The Zoige wetland is the biggest alpine wetland in the world,and an important water resource of the Yellow River.Due to natural and human factors,the Zoige wetland has been seriously degraded.Existing studies on the Z...The Zoige wetland is the biggest alpine wetland in the world,and an important water resource of the Yellow River.Due to natural and human factors,the Zoige wetland has been seriously degraded.Existing studies on the Zoige wetland mainly focus on the macro features of the wetland,while the influence of the surrounding faults on the Zoige wetland degradation is rarely studied.This study uses terrain data to analyze the cover change and the water loss caused by the Wqie-Seji fault based on the distributed hydrological model.The simulated water loss demonstrates that the Normalized Difference Vegetation Index(NDVI) is the most important factor for inducing water loss.The fault is also a factor that cannot be neglected,which has caused 33% of the wetland water loss.Therefore,it is of importance to study the influence of the fault on the wetland degradation.展开更多
Soil and water loss has been the most serious eco-environmental problem in the Three Gorges Reservoir Area of Chongqing.In this paper the authors studied the spatiotemporal features of soil and water loss from 1999 to...Soil and water loss has been the most serious eco-environmental problem in the Three Gorges Reservoir Area of Chongqing.In this paper the authors studied the spatiotemporal features of soil and water loss from 1999 to 2004 based on RS and GIS techniques.The results showed that:(1) The soil and water loss area decreased from 1999 to 2004.(2) Soil and water loss mainly exists in purple soil,yellow soil,limestone soil,paddy soil and yellow brown soil distributed areas.(3) The dry slope land and sparse woodland that are intensively influenced by human activities experienced most serious soil and water loss.(4) Soil and water loss in the study area indicated an obvious vertical differentiation characteristic.(5) There is a significant correlation between soil and water loss and slope.(6) There is no obvious correlation between soil and water loss and aspect.(7) Soil and water loss mainly exists in the values of R between 300 and 340 distribution area.The very-high soil and water loss has obvious correlation with R.展开更多
Postharvest water loss is a critical factor that determines the quality and shelf life of fresh fruit.Cuticular wax constitutes a key barrier to reduce fruit water loss.Our previous study has shown that HJ(Citrus reti...Postharvest water loss is a critical factor that determines the quality and shelf life of fresh fruit.Cuticular wax constitutes a key barrier to reduce fruit water loss.Our previous study has shown that HJ(Citrus reticulata)has a significantly higher postharvest water loss rate than ZK(Poncirus trifoliata).Here,we investigated the fruit water loss rate of the HJ×ZK F1pseudo-testcross population in 2016 and 2019.QTL mapping for fruit water loss rate was performed by high-density genetic map and bulk segregant analysis,and QTL9 was identified to be associated with fruit water loss.The expression of NAC042 from QTL9 in ZK was 170-fold that in HJ.Heterologous expression in Arabidopsis showed that NAC042could reduce the water loss of leaves by increasing the cuticular wax content(especially alkanes).Further expression analysis revealed that NAC042 could enhance the expression of many wax-related genes in Arabidopsis leaves,including AtKCS1,AtKCS2,AtKCS9,AtKCS20,At CER1 and At CER3.Therefore,NAC042 might be involved in fruit cuticular wax synthesis to reduce fruit water loss.The findings provide new insights into the regulation of cuticular wax and fruit water loss as well as valuable information for breeding of citrus with better storability.展开更多
The effects of specimen size and shape on development of water loss and shrinkage of mortar and concrete respectively were investigated. The experimental results showed that the effects of specimen size and shape on w...The effects of specimen size and shape on development of water loss and shrinkage of mortar and concrete respectively were investigated. The experimental results showed that the effects of specimen size and shape on water loss ratio were consistent with those on drying shrinkage strain. It is also indicated that drying shrinkage strain has obvious linear correlation with water loss ratios independent of specimen size and shape. The effects of specimen size and shape on the water loss ratio were embodied in established model of averaged relative humidity improved by considering effects of sequential hydration and calculated by finite difference method. Furthermore, the effects of specimen size and shape on drying shrinkage strain of concrete were experimentally deduced and applied to modify criterion EB-FIP1990. The comparison between experimental and calculated results shows that the modified EB-FIP1990 can be adopted to predict drying shrinkage strain of concrete with reasonable accuracy.展开更多
We introduced a parameter r_s(the radius of the pores where the meniscus forms),which is composed of two factors,i e,water loss and cumulative pore size distribution(PSD),to provide a better explanation of the influen...We introduced a parameter r_s(the radius of the pores where the meniscus forms),which is composed of two factors,i e,water loss and cumulative pore size distribution(PSD),to provide a better explanation of the influence of superplasticizers(SPs)on early-age drying shrinkage.In our experiments,it is found that the addition of three types of SPs leads to a significant increase in the early-age drying shrinkage of cement paste,and drying shrinkage increases with the dosage of SPs.Based on the results above,we further studied the mechanism of the effects of SPs on the early-age drying shrinkage of cement paste by PSD and water loss,which are two components of r_s.The experimental results indicate that r_s can be a better index for the early-age drying shrinkage of cement-based materials with SPs than a single factor.In addition,the effects of SPs on other factors such as hydration degree and elastic modulus were also investigated and discussed.展开更多
According to a lot of hydrological and environmental monitoring data, the condition of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is described. The occurrence and devel...According to a lot of hydrological and environmental monitoring data, the condition of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is described. The occurrence and development of soil and water loss is analyzed. The conclusion is that: (1) generally, the situation of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is light, however, soil and water loss in some regions is serious, especially in the middle reach area of the river; (2) soil and water loss in the Lancang River Mekong River (in Yunnan section, China) watershed presents developing tendency and it is mainly caused by human beings. In accordance with these results, the control measures for soil and water loss are discussed.展开更多
Based on natural precipitation observations, impacts of different types of land use on processes of soil and water loss over purple soil related slopeland were studied by simulated rainfall experiments. Measurement da...Based on natural precipitation observations, impacts of different types of land use on processes of soil and water loss over purple soil related slopeland were studied by simulated rainfall experiments. Measurement data revealed that rainstorms and slope length are the essential factors accountable for soil and water loss on purple soil slopeland for intense rill erosion can be caused on 10 meter long purple soil slopes by high intensity rainfall. Under circumanstances of rainstorms, annual hedge plants grown on slopeland of 25 degrees can cause a reduction of runoff by 22 43 percent and that of erosion induced sand content by 94 98 percent. Stone bund horizontal terraces can lead to a runoff reduction by 62 67 percent in comparison with steep slopelands and that of erosion induced sediment by 97.8 99 percent. Soil and water loss can be substantially decreased on steep slopes by hedge plants with a cost of only 10 20 percent that of the stone bund horizontal terraces. Hence it is an effective way to control soil and water loss in terms of slopeland amelioration and utilization in the Three Gorges Reservoir Area.展开更多
The primary purpose of this study was to assess water losses by evapotranspiration, evaporation and seepage in arid zone.Normally, evaporation and seepage are the main causes of water losses.For modeling water losses,...The primary purpose of this study was to assess water losses by evapotranspiration, evaporation and seepage in arid zone.Normally, evaporation and seepage are the main causes of water losses.For modeling water losses,a combination of Genetic Programming(GP),Penman-Monteith(PM) and Penman combination model for measurement of evapotranspiration,evaporation and seepage has been developed.The results were found to be varying depending on how the evaporation and seepage phenomena are modeled.These results show that that there is an improvement in reducing evapotranspiration,evaporation and seepage losses in arid and semi-arid region.展开更多
To better understand the physiological characteristics of the silky starling（Sturnus sericeus）, its body temperature（Tb）, basal metabolic rate（BMR）, evaporative water loss（EWL） and thermal conductance（C） eli...To better understand the physiological characteristics of the silky starling（Sturnus sericeus）, its body temperature（Tb）, basal metabolic rate（BMR）, evaporative water loss（EWL） and thermal conductance（C） elicited by different ambient temperatures（Ta）（5-30 ℃） were determined in the present study. Our results showed that they have a high Tb（41.6±0.1 ℃）, a wide thermal neutral zone（TNZ）（20-27.5 ℃） and a relatively low BMR within the TNZ（3.37±0.17 mL O2/g·h）. The EWL was nearly stable below the TNZ（0.91±0.07 mg H2O/g·h） but increased remarkably within and above the TNZ. The C was constant below the TNZ, with a minimum value of 0.14±0.01 mL O2/g·h·℃. These findings indicate that the BMR, Tb and EWL of the silky starling were all affected by Ta, especially when Ta was below 20℃ and the EWL plays an important role in thermal regulation.展开更多
Loess Plateau is the most serious region of soil and water loss in China and the world. The sediment carried into the Yellow River amounts to 1.6 billion tons every year. This paper reviews the factors and reasons for...Loess Plateau is the most serious region of soil and water loss in China and the world. The sediment carried into the Yellow River amounts to 1.6 billion tons every year. This paper reviews the factors and reasons for erosion in this area, and puts forward a comprehensive controlling policy on the basis of the principles of ecology and practise of Chinese scientists for 40 years. In conformity with the policy, a number of technical measures for controlling soil and water loss are suggested.展开更多
De-farming slope farmland has been an effective measure in recent years for the improvement of the eco-environment and the mitigation of soil and water loss on the Loess Plateau. This paper, taking the Yangou Basin as...De-farming slope farmland has been an effective measure in recent years for the improvement of the eco-environment and the mitigation of soil and water loss on the Loess Plateau. This paper, taking the Yangou Basin as a case study and using day-by-day mete- orological data of Yah＇an station in 2005, simulated and analyzed the quantitative relation between crop yield, soil and water loss and topographic condition with the aid of WIN-YIELD software. Results show that： 1） topographic gradient has important influence on crop yield. The bigger gradient is, the lower the crop yield. Yields of sorghum and corn decrease by 15.44% and 14.32% respectively at 25° in comparison to the case of 0°. In addition, yields of soya, bean and potato decrease slightly by 5.26%, 4.67% and 3.84%, respectively. The influences of topographic height and slope aspect on crop yield are slight. 2） Under the same topographic condition, different crops＇ runoff and soil loss show obvious disparity. Topographic gradient has important influence on soil and water loss. In general, the changing trend is that the soil and water loss aggregates with the increase of gradient, and the maximal amount occurs around 20°. The influence of topographic height is slight. Topographic aspect has a certain effect, and the fundamental characteristic is that values are higher at the aspect of south than north. 3） Topographic gradients of 5° and 15° are two important thresholds. The characteristic about soil and water loss with the variation of topographic gradients show that： the slope farmland with gradient less than 5° could remain unchanged, and the slope farmland more than 15° should be de-farmed as early as possible.展开更多
In order to determine water losses in irrigation canals,a systematic approach was developed,consisting of two main components:a seepage simulation model and a hydraulic simulation model.The SEEP/W module of the Geo-St...In order to determine water losses in irrigation canals,a systematic approach was developed,consisting of two main components:a seepage simulation model and a hydraulic simulation model.The SEEP/W module of the Geo-Studio software was used to simulate the seepage rate,and the Hydrologic Engineering Center-River Analysis System(HEC-RAS)hydrodynamic model was used for hydraulic simulation.Different operation scenarios were designed to investigate all possible situations in daily operation of water distribution and delivery systems.The seepage simulation results show that the seepage losses were higher at the bottom and corners of the canal,because the hydraulic gradient was affected by the hydraulic load.The hydraulic simulation results show that due to physical and management infrastructure(using non-automated and operator-based regulation structures),operational losses accounted for a significant volume of losses compared to seepage losses.In most operation scenarios,the maximum seepage loss was 10%,and the remaining 90%was related to operational losses.It is concluded that any factor(decrease or increase of inflow to the canal)that causes an increase or decrease of operational losses is ultimately a determining factor in reducing or increasing total losses.Therefore,management approaches should be adopted to improve performance of the system and reduce losses,especially operational losses,by improving the operation methods of water level regulation and off-take structures.展开更多
The three methods of slash disposal in this experiment were no treatment, strip piling and burning. The results obtained from this study showed that the soil erosion, water and nutrient loss were higher in the logged ...The three methods of slash disposal in this experiment were no treatment, strip piling and burning. The results obtained from this study showed that the soil erosion, water and nutrient loss were higher in the logged areas by burning than in the logged areas by no treatment and strip piling. The soil and water loss was not serious when the slope degree of the logged area was less than 16o. The survival rate of planted seedlings was higher and the growth was better in the logged areas followed by burning than in the logged areas by no treatment and strip piling. Burning should not be used when the slope was more than 23o.展开更多
A study was conducted with the objective of improvement of water use efficiency (WUE) and yield of winter wheat for Lowland Dryland Farming systems through a breeding approach. Various genotypes were screened in 1988 ...A study was conducted with the objective of improvement of water use efficiency (WUE) and yield of winter wheat for Lowland Dryland Farming systems through a breeding approach. Various genotypes were screened in 1988 for rate of water loss of excised leaves (RWL) , followed by inter-crossing of diverse parents in 1993. Analysis of the relationship between RWL and yield components and plant traits demonstrated significant differences in RWL among genotypes. Under most circumstances, RWL was correlated negatively with yield and grain weight, and positively with plant height. The results demonstrated a basis for simultaneous selection for high yield and low RWL. It was found that genotypic rank varied with the duration of water loss. Correlation between RWL and yield was reduced by extended water loss duration. Analysis of the genetic variation and segregation of RWL of progenies and the effect of simultaneous screening for RWL and agronomic traits showed that good lines with improved yield and water use performance could be obtained.展开更多
The factor of human project activity is often the immediate cause resulting in soil and water loss. The Baoji-Lanzhou second railway in construction is an example. The soil and water loss law caused by earth and stone...The factor of human project activity is often the immediate cause resulting in soil and water loss. The Baoji-Lanzhou second railway in construction is an example. The soil and water loss law caused by earth and stone mountain railway engineering construction in the northwestern China is studied systematically and that caused possibly by the road bed project, the road moat project, the field project, the tunnel project and the service road project in construction is probed. At the same time, the type, t...展开更多
The land use information extraction technology for the high-resolution remote sensing images of the Gaofen No. 1 satellite was construc-ted. According to the spectral, band, texture and shape attributes, land use typ...The land use information extraction technology for the high-resolution remote sensing images of the Gaofen No. 1 satellite was construc-ted. According to the spectral, band, texture and shape attributes, land use types were divided, and the changing laws of land use types were ana- lyzed. Aftewards,according to the Table of Grading Standard of Sooil Erosion Intensity（SL190-96）,as well as vegetation coverage index NDVI slope, the risks of soil and water loss were assessed. Meanwhile, the level, scale, location and scope of changes in the risks of soil and water loss were monitored by using spatial visualization and spatial statistical techniques. The results showed that the area of areas without soil erosion and moderate soil erosion areas decreased obviously from 2015 to 2017, and the decreases were up to 22.929 3 and 13.626 3 km2 respectively. The ar-ea of mild soil erosion areas increased fast, and the increase reached 31.140 0 km2. The area of extremely strong soil erosion areas increased by 7.267 4 km2. In the city, moderate and strong soil erosion areas reduced, while extremely strong soil erosion patches increased fast, which was mainly related to road construction and construction and development of orchards. The extremely strong soil erosion areas were distributed in the shape of a banded loop, surrounded the suburbs of the city, and shrank towards the center of Ruijin City. The constructed technology to monitor the changes in land use and soil and water loss, as well as the changing laws of land use and soil and water loss provide the theoretical basis and plan-ning basis of soil and water conservation for urban planning departments and soil and water conservation departments.展开更多
Drinking water loss or Non-Revenue Water (NRW) threatens the financial viability of water utilities and sustainable natural water resource management. However, little attention has been paid to quantitative assessment...Drinking water loss or Non-Revenue Water (NRW) threatens the financial viability of water utilities and sustainable natural water resource management. However, little attention has been paid to quantitative assessment of the spatial distribution of water losses in Rwanda. Therefore, this study focused on the magnitude of water losses, the associated environmental and socio-economic consequences, as well as the potential benefits from water loss reduction in Rwanda. Based on water usage records from the Water and Sanitation Corporation (WASAC) of Rwanda, NRW was calculated for 15 WASAC branches and Provinces, from July 2013 to June 2014, by using the International Water Association (IWA) standard water balance approach. The results highlight an annual NRW of 16,502,198 or 41% of the total water produced, inducing a revenue loss of US$ 8,713,156. In 14 of the 15 WASAC water branches and all Rwandan provinces, the NRW ratios exceed the NRW threshold (10%) recommended by the American Water Works Association (AWWA). Because of the lost revenue, the water facilities may not expand quickly enough to meet the demands of the rapidly growing population. The suggested 50% reduction in NRW would provide additional 8,251,100 m<sup>3</sup> of treated water yearly, enough to serve extra 41,925 households or irrigate 661 ha of cropland and save US$ 4,356,579, which would reduce the financial gap in Rwanda’s National Water Improvement Project by more than 24%.展开更多
Jordan is located in theMiddle Eastand covers an area of89,342 km2. The total population ofJordanis 6,508,271.Jordanis rapidly facing a severe water supply crisis due to greater demands on a finite quantity of availab...Jordan is located in theMiddle Eastand covers an area of89,342 km2. The total population ofJordanis 6,508,271.Jordanis rapidly facing a severe water supply crisis due to greater demands on a finite quantity of available water. If current trends continue, it has been estimated that the country will experience a chronic water shortage by 2020. Despite these shortages, water loss in the distribution network is relatively high where it reaches 46%. Mafraq Governorate has the maximum water loss. Continuous records and data for the period 1999-2004 for Mafraq water authority were investigated for the water supply and lose. Water losses were evaluated, and suggestions were given to minimize the loss.展开更多
The Chinese government has raised great attention on water resources and environment over the past several years. In dealing with the issues of water pollution, water management, and the imbalance of water resources, ...The Chinese government has raised great attention on water resources and environment over the past several years. In dealing with the issues of water pollution, water management, and the imbalance of water resources, China’s state council released “Water Pollution Prevention and Control Action Plan” in 2015. This policy has become a guideline to promote water sustainability in the long run. Since then, a number of regulatory policies were released to increase the focus on water conservation. Among those actions, water loss control associated with distribution systems is regarded as a key solution to improve water supply efficiency. This paper provided a comprehensive introduction to the framework of water loss control policy in China.展开更多
The low degree of development and utilization as well as the contradiction between supply and demand of water resources in Huangshui River basin are the main restricting factors of the local agricultural development. ...The low degree of development and utilization as well as the contradiction between supply and demand of water resources in Huangshui River basin are the main restricting factors of the local agricultural development. The study on the simulation of irrigation water loss based on the VSMB model has very important significance to strengthening regional water management and improving water resource utilization efficiency. Five groundwater wells were set up to carry out the farmland irrigation water infiltration and the experimental study on groundwater dynamic effect. Two soil moisture monitoring sites were set up in two typical plots of Daxia and Guanting irrigation area at the same time and TDR300 was used to monitor four kinds of deep soil moisture( 10 cm,30 cm,50 cm and 70 cm). On this basis,the VSMB model was used to study the irrigation water loss in the irrigation area of Yellow River valley of Qinghai Province,including soil moisture content,the actual evapotranspiration,infiltration,runoff,groundwater buried depth and so on. The results showed that the water consumption caused by soil evaporation and crop transpiration accounted for 46. 4% and 24. 1% of the total precipitation plus irrigation,respectively,and the leakage accounted for 30. 3% and 60. 6% of the total precipitation plus irrigation,respectively,from March 1,2013 to April 30,and from August 1 to September 30. The actual evaporation of the GT- TR1 and GT- TR2 sites in the whole year of 2013 was 632. 6 mm and 646. 9 mm,respectively,and the leakage accounted for 2. 6% and 1. 2% of the total precipitation plus irrigation,respectively. RMSE of the simulation results of the groundwater depth in Daxia irrigation area during the two periods was 92. 3 mm and 27. 7 mm,respectively. And RMSE of the simulation results of the water content of soil profile in the two monitoring sites of Guanting irrigation area was 2. 04% and 5. 81%,respectively,indicating that the simulation results were reliable.展开更多
基金supported by the National Key Project of Scientific and Technical Supporting Programs of the Ministry of Science&Technology of China(Grant No.2007BAC18B01)the Project of Ministry of Environmental Protection of China(Grant No.200809086),the Project of Ministry of Environmental Protection of China(Grant No.200909060)the Project of Scientific Research and Technological Development of Guangxi(Grant NO.GKG1140002-2-4)
文摘The Zoige wetland is the biggest alpine wetland in the world,and an important water resource of the Yellow River.Due to natural and human factors,the Zoige wetland has been seriously degraded.Existing studies on the Zoige wetland mainly focus on the macro features of the wetland,while the influence of the surrounding faults on the Zoige wetland degradation is rarely studied.This study uses terrain data to analyze the cover change and the water loss caused by the Wqie-Seji fault based on the distributed hydrological model.The simulated water loss demonstrates that the Normalized Difference Vegetation Index(NDVI) is the most important factor for inducing water loss.The fault is also a factor that cannot be neglected,which has caused 33% of the wetland water loss.Therefore,it is of importance to study the influence of the fault on the wetland degradation.
基金National Natural Science Foundation of China,No.40801077Science & Technology Research Project Supported by Chongqing Municipal Education Commission,No.KJ070811+1 种基金Doctoral Fund of Chongqing Normal University,No.06XLB004Project by Chongqing Water Conservancy Bureau
文摘Soil and water loss has been the most serious eco-environmental problem in the Three Gorges Reservoir Area of Chongqing.In this paper the authors studied the spatiotemporal features of soil and water loss from 1999 to 2004 based on RS and GIS techniques.The results showed that:(1) The soil and water loss area decreased from 1999 to 2004.(2) Soil and water loss mainly exists in purple soil,yellow soil,limestone soil,paddy soil and yellow brown soil distributed areas.(3) The dry slope land and sparse woodland that are intensively influenced by human activities experienced most serious soil and water loss.(4) Soil and water loss in the study area indicated an obvious vertical differentiation characteristic.(5) There is a significant correlation between soil and water loss and slope.(6) There is no obvious correlation between soil and water loss and aspect.(7) Soil and water loss mainly exists in the values of R between 300 and 340 distribution area.The very-high soil and water loss has obvious correlation with R.
基金supported by the National Natural Science Foundation of China (Grant Nos.31772368,31972473)China Agriculture Research System of MOFMARA。
文摘Postharvest water loss is a critical factor that determines the quality and shelf life of fresh fruit.Cuticular wax constitutes a key barrier to reduce fruit water loss.Our previous study has shown that HJ(Citrus reticulata)has a significantly higher postharvest water loss rate than ZK(Poncirus trifoliata).Here,we investigated the fruit water loss rate of the HJ×ZK F1pseudo-testcross population in 2016 and 2019.QTL mapping for fruit water loss rate was performed by high-density genetic map and bulk segregant analysis,and QTL9 was identified to be associated with fruit water loss.The expression of NAC042 from QTL9 in ZK was 170-fold that in HJ.Heterologous expression in Arabidopsis showed that NAC042could reduce the water loss of leaves by increasing the cuticular wax content(especially alkanes).Further expression analysis revealed that NAC042 could enhance the expression of many wax-related genes in Arabidopsis leaves,including AtKCS1,AtKCS2,AtKCS9,AtKCS20,At CER1 and At CER3.Therefore,NAC042 might be involved in fruit cuticular wax synthesis to reduce fruit water loss.The findings provide new insights into the regulation of cuticular wax and fruit water loss as well as valuable information for breeding of citrus with better storability.
基金Funded by the National Basic Research Program of China(No.2009CB623200)Zhejiang Natural Science Foundation(No.LQ12E08002)+1 种基金Ningbo Natural Science Foundation(No.2012A610159)the School Disciplinary Projects(No.zj1113,XKL11D2081)
文摘The effects of specimen size and shape on development of water loss and shrinkage of mortar and concrete respectively were investigated. The experimental results showed that the effects of specimen size and shape on water loss ratio were consistent with those on drying shrinkage strain. It is also indicated that drying shrinkage strain has obvious linear correlation with water loss ratios independent of specimen size and shape. The effects of specimen size and shape on the water loss ratio were embodied in established model of averaged relative humidity improved by considering effects of sequential hydration and calculated by finite difference method. Furthermore, the effects of specimen size and shape on drying shrinkage strain of concrete were experimentally deduced and applied to modify criterion EB-FIP1990. The comparison between experimental and calculated results shows that the modified EB-FIP1990 can be adopted to predict drying shrinkage strain of concrete with reasonable accuracy.
基金Funded by the Key Research and Development Program of Zhejiang Province in 2018(No2018C03033-1)。
文摘We introduced a parameter r_s(the radius of the pores where the meniscus forms),which is composed of two factors,i e,water loss and cumulative pore size distribution(PSD),to provide a better explanation of the influence of superplasticizers(SPs)on early-age drying shrinkage.In our experiments,it is found that the addition of three types of SPs leads to a significant increase in the early-age drying shrinkage of cement paste,and drying shrinkage increases with the dosage of SPs.Based on the results above,we further studied the mechanism of the effects of SPs on the early-age drying shrinkage of cement paste by PSD and water loss,which are two components of r_s.The experimental results indicate that r_s can be a better index for the early-age drying shrinkage of cement-based materials with SPs than a single factor.In addition,the effects of SPs on other factors such as hydration degree and elastic modulus were also investigated and discussed.
文摘According to a lot of hydrological and environmental monitoring data, the condition of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is described. The occurrence and development of soil and water loss is analyzed. The conclusion is that: (1) generally, the situation of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is light, however, soil and water loss in some regions is serious, especially in the middle reach area of the river; (2) soil and water loss in the Lancang River Mekong River (in Yunnan section, China) watershed presents developing tendency and it is mainly caused by human beings. In accordance with these results, the control measures for soil and water loss are discussed.
文摘Based on natural precipitation observations, impacts of different types of land use on processes of soil and water loss over purple soil related slopeland were studied by simulated rainfall experiments. Measurement data revealed that rainstorms and slope length are the essential factors accountable for soil and water loss on purple soil slopeland for intense rill erosion can be caused on 10 meter long purple soil slopes by high intensity rainfall. Under circumanstances of rainstorms, annual hedge plants grown on slopeland of 25 degrees can cause a reduction of runoff by 22 43 percent and that of erosion induced sand content by 94 98 percent. Stone bund horizontal terraces can lead to a runoff reduction by 62 67 percent in comparison with steep slopelands and that of erosion induced sediment by 97.8 99 percent. Soil and water loss can be substantially decreased on steep slopes by hedge plants with a cost of only 10 20 percent that of the stone bund horizontal terraces. Hence it is an effective way to control soil and water loss in terms of slopeland amelioration and utilization in the Three Gorges Reservoir Area.
基金funded by the State Key Development Program for Basic Research of China(973 program,Grant No.2010CB951002)National Natural Science Funds of China(Grant No.40972218)+1 种基金the Natural Sciences Foundation ofChina(Grant No.40871027)the Knowledge Innovation project of Chinese Academy of science(Grant No.KZCX2–YW–334)
文摘The primary purpose of this study was to assess water losses by evapotranspiration, evaporation and seepage in arid zone.Normally, evaporation and seepage are the main causes of water losses.For modeling water losses,a combination of Genetic Programming(GP),Penman-Monteith(PM) and Penman combination model for measurement of evapotranspiration,evaporation and seepage has been developed.The results were found to be varying depending on how the evaporation and seepage phenomena are modeled.These results show that that there is an improvement in reducing evapotranspiration,evaporation and seepage losses in arid and semi-arid region.
基金This study was financially supported the National Natural Science Foundation of China （31070366）, the Natural Science Foundation （LY13C030005） in Zhejiang Province and the Zhejiang Province ＇Xinmiao＇ Project.
文摘To better understand the physiological characteristics of the silky starling（Sturnus sericeus）, its body temperature（Tb）, basal metabolic rate（BMR）, evaporative water loss（EWL） and thermal conductance（C） elicited by different ambient temperatures（Ta）（5-30 ℃） were determined in the present study. Our results showed that they have a high Tb（41.6±0.1 ℃）, a wide thermal neutral zone（TNZ）（20-27.5 ℃） and a relatively low BMR within the TNZ（3.37±0.17 mL O2/g·h）. The EWL was nearly stable below the TNZ（0.91±0.07 mg H2O/g·h） but increased remarkably within and above the TNZ. The C was constant below the TNZ, with a minimum value of 0.14±0.01 mL O2/g·h·℃. These findings indicate that the BMR, Tb and EWL of the silky starling were all affected by Ta, especially when Ta was below 20℃ and the EWL plays an important role in thermal regulation.
文摘Loess Plateau is the most serious region of soil and water loss in China and the world. The sediment carried into the Yellow River amounts to 1.6 billion tons every year. This paper reviews the factors and reasons for erosion in this area, and puts forward a comprehensive controlling policy on the basis of the principles of ecology and practise of Chinese scientists for 40 years. In conformity with the policy, a number of technical measures for controlling soil and water loss are suggested.
基金Knowledge Innovation Project of the Chinese Academy of Sciences,No.KZCX2-XB2-05-01National Natural Science Foundation of China,No.40771086
文摘De-farming slope farmland has been an effective measure in recent years for the improvement of the eco-environment and the mitigation of soil and water loss on the Loess Plateau. This paper, taking the Yangou Basin as a case study and using day-by-day mete- orological data of Yah＇an station in 2005, simulated and analyzed the quantitative relation between crop yield, soil and water loss and topographic condition with the aid of WIN-YIELD software. Results show that： 1） topographic gradient has important influence on crop yield. The bigger gradient is, the lower the crop yield. Yields of sorghum and corn decrease by 15.44% and 14.32% respectively at 25° in comparison to the case of 0°. In addition, yields of soya, bean and potato decrease slightly by 5.26%, 4.67% and 3.84%, respectively. The influences of topographic height and slope aspect on crop yield are slight. 2） Under the same topographic condition, different crops＇ runoff and soil loss show obvious disparity. Topographic gradient has important influence on soil and water loss. In general, the changing trend is that the soil and water loss aggregates with the increase of gradient, and the maximal amount occurs around 20°. The influence of topographic height is slight. Topographic aspect has a certain effect, and the fundamental characteristic is that values are higher at the aspect of south than north. 3） Topographic gradients of 5° and 15° are two important thresholds. The characteristic about soil and water loss with the variation of topographic gradients show that： the slope farmland with gradient less than 5° could remain unchanged, and the slope farmland more than 15° should be de-farmed as early as possible.
文摘In order to determine water losses in irrigation canals,a systematic approach was developed,consisting of two main components:a seepage simulation model and a hydraulic simulation model.The SEEP/W module of the Geo-Studio software was used to simulate the seepage rate,and the Hydrologic Engineering Center-River Analysis System(HEC-RAS)hydrodynamic model was used for hydraulic simulation.Different operation scenarios were designed to investigate all possible situations in daily operation of water distribution and delivery systems.The seepage simulation results show that the seepage losses were higher at the bottom and corners of the canal,because the hydraulic gradient was affected by the hydraulic load.The hydraulic simulation results show that due to physical and management infrastructure(using non-automated and operator-based regulation structures),operational losses accounted for a significant volume of losses compared to seepage losses.In most operation scenarios,the maximum seepage loss was 10%,and the remaining 90%was related to operational losses.It is concluded that any factor(decrease or increase of inflow to the canal)that causes an increase or decrease of operational losses is ultimately a determining factor in reducing or increasing total losses.Therefore,management approaches should be adopted to improve performance of the system and reduce losses,especially operational losses,by improving the operation methods of water level regulation and off-take structures.
基金Chinese Academy of Science and National Natural Science Foundation of China!(No. 39770609).
文摘The three methods of slash disposal in this experiment were no treatment, strip piling and burning. The results obtained from this study showed that the soil erosion, water and nutrient loss were higher in the logged areas by burning than in the logged areas by no treatment and strip piling. The soil and water loss was not serious when the slope degree of the logged area was less than 16o. The survival rate of planted seedlings was higher and the growth was better in the logged areas followed by burning than in the logged areas by no treatment and strip piling. Burning should not be used when the slope was more than 23o.
文摘A study was conducted with the objective of improvement of water use efficiency (WUE) and yield of winter wheat for Lowland Dryland Farming systems through a breeding approach. Various genotypes were screened in 1988 for rate of water loss of excised leaves (RWL) , followed by inter-crossing of diverse parents in 1993. Analysis of the relationship between RWL and yield components and plant traits demonstrated significant differences in RWL among genotypes. Under most circumstances, RWL was correlated negatively with yield and grain weight, and positively with plant height. The results demonstrated a basis for simultaneous selection for high yield and low RWL. It was found that genotypic rank varied with the duration of water loss. Correlation between RWL and yield was reduced by extended water loss duration. Analysis of the genetic variation and segregation of RWL of progenies and the effect of simultaneous screening for RWL and agronomic traits showed that good lines with improved yield and water use performance could be obtained.
文摘The factor of human project activity is often the immediate cause resulting in soil and water loss. The Baoji-Lanzhou second railway in construction is an example. The soil and water loss law caused by earth and stone mountain railway engineering construction in the northwestern China is studied systematically and that caused possibly by the road bed project, the road moat project, the field project, the tunnel project and the service road project in construction is probed. At the same time, the type, t...
基金Supported by Scientific Research Foundation of Wuhan Institute of Technology(16QD24)
文摘The land use information extraction technology for the high-resolution remote sensing images of the Gaofen No. 1 satellite was construc-ted. According to the spectral, band, texture and shape attributes, land use types were divided, and the changing laws of land use types were ana- lyzed. Aftewards,according to the Table of Grading Standard of Sooil Erosion Intensity（SL190-96）,as well as vegetation coverage index NDVI slope, the risks of soil and water loss were assessed. Meanwhile, the level, scale, location and scope of changes in the risks of soil and water loss were monitored by using spatial visualization and spatial statistical techniques. The results showed that the area of areas without soil erosion and moderate soil erosion areas decreased obviously from 2015 to 2017, and the decreases were up to 22.929 3 and 13.626 3 km2 respectively. The ar-ea of mild soil erosion areas increased fast, and the increase reached 31.140 0 km2. The area of extremely strong soil erosion areas increased by 7.267 4 km2. In the city, moderate and strong soil erosion areas reduced, while extremely strong soil erosion patches increased fast, which was mainly related to road construction and construction and development of orchards. The extremely strong soil erosion areas were distributed in the shape of a banded loop, surrounded the suburbs of the city, and shrank towards the center of Ruijin City. The constructed technology to monitor the changes in land use and soil and water loss, as well as the changing laws of land use and soil and water loss provide the theoretical basis and plan-ning basis of soil and water conservation for urban planning departments and soil and water conservation departments.
文摘Drinking water loss or Non-Revenue Water (NRW) threatens the financial viability of water utilities and sustainable natural water resource management. However, little attention has been paid to quantitative assessment of the spatial distribution of water losses in Rwanda. Therefore, this study focused on the magnitude of water losses, the associated environmental and socio-economic consequences, as well as the potential benefits from water loss reduction in Rwanda. Based on water usage records from the Water and Sanitation Corporation (WASAC) of Rwanda, NRW was calculated for 15 WASAC branches and Provinces, from July 2013 to June 2014, by using the International Water Association (IWA) standard water balance approach. The results highlight an annual NRW of 16,502,198 or 41% of the total water produced, inducing a revenue loss of US$ 8,713,156. In 14 of the 15 WASAC water branches and all Rwandan provinces, the NRW ratios exceed the NRW threshold (10%) recommended by the American Water Works Association (AWWA). Because of the lost revenue, the water facilities may not expand quickly enough to meet the demands of the rapidly growing population. The suggested 50% reduction in NRW would provide additional 8,251,100 m<sup>3</sup> of treated water yearly, enough to serve extra 41,925 households or irrigate 661 ha of cropland and save US$ 4,356,579, which would reduce the financial gap in Rwanda’s National Water Improvement Project by more than 24%.
文摘Jordan is located in theMiddle Eastand covers an area of89,342 km2. The total population ofJordanis 6,508,271.Jordanis rapidly facing a severe water supply crisis due to greater demands on a finite quantity of available water. If current trends continue, it has been estimated that the country will experience a chronic water shortage by 2020. Despite these shortages, water loss in the distribution network is relatively high where it reaches 46%. Mafraq Governorate has the maximum water loss. Continuous records and data for the period 1999-2004 for Mafraq water authority were investigated for the water supply and lose. Water losses were evaluated, and suggestions were given to minimize the loss.
文摘The Chinese government has raised great attention on water resources and environment over the past several years. In dealing with the issues of water pollution, water management, and the imbalance of water resources, China’s state council released “Water Pollution Prevention and Control Action Plan” in 2015. This policy has become a guideline to promote water sustainability in the long run. Since then, a number of regulatory policies were released to increase the focus on water conservation. Among those actions, water loss control associated with distribution systems is regarded as a key solution to improve water supply efficiency. This paper provided a comprehensive introduction to the framework of water loss control policy in China.
基金Supported by Study of Water Consumption Coefficient in the Irrigation Area of the Yellow River Basin in Qinghai Province(QX2012-019)
文摘The low degree of development and utilization as well as the contradiction between supply and demand of water resources in Huangshui River basin are the main restricting factors of the local agricultural development. The study on the simulation of irrigation water loss based on the VSMB model has very important significance to strengthening regional water management and improving water resource utilization efficiency. Five groundwater wells were set up to carry out the farmland irrigation water infiltration and the experimental study on groundwater dynamic effect. Two soil moisture monitoring sites were set up in two typical plots of Daxia and Guanting irrigation area at the same time and TDR300 was used to monitor four kinds of deep soil moisture( 10 cm,30 cm,50 cm and 70 cm). On this basis,the VSMB model was used to study the irrigation water loss in the irrigation area of Yellow River valley of Qinghai Province,including soil moisture content,the actual evapotranspiration,infiltration,runoff,groundwater buried depth and so on. The results showed that the water consumption caused by soil evaporation and crop transpiration accounted for 46. 4% and 24. 1% of the total precipitation plus irrigation,respectively,and the leakage accounted for 30. 3% and 60. 6% of the total precipitation plus irrigation,respectively,from March 1,2013 to April 30,and from August 1 to September 30. The actual evaporation of the GT- TR1 and GT- TR2 sites in the whole year of 2013 was 632. 6 mm and 646. 9 mm,respectively,and the leakage accounted for 2. 6% and 1. 2% of the total precipitation plus irrigation,respectively. RMSE of the simulation results of the groundwater depth in Daxia irrigation area during the two periods was 92. 3 mm and 27. 7 mm,respectively. And RMSE of the simulation results of the water content of soil profile in the two monitoring sites of Guanting irrigation area was 2. 04% and 5. 81%,respectively,indicating that the simulation results were reliable.
