Physical and Chemical Properties of Soil at Southeastern Edge of Anabasis salsa in Junggar Basin北大核心CSCD

【Objective】Soil is heterogenous and its physical and chemical properties vary spatiotemporally. The purpose of this paper is to present the results of an experimental study on the physical and chemical properties of soil in Anabasis salsa in Gobi region at the southeastern edge of Junggar basin.【Method】We measured organic matter, total phosphorus, total nitrogen, electrical conductivity, pH and water content in soil at locations 5 cm and 10 cm from the center of shrubs, and 20 cm from the outer edge of shrubs.【Result】In horizonal direction, there was no significant difference in organic matter, total nitrogen, total phosphorus, electrical conductivity, pH and water content in the 0~50 cm soil at all locations. In vertical direction, the organic matter and total phosphorus in the proximity of the Anabasis salsa decreased monotonically along the soil profile, while the total nitrogen increased first with the depth followed by a decrease. Both electrical conductivity and pH increased with depth, and soil moisture peaked somewhere within the soil profile.【Conclusion】Our results showed that the physical and chemical properties of soil in Anabasis salsa did not show significant change in lateral direction but varied erratically in the vertical direction. © 2019 Authors. All rights reserved.     

Characteristics of soil organic carbon andtotal nitrogen storages for differentland-use types in Central Yunnan Plateau

Two-factor analysis of variance and redundancy analysis were used to analyze the characte-ristics of soil organic carbon total nitrogen storage in garden land, forestland, grassland, farmland, and bare land in the Dachunhe watershed of Jinning District, Kunming City, Yunnan Province, China. The effects of the soil organic carbon, total nitrogen stratification ratio, soil physical and chemical factors on the storage characteristics of organic carbon and total nitrogen of different land-use types ...     

有机栽培水肥一体化系统设计与试验

A water and fertilizer integrated system for organic cultivation was designed. The system integrated functions of preparing and compounding organic liquid as well as automatical irrigation. Through different subroutines of the system, the aerobic fermentation of organic materials, liquid filtration, compounding and dilution of stock solution, and decision and execution of irrigation strategy can be conducted. Thus, the integration of preparation and management of nutrient solution in organic cultivation, as well as high efficiency and fine management in water and fertilizer could be achieved. In order to verify the reliability and applicability of the system, coconut chaff was selected as organic matrix and non soil and organic cultivation experiment of cucumber was carried out in the solar greenhouse. The results showed that the system was operated stably in preparation of organic liquid and management of water and fertilizer was good in cucumber cultivation. The mechanization and automation of organic fertilizer and water management was implemented. The yield of cucumber was up to 48165kg/hm2, the content of total soluble sugar, vitamin C and titratable acidity were 2.7%, 99.2mg/kg and 008%, respectively. The development and application of this system would break through the bottleneck that existed in water and fertilizer management in organic cultivation, and it had important realistic significances.     

Effects of Biochar for Abating Salt Stress and Promoting Seeding Growth of Winter Wheat in a Saline Soil北大核心CSCD

The surface soil of the Yellow River Delta is rich in salt, which makes the soil salinized, compact and barren. The salinization hazard with NaCl as the main component directly affects the quality of coastal soil. Adding biochar to saline-alkali farmland can improve soil properties and promote crop growth.【Objective】The purpose of this paper is to clarify the changes of soil salt ions and winter wheat seedling growth after adding biochar to saline soil.【Method】A field experiment was conducted to investigate the effects of low dose (0~4 g/kg) of Reed carbon on soil salt ions, potassium-sodium ratio in wheat seedlings, potassium utilization efficiency and seedling biomass.【Result】The application of biochar could reduce the salt ions in soil solution, increased the potassium-sodium ratio in the winter wheat seedlings and the potassium use efficiency of the wheat seedlings, and increased the seedling biomass of winter wheat; The salt reduction and the incremental effect under the addition of 4 g/kg biochar use was the most obvious. Compared with CK, the Na+ in soil solution decreased by 9.43%, the K/Na and potassium use efficiency of seedlings increased by 56.80% and 25.48%, respectively, and the biomass of wheat seedling increased by 15.72%.【Conclusion】Biochar application can promote the increase of biomass by holding Na+ in soil solution and increasing K/Na and potassium utilization of winter wheat seedlings. The research can provide a theoretical basis for the process mechanism of biochar for salt reduction and fertilization, increase efficiency and increase yield, and provide preliminary guidance for the feasibility of biochar for salinized soil improvement. © 2019 Office of Journal of Irrigation and Drainage, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences. All rights reserved.     

Ammonia Volatilization from Pit Wall under Different N Top-addressing from Water Storage Irrigation Pit in Apple Orchard北大核心CSCD

【Objective】Water storage pit is a common technology to bank precipitation for irrigation in arid region. In this paper, we studied ammonia volatilization from the wall of the pits under different N top-addressing in an apple orchard.【Method】We compared seven nitrogen top-addressing in the experiment: topdressing 600, 300 and 0 kg/hm2 at anthesis stage and fruit enlargement stage respectively. The ammonia volatilization from the wall of the water storage pit was measured using glycerophosphate-ventilation. We analyzed the dependence of ammonia volatilization on soil ammonium, soil nitrate, soil temperature, air temperature and humidity respectively.【Result】Ammonia volatilization increased with the topdressing amount after irrigation and fertilization. Top-addressing after anthesis stage could prolong ammonia volatilization for a significant period with a peak within 52.93 to 576.80 mg/(m2·d) occurring 3~5 days after the top-addressing. Top-addressing during fruit enlargement stage resulted in a short period of ammonia volatilization with a peak within 81.11 to 1 047.79 mg/(m2·d) occurring two days after the top-dressing. The accumulated ammonia volatilization (calculated by N) after one-off topdressing after anthesis stage and fruit expansion stage was 3 332.88~7 052.01 mg and 2 178.14~5 126.97 mg respectively. Compared to one-off topdressing, two top-addressing reduced ammonia volatilization to 2 013.21~ 4 642.11 mg, 34.17%~39.60% lower than that under one-off topdressing after the anthesis stage. Ammonia volatilization from the water storage pit wall accounted for 0.57%~1.40% of nitrogen loss, being the highest under one-off topdressing at anthesis stage followed by one-off topdressing at fruit expansion stage. Ammonia volatilization was positively correlated with soil ammonium and air temperature (P<0.05). Soil temperature and nitrate also played a role in ammonia volatilization. Rise in air humidity and rainfall after fertilization can reduce ammonia volatilization, and the dynamical change in accumulated ammonia volatilization can be well described by the Elovich dynamic equation, in which the rate constant parameter was positively correlated to the amount of top-addressing nitrogen and negatively correlated to soil temperature, both at significant level.【Conclusion】Ammonia volatilization from water storage pit wall can be controlled by managing the amount of fertilizer application and time at which the fertilizer was applied. Our results suggested that reducing the top-addressing amounts and top-addressing twice can effectively reduce nitrogen loss via ammonia volatilization. © 2019 Authors. All rights reserved.     

Calculation of Irrigation Infiltration Recharge Coefficient and Analysis of Influencing Factors in the Lower Reaches of Aksu River北大核心CSCD

【Objective】In order to obtain the irrigation infiltration recharge coefficient in the lower reaches of Aksu river and improve the numerical simulation accuracy of groundwater in the study area,the influencing factors of the irrigation infiltration recharge coefficient in this area were analyzed. 【Method】In this paper,field sampling and indoor irrigation experiments were carried out by selecting representative points under different irrigation schemes,vadose zone thickness and soil structure in the lower Aksu area,and numerical simulation of vadose zone flow was carried out in combination with Hydrus-1d. Hydrus-1d model was used to calculate irrigation inflow under this soil structure by changing irrigation schemes and vadose zone thickness. Change of seepage recharge coefficient. On the basis of the calculation results of the model,the relationship between irrigation schedule,aeration zone thickness and irrigation infiltration recharge coefficient is analyzed firstly,and then the main factors affecting irrigation infiltration recharge coefficient in soil structure are analyzed with the method of model calculation and mathematical statistics. 【Result】The results showed that the irrigation infiltration recharge coefficient ranged from 0.320 to 0.474 under drip irrigation and from 0.408 to 0.561 under border irrigation. The irrigation infiltration recharge coefficient varied under different irrigation schemes,while the irrigation infiltration recharge coefficient decreased with the increase of aeration zone thickness. The main factors affecting irrigation infiltration recharge are soil permeability coefficient,soil bulk density and initial soil water content. 【Conclusion】According to indoor experiment combined with numerical model to calculate the irrigation infiltration coefficient under different irrigation system range, it is concluded that the influence factors of irrigation infiltration coefficient of irrigation system, the thickness of the vadose zone and reflects soil permeability coefficient of soil structure, soil quality and soil initial moisture content, volume for the downstream area irrigation infiltration coefficient selection in arid areas and provides the theory basis for further research. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Spatial Variability of Soil Moisture at Different Scales in Sandy Loam in Northern Henan Province北大核心CSCD

[Objective]Soil moisture plays an important role in ecosystem function and hydrological processes. This paper investigated the hieratical distribution of soil moisture at different scales over a maize field.[Method] The studied site was a 50 m×50 m plot at the Experiment Station of Chinese Academy of Agricultural Sciences in Xinxiang, Henan province. We measured soil moisture in 0~100 cm soil from 36 locations at 10 m×10 m and 2 m×2 m scale, respectively.[Result]Geostatistical analysis revealed that the soil moisture was normally distributed and its confidence level at every scale was higher than that of logarithmic normal distribution. The value of the confidence level decreased as the sampling scale increased, and the difference between average soil moisture content at fine scale and moderate scale was smaller than the difference between moderate scale and large scale. In general, the confidence interval, standard deviation and coefficient of variation of the soil moisture increased with sampling scale. At large scale, the semi-variance function increased with lag distance, while at small and moderate scale, the variation function appeared to be independent of the lag distance. To achieve the same confidence level and accuracy in estimating soil moisture, the number of samples needed to be taken from the field increased with sampling scale. We also found that in estimating soil moisture, the number of samples needed to be taken depended on the required accuracy more than on the confidence level.[Conclusion]The probabilistic distribution and statistical characteristics of soil moisture in the field was scale-dependent. In estimating soil moisture, the number of sampled taken from the field needs to consider the scales to which the measured data will be applied. © The Author(s) 2019.     

Using Biogas Slurry to Regulate Growth,Field and Fruit Quality of Greenhouse Tomato and Nitrogen Dynamics in Root Zone北大核心CSCD

【Objective】The physiological development of tomato is affected by a number of integrative abiotic and biotic factors and the purpose of this paper is to investigate how irrigation with biogas slurry alerts the yield and fruit quality of greenhouse tomato.【Method】The experiment was conducted in a greenhouse from autumn in 2017 to spring in 2018 by irrigating the tomato with a mixture of fresh water and biogas slurry at volumetric ratio of 1∶8, 1∶6 and 1∶4 at flowering stage and fruit-elongation stage respectively. In each treatment, we measured growth, yield, and fruit quality of the tomato, as well as the dynamics of total nitrogen in the root zone. 【Result】The tomato growth was positively related to the biogas slurry ratio at significant level, and the 1∶6 and 1∶4 ratio gave the highest total dry matter at the flowering stage and the fruit expansion stage respectively. The 1∶6 treatment gave the best return, and compared to CK (without biogas slurry), it increased the return by 12.93% in autumn and 12.31% in spring respectively. Irrigating with 1∶4 ratio at fruit elongation stage gave the highest yield, and compared to CK, it increased the yield by 26.59% in autumn and 27.71% in spring respectively. The 1∶4 treatment gave 4.32% increase in yield compared to chemical fertilizer application in spring. T5 and T6 treatments improved soluble sugar and solid, as well as and sugar-acid ratio, while T2 and T3 treatments increased titratable acid and vitamin C content.【Conclusion】Irrigation by mixing biogas slurry and freshwater at 1∶6 and 1∶4 volumetric ratio at flowering-fruiting stage and fruit expansion stage can considerably improve yield and quality of tomato. © 2019 Authors. All rights reserved.     

Water and nitrogen transport characteristics of single-line interference infiltration under film hole irrigation with muddy water and fertilizer

Based on the experimental data, this study investigated the effect of sand content of muddy water on water and nitrogen transport characteristics of the single-line interference infiltration under film hole irrigation with muddy water and fertilizer. The relationship between the single-line interference infiltration parameters, the sand content, the wetting front movement distances, and the sand content were all established. The model of the cumulative infiltration volume of per unit film pore a...     

Experimental Study of the Suitable N-fertilizer Amount for Corn under Drip Irrigation in Aeolian Sandy Soil北大核心CSCD

【Objective】The purpose of this paper is to determine the suitable N-fertilizer amount for corn under drip Irrigation in Aeolian sandy soil. 【Method】The experiment was conducted in a field, and the amount of water and N-fertilizer were selected as experiment factors. Two levels of water amount (high and low) and three levels of N-fertilizer dosage (high, middle and low) were scheduled and thus six treatments were carried out. Effects of treatments on the growth and yield of corn were studied. 【Result】The results showed that, under low watering condition, increasing N-fertilizer amount was good for plant growth and had higher plant height and larger leaf area index, while under high watering condition, the positive effects were limited. Under both water condition, the fresh and dry weight of over ground part increased as N-fertilizer application increased, while its water contend, stem diameter and SPAD litter varied. Besides, higher N-fertilizer amount was beneficial to get longer ear, larger diameter, and more seeds, also was likely to got higher yield. The yield of high N-fertilizer amount under low and high watering condition were 13.0 and 13.7 t/hm2 respectively, 20.4% and 17.1% higher than the yield of low N-fertilizer amount treatments. 【Conclusion】In Aeolian sandy soil, higher N-fertilizer amount would be conducive plant growth and yield, especially when irrigation water was limited. Therefore, according to the experiment, N-fertilizer amount of 300 kg/hm2 was recommended in Aeolian sandy soil of northwest Liaoning. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Effect of water and fertilizer coupling optimization test on water use efficiency of rice in black soil regions

How to improve the water use efficiency of rice in black soil regions was studied. The black soil region in paddy fields was chosen as the research object. The research showed the fertilizer coupling mathematical model with N,P,K, irrigation water (W) and water use efficiency(WUE), which was set up under the condition of controlled irrigation with quadratic D-416 optimized saturation design. The results showed that the decending order of single factor′s influence on the WUE was N,K,P,W. All the interactions between N＆P, N＆K, N＆W, K＆P, P＆W and K＆W on the WUE were raised initially, and when they reached a certain value, it began to decline. The decending order of each interaction on the WUE was K＆P,K＆W,N＆K,N＆P,P＆W,N＆W. When the WUE was targeted within 18-25 kg／km3, an optimized proportion plan was obtained in the 95％ confidence interval, i.e. N 8776-10332 kg／hm2,K2O 5237-6653 kg／hm2 and P2O5 3680-4671 kg／hm2. Furthermore, the late tillering of the soil moisture content was 7007％-7257％ of the saturated moisture content.     

Multi-factor Analysis of the Effective Precipitation for Crops in Semi-arid Region北大核心CSCD

【Objective】The purpose of this paper is to present a method to estimate the effective precipitation for crops in arid region.【Method】The model considered precipitation, soil and crop, and it was based on four modules: canopy interception, soil water tolerance, surface runoff, precipitation and deep percolation. The results calculated by the model were compared to those calculated from water balance using the data measured from the field. We applied the model to calculate spatiotemporal distribution of the effective precipitation for crops in five counties in Hebei plain.【Result】①The coefficient of determination (R2) and Nash-Sutcliffe efficiency (NSE) in all results were above 0.85, proving the reliability of the model. ②The effective precipitation for growing season of the wheat-maize in the five counties was 400.03 mm, and the infiltration coefficient of precipitation was 0.84. In wet, normal and dry year, the effective precipitation for crops was 419, 454 and 355 mm respectively, and infiltration coefficient of precipitation was 0.76, 0.86 and 0.83 respectively. The effective precipitation for crops in Luancheng and Yuanshi was higher than that for other counties.【Conclusion】The proposed model was reliable for estimating effective precipitation for crops at large scale in semi-arid region. © 2019 Authors. All rights reserved.     

Comparative Analysis of Stratified Physical Characteristics of Seasonal Snow Cover With or Without Shading北大核心CSCD

【Objective】Snow melting runoff is an important recharge component of arid inland rivers. Seasonal snow cover is very sensitive to environmental change. Therefore, it is of great significance to study and control the key factors affecting seasonal snow accumulation and snow melting process for basin safety and sustainable utilization of water resources under changing environment. 【Method】By observing the physical characteristics of seasonal snow layers under the conditions of sheltered or not (under canopy and open land) in the Urumqi River Basin experimental area on the northern slope of Tianshan Mountains in Xinjiang from November 2017 to February 2018, the differences of physical characteristics of seasonal snow layers were analyzed. 【Result】① the temperature of open land was slightly higher than that of under canopy, and the relative humidity under canopy was higher than that of open land. ②The average depth of snow under canopy was less than that of open land, and the proportion of deep frost layer to coarse snow layer was larger in stratified snow cover. ③The vertical profile of snow density under canopy was basically the same as that under open land. The snow density increased gradually from the new snow layer down to the peak of coarse snow layer (open land) and medium-sized snow layer (under canopy). ④ Snow temperature and liquid water content of layers under canopy and open land increased from new snow layer to deep frost layer. ⑤ The variation trend of snow water equivalence under canopy and open ground was basically the same during observation period. The value of snow water equivalence under open ground was obviously larger than that under canopy. 【Conclusion】Snow surface temperature is a significant factor affecting the liquid water content of snow under canopy and open land. © 2019 Office of Journal of Irrigation and Drainage, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences. All rights reserved.     

Study on the Variation Characteristics of Rising Capillary Water of Layered Soil under Variation of Sand Layer and Thickness北大核心CSCD

【Objective】The purpose of this paper is to solve secondary salinization of soil in Northwest China. 【Method】the capillary water rising movement characteristics of layered soil has been analyzed through indoor test. And the variation characteristics of capillary water movement under the influence of common change of layer and thickness of sand layer has been considered in this paper, and functional relationship between groundwater recharge and height of capillary water rising with time changing has been built. Furthermore, contour distribution of groundwater recharge and capillary water rising height has been also comparative analyzed.【Result】There was a very significant positive correlation between the horizon and the volume constant and the height constant （P<0.01）. And there was a significant negative correlation between the horizon and the stable recharge rate of groundwater and the rate of steady increase of capillary water （P<0.05）. There was a significant negative correlation between the thickness of sand layer and stable recharge rate and steady rising rate（P<0.05）. When the duration of the capillary water height was rising was 0~4 days, the sandy layer was 30~50 cm, the thickness of sand layer was 0~15 cm, which has a significant effect on the change of groundwater recharge and height of capillary water. When the duration of the capillary water height was rising was 4~12 days, the sand layer is distributed in 15~30 cm, the thickness of sand layer was 15~30 cm, which has a significant effect on the change of groundwater recharge and height of capillary water. To summarize, the results of this study were of great significance for the study of water salt movement and soil salinization in layered soils.【Conclusion】The fitting parameters of the function including volume constant (v), stable recharge rate (q*), groundwater recharge time constant (τQ), capillary water rising height (υ), steady rising rate (μ*) and rising height time constant (τh) were determined by the variation of capillary groundwater recharge and capillary water height with time changing respectively. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Retrieving Soil Moisture Using Spectral Mixture Analysis of Landsat8 and the Moderate Resolution Imaging Spectroradiometer北大核心CSCD

【Objective】Soil moisture plays a critical role in many hydrological and ecological processes and understanding its spatiotemporal changes is imperative to ecosystem management and irrigation design. This paper presents and tests a method to estimate soil moisture distribution using satellite technologies.【Method】We took Guangli Irrigation District at Jiaozuo in Henan Province as our study area. The Landsat-8 and MODIS imageries from the area were used to retrieve soil moisture with the apparent thermal inertia and vegetation water supply index, respectively. Using the abundance of vegetation and soil moisture decomposed by the spectral mixture analysis as weighting factors, we retrieved the soil moisture distribution in the area using the two methods.【Result】The correlation coefficient between the measured soil moisture and the retrieved using the vegetation water supply index method and the apparent thermal inertia method was 0.47 and 0.51 respectively. We found that combining the two methods could improve the correlation coefficient between the measured and retrieved soil moisture to 0.73. 【Conclusion】Our results showed that the proposed method is reliable and can adequately estimate soil moisture in irrigation district grown with a diverse of crops. © 2019 Authors. All rights reserved.     

Autumn Irrigation Alerted the Geochemistry of Groundwater in Hetao Irrigation District：Take Yichang Irrigation District as an Example北大核心CSCD

【Objective】Surface infiltration could change biogeochemical reactions in groundwater thereby alerting its chemical compositions. The aim of this paper is to investigate the responsive change in chemical composition of groundwater to infiltration following the autumn irrigation in irrigation districts.【Method】The experiment was conducted in Hetao Irrigation District, during which we measured the change in concentration of Na+, K+, Ca2+, Mg2+, SO42-, Cl-, HCO3- and CO32- and then statistically analyzed them.【Result】The irrigation increased the concentration of Cl-, SO42-, KNa, Mg2 and HCO3-, but slightly reduced the concentration of Ca2+. The TDS was higher in south and lower in north of the irrigation district. The Piper diagram showed that the Cl-Na was the dominant groundwater type, accounted for 75% and 61% of the studied area before and after the irrigation respectively. Irrigation turned groundwater in 16.7% of the studied area to Mg-SO4-Cl type. The Gibbs model and ion proportional coefficient diagram revealed that the chemistry of groundwater in the studied region was mediated by evaporation, weathering and leaching of silicate and evaporite, and is independent of precipitation. 【Conclusion】The mean TDS in the groundwater increased by 32.9% after the autumn irrigation, indicating the impact of soil leaching. Improving drainage after the autumn irrigation is hence essential. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Manipulation of vertical fence wake using passive vortex generators

The effect of streamwise vortices generated from passive vortex generators was investigated to manipulate the separation bubble behind the vertical fence. The experiments were carried out in a circulating water channel and the velocity fields were measured using 2D and stereoscopic PIV method.The distance between the vortex generator and fence and the effect of the Reynolds number were investigated. In addition,the effect of boundary layer thickness was also investigated. The averaged recirculation lengths were compared with that of uncontrolled fence flow. The results showed the oscillatory variation of recirculation region appeared under the existence of vortex generators. The reduction of the separation bubble became larger when the fence was submerged in the thick boundary layer with increasing the distance between the generator and fence. When the boundary layer is thin,vortex generator can only suppress the separation bubble under the specific condition.     

Effects of Waterlogging on Morphology and Chlorophyll Fluorescence Characteristics of Cherry Tomato at Seedling Stage北大核心CSCD

【Objective】The aim of this study was to investigate the responses of cherry tomato to waterlogging at seedling stage, and to provide reference for waterlogging resistance cultivation of off-season cherry tomato in the tropical area.【Method】Five different varieties of cherry tomatoes were used as materials in pot culture experiment, with soil waterlogging treatment and normal moisture treatment as the control (CK). The morphological characteristics indexes of shoot and root and chlorophyll fluorescence parameters in leaves of cherry tomato were measured in different days of waterlogging. And the effects of waterlogging on morphological characteristics and chlorophyll fluorescence parameters at seedling stage of cherry tomato were analyzed.【Result】Results showed that waterlogging significantly decreased the plant height, stem diameter, leaf area, leaf number and SPAD value of cherry tomato, but had no significant effect on leaf thickness. The root diameter of cherry tomato had no significant affects, but the root volume was significantly increased in HongFei 6 and TaiwanZanMei during waterlogging. Compared with CK, the root length and root surface area of HongFei 6 increased significantly, while that of QianXi decreased significantly during waterlogging. Additionally, waterlogging increased the initial fluorescence (Fo) and non-photochemical quenching coefficient (NPQ), and significantly decreased the maximum photochemical efficiency (Fv/Fm), apparent electron transfer rate (ETR) and photochemical quenching coefficient (qP) of cherry tomato leaves, besides HongFei 6.【Conclusion】The results above indicated that during waterlogging the growth and development and chlorophyll fluorescence in leaves of cherry tomato were seriously affected, but there had different effects among five different varieties . Among five varieties of cherry tomatoes, the strongest waterlogging resistance was HongFei 6, while the weakest waterlogging resistance was QianXi. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Manipulation of vertical fence wake using passive vortex generators

he effect of streamwise vortices generated from passive vortex generators was investigated to manipulate the separation bubble behind the vertical fence. The experiments were carried out in a circulating water channel and the velocity fields were measured using 2D and stereoscopic PIV method. The distance between the vortex generator and fence and the effect of the Reynolds number were investigated. In addition, the effect of boundary layer thickness was also investigated. The averaged recirculation lengths were compared with that of uncontrolled fence flow. The results showed the oscillatory variation of recirculation region appeared under the existence of vortex generators. The reduction of the separation bubble became larger when the fence was submerged in the thick boundary layer with increasing the distance between the generator and fence. When the boundary layer is thin, vortex generator can only suppress the separation bubble under the specific condition.     

Responsive Change in Groundwater Table in Karst to Precipitation and Yellow River in Pingyin County北大核心CSCD

【Objective】This paper aims to unravel the relationship between groundwater table fluctuation in karst and the precipitation and water level of the Yellow River at Pingyin in Shandong province.【Method】The analysis was based on data measured from groundwater in two karsts in the proximity of the Yellow River, precipitation and change in water level in the river from 2007 to 2018. The response of groundwater table fluctuation to precipitation and water level in the Yellow River was calculated using cross- correlation analysis, continuous wavelet transform and cross- wavelet transform.【Result】Both precipitation and groundwater table fluctuation had a 12- month period. The responsive change in groundwater table lagged behind the precipitation by 1~8 months, and the water level in the Yellow River by 0~10 months. The precipitation and groundwater table oscillated with a period of 0.86~1.20 a and 0.86~1.36 a respectively, while the oscillation period of the Yellow River water was 1 a and 3 a. The average velocity at which water flowed from the Yellow River to the karst was 21.62~ 25.53 m/d.【Conclusion】The responsive change in groundwater table in the karst in Pingyin to water level in the Yellow River was slightly slower than to precipitation. © 2019 Authors. All rights reserved.