Late Quaternary fluvial terrace formation in the Luan River drainage basin,north China and its possible linkages with climate change and tectonic activation

The Luan River is the most important water system in north-eastern Hebei Province,China and is located in the transitional zone of the Eastern Yan Mountains,North China Plain and Songliao Plain.The well-developed river terraces of its tributary,the Yixun River,provide excellent information for studying neotectonics and climate change.There are seven terraces in the lower reaches of the Yixun River,numbered T7-T1.The optically stimulated luminescence dating results of 23 samples show that terraces T7-T2 formed at 111.36±5.83 ka,78.20±4.45 ka,65.29±4.15 ka,56.44±3.07 ka,40.08±2.66 ka,and 13.14±0.76 ka,respectively.A comparison with the oxygen isotope curves of deep-sea sediments reveals that the sediment formation of each terrace corresponded to cold periods of marine isotope stages MIS 4 and MIS 2 and the relatively cold periods of MIS 5e,MIS 3,and MIS 1.Since the Late Pleistocene,the incision rate of the Yixun River has ranged from 0.371-1.740 mm/a.During the formation of T7-T6,T5-T4,T4-T3,and T3-T2,the incision rate was low.However,in the two stages during which T6-T5 and T2-T1 formed(13.14±0.76 ka to 0.58±0.08 ka and 10.79±0.64 ka to 0.16±0.01 ka),these rates reached 1.554 mm/a and 1.592-1.740 mm/a,respectively.At approximately 30 ka,the activity of the Langying Fault increased,leading to footwall uplift.The river gathered in the north of Langying to form the ancient Erdaowan Lake,which resulted in the drying of the river in the lower reaches of the Yixun River during the last glacial maximum without forming river deposits.In the Early Holocene,headward erosion in the lower reaches of the Yixun River was enhanced,which resulted in the disappearance of the lake,and incised meandering formed due to increased neotectonism.Based on the analyses of river incision and the formation of ancient lakes and incised meandering,it was inferred that there have been three periods of strong tectonism in the river basin since the Late Pleistocene.

Tectonic and climatic controls for fluvial terraces of the Yellow River over the past 2.6 Ma at Northeast Tibetan Plateau and Ordos Block

The Yellow River is usually assumed to record tectonic activities and climatic changes;however,a systematic study was lack in the sedimentology,stratigraphy,geomorphology and geochronology for the entire Yellow River though various geologic scholars have conducted numerous works in individual basins.This review focused on well-preserved fluvial terrace sequences that formed along this river on northeastern(NE)Tibetan Plateau and Ordos Block over the past 2.6 Ma.After comparing numerous initial incision ages at different segments along the Yellow River,we found out that the youngest initial incision may occur at ca.150 ka at the Longyang Gorge.The Yellow River may transit from multiple separated endorheic drainages to an entire external drainage after 150 ka,which may cause differentiations in the apparent incision rates before and after 150 ka;thus apparent net incision rates were calculated respectively for the Yellow River before 150 ka and the drainage network post 150 ka.Apparent net incision rates prior to 0.15 Ma were calculated as 0.15,0.29,0.10,0.12 and 0.03 mm/a respectively in Tongde-Xunhua,Lanzhou-Linxia basins,Heishan,Jinshan and Fenwei-Sanmen Gorges in this review,which mainly reflected Kunhuang-Gonghe Tectonic Event,generated by the Indo-Asian collision and diminishing as the NE Tibetan Plateau eastward extruding at ca.1.8-0.15 Ma.Apparent net incision rates post 0.15 Ma were calculated respectively for NE Tibetan Plateau and Ordos Block,considering their different base level.On NE Tibetan Plateau,four fluvial degradational phases were identified between ca.105~70,53~40,25~16 and 12~6 ka associated with terrace levels respectively,at average elevations of 96,40,20 and 10.5 meters above the current river level(m arl)within a range of 5~96 m arl;and four broad periods in the last 150 ka on Ordos Block:possibly marine oxygen isotope stage(MIS)5,ca.118 to 72 ka,most of MIS 3,ca.44~28 ka,transition from LGM to last deglacial ca.20 to 16 ka,and 4~3 ka at average elevations of 67.5,26,19 and 11.5 m arl.These degradational phases post 0.15 Ma were associated with multiple processes including enhanced fluvial discharge with an increase in monsoonal precipitation and/or melt water in deglaciation.

Analysis of wave shoaling and shore-breakers on a low tide terrace beach based on in-situ measurements at Xisha Bay on South China coast

Low tide terrace beach is a main beach type along South China coasts with strong tidal actions.How strong tides affect wave transformations on low tide terrace beach still remains unclear.In this study,in-situ measurements are conducted on the low terrace beach at Xisha Bay to provide quantitative descriptions of wave shoaling and shore-breaker phenomena under the tidal effects.It is found that wave breaking is unsaturated on the low tide terrace beach at Xisha Bay.Magnitudes of wave skewness and asymmetry increase as wave shoals and achieve the maximum value at the shore-breaker,and then decrease rapidly.Mean energy dissipation rates of shore-breakers are tide-modulated since the bottom slope changes at the shoreward boundary of wave propagation in a tidal cycle.The remaining wave energy flux at the initialization of the shore-breaker is 1%–12%of offshore wave energy flux,and the energy flux ratio decreases with increasing offshore wave heights.Wave attenuation at shore-breakers can be estimated directly from offshore wave conditions based on findings in this study,favoring designs of seawalls or beach nourishment projects.Field datasets on wave transformations can also be used for verifications of wave numerical models.

First application of plutonium in soil erosion research on terraces

The spatial distributions of ^(239+240)Pu and ^(137)Cs in soils from Longji Rice Terraces were investigated to evaluate soil erosion.The activity concentrations of ^(239+240)Pu and ^(137)Cs in the surface soils of the paddy fields were in the range of 0.089–0.734 and1.80–7.88 mBq/g,respectively.The activities of ^(239+240)Pu and ^(137)Cs showed very similar distribution trends,first increasing and then decreasing with increasing elevation.The 240Pu/239Pu atom ratios in the surface soils ranged from 0.162 to 0.232.The activities of ^(239+240)Pu and ^(137)Cs in the soil cores tended to be uniformly distributed within the plowed layer and declined exponentially below this depth.The mean soil erosion rates of Longji Rice Terraces estimated by ^(239+240)Pu and ^(137)Cs tracer methods were 5.44 t/(ha·a)and 5.16 t/(ha·a),respectively,which demonstrated that plutonium can replace ^(137)Cs as an ideal tracer for soil erosion research in the future.Landform features are the main factors affecting the distribution of plutonium and ^(137)Cs as well as soil erosion in the Longji Rice Terraces.

Mitigating risks of hybrid rice use in terrace agriculture

The Honghe Hani Rice Terraces of Yunnan Province have become a national emblem for China and a UNESCO World Heritage Site,but some are beginning to crumble.This research attempts to address why this is happening and what can be done about it.Previous work has failed to adequately address the possible shortcomings of recently introduced seed and water management technologies,their particular effect on rice terraces and the people who depend upon them.In an effort to better understand the issue,field observation was triangulated with in-depth interviews with local people,and the examination of scientific literature.To do this,the authors spent time in China with a translator in a key village known to be first in the area to truly succeed in carving the rice terraces and in making the mountain slope irrigation system required actually working.Results validated by experts in each field indicate that while the new seed and technologies do save water and improve lives,paired with migration,they may also be threatening the long-term viability of rice terracing in the region.The authors conclude that an integrated approach is needed and put forward a strategic blueprint to reinforce ecological,social and economic longevity.They also call for more research into the applicability of these resilience measures in other hybrid rice terracing regions,such as in the Philippines and Vietnam.

Landscape Pattern of Ancient Terraces in Huangping County and Slopeto-Terrace Strategy

Formation and development of ancient terraces proves that slope-to-terrace project is a signifi cant measure for conserving water and soil in mountainous areas. UAV remote sensing technology was applied to obtain RS images with a resolution ratio of 0.1–0.5 m, Arc GIS was applied for data processing, and Fragstats3.3 was used to calculate characteristic indexes, to study landscape pattern of 4 ancient terraces in Huangping County, Guizhou Province. The results showed that terrace landscapes and woodland landscapes in the study area account for nearly 80% of the whole landscape(terrace 30%, woodland 50%); mean area of single fi eld is mainly concentrated between 100 m^2 and 200 m^2, and height between 0.7 m and 1.7 m, breadth 0.5 m and 0.6 m; most terraces have a gradient of 5–25°, accounting for 70% of the total number of fi eld. The water and soil conservation concept in the ancient terraces provides references for the slope-to-terrace project and the water and soil loss control of slope farmland.

Formation of the Yalong Downstream Terraces in the SE Tibetan Plateau and Its Implication for the Uplift of the Plateau

The Yalong River is an important river that runs across the abruptly changing terrain of the SE Tibetan Plateau. The terraces and Quaternary sediments in its valleys preserve the information of tectonic uplift, climate changes, and landform evolution since the Middle Pleistocene. Based on geomorphological, sedimentological, and chronological investigations, 6-8 terraces are identified in the lower reaches of Yalong catchment and its tributary--the Anning River. The electron spin resonance （ESR） or optically stimulated luminescence （OSL） data on the alluvial sediments in the upper portion of terraces indicate that they formed in 1.10, 0.90, 0.72, 0.06-0.04, 0.03-0.02, and 0.01 Ma. Tectonic uplift and the climatic cycle controlled the formation of the Yalong River terraces. The former dominated the dissection depths and incision rates, whereas the latter controlled the transformation between accumulation, which developed during the glacial period, and incision, which developed during the glacial-interglacial transition. The Yalong downstream incised rapidly from 1.10 to 0.72 Ma and rapidly from 0.06 Ma until the present; the terraces developed during these two periods. The incision rates in space during the two periods indicate the uplifting extent of the Jinpingshan area, which decreases toward the east and the south. The results reveal two rapidly uplifting stages in the SE Tibetan Plateau, including an accelerated uplifting since 0.06 Ma. Since the Middle Pleistocene, the tectonic uplift of the SE and NE parts of the Tibetan Plateau is synchronous, according to the same development stages of the river terraces of the Yalong downstream and the Yellow River in the Lanzhou area of the NE Tibetan Plateau. The difference in the horizontal displacement between the Xianshuihe Fault and the Anninghe Fault bend resulted in the rapid uplift of the Jinpingshan area. The incision rate for the spatial distribution of the Yalong downstream is the geomorphologicai response of crustal shortening and uplift differences in the SE margin block of the Tibetan Plateau. The southeastward diffusion process of the Tibetan Plateau was recorded.

Chronological Link Between the Abrupt Change of the Loess Grain Size Sequence and the Formation of River Terraces on the Eastern Margin of the Qinghai-Tibetan Plateau Since the Late Early-Pleistocene

Based on the study of magnetostratigraphy,magnetic susceptibility and grain size of Garze A section on the southeastern margin of the Qinghai-Tibetan Plateau since the late early-Pleistocene,the basal age of Garze loess is located at～1.16 MaBP and a series of abrupt paleoclimatic changes is detected.The times of abrupt changes are of distinct series features,and the interval between each two adjacent abrupt changes is～50 kyr or～100 kyr.The most significant abrupt changes occur at around 1.06,0.85,0.6,0.46,0.39 and 0.14 MaBP.There is a chronological link between the abrupt changes of paleoclimate and the formation of river terraces and it is almost simultaneous with a strengthening trend of neotectonic activities.Therefore,maybe the climatic transition controll the timing of terrace formation,and the tectonic uplift originate potential energy and has a direct effect on channel incision, both the climatic transition and the tectonic uplift are important.Terraces are the products of the interaction of instable climatic variations and tectonic uplift.Like the loess-paleosol sequences,river terrace sequences are also controlled by the climate-tectonic coupling system and are ruled by climate-tectonic gyration with a～100 kyr paracycle,which may be the short eccentricity period of the earth.

Distribution and Forming Model of Fluvial Terrace in the Huangshui Catchment and its Tectonic Indication

The Huang Shui River, a main tributary of the Yellow River, crosses a series of tectonically subsided and uplifted areas that show different patterns of terrace formation. The distribution of fluvial terrace of the Huang Shui River is studied through topographic and sedimentologic terrace mapping. Three terraces in the Haiyan Basin, four terraces in the Huangyuan Basin, 19 terraces in the Xi＇ning Basin （the four high terraces may belong to another river）, nine terraces in the Ping＇an Basin, five terraces in the Ledu Basin and 12 terraces in the Minhe Basin are recognized. Sedimentology research shows that the geomorphologic and sedimentological pattern of the Huang Shui River, which is located at the margin of Tibet, are different from that of the rivers at other regions. The formation process of the terrace is more complicated at the Huang Shui catchment： both accumulation terrace and erosion terrace were formed in each basin and accumulation terraces were developed in some basins when erosion terraces were formed in other basins, indicating fluvial aggradation may occur in some basins simultaneously with river incision in other basins. A conceptual model of the formation process of these two kinds of fluvial terraces at Huang Shui catchment is brought forward in this paper. First, the equilibrium state of the river is broken because of climatic change and/or tectonic movement, and the river incises in all basins in the whole catchment until reaching a new equilibrium state. Then, the downstream basin subsides quickly and the equilibrium state is broken again, and the river incises at upstream basins while the river accumulates at the subsidence basin quickly until approaching a new equilibrium state again. Finally, the river incises in the whole catchment because of climatic change and/or tectonic movement and the accumulation terrace is formed at the subsidence basin while the erosion terrace is formed at other basins. The existence of the accumulation terrace implied the tectonic subsidence in the sub-basins in Huang Shui catchment. These tectonic subsidence movements gradually developed from the downstream Minhe Basin to the upstream Huangyuan Basin. Dating the terrace sequence has potential to uncover the relationship between the subsidence in the catchment and the regional tectonic at the northeastern Tibetan Plateau.

Elevation and Land Use Types Have Significant Impacts on Spatial Variability of Soil Organic Matter Content in Hani Terraced Field of Yuanyang County,China

Soil organic matter （SOM） content is one of the most important indicators of the sustainability of soil. To maintain sustainable soil utilization and management in fragile Hani terraced field, it is meaningful to investigate the effects of topography and land use type on SOM content. Descriptive statistics and geostatistics were used to analyze the data and the kriging method was applied to map the spatial patterns of SOM content. The results showed that the mean SOM content was 32.76 g/kg, with a variation coefficient of 40%. The SOM content was affected by elevation and land use type. As the increase of elevation, the SOM content in Hani terraced field also increased obviously. The SOM content in tea garden, which is almost at high elevation, was the highest in all six land use types, and the SOM content decreased in a following sequence： tea garden 〉 paddy field 〉 corn field 〉 banana garden 〉 cassava field 〉 sugarcane field. In addition, at the same elevation, the paddy field had the highest SOM content compared with other land use types. All these results demonstrate that paddy field is the most efficient and suitable land use type for SOM conservation at high, middle or low elevations in the fragile Hani terraced field. In order to protect soil quality and maintain the sustainable agricultural development, it is necessary to maintain or even to enlarge the area of paddy field in Yuanyang county, Yunnan Province, China.

Tourist preferences for agricultural landscapes:a case study of terraced paddy fields in Noto Peninsula,Japan

Many agricultural landscapes have been formed through the interaction and co-evolution of nature and people, and represent the living landscapes shaped over time through intensive and continuous human cultivation. Terraced paddy fields are being re-evaluated to take into account the multiple functions they fill beyond only rice cultivation, particularly their contribution to the national biodiversity strategy of Japan. Since the 1990 s, terraced paddy fields have been considered a representative cultural landscape of Japan and, at the same time, multi-stakeholder conservation activities have been conducted throughout Japan to reverse the increasing abandonment of terraces. Shiroyone Senmaida is an outstanding cultural landscape and a major tourist attraction in Noto Peninsula, Ishikawa Prefecture, which was designated through an initiative by the Food and Agriculture Organization(FAO) as a Globally Important Agricultural Heritage Systems(GIAHS) pilot site in 2011. It is important to clarify tourist preference for terraced paddy field landscapes to contribute to future policy making toward improved agricultural landscape conservation. A key finding of this study is that tourists visiting toenjoy the agricultural landscape are also concerned on the sustainability of the farming methods and preferred to maintain the naturalness of the landscape. Respondents with higher educational levels and greater concern for the biological and traditional farming knowledge aspects of the rice terraces were also more inclined to favor sustainable farming practices. Tourists preferred to maintain the naturalness and rurality of the agricultural landscape, and indicated that construction of excessive tourist facilities would cause the landscape to deteriorate. It was suggested that the local community and surroundings, including rural settlements, hills, and forests, should also be conserved together with the scenic terrace.

Magnetostratigraphy of a Loess-Paleosol Sequence from Higher Terrace of the Daduhe River in the Eastern Margin of the Tibetan Plateau and Its Geological Significance

The eolian deposits distributed in the river valleys in the eastern margin of the Tibetan Plateau （TP） are very useful in neotectonic and paleoclimatic studies. Firstly, the climate in the eastern margin of the TP is mainly controlled by the Indian summer monsoon, and detailed studies on the loess-paleosol sequences in this region can provide valuable terrestrial evidence of past changes in the Indian summer monsoon. Secondly, the river terraces in the eastern margin of the TP are considered to be a sensitive recorder of neotectonism to reflect the timing and amplitude of the TP uplift.

A combined survey to evaluate the thermal behavior of loess for a landslide-prone slope on the Heifangtai terrace in Northwest China

A combined survey including infrared thermography(IRT)and field-laboratory tests were conducted to analyze the thermal responses and thermal properties of loess on a landslide-prone loess slope in the Heifangtai terrace in Northwest China aiming at preliminarily demonstrating the potential of IRT as a complementary technique to the investigation of irrigation-induced loess landslides.Multitemporal thermographic surveys corresponding to various solar radiation intensities during the afternoon were carried out on the landslide-prone loess slope.Accordingly,the spatiotemporal distribution of the thermal responses within the observed slope surface was analyzed qualitatively and quantitatively.Meanwhile,field and laboratory investigations were also performed on the thermal properties of different landslide materials.The results indicate that loess,a landslide-prone deposit that usually has a relatively high water content,exhibits different thermal properties and anomalies,including a lower surface temperature and greater thermal inertia,compared to surrounding zones without landslides.The groundwater table and corresponding seepage line could also be obtained by determining the potential boundary between the thermal response distribution of landslide scarps and that of saturated deposits in the presence of landslides.The results of these investigations are expected to provide insight for future endeavors combining infrared thermography with other efficient survey methodologies(e.g.,InSAR,which can monitor the active displacement of a loess slope)to evaluate the activity of this kind of excessive irrigation-induced loess landslide.

Assessment of Soil Loss in the Mirabah Basin: An Overview of the Potential of Agricultural Terraces as Ancestral Practices (Saudi Arabia)

Water erosion remains the major problem in many countries, especially those with an extension in the arid and semi-arid area and those marked by a long dry season. The intensification of land degradation which is a result of the strong erosive dynamics on a global scale has stimulated the initiative of multidisciplinary researchers investigate the issue of water erosion from its various facets [1] [2]. The goal is to preserve water and soil, two resources threatened. Multiple attempts were made to diagnose and implement empirical and experimental methods for quantitative estimation of soil loss caused by diffuse erosion. Indeed, the Eastern slope of the high mountains of Asir (Saudi Arabia), formerly worn and cut by the depression of rivers and undeniable branching of the river system, deserves to be studied in detail given the release of a huge erosive potential that is responsible for soil losses that are increasing gradually and continuously. The purpose of this paper was to validate the suitability of agricultural terraces in terms of soil preservation, using the results of the soil loss application as an indicator of the state of function of these latter. Many studies have addressed the agricultural terraces, however, only a few of them have focused on the relationship between erosion and agricultural terraces through an experimental approach. Previous work has concentrated mainly on their socio-economic impact;whilst the knowledge of their environmental impact remained scarce. In terms of the climate change context, soil erosion is becoming a central problem in Asir region. Thus, in this way, the application of the universal equation of soil loss was very helpful to explain and predict the role of each factor. Nevertheless, extreme caution and great care must be taken because of the application of this model outside its frame.

Exploitation Countermeasures of Farming Culture Tourism in the Dabie Mountains: Thinking on the Investigation of Hani Terrace Tourism Development in Yunan Province

Farming culture is the main part of Chinese outstanding traditional culture and also the important spiritual and cultural resources to construct the core values of the Chinese nation. In the new era, fully exploring and making full use of farming culture resources has important practical significance for the protection, inheritance and innovation of Chinese excellent traditional culture. The rapid development and successful brand shaping of Hani terrace tourism could provide experience for the exploration and utilization of farming culture tourism resources in other areas of China. Based on the analysis of development process of Hani terrace tourism as well as the successful experience of other regions for reference, ideas of developing farming culture tourism in the Dabie Mountains were proposed.

Origin and Distribution of Heavy Minerals in the Surficial and Subsurficial Sediments of the Alluvial Nile River Terraces

Origin and distribution of the heavy minerals of surficial and subsurficial sediments has been investigated in the alluvial Nile River terraces, Khartoum North, Sudan. Heavy mineral assemblages in the very fine sand fraction (0.063 - 0.125 mm) of 10 sediment samples were identified using petrography microscope. Results of descriptive statistical parameters revealed that most sediments samples belonged within very poorly sorted to extremely poorly sorted, strongly negative skewed to strongly positive skewed and mesokurtic to very leptokurtic. The quartz was the dominant in the opaque minerals in all sediments. The non-opaque heavy minerals were dominant by zircon, tourmaline, rutile, garnet, sillimanite, and andalusite. Results revealed that the ultrastable minerals (zircon, tourmaline and rutile) were found in all sediments with range from (2% - 47.36%, 2.08% - 29% and 3% - 24.99%), respectively. Garnet, sillimanite and andalusite were also found with range from (5% - 67%, 1% - 9.09% and 1% - 50%), respectively. Heavy mineral assemblage indentifies sources that are not bounded to the local origin. The proportion and presence of heavy minerals from outside source rocks indicated relatively strong reworking of zircon sand from the outer-shelf to inner-shelf as well relatively long distance of transport. Fluvial and Aeolian sediments were the dominant environments in the investigated area. We conclude that most heavy minerals in the study area are originally derived from gneisses and schist metamorphic rocks and some igneous rocks of the Ethiopian plateau.

Distribution and Formation of Fluvial Terraces in Huangshui Catchment(Northeastern Tibetan Plateau) and Its Tectonic Implication

River evolution at margins of the Tibetan Plateau may provide valuable information for understanding climatic change and tectonic movement of the past. Here we focus on the Huangshui River,a tributary of the Yellow River,crossing a series of tectonically subsided and uplifted areas that show diversity patterns of terrace formation.The distribution of fluvial terrace is studied by mapping and dating.Three terraces in Haiyan basin,four terraces in Huangyuan basin,19 terraces in Xi’ning basin,nine terraces in Ping’an basin,five terraces in Ledu basin and 12 terraces in Minhe basin are recognized.Magne-

Enhanced electrochemical CO_(2)-to-C_(2+) conversion from synergistic interaction between terrace and step sites on monocrystalline highindex Cu facets

1. Introduction The increasing global demand for sustainable energy sources and emerging environmental issues have pushed the development of energy conversion and storage technologies to the forefront of chemical research [1,2]. In particular, electrochemical CO_(2) reduction(CO_(2) R) to value-added fuels and chemicals presents a feasible pathway for renewable energy storage and could help mitigate the ever-increasing CO_(2) emissions [3].

RESPONSE OF RIVER TERRACES TO HOLOCENE CLIMATIC CHANGES IN HEXICORRIDOR,GANSU,CHINA

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The edges and terrace effect of Ag particles on optical resonance absorption property

Alternative Ag and Si02 multilayers are prepared by using radio frequency magnetron sputtering. The Ag particles are found to diffuse toward and mostly accumulate near the surface of the Ag-SiO2 composite film via a rapid thermal treatment. Different shapes of the Ag particles are obtained by changing the thickness of each Ag and SiO2 layer. The response absorption property of the Ag composite film is also investigated. We relate the resonance absorption to the surface level and the Fermi level. To induce the obvious resonance absorption in an Ag composite film, it is necessary to maintain special shapes with sharp edges and wide terraces and to maintain the particle sizes ranging from 0 nm to