Subjects: Geosciences >> Geography submitted time 2023-12-20 Cooperative journals: 《干旱区科学》
Abstract： Infiltration is an important part of the hydrological cycle, and it is one of the main abstractions accounted for in the rainfall-runoff modeling. The main purpose of this study is to compare the infiltration models that were used to assess the infiltration rate of the Mitidja Plain in Algeria. Field infiltration tests were conducted at 40 different sites using a double ring infiltrometer. Five statistical comparison criteria including root mean squared error (RMSE), normalized root mean squared error (NRMSE), coefficient of correlation (CC), Nash-Sutcliffe efficiency (NSE), and Kling-Gupta efficiency (KGE) were used to determine the best performing infiltration model and to confirm anomalies between predicted and observed values. Then we evaluated performance of five models (i.e., the Philip model, Kostiakov model, Modified Kostiakov model, Novel model, and Horton model) in simulating the infiltration process based on the adjusted performance parameters cited above. Results indicated that the Novel model had the best simulated water infiltration process in the Mitidja Plain in Algeria. However, the Philip model was the weakest to simulate the infiltration process. The conclusion of this study can be useful for estimating infiltration rate at various sites using a Novel model when measured infiltration data are not available and are useful for planning and managing water resources in the study area.
Subjects: Geosciences >> Geography submitted time 2023-12-20 Cooperative journals: 《干旱区科学》
Abstract： The Ili River Delta (IRD) is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia. In this study, we selected the IRD as a typical research area, and simulated the water yield and water conservation from 1975 to 2020 using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. We further analyzed the temporal and spatial variations in the water yield and water conservation in the IRD from 1975 to 2020, and investigated the main driving factors (precipitation, potential evapotranspiration, land use/land cover change, and inflow from the Ili River) of the water conservation variation based on the linear regression, piecewise linear regression, and Pearson's correlation coefficient analyses. The results indicated that from 1975 to 2020, the water yield and water conservation in the IRD showed a decreasing trend, and the spatial distribution pattern was "high in the east and low in the west"; overall, the water conservation of all land use types decreased slightly. The water conservation volume of grassland was the most reduced, although the area of grassland increased owing to the increased inflow from the Ili River. At the same time, the increased inflow has led to the expansion of wetland areas, the improvement of vegetation growth, and the increase of regional evapotranspiration, thus resulting in an overall reduction in the water conservation. The water conservation depth and precipitation had similar spatial distribution patterns; the change in climate factors was the main reason for the decline in the water conservation function in the delta. The reservoir in the upper reaches of the IRD regulated runoff into the Lake Balkhash, promoted vegetation restoration, and had a positive effect on the water conservation; however, this positive effect cannot offset the negative effect of enhanced evapotranspiration. These results provide a reference for the rational allocation of water resources and ecosystem protection in the IRD.
Subjects: Geosciences >> Geography submitted time 2023-12-18 Cooperative journals: 《干旱区科学》
Abstract： This study proposes a novel form of environmental reservoir operation through integrating environmental flow supply, drought analysis, and evolutionary optimization. This study demonstrates that simultaneous supply of downstream environmental flow of reservoir as well as water demand is challenging in the semi-arid area especially in dry years. In this study, water supply and environmental flow supply were 40% and 30% in the droughts, respectively. Moreover, mean errors of supplying water demand as well as environmental flow in dry years were 6 and 9 m3/s, respectively. Hence, these results highlight that ecological stresses of the downstream aquatic habitats as well as water supply loss are considerably escalated in dry years, which implies even using environmental optimal operation is not able to protect downstream aquatic habitats properly in the severe droughts. Moreover, available storage in reservoir will be remarkably reduced (averagely more than 30´106 m3 compared with optimal storage equal to 70´106 m3), which implies strategic storage of reservoir might be threatened. Among used evolutionary algorithms, particle swarm optimization (PSO) was selected as the best algorithm for solving the novel proposed objective function. The significance of this study is to propose a novel objective function to optimize reservoir operation in which environmental flow supply is directly addressed and integrated with drought analysis. This novel form of optimization system can overcome uncertainties of the conventional objective function due to considering environmental flow in the objective function as well as drought analysis in the context of reservoir operation especially applicable in semi-arid areas. The results indicate that using either other water resources for water supply or reducing water demand is the only solution for managing downstream ecological impacts of the river ecosystem. In other words, the results highlighted that replanning of water resources in the study area is necessary. Replacing the conventional optimization system for reservoir operation in the semi-arid area with proposed optimization system is recommendable to minimize the negotiations between stakeholders and environmental managers.
Subjects: Geosciences >> Geography submitted time 2023-12-18 Cooperative journals: 《干旱区科学》
Abstract： The effect of global climate change on vegetation growth is variable. Timely and effective monitoring of vegetation drought is crucial for understanding its dynamics and mitigation, and even regional protection of ecological environments. In this study, we constructed a new drought index (i.e., Vegetation Drought Condition Index (VDCI)) based on precipitation, potential evapotranspiration, soil moisture and Normalized Difference Vegetation Index (NDVI) data, to monitor vegetation drought in the nine major river basins (including the Songhua River and Liaohe River Basin, Haihe River Basin, Yellow River Basin, Huaihe River Basin, Yangtze River Basin, Southeast River Basin, Pearl River Basin, Southwest River Basin and Continental River Basin) in China at 1-month–12-month (T1–T12) time scales. We used the Pearson's correlation coefficients to assess the relationships between the drought indices (the developed VDCI and traditional drought indices including the Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Soil Moisture Index (SSMI) and Self-calibrating Palmer Drought Severity Index (scPDSI)) and the NDVI at T1–T12 time scales, and to estimate and compare the lag times of vegetation response to drought among different drought indices. The results showed that precipitation and potential evapotranspiration have positive and major influences on vegetation in the nine major river basins at T1–T6 time scales. Soil moisture shows a lower degree of negative influence on vegetation in different river basins at multiple time scales. Potential evapotranspiration shows a higher degree of positive influence on vegetation, and it acts as the primary influencing factor with higher area proportion at multiple time scales in different river basins. The VDCI has a stronger relationship with the NDVI in the Songhua River and Liaohe River Basin, Haihe River Basin, Yellow River Basin, Huaihe River Basin and Yangtze River Basin at T1–T4 time scales. In general, the VDCI is more sensitive (with shorter lag time of vegetation response to drought) than the traditional drought indices (SPEI, scPDSI and SSMI) in monitoring vegetation drought, and thus it could be applied to monitor short-term vegetation drought. The VDCI developed in the study can reveal the law of unclear mechanisms between vegetation and climate, and can be applied in other fields of vegetation drought monitoring with complex mechanisms.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： Chlorophyll content is a crucial indicator for characterizing vegetation growth. In this study, we utilized high-spectral technology to rapidly monitor the chlorophyll contents of cotton leaves. We collected 125 cotton leaf seedling samples from Xinjiang and measured their chlorophyll content and spectral data. To achieve this, we employed various spectral preprocessing techniques and used a combination of vegetation indices. Subsequently, we constructed a whale optimization algorithm/random forest regression (WOA-RFR) quantitative inversion model for cotton leaf chlorophyll content. Finally, we conducted a comparative analysis, contrasting the results of the WOA-RFR model with those obtained from the support vector regression (SVR) and RFR models. The results indicated that the spectral transformation methods (logarithm transformation, fractional order differentiation, and wavelet transformation) effectively improved the correlation between the vegetation indices and the chlorophyll content. We also found that the best inversion performance was achieved with the WOA-RFR model using a fractional order differentiation with a transformation order of 0.9 and the Vogelmann3, RVI, DVI, SR 675-700 , Mndvi705, ND, VOG1, NVI, TVI, VOG2 combined vegetation indices. The model exhibited R2 values of 0.920 and 0.955 for the training set and validation set, respectively. The corresponding RMSE values were 0.987 and 0.986, while the MRE values were 0.013 and 0.014. Compared to the RFR and SVR models, the WOA-RFR model demonstrated higher predictive accuracy, and the optimization effect of the WOA algorithm was evident. As a result, this study provides valuable decision- making support for accurately quantifying cotton leaf chlorophyll content.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： This study used yield and water and fertilizer usage efficiency as targets to explore a magnetized water fertilization system suitable for tomato processing via drip irrigation under film. Four magnetized water samples with an intensity of 0 Gs (M0), 2000 Gs (M1), 3000 Gs (M2), and 4000 Gs (M3) as well as three nitrogen application levels of 200 kg N·hm−2 (N1), 250 kg N·hm−2 (N2), and 300 kg N·hm−2 (N3) were set up, and a split zone test design was adopted. Field experiments were conducted. By monitoring the soil moisture content, plant height, stem diameter, and above- ground biomass during the growth period of processed tomatoes, combined with the final yield index, the effects of magnetic nitrogen combination on the water and fertilizer usage efficiency of processed tomatoes were explored. The results showed that magnetized water drip irrigation significantly increased soil moisture content and soil water storage. Magnetic nitrogen coupling was also shown to significantly increase the soil moisture content in the 20- 40 cm soil layer. When the magnetized water intensity was 2270-3678 Gs and the nitrogen rate was 220-230 kg·hm-2, the growth of processed tomatoes was promoted. However, when the magnetization intensity was greater than 4000 Gs and the nitrogen rate was more than 250 kg · hm- 2, the growth of processed tomatoes could not be further improved. As magnetization was increased, the yield and water and fertilizer use efficiency of processed tomatoes increased before decreasing. As the nitrogen application rate was increased, the yield and water use efficiency increased, but the partial productivity of nitrogen fertilizer decreased. Among them, the M2N3 treatment had the highest yield and water use efficiency (169.67 t ·hm- 2 and 35.61 kg ·m- 3), while the M2N1 treatment had the highest nitrogen partial productivity (822.54 kg·kg-1). Using regression and spatial analyses, the magnetic nitrogen range of yield, water use efficiency, and nitrogen partial productivity was 2270-3678 Gs and 220-230 kg N·hm- 2. This study can provide theoretical support for the scientific application of magnetized water and nitrogen fertilizer in tomato processing in Xinjiang and provide scientific guidance for optimizing the magnetic nitrogen combination configuration to improve the yield of tomato processing.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： Human activities are the main drivers of land use change, Which indirectly affects the value of ecological services by influencing the structure and function of terrestrial ecosystems. In this article, We analyze the characteristics of land use change based on a land use transfer matrix and dynamic attitude method. We applied the InVEST model to estimate carbon storage, and we estimated the economic value of carbon storage in each period by combining this value with the compound present value formulas from 2000 to 2020 in the Qilian Mountain region. The results showed that, between 2000 and 2020, grassland and unused land were the main land use types in the Qilian Mountains, accounting for more than 80% of the total area of land, and that the conversion these two land use type was the most obvious conversion. The area of forested and unused land decreased between 2000 and 2020, and the area of other land types increased in the Qilian Mountains due to the intensification of human activities and increased urbanization. From 2000 to 2020, carbon storage was significantly correlated with the distribution of land- use types and showed a spatial distribution of“low in the north- west and high in the south- east”. In addition, carbon storage increased by 44.26 × 104 t in the Qilian Mountains due to the appropriate geographic environment, the strengthening of vegetation protection, and the efforts of artificial management. the carbon storage in arable land, grassland, and waters increased by 73.1×104 t, while the carbon storage of forest land and unused land decreased by 28.8×104 t. The economic value of carbon storage in the Qilian Mountains from 2000 to 2020 increased from 2325.9×106 yuan to 3908.8×106 yuan, with an increment of 1582.9×106 yuan and a growth rate of 68.1%. In particular, the economic value of grassland carbon storage increased by 851.8×106 yuan over the 20-year period, a growth rate of 71.5%, which was the main driver of the increase in the economic value of carbon storage in the region. Carbon storage is increasing in the Qilian Mountains, and the relevant authorities should continue the previous management schemes while remaining alert to the impact of the climate change on carbon storage in the future. This study provides a scientific basis for setting regional targets for optimizing land use, promoting sustainable development and responding to global climate change.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： The Loess Plateau is an important ecological barrier in China. In the context of global change, the carbon balance of the region is of great concern. In this study, based on MOD17A3HGF data, we analyzed the carbon source/sink characteristics of the local area of the Loess Plateau from 2000 to 2020 using the geostatistical model of soil respiration (GSMSR) model, trend analysis, difference analysis, and Geodetector, to reveal the spatial and temporal patterns of the region’s net ecosystem productivity (NEP) and its driving factors from 2000 to 2020. Meanwhile, the study area was divided longitudinally into three subregions, west, center, and east, to compare the variability of drivers within different regions. The results showed that: (1) 49.69% of the localized area of the Loess Plateau shifted from a carbon source to a carbon sink within 21 years. NEP fluctuated upward with time, and was higher in the southeast than in the northwest, with a multi-year average of 12 g C·m−2·a−1· (2) Moisture condition was the main natural factor affecting the spatial distribution of NEP, while land use type was the main anthropogenic factor influencing the spatial distribution of NEP. In addition, the influence of the interaction between different factors on NEP was generally greater than that of single factors. The effects of interactions between different factors on NEP were generally greater than those of individual factors. (3) The factors driving NEP in the three subregions of west, central, and east have clear spatial differentiation characteristics, the central and western regions are more affected by climate, with precipitation, humidity, and other moisture conditions as the main ones. The eastern region is affected by a combination of factors such as topography, climate, and human activities, and anthropogenic interference, represented by land use type, is the strongest among these factors. This knowledge can serve as a basis for effective carbon management strategies and ecosystem conservation efforts in the region.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： The analysis of Net Primary Productivity (NPP) and the driving factors in the Qinghai Lake Basin can provide certain references for the ecological management and sustainable development of the basin. This study estimated the NPP value of the Qinghai Lake Basin based on the Carnegie-Ames-Stanford Approach (CASA) model and quantitatively evaluated the dynamic changes and driving factors of NPP in the Qinghai Lake Basin between 2000 and 2018 through trend analysis, Hurst index, and Geographic Detector. From the perspective of spatial distribution, the results show that the annual average NPP value of the Qinghai Lake Basin was 218.88 g C·m−2. The highest value of the annual average NPP was distributed in the north and south of the Qinghai Lake (375.85 g C·m−2) and the lowest value was distributed on the east bank of the Qinghai Lake (0.11 g C·m−2). From the perspective of time change, the annual average NPP of the basin showed an upward trend between 2000 and 2018, with an increase of 1.61 g C·m−2·a−1, reaching the highest value of 247.30 g C·m−2 in 2018. The seasonal variation showed that the NPP value was highest in July and lowest in January. In the future trend of NPP, Hurst index of less than 0.5 accounted for 75.6% of the study area, indicating that the future trend of NPP of vegetation in the Qinghai Lake Basin may be opposite to the present. Land use types are greatly affected by natural factors; therefore, more attention should be paid to watershed topographic factors and human activities.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： Understanding the species diversity of submerged plant communities in response to nitrogen and phosphorus nutrition levels in sediments can clarify the relationship between the two. This relationship has direct theoretical and practical significance for studying the spatial and temporal changes of wetland vegetation and environment, and has implications for habitat restoration, pollution control, and planning management in the study area and similar areas. In this study, the wetland areas (lakes and ditches) of Yinchuan Plain were used as the research area to conduct a field survey of the submerged plant communities to obtain an understanding of the environmental sediment nutrients. Three typical submerged plant communities were screened out by the community classification method, and the nitrogen and phosphorus nutrient levels of the wetland sediment were evaluated. A structural equation model was used to analyze the relationship between the species diversity of typical submerged plant communities and the nitrogen and phosphorus nutrient components of the sediments. The results revealed that eight common submerged plants exist in the wetlands of Yinchuan Plain. The typical submerged plant communities were identified as a Potamogeton pectinatus community, a Myriophyllum spicatum community, and a Potamogeton crispus community. The species composition diversity and species contribution of the Potamogeton crispus community were high, and the species distribution was uniform. The species in the Potamogeton pectinatus community showed cluster or patchy distribution. Three levels (rich, moderate, and poor) of nitrogen and phosphorus fertility were identified in the sediment of the wetlands of Yinchuan Plain, and moderate and poor levels of fertility were most commonly found. The Potamogeton pectinatus and Myriophyllum spicatum communities were found to grow mainly in the poor- and moderate-level fertility sediment areas, while the Potamogeton crispus community was found to grow in all three levels of sediment nutrient content. The nitrogen and phosphorus nutrition level of the sediment had a significant positive effect on the three typical submerged plant communities, promoting an increase in the community diversity index. The characteristics of the three typical submerged plant communities were mainly affected by species evenness. The nitrogen and phosphorus fertility level of the sediment was mainly affected by the phosphorus level in the sediment.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： To reveal the survival strategy of plants in semi- arid coal mining subsidence areas faced with soil erosion stress, 2-3-year-old Artemisia ordosica plants were used as the test materials and in- situ root structure destruction tests were carried out at four levels: severe stress (P1), moderate stress (P2), mild stress (P3), and control (CK). The changes in growth indices, photosynthetic characteristics, and physiological traits of A. ordosica were measured. The results showed that soil erosion stress significantly inhibited the growth rate of A. ordosica, and that the greater the degree of simulated damage, the more significant the growth inhibition. After severe stress, the growth rates of plant height, crown width, branch length, and branch diameter of A. ordosica decreased by an average of 36.91%, 43.90%, 69.76%, and 66.76 %, respectively, compared to control plants. Soil erosion stress also conferred a significant negative effect on the photosynthesis of A. ordosica, and the greater the degree of damage, the stronger the negative effect. After severe stress, the net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration, transpiration rate, and chlorophyll content of A. ordosica decreased by 39.86%, 59.26%, 7.82%, 51.55%, and 12.33%, respectively, compared to control plants. After 70 days of erosion stress, the activities of superoside dismutase (SOD), peroxidase (POD), and oxidoreductase (CAT) in A. ordosica initially increased and later decreased, and tended to be stable when compared with the control. The malondialdehyde (MDA) content fluctuated within a certain range. Redundancy analysis showed that the level of SOD activity had the most significant effect on the photosynthetic characteristics of A. ordosica. Comprehensive analysis showed that the root fracture of A. ordosica caused by soil erosion in coal mining subsidence areas will reduce its growth rate and inhibit photosynthesis. However, A. ordosica can maintain its growth by regulating the activity of its antioxidase systems and can therefore be considered to be an ecological restoration plant species due to its excellent resistance and adaptability in erosive areas
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： Exploring the differences in the physical and chemical properties of biological soil crusts (BSCs) in different shrub communities in the Gonghe Basin of Qinghai Province to provide theoretical reference for the protection and rational utilization of BSCs resources. The BSCs at different stages of Artemisia desertorum, Caragana microphylla, Salix cheilophila communities in the Gonghe Basin were investigated. Particle composition and nutrient characteristics were studied through field sampling and indoor analysis. The results showed that the particle composition of BSCs in the three shrub communities was dominated by sand (45%– 90%). The sand content of Caragana microphylla>Salix cheilophila>Artemisia desertorum was significantly higher than that of bare sand between shrubs. The contents of total nitrogen, total carbon, organic matter, available phosphorus, available potassium, alkali- hydrolyzable nitrogen, total phosphorus in the BSCs of the Salix cheilophila community were significantly higher than other, and the contents increased with the development of BSCs in the three shrub communities. The shrub community mostly influenced the physical and chemical properties of BSCs, and the shrub biomass was significantly positively correlated with the coverage, thickness, total nitrogen, total carbon, organic matter, available phosphorus, available potassium, available nitrogen, and total phosphorus of BSCs, and significantly negatively correlated with sand content (P<0.05). The shrub community effectively improved the soil structure of BSCs in the sandy land of the Gonghe Basin. The Artemisia desertorum community was more conducive to soil refinement, and the Salix cheilophila community was more conducive to nutrient accumulation.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： To explore the main factors influencing soil salinization in irrigation region of Yellow River of Hongsipu, correlation analysis and principal component analysis were used to study the salinization characteristics of the 0-100 cm soil profile. The results showed the following: (1) The overall soil in the study area is strongly alkaline, with the pH of the lower layer of 20-100 cm soil being significantly higher than that of the upper layer of 0-20 cm (P<0.05), which increases with increasing soil depth. The total salt content of soil also increases with increasing soil depth, showing a bottom aggregation-type profile feature of high at the bottom and low at the surface. The difference in total salt content of each layer of soil was not significant (P<0.05), which the pH of each layer of soil exhibited weak variability, with a relatively uniform spatial distribution. The total salt content of soil in the upper layer showed moderate variability at depths of 0-20 cm, while in the lower layer of depths of 20-100 cm it showed strong variabilily, with differences in spatial distribution appearing with changes in depth. (2) The main cation in the study area is Na++K+, with significant differences in the content of each cation (P<0.05). The main anion is SO2- 4 , which significant difference compared with other anions (P<0.05). The contents of the ions are in following order: SO2- 4 > Na+ +K+ > Ca2 + > Mg2 + > HCO-3 > Cl− > CO2- 3 , and the concentration of each ion also increases with increasing of soil depth, consistent with the changes in total salt and pH. (3) Through correlation analysis and principal component analysis, it was found that the main factors affecting total salt in the irrigation area are SO2- 4 , Cl−, Na++K+, and Mg2+, while the main factors affecting pH are CO2- 3 and HCO-3 . The main salts are sulfate and chloride, but there are significant differences in salt types at different depth profiles. The upper layer of salt is mainly chloride, while the lower layer is a composite of sulfate and chloride. The results of this study prove the main factors affecting the soil salinity characteristics of irrigation region of Yellow River of Hongsipu, and provide a theoretical basis for the treatment of alkali soil in the study area.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： To explore the characteristics of nutrient and enzyme activity in salt-affected soils of different degrees in the Qaidam Basin, five sampling points along the direction from Chahan Salt Lake to Kunlun Mountains were selected. The soil nutrient and enzyme activity characteristics and their correlations were analyzed. The results showed that soil salinization degree, soil depth, and their interactions significantly affected soil nutrient content and enzyme activity (P<0.05), except for soil total potassium. In soils with lower salinity, nutrient availability (except for available potassium) and enzyme activity were higher and decreased with increasing soil depth. Taking organic carbon and invertase as examples, the contents in the S5 sampling site with the lowest salinity degree were 13.83 g·kg−1 and 21.01 mg·g−1·d−1(0-5 cm), 12.85 g·kg−1 and 19.29 mg·g−1·d−1(5-10 cm), and 9.83 g·kg− 1 and 12.19 mg·g− 1 ·d− 1(10-20 cm), significantly higher than those in the S1 site with the highest salinity degree, which had 8.56 g·kg−1 and 1.41 mg·g−1·d−1(0-5 cm), 8.40 g·kg−1 and 1.30 mg·g−1·d−1(5-10 cm), and 8.33 g·kg−1 and 1.26 mg·g−1·d−1(10-20 cm). The correlation analysis showed that in lower salinity areas, soil enzyme activity had a significant or extremely significant positive correlation with most soil nutrients (P<0.05). Therefore, differences were observed in the characteristics of soil nutrients and enzyme activity in salt- affected soils of different degrees in the Qaidam Basin. Soil salinization reduces the effectiveness of soil nutrients, inhibits soil enzyme activity, and reduces the decomposition rate of soil organic matter.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： In order to further explore the influence of precipitation and soil and water conservation measures on runoff sediment, and to gain an in-depth understanding of the driving factors of water and sand changes in small and medium-sized rivers of the Yellow River, M-K test, Morlet wavelet, linear regression and structural equation modeling were used to study the changes in precipitation and the area of soil and water conservation measures in the upper Guanchuan River from 1957-2021, as well as their the mechanism and process of action were studied. The results showed that annual precipitation showed a non-significant decreasing trend (P >0.05), runoff modulus and sand transport modulus showed a significant decreasing trend (P<0.05), and the area of soil and water conservation measures showed an increasing trend. The response of runoff modulus and sand transport modulus to precipitation got weakened, and the response to soil and water conservation measures was gradually strengthened; the key path of precipitation and soil and water conservation measures affecting the change of water and sand was“area of soil and water conservation measures→runoff modulus”, followed by“area of soil and water conservation measures→runoff→sand transport modulus”, then“precipitation→runoff modulus”, and finally“precipitation→runoff modulus→sand transport modulus”. The total effect of precipitation on water and sand change is 0.42 and 0.38 respectively, while the total effect of soil and water conservation measures on water and sand change is - 0.72 and - 0.65 respectively. The main factor affecting water and sand change in the watershed is the area of soil and water conservation measures, and the secondary factor is the amount of precipitation.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： The Bortala River Basin in Xinjiang is short of water resources and is unevenly distributed in time and space. It is important to quantitatively calculate the conversion rates of the surface water and groundwater in different reaches of the basin and as well as at different periods for the purposes of groundwater exploitation and replenishment and for the optimal allocation of water resources. Based on the daily flow measurement data from five monitored sections in the middle reaches of Bortala River from December 1, 2021, to November 30, 2022, Using river runoff analysis method, combined with the P-III distribution frequency curve, comparisons of water quantity between different monitoring sections, and hydrogeological cross-sections. The relationship between the infiltration rate and the runoff in the leaking river section was also fitted. The results showed that: (1) among the five monitoring stations, Bole Hydrology Station had the largest annual runoff, while Chaxiang Bridge had the smallest; (2) the runoff in the middle reaches of Bortala River was in a normal flow year year of 2022. (3) in the upper part of the middle reaches of the Bortala River, groundwater is converted to recharge surface water; The surface water in the section that runs from the Kundelun canal head to Chaxiang Bridge has a large amount of infiltration to recharge groundwater (infiltration coefficient: 0.67), and the infiltration rate was found to be significantly negatively correlated with the quantity of incoming water; In the lower part, groundwater spilled over the surface. The middle reaches of the Bortala River experienced three conversions of surface water and groundwater, with an overall performance of groundwater overflow supplementing surface water.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： Based on precipitation and soil water isotope data at different elevations in the north and south mountains of Lanzhou from April to October 2018, the lc-excess method and the lc-excess equilibrium equation were used to qualitatively and quantitatively analyze the soil water infiltration process in this area. The infiltration process of soil water, indicated by the soil water lc-excess value, was verified by correlation analysis and single factor analysis. The results showed that there are obvious variations in soil water content in the study area on a monthly scale and at different depths, with loss dominating from April to June and accumulation dominating from July to September. The soil water content in the high altitude areas was found to be greater than that in the low altitude areas, and the soil water content in the north mountains was found to be greater than that in the south mountains. Stable isotopes of soil water at each sampling site we found to be most depleted from August to September. At increasing soil depth, soil water isotopes showed a trend of gradual depletion and stabilization. The soil water lc-excess results showed that the piston flow mode and the priority flow mode coexist in the infiltration and recharge process of soil water in the study area. The priority flow signal appeared at all sampling sites from July to August. The contribution of the preferred flow pattern to deep soil water was higher at the low elevation sampling sites than at the high elevation sampling sites. The soil water content and soil water lc-excess were found to be positively correlated. The monthly scale and depth of soil water lc-excess were not significantly different between the north and south mountain, indicating that the infiltration and recharge patterns of soil water in the north and south mountains are the same, and that both are dominated by the piston flow infiltration pattern of precipitation recharge. However, in the south mountains, where there is greater vegetation cover, the preferential flow pattern signal appeared more often, especially in July and August, when precipitation is concentrated. Based on the soil water infiltration and replenishment processes in the north and south mountains, it the selection of salt- and drought- tolerant, shallow- rooted shrubs and perennial grasses is recommended for the north mountains, while reasonable irrigation is recommended in the south mountains during the plant growing season (from April to June). The results of this study provide a theoretical reference for understanding the hydrological process in the north and south mountains of Lanzhou.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： This study was implemented to accurately identify the avalanche flow characteristics and flow information, and comprehensively analyze avalanche motion. This study was based on UAV tilt photography technology to obtain high-resolution aerial photography data, taking the avalanche-prone area of Aerxiangou as an example. Through on-site investigation and UAV remote sensing interpretation to detect avalanche activity in a high-resolution manner, the goals were to determine the input parameters of the RAMMS model, to simulate and reconstruct different types of avalanche events on this basis, and to comparatively analyze the differences among the results of conventional ground-based investigation, UAV remote sensing interpretation, and simulation results to explore avalanche activity in different types and different snow layer release conditions. The results of the study show that (1) the avalanche investigation and analysis system based around tilt photography technology, which combines conventional ground- based investigation methods with UAV remote sensing and numerical simulation to verify each other, improves the accuracy of the assessment of disaster development status. (2) In mid- February, the snow on the slopes of Aerxiangou approaches the critical thickness value, and continuous snowfall destabilizes the snow layer and triggers new avalanches. The investigation is still in the disaster breeding stage, the snow layer cracks intensified deformation, the role of the wind snow eave self- weight gradually increased, there is more than the trend of the breaking strength of the snow, and the overall stability is poor. (3) In slope-type avalanches with a snow platform above the slope surface as the potential release area, the release volume can reach 8.2669 × 104 m3, the movement duration is about 128 s, and the flow height of the accumulation area peaks in 120 s at about 3.55 m, the flow velocity is about 18.34 m·s-1, and the impact force is about 32.67 kPa. In addition, the accumulation area is formed into an accumulation with an area of 3369.7 m2 and a volume of 1.8525×104 m3 of the pile. Through mutual verification, the slope-type avalanche does not involve release of the snow platform, and there is a discrepancy between the ground- based investigation results and numerical simulation interpretation results. (4) Trench-slope composite avalanches are released by fracture of the snow layer on the trench-slope, where the depth of fracture is only about 60% of the critical thickness value, the avalanche duration is close to 300 s in this case, and the impact range is 1178.5 m2 in the accumulation area, with an average accumulation depth of 1.64 m. The flushing-out volume is 3107.76 m3, the maximum flow rate in the accumulation area is 6.58 m·s− 1, and the maximum impact force is 17.97 kPa. The results of the ground-based investigation are roughly the same as those of the numerical simulation based on the 3D model. The results of the study have improved the accuracy with which avalanche event information can be acquired and can provide strong data support and a scientific basis for predicting future avalanche potential hazards, risk avoidance, and disaster emergency response.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： Based on daily temperature observation data and reanalysis data of the geopotential height, sea levelpressure, and wind field from 1961 to 2020, the characteristics of spatial and temporal change of cold waves,strong cold waves, and exceptionally strong cold waves lasting 24 h, 48 h, and 72 h were studied in Ningxia overthe past 60 years. The causes of atmospheric circulation anomalies of cold waves were also revealed. The resultsshow the following: (1) In the past 60 years, cold waves of different intensities and different durations in Ningxiaconsistently showed the distribution characteristics of“shifting eastwards and northwards.”(2) The cumulativefrequencies of cold waves, strong cold waves, and exceptionally strong cold waves in the region accounted for71.7%, 22.6%, and 5.7% of the total annual cold wave frequencies, respectively, among which cold wavesdominated by process lasting 24 h and 48 h. The proportions of various durations for strong cold waves andexceptionally strong cold waves were equivalent. They mainly occured in October to April, during which theaccumulated cold waves, strong cold waves, and exceptionally strong cold waves in the region accounted for99%, 98%, and 95% of those throughout the year, and there was a decreasing trend from January to April andincreasing trend from October to December. (3) In the past 60 years, the cold waves, strong cold waves, andexceptionally strong cold waves have been decreasing at a rate of 4.5, 2.8, and 0.18 per station every 10 years,respectively. Among them, the frequencies of waves of 24 h and 48 h as short durations were decreasing, but thatof waves of 72 h as a long duration was decreasing. All types of cold waves decreased from the 1960s to the1990s, reaching a minimum in the 1990s and increasing since the 2000s, with a sudden change around 1990. (4)Under the influence of global warming, the atmospheric circulation showed completely the opposite distributioncharacteristics between before and after the sudden change of cold waves in Ningxia. The key systemsinfluencing cold waves in Ningxia are consistent. When the blocking high pressure in the Ural Mountains wasstronger, the East Asian trough was deeper, the west Pacific subtropical high was weaker, the western side ofLake Baikal was dominated by cyclonic circulation, and cold high pressure at the ground was active, this wasconducive to the southward movement of cold air in middle and high latitudes, and more cold waves in Ningxia.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： This study used the Sen+M-K trend analysis, the gravity center movement model, the standardizedregression coefficient, and the spatial clustering methods to reveal the spatial characteristics of the variation,trends, and movement of dust days of various types and the contribution rate of their influencing factors in theTarim Basin based on the annual data of 32 meteorological stations between 1964 and 2022. The resultsindicated: (1) Floating dust, followed by blowing sand and sandstorms, dominate the Tarim Basin, showing aspatial distribution pattern of more in the south and less in the north, and the dust days of various types showsignificantly decreasing trends. (2) The gravity centers of dust days of various types in the Tarim Basin tended tomove southeast, and the gravity center of sandstorm days moved the most. (3) Warmer temperatures, lower windspeeds, and fewer gale days were the main factors in the decreased dust days in the Tarim Basin, whereasprecipitation had the least influence. (4) The high contribution rates of precipitation to dust days are clustered inthe western part of the Tarim Basin, mean temperature and mean maximum temperature in the southern andwestern parts, respectively, and gale days and mean wind speed in the northwestern and southeastern parts,respectively. This study’s results can provide a scientific basis for developing regionally applicable windbreakingand sand-fixing measures in the Tarim Basin.
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