply of P. euphratica trees. Besides single soil and sediment parameters, such as salt content and mineral composition, layer types (vertical sequence of soil horizons and sediment layers) have been identified as leading factors determining near surface and subsurface water passage and water storage features of the Tarim Riparian Ecosystem.
Studies on playas (known locally as inland sabkhat) are rare and lack a focus on their role as ge... more Studies on playas (known locally as inland sabkhat) are rare and lack a focus on their role as geoarchives for Holocene climate and environmental change.We present characteristic sediments and processes that illustrate the change from relatively humid to hyperarid conditions within the sedimentary record of the playa of Tayma (Saudi Arabia). The shift from the Holocene humid period (10e8 ka BP) to the hyperarid conditions of today left traces in this geoarchive. During the humid period, a perennial lake had formed in the playa depression. The occurrence of biota, especially ostracod valves and foraminifer shells, adapted to salinity fluctuations and physiochemical reactions of ostracods and foraminifers testify environmental changes. Phases of lake contraction and high salinities were responsible for the formation of ‘open water’ evaporites, such as aragonite needles, and ooids. Dilution occurred during rain events and flooding of the playa; it is characterised in the sedimentary infill by clastic layers that were deposited in graded sequences. The smooth surface, the phenomenon of microsomia and sieve pore variations of the ostracod valves provide evidence for changing salinities, which are testimony to short lived changes. These processes and further aridisation resulted in the formation of ‘capillary’ evaporites, which are dominated by sulphate minerals. The precipitates undergo fractionation and re-dissolution, which results in a typical stratification of salts with different solubilities.
The channel flow and respectively the discharge of the Tarim River is characterized by strong sea... more The channel flow and respectively the discharge of the Tarim River is characterized by strong seasonal differences. Due to the fact, that most of its main tributary headwaters – the Aksu, Muzat (both Tian Shan), Yarkant, Hotan (both Kunlun Shan) and Kashgar (Pamir) rivers – are located in the high mountains surrounding the Taklamakan desert, the runoff generation between October and April is very limited. High discharge and floods occur between May and September during the snow and glacier melting period. Among the tributaries only the Aksu continuously reaches the Tarim throughout the year. It contributes approximately 70-80% of Tarim’s total discharge, which is mostly generated in the Kyrgyz part of the Tian Shan mountains. The Yarkant River is the longest of the Tarim tributaries and downstream of the city of Aksu, near Yichang, it joins the Aksu and Hotan rivers to form the Tarim River. The Yarkant-Tarim river system is the longest inland river in China, and the second largest i...
An early to mid-Holocene humid period has been inferred from a variety of geo-bio-archives of the... more An early to mid-Holocene humid period has been inferred from a variety of geo-bio-archives of the Sahara and the Arabian Peninsula including sabkhas, palaeo-lakes, sand dunes, wadis, speleothems or marine sediments. On the Arabian Peninsula, most of these records are located in the southern and southeastern part. Studies from the northern part are rare. This paper presents the first results from palaeo-environmental and hydrological investigations on the sabkha basin of the Tayma oasis, northwestern Saudi Arabia. Sedimentary characteristics, micro-and macrofauna, a digital elevation model based on DGPS measurements, and 14 C-AMS data indicate the presence of a perennial lake with a minimum depth of 13 m, a stored water volume of 1.16 Â 10 7 m 3 and a surface of 18.45 km 2 between 10,000e9000 cal BP. Foraminiferal test malformations and the shape of sieve pores on ostracod valves were used to detect trends in palaeo-salinity and ecological stress conditions. The reconstructed gradual contraction of the lake at least after 8500 cal BP reflects the long-term aridisation trend on the Arabian Peninsula after the early Holocene. Based on the hydrological water balance equation, quantitative data on minimum palaeo-rainfall during the early Holocene humid period were calculated. Input parameters for the equation are the minimum lake level, lake surface, and lake volume during the peak of the early Holocene humid period as well as palaeo-evapotranspiration, groundwater infiltration, and surface runoff. Accordingly, a perennial lake in the endorheic basin of the modern sabkha with a lake level at the same elevation as the uppermost shoreline deposit would have required a minimum annual precipitation of 150 AE 25 mm. This value amounts to c. 300% of recent precipitation rates.
Durch Mikrorelief-, Sediment-und pedo-hydrologische Untersuchungen konnte nachgewiesen werden, da... more Durch Mikrorelief-, Sediment-und pedo-hydrologische Untersuchungen konnte nachgewiesen werden, dass die Substrat-genese und -umformung, die Schicht-und Horizontkonstellation sowie einzelne Bodenmerkmale wie z.B. Textur, Humus-gehalt, Porosität, Mineral-und Salzgehalt einen bedeutenden Einfluss auf die Vitalität und das Überleben der Populus euphratica Bestände haben. Von der Tiefenlage feinerdereicher Horizonte hängt die Wasserspeicherfähigkeit, von der Mächtig-keit der Sandüberdeckung hängen der Verdunstungsschutz und die Wassertrans-fereigenschaften ab. Diese bestimmen die
Excessive withdrawal of water for farmland irrigation, and water losses from water reservoirs and... more Excessive withdrawal of water for farmland irrigation, and water losses from water reservoirs and channels, have caused water deficit problems along the Tarim River in Northwestern China. Especially, the lower reaches have been severely threatened since the 1950s, and are experiencing a drastic increase in the mineralisation of the river water. Additionally, large scale deposition of aeolian sand and dust is another major threat for the Tarim Riparian Ecosystem (TaRiEc). This development reached its “climax” with the desiccation of the Taitema Lake in 1972, and the “climax” was well expressed by severe degradation of the TaRiEc, which is in turn predominately characterized by the dying of Populus euphratica stands. All these developments led to the initiation of the “EcologicalWater Diversion Project” (EWDP). The main objective of this project is to ensure a constant water supply to the lower reaches of the Tarim River via the water transfer both from the Bosten Lake catchment and from Tarim’s upper and middle reaches. In this study, the processes and trends of the vegetation change during this period of intermittent water transfer were examined on the basis of remote sensing data. The results show that with the water transfer only some of the P. euphratica trees reached a more vital state. Common hypotheses about factors influencing the tree vitality under stressful conditions deal with the water level in the river, the groundwater level and the distance of the trees from the river. However, soil and sediment, as well as micro-relief conditions also play an important role and take influence on the vitality of the trees. The main objective of the present study was to analyse the features of soil and sediment concerning water passage and water storage processes in near surface and subsurface positions of the lower Tarim Riparian Ecosystem. For that purpose, 2010 and 2011 field and laboratory analyses of soil and sediment profiles were performed. Laboratory results comprise grain size measurements, pore size distribution, total organic content (TOC) and data from XRD-measurements on the soil’s mineral composition for all studied sites within the lower Tarim study area and for selected ecosystem types as well. These parameters allow conclusions about water storage and water passage conditions, which play a key role for water availability and water supply of P. euphratica trees. Besides single soil and sediment parameters, such as salt content and mineral composition, layer types (vertical sequence of soil horizons and sediment layers) have been identified as leading factors determining near surface and subsurface water passage and water storage features of the Tarim Riparian Ecosystem.
Studies on playas (known locally as inland sabkhat) are rare and lack a focus on their role as ge... more Studies on playas (known locally as inland sabkhat) are rare and lack a focus on their role as geoarchives for Holocene climate and environmental change.We present characteristic sediments and processes that illustrate the change from relatively humid to hyperarid conditions within the sedimentary record of the playa of Tayma (Saudi Arabia). The shift from the Holocene humid period (10e8 ka BP) to the hyperarid conditions of today left traces in this geoarchive. During the humid period, a perennial lake had formed in the playa depression. The occurrence of biota, especially ostracod valves and foraminifer shells, adapted to salinity fluctuations and physiochemical reactions of ostracods and foraminifers testify environmental changes. Phases of lake contraction and high salinities were responsible for the formation of ‘open water’ evaporites, such as aragonite needles, and ooids. Dilution occurred during rain events and flooding of the playa; it is characterised in the sedimentary infill by clastic layers that were deposited in graded sequences. The smooth surface, the phenomenon of microsomia and sieve pore variations of the ostracod valves provide evidence for changing salinities, which are testimony to short lived changes. These processes and further aridisation resulted in the formation of ‘capillary’ evaporites, which are dominated by sulphate minerals. The precipitates undergo fractionation and re-dissolution, which results in a typical stratification of salts with different solubilities.
The channel flow and respectively the discharge of the Tarim River is characterized by strong sea... more The channel flow and respectively the discharge of the Tarim River is characterized by strong seasonal differences. Due to the fact, that most of its main tributary headwaters – the Aksu, Muzat (both Tian Shan), Yarkant, Hotan (both Kunlun Shan) and Kashgar (Pamir) rivers – are located in the high mountains surrounding the Taklamakan desert, the runoff generation between October and April is very limited. High discharge and floods occur between May and September during the snow and glacier melting period. Among the tributaries only the Aksu continuously reaches the Tarim throughout the year. It contributes approximately 70-80% of Tarim’s total discharge, which is mostly generated in the Kyrgyz part of the Tian Shan mountains. The Yarkant River is the longest of the Tarim tributaries and downstream of the city of Aksu, near Yichang, it joins the Aksu and Hotan rivers to form the Tarim River. The Yarkant-Tarim river system is the longest inland river in China, and the second largest i...
An early to mid-Holocene humid period has been inferred from a variety of geo-bio-archives of the... more An early to mid-Holocene humid period has been inferred from a variety of geo-bio-archives of the Sahara and the Arabian Peninsula including sabkhas, palaeo-lakes, sand dunes, wadis, speleothems or marine sediments. On the Arabian Peninsula, most of these records are located in the southern and southeastern part. Studies from the northern part are rare. This paper presents the first results from palaeo-environmental and hydrological investigations on the sabkha basin of the Tayma oasis, northwestern Saudi Arabia. Sedimentary characteristics, micro-and macrofauna, a digital elevation model based on DGPS measurements, and 14 C-AMS data indicate the presence of a perennial lake with a minimum depth of 13 m, a stored water volume of 1.16 Â 10 7 m 3 and a surface of 18.45 km 2 between 10,000e9000 cal BP. Foraminiferal test malformations and the shape of sieve pores on ostracod valves were used to detect trends in palaeo-salinity and ecological stress conditions. The reconstructed gradual contraction of the lake at least after 8500 cal BP reflects the long-term aridisation trend on the Arabian Peninsula after the early Holocene. Based on the hydrological water balance equation, quantitative data on minimum palaeo-rainfall during the early Holocene humid period were calculated. Input parameters for the equation are the minimum lake level, lake surface, and lake volume during the peak of the early Holocene humid period as well as palaeo-evapotranspiration, groundwater infiltration, and surface runoff. Accordingly, a perennial lake in the endorheic basin of the modern sabkha with a lake level at the same elevation as the uppermost shoreline deposit would have required a minimum annual precipitation of 150 AE 25 mm. This value amounts to c. 300% of recent precipitation rates.
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Papers by Andreas Ginau
channels, have caused water deficit problems along the Tarim River in Northwestern China. Especially,
the lower reaches have been severely threatened since the 1950s, and are experiencing a drastic increase
in the mineralisation of the river water. Additionally, large scale deposition of aeolian sand and dust is
another major threat for the Tarim Riparian Ecosystem (TaRiEc). This development reached its “climax”
with the desiccation of the Taitema Lake in 1972, and the “climax” was well expressed by severe
degradation of the TaRiEc, which is in turn predominately characterized by the dying of Populus
euphratica stands. All these developments led to the initiation of the “EcologicalWater Diversion Project”
(EWDP). The main objective of this project is to ensure a constant water supply to the lower reaches of
the Tarim River via the water transfer both from the Bosten Lake catchment and from Tarim’s upper and
middle reaches. In this study, the processes and trends of the vegetation change during this period of
intermittent water transfer were examined on the basis of remote sensing data. The results show that
with the water transfer only some of the P. euphratica trees reached a more vital state.
Common hypotheses about factors influencing the tree vitality under stressful conditions deal with the
water level in the river, the groundwater level and the distance of the trees from the river. However, soil
and sediment, as well as micro-relief conditions also play an important role and take influence on the
vitality of the trees. The main objective of the present study was to analyse the features of soil and
sediment concerning water passage and water storage processes in near surface and subsurface positions
of the lower Tarim Riparian Ecosystem. For that purpose, 2010 and 2011 field and laboratory analyses of
soil and sediment profiles were performed. Laboratory results comprise grain size measurements, pore
size distribution, total organic content (TOC) and data from XRD-measurements on the soil’s mineral
composition for all studied sites within the lower Tarim study area and for selected ecosystem types as
well. These parameters allow conclusions about water storage and water passage conditions, which play
a key role for water availability and water supply of P. euphratica trees. Besides single soil and sediment
parameters, such as salt content and mineral composition, layer types (vertical sequence of soil horizons
and sediment layers) have been identified as leading factors determining near surface and subsurface
water passage and water storage features of the Tarim Riparian Ecosystem.
for Holocene climate and environmental change.We present characteristic sediments and processes that
illustrate the change from relatively humid to hyperarid conditions within the sedimentary record of the
playa of Tayma (Saudi Arabia). The shift from the Holocene humid period (10e8 ka BP) to the hyperarid
conditions of today left traces in this geoarchive. During the humid period, a perennial lake had formed
in the playa depression. The occurrence of biota, especially ostracod valves and foraminifer shells,
adapted to salinity fluctuations and physiochemical reactions of ostracods and foraminifers testify
environmental changes. Phases of lake contraction and high salinities were responsible for the formation
of ‘open water’ evaporites, such as aragonite needles, and ooids. Dilution occurred during rain events and
flooding of the playa; it is characterised in the sedimentary infill by clastic layers that were deposited in
graded sequences. The smooth surface, the phenomenon of microsomia and sieve pore variations of the
ostracod valves provide evidence for changing salinities, which are testimony to short lived changes.
These processes and further aridisation resulted in the formation of ‘capillary’ evaporites, which are
dominated by sulphate minerals. The precipitates undergo fractionation and re-dissolution, which
results in a typical stratification of salts with different solubilities.
channels, have caused water deficit problems along the Tarim River in Northwestern China. Especially,
the lower reaches have been severely threatened since the 1950s, and are experiencing a drastic increase
in the mineralisation of the river water. Additionally, large scale deposition of aeolian sand and dust is
another major threat for the Tarim Riparian Ecosystem (TaRiEc). This development reached its “climax”
with the desiccation of the Taitema Lake in 1972, and the “climax” was well expressed by severe
degradation of the TaRiEc, which is in turn predominately characterized by the dying of Populus
euphratica stands. All these developments led to the initiation of the “EcologicalWater Diversion Project”
(EWDP). The main objective of this project is to ensure a constant water supply to the lower reaches of
the Tarim River via the water transfer both from the Bosten Lake catchment and from Tarim’s upper and
middle reaches. In this study, the processes and trends of the vegetation change during this period of
intermittent water transfer were examined on the basis of remote sensing data. The results show that
with the water transfer only some of the P. euphratica trees reached a more vital state.
Common hypotheses about factors influencing the tree vitality under stressful conditions deal with the
water level in the river, the groundwater level and the distance of the trees from the river. However, soil
and sediment, as well as micro-relief conditions also play an important role and take influence on the
vitality of the trees. The main objective of the present study was to analyse the features of soil and
sediment concerning water passage and water storage processes in near surface and subsurface positions
of the lower Tarim Riparian Ecosystem. For that purpose, 2010 and 2011 field and laboratory analyses of
soil and sediment profiles were performed. Laboratory results comprise grain size measurements, pore
size distribution, total organic content (TOC) and data from XRD-measurements on the soil’s mineral
composition for all studied sites within the lower Tarim study area and for selected ecosystem types as
well. These parameters allow conclusions about water storage and water passage conditions, which play
a key role for water availability and water supply of P. euphratica trees. Besides single soil and sediment
parameters, such as salt content and mineral composition, layer types (vertical sequence of soil horizons
and sediment layers) have been identified as leading factors determining near surface and subsurface
water passage and water storage features of the Tarim Riparian Ecosystem.
for Holocene climate and environmental change.We present characteristic sediments and processes that
illustrate the change from relatively humid to hyperarid conditions within the sedimentary record of the
playa of Tayma (Saudi Arabia). The shift from the Holocene humid period (10e8 ka BP) to the hyperarid
conditions of today left traces in this geoarchive. During the humid period, a perennial lake had formed
in the playa depression. The occurrence of biota, especially ostracod valves and foraminifer shells,
adapted to salinity fluctuations and physiochemical reactions of ostracods and foraminifers testify
environmental changes. Phases of lake contraction and high salinities were responsible for the formation
of ‘open water’ evaporites, such as aragonite needles, and ooids. Dilution occurred during rain events and
flooding of the playa; it is characterised in the sedimentary infill by clastic layers that were deposited in
graded sequences. The smooth surface, the phenomenon of microsomia and sieve pore variations of the
ostracod valves provide evidence for changing salinities, which are testimony to short lived changes.
These processes and further aridisation resulted in the formation of ‘capillary’ evaporites, which are
dominated by sulphate minerals. The precipitates undergo fractionation and re-dissolution, which
results in a typical stratification of salts with different solubilities.