Current Location:home > Browse

Institution

1. chinaXiv:202101.00071 [pdf]

Damage by wind-blown sand and its control measures along the Taklimakan Desert Highway in China

LI Congjuan; WANG Yongdong; LEI Jiaqiang; XU Xinwen; WANG Shijie; FAN Jinglong; LI Shengyu
Subjects: Geosciences >> Geography

Desertification is one of the most serious environmental problems in the world, especially in the arid desert regions. Combating desertification, therefore, is an urgent task on a regional or even global scale. The Taklimakan Desert in China is the second largest mobile desert in the world and has been called the ''Dead Sea'' due to few organisms can exist in such a harsh environment. The Taklimakan Desert Highway, the longest desert highway (a total length of 446 km) across the mobile desert in the world, was built in the 1990s within the Taklimakan Desert. It has an important strategic significance regarding oil and gas resources exploration and plays a vital role in the socio-economic development of southern Xinjiang, China. However, wind-blow sand seriously damages the smoothness of the desert highway and, in this case, mechanical sand control system (including sand barrier fences and straw checkerboards) was used early in the life of the desert highway to protect the road. Unfortunately, more than 70% of the sand barrier fences and straw checkerboards have lost their functions, and the desert highway has often been buried and frequently blocked since 1999. To solve this problem, a long artificial shelterbelt with the length of 437 km was built along the desert highway since 2000. However, some potential problems still exist for the sustainable development of the desert highway, such as water shortage, strong sandstorms, extreme environmental characteristics and large maintenance costs. The study aims to provide an overview of the damages caused by wind-blown sand and the effects of sand control measures along the Taklimakan Desert Highway. Ultimately, we provide some suggestions for the biological sand control system to ensure the sustainable development of the Taklimakan Desert Highway, such as screening drought-resistant species to reduce the irrigation requirement and ensure the sound development of groundwater, screening halophytes to restore vegetation in the case of soil salinization, and planting cash crops, such as Cistanche, Wolfberry, Apocynum and other cash crops to decrease the high cost of maintenance on highways and shelterbelts.

submitted time 2021-01-22 From cooperative journals:《Journal of Arid Land》 Hits66Downloads30 Comment 0

2. chinaXiv:202101.00072 [pdf]

How precipitation and grazing influence the ecological functions of drought-prone grasslands on the northern slopes of the Tianshan Mountains, China?

HUANG Xiaotao; LUO Geping; CHEN Chunbo; PENG Jian; ZHANG Chujie; ZHOU Huakun; YAO Buqing; MA Zhen; XI Xiaoyan
Subjects: Geosciences >> Geography

Drought-prone grasslands provide a critical resource for the millions of people who are dependent on livestock for food security. However, this ecosystem is potentially vulnerable to climate change (e.g., precipitation) and human activity (e.g., grazing). Despite this, the influences of precipitation and grazing on ecological functions of drought-prone grasslands in the Tianshan Mountains remain relatively unexplored. Therefore, we conducted a systematic field investigation and a clipping experiment (simulating different intensities of grazing) in a drought-prone grassland on the northern slopes of the Tianshan Mountains in China to examine the influences of precipitation and grazing on aboveground biomass (AGB), soil volumetric water content (SVWC), and precipitation use efficiency (PUE) during the period of 2014–2017. We obtained the meteorological and SVWC data using an HL20 Bowen ratio system and a PR2 soil profile hydrometer, respectively. We found that AGB was clearly affected by both the amount and seasonal pattern of precipitation, and that PUE may be relatively low in years with either low or excessive precipitation. The PUE values were generally higher in the rapid growing season (April–July) than in the entire growing season (April–October). Overall, moderate grazing can promote plant growth under water stress conditions. The SVWC value was higher in the clipped plots than in the unclipped plots in the rapid growing season (April–July), but it was lower in the clipped plots than in the unclipped plots in the slow growing season (August–October). Our findings can enhance the understanding of the ecological effects of precipitation and grazing in drought-prone grasslands and provide data that will support the effective local grassland management.

submitted time 2021-01-22 From cooperative journals:《Journal of Arid Land》 Hits60Downloads31 Comment 0

3. chinaXiv:202101.00073 [pdf]

Transformation of vegetative cover on the Ustyurt Plateau of Central Asia as a consequence of the Aral Sea shrinkage

Adilov BEKZOD; Shomurodov HABIBULLO; FAN Lianlian; LI Kaihui; MA Xuexi; LI Yaoming
Subjects: Geosciences >> Geography

The gradual shrinkage of the Aral Sea has led to not only the degradation of the unique environments of the Aral Sea, but also numerous and fast developing succession processes in the neighborhood habitats surrounding the sea. In this study, we investigated the vegetative succession processes related to the Aral Sea shrinkage in the Eastern Cliff of the Ustyurt Plateau in Republic of Uzbekistan, Central Asia. We compared the results of our current investigation (2010–2017) on vegetative communities with the geobotany data collected during the 1970s (1970–1980). The results showed great changes in the mesophytic plant communities and habitat aridization as a result of the drop in the underground water level, which decreased atmospheric humidity and increased the salt content of the soil caused by the shrinkage of the Aral Sea. In the vegetative communities, we observed a decrease in the Margalef index (DMg), which had a positive correlation with the poly-dominance index (I-D). The main indications of the plant communities' transformation were the loss of the weak species, the appearance of new communities with low species diversity, the stabilization of the projective cover of former resistant communities, as well as the appearance of a new competitive species, which occupy new habitats.

submitted time 2021-01-22 From cooperative journals:《Journal of Arid Land》 Hits51Downloads25 Comment 0

4. chinaXiv:202101.00074 [pdf]

Long-term variations in runoff of the Syr Darya River Basin under climate change and human activities

Sanim BISSENBAYEVA; Jilili ABUDUWAILI; Assel SAPAROVA; Toqeer AHMED
Subjects: Geosciences >> Geography

In this study, we analyzed the hydrological and meteorological data from the Syr Darya River Basin during the period of 1930–2015 to investigate variations in river runoff and the impacts of climate change and human activities on river runoff. The Syr Darya River, which is supplied by snow and glacier meltwater upstream, is an important freshwater source for Central Asia, as nearly half of the population is concentrated in this area. River runoff in this arid region is sensitive to climate change and human activities. Therefore, estimation of the climatic and hydrological changes and the quantification of the impacts of climate change and human activities on river runoff are of great concern and important for regional water resources management. The long-term trends of hydrological time series from the selected 11 hydrological stations in the Syr Darya River Basin were examined by non-parametric methods, including the Pettitt change point test and Mann-Kendall trend tests. It was found that 8 out of 11 hydrological stations showed significant downward trends in river runoff. Change of river runoff variations occurred in the year around 1960. Moreover, during the study period (1930–2015), annual mean temperature, annual precipitation, and annual potential evapotranspiration in the river basin increased substantially. We employed hydrological sensitivity method to evaluate the impacts of climate change and human activities on river runoff based on precipitation and potential evapotranspiration. It was estimated that human activities accounted for over 82.6%–98.7% of the reduction in river runoff, mainly owing to water withdrawal for irrigation purpose. The observed variations in river runoff can subsequently lead to adverse ecological consequences from an ecological and regional water resources management perspective.

submitted time 2021-01-22 From cooperative journals:《Journal of Arid Land》 Hits47Downloads23 Comment 0

5. chinaXiv:202101.00075 [pdf]

Development of a large-scale remote sensing ecological index in arid areas and its application in the Aral Sea Basin

WANG Jie; LIU Dongwei; MA Jiali; CHENG Yingnan; WANG Lixin
Subjects: Geosciences >> Geography

The Aral Sea Basin in Central Asia is an important geographical environment unit in the center of Eurasia. It is of great significance to the ecological protection and sustainable development of Central Asia to carry out dynamic monitoring and effective evaluation of the eco-environmental quality of the Aral Sea Basin. In this study, the arid remote sensing ecological index (ARSEI) for large-scale arid areas was developed, which coupled the information of the greenness index, the salinity index, the humidity index, the heat index, and the land degradation index of arid areas. The ARSEI was used to monitor and evaluate the eco-environmental quality of the Aral Sea Basin from 2000 to 2019. The results show that the greenness index, the humidity index and the land degradation index had a positive impact on the quality of the ecological environment in the Aral Sea Basin, while the salinity index and the heat index exerted a negative impact on the quality of the ecological environment. The eco-environmental quality of the Aral Sea Basin demonstrated a trend of initial improvement, followed by deterioration, and finally further improvement. The spatial variation of these changes was significant. From 2000 to 2019, grassland and wasteland (saline alkali land and sandy land) in the central and western parts of the basin had the worst ecological environment quality. The areas with poor ecological environment quality are mainly distributed in rivers, wetlands, and cultivated land around lakes. During the period from 2000 to 2019, except for the surrounding areas of the Aral Sea, the ecological environment quality in other areas of the Aral Sea Basin has been improved in general. The correlation coefficients between the change in the eco-environmental quality and the heat index and between the change in the eco-environmental quality and the humidity index were –0.593 and 0.524, respectively. Climate conditions and human activities have led to different combinations of heat and humidity changes in the eco-environmental quality of the Aral Sea Basin. However, human activities had a greater impact. The ARSEI can quantitatively and intuitively reflect the scale and causes of large-scale and long-time period changes of the eco-environmental quality in arid areas; it is very suitable for the study of the eco-environmental quality in arid areas.

submitted time 2021-01-22 From cooperative journals:《Journal of Arid Land》 Hits56Downloads29 Comment 0

6. chinaXiv:202101.00076 [pdf]

Investigation of crop evapotranspiration and irrigation water requirement in the lower Amu Darya River Basin, Central Asia

Durdiev KHAYDAR; CHEN Xi; HUANG Yue; Makhmudov ILKHOM; LIU Tie; Ochege FRIDAY; Abdullaev FARKHOD; Gafforov KHUSEN; Omarakunova GULKAIYR
Subjects: Geosciences >> Geography

High water consumption and inefficient irrigation management in the agriculture sector of the middle and lower reaches of the Amu Darya River Basin (ADRB) have significantly influenced the gradual shrinking of the Aral Sea and its ecosystem. In this study, we investigated the crop water consumption in the growing seasons and the irrigation water requirement for different crop types in the lower ADRB during 2004–2017. We applied the FAO Penman–Monteith method to estimate reference evapotranspiration (ET0) based on daily climatic data collected from four meteorological stations. Crop evapotranspiration (ETc) of specific crop types was calculated by the crop coefficient. Then, we analyzed the net irrigation requirement (NIR) based on the effective precipitation with crop water requirements. The results indicated that the lowest monthly ET0 values in the lower ADRB were found in December (18.2 mm) and January (16.0 mm), and the highest monthly ET0 values were found in June and July, with similar values of 211.6 mm. The annual ETc reached to 887.2, 1002.1, and 492.0 mm for cotton, rice, and wheat, respectively. The average regional NIR ranged from 514.9 to 715.0 mm in the 10 Irrigation System Management Organizations (UISs) in the study area, while the total required irrigation volume for the whole region ranged from 4.2×109 to 11.6×109 m3 during 2004–2017. The percentages of NIR in SIW (surface irrigation water) ranged from 46.4% to 65.2% during the study period, with the exceptions of the drought years of 2008 and 2011, in which there was a significantly less runoff in the Amu Darya River. This study provides an overview for local water authorities to achieve optimal regional water allocation in the study area.

submitted time 2021-01-22 From cooperative journals:《Journal of Arid Land》 Hits53Downloads28 Comment 0

7. chinaXiv:202101.00077 [pdf]

Spatial and temporal gradients in the rate of dust deposition and aerosol optical thickness in southwestern Iran

Mansour A FOROUSHANI; Christian OPP; Michael GROLL
Subjects: Geosciences >> Geography

The southwestern Iran is one of the regions that are most prone to dust events. The objective of this study is the analysis of the spatial and temporal distributions of dust deposition rate as a key factor for finding the relative impact of the dust. First, the monthly mean aerosol optical thickness (AOT) from Moderate Resolution Imaging Spectroradiometer (MODIS) was analyzed and compared with the dust amount variations from ground deposition rate (GDR), and the results were further used to investigate the spatial and temporal distributions of dust events in southwestern Iran for the period between 2014 and 2015. Moving air mass trajectories, using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, were proven to be a discriminator of their local and regional origin. The results from GDR analysis produced a correlation coefficient between dust event history and deposition rates at dust magnitudes of >0.93 that is meaningful at the 95% confidence level. Furthermore, the deposition rates varied from 3 g/m2 per month in summer to 10 g/m2 per month in spring and gave insight into the transport direction of the dust. Within the same time series, AOT correspondences with MODIS on Terra in four aerosol thickness layers (clean, thin, thick, and strong thick) were shown in relation to each other. The deepest mixed layers were observed in spring and summer with a thickness of approximately 3500 m above ground level in the study area. Investigations of ground-based observations were correlated with the same variations for each aerosol thickness layer from MODIS images and they can be applied to discriminate layers of aeolian dust from layers of other aerosols. Together, dust distribution plots from AOT participated to enhance mass calculations and estimation deposition rates from the thick and strong thick aerosol thickness layers using the results from GDR. Despite all the advances of AOT, under certain circumstances, ground-based observations are better able to represent aerosol conditions over the study area, which were tested in southwestern Iran, even though the low number of observations is a commonly acknowledged drawback of GDR.

submitted time 2021-01-22 From cooperative journals:《Journal of Arid Land》 Hits47Downloads26 Comment 0

8. chinaXiv:202101.00067 [pdf]

基于最优供需分配的公共设施空间可达性分析

翟石艳; 何新新; 孔云峰; 罗静静; 宋根鑫
Subjects: Geosciences >> Geography

空间可达性是衡量公共服务设施公平性的重要指标,在医疗、教育、休闲等公共服务的布局规划中得到广泛应用。然而,现有可达性模型难以充分反映服务供需关系,计算指标也缺乏物理意义。本文提出新的可达性计算方法取代现有方法。该方法基于最优供需分配模型,将设施服务分配给需求者,根据分配结果计算空间可达性指标。给定服务设施与需求的空间分布,以最小化旅行成本为目标,顾及设施服务能力,采用经典的运输问题模型确定最优的服务供需分配方案,进而度量服务的空间可达性。以郑州市某区社区卫生服务为例,求解 25个中心与1333个居住小区的最优服务配置。使用最优配置结果确定每个设施的服务范围、每个居住小区使用服务的旅行时间,以及特定时间阈值的服务覆盖比率。与流行的两步移动搜索法相比,新方法的计算指标具有明确的物理意义。本文提出的可达性评价方法无需参数,计算高效,结果易于解释,在公共服务评价及设施布局规划方面具有应用潜力。

submitted time 2021-01-19 Hits122Downloads60 Comment 0

9. chinaXiv:202101.00045 [pdf]

Spectral parameter-based models for leaf potassium concentration estimation in Ping'ou hybrid hazelnut

ZHAO Shanchao; PAN Cunde
Subjects: Geosciences >> Geography

Ping′ou hybrid hazelnut is produced by cross cultivation and is widely cultivated in northern China with good development prospects. Based on a field experiment of fertilizer efficiency, the leaf spectral reflectance and leaf potassium (K) concentration were measured with different quantities of K fertilizer applied at four fruit growth stages (fruit setting stage, fruit rapid growth stage, fruit fat-change stage, and fruit near-maturity stage) of Ping′ou hybrid hazelnut in 2019. Spectral parameters that were significantly correlated with leaf K concentration were selected using Pearson correlation analysis, and spectral parameter estimation models of leaf K concentration were established by employing six different modelling methods (exponential function, power function, logarithmic function, linear function, quadratic function, and cubic function). The results indicated that at the fruit setting period, leaf K concentration was significantly correlated with Dy (spectra slope of yellow edge), Rg (reflectance of the green peak position), λo (red valley position), SDb (blue edge area), SDr/SDb (where SDr represents red edge area), and (SDr–SDb)/(SDr+SDb) (P<0.01). There were significant correlations of leaf K concentration with Dy, Rg, SDb, Rg/Ro (where Ro is the reflectance of the red valley position), and (Rg–Ro)/(Rg+Ro) at the fruit rapid growth stage (P<0.01). Further, significant correlations of leaf K concentration with Rg, Ro, RNIR/Green, and RNIR/Blue were obtained at the fruit fat-change period (P<0.01). Finally, leaf K concentration showed significant correlations with Dr, Rg, Ro, SDy (yellow edge area), and SDr at the fruit near-maturity stage (P<0.01). Through a cubic function analysis, regression estimation model of leaf K concentration with highest fitting degree (R2) values at the four fruit growth stages was established. The findings in this study demonstrated that it is feasible to estimate leaf K concentration of Ping′ou hybrid hazelnut at the various phenological stages of fruit development by establishing regression models between leaf K concentration and spectral parameters.

submitted time 2021-01-15 From cooperative journals:《Journal of Arid Land》 Hits103Downloads39 Comment 0

10. chinaXiv:202101.00046 [pdf]

Germination strategies of annual and short-lived perennial species in the Arabian Desert

Arvind BHATT; David J GALLACHER; Paulo R M SOUZA-FILHO
Subjects: Geosciences >> Geography

Germination timing is highly regulated in short-lived plant species since it strongly influences recruitment success of vegetation. In deserts, the spatiotemporal distribution of plant-available water is highly episodic and unpredictable, making winter months more favorable for seed germination when other abiotic conditions co-occur. We hypothesized that changes in photoperiod and thermoperiod would impact germination more in seeds that had undergone in situ storage. We assessed 21 annual and short-lived perennial species in the Arabian Desert to find (1) if seeds were dormant at maturity, (2) if in situ seed storage increased germination percentage compared with no storage, (3) if photoperiod and thermoperiod germination requirements were influenced by in situ storage, and (4) if a phylogenetic association in seed germination could be observed. Seeds of each species collected in early 2017 were divided into two batches. One was tested for germination within one week (fresh seeds). The other was stored in situ at the maternal location (stored seeds) until October 2017 and tested for seed germination in the first week of November. Seed germination was conducted in incubators at two thermoperiods (15°C/20°C and 20°C/30°C; 12 h/12 h), and two photoperiods (12 and 0 h light per day). Results indicated that seed germination percentages of 13 species were significantly enhanced by in situ storage. A thermoperiod response was exhibited by stored, but not fresh seeds. Light exposure increased germination of fresh seeds but had only a minimal effect on stored seeds. Germination traits exhibited no phylogenetic correlation. This result indicated that selection pressure for germination strategy was stronger than that for taxonomic traits of these desert species.

submitted time 2021-01-15 From cooperative journals:《Journal of Arid Land》 Hits108Downloads45 Comment 0

12345678910  Last  Go  [104 Pages/ 1040 Totals]