The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific consideration...The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K<sup>+</sup>), Magnesium (Mg2<sup>+</sup>), Sulphur (S), CN ratio and Sodium (Na<sup>+</sup>) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.展开更多
The aim of this study is to determine the effects of deficit irrigation on nitrogen consumption,yield,and quality in grafted and ungrafted watermelon.The study was conducted in Cukurova region,Eastern Mediterranean,Tu...The aim of this study is to determine the effects of deficit irrigation on nitrogen consumption,yield,and quality in grafted and ungrafted watermelon.The study was conducted in Cukurova region,Eastern Mediterranean,Turkey,between 2006 and 2008,and employed 3 irrigation rates(full irrigation(l_(100)) with no stress,moderate irrigation(Dl_(70)),and low irrigation(Dl_(50));Dl_(70) and Dl_(50) were considered deficit irrigation) on grafted(CTJ,Crimson Tide+Jumbo) and the ungrafted(CT,Crimson Tide) watermelon.The amount of irrigation water(IR) applied to the study plots were calculated based on cumulative pan evaporation that occurred during the irrigation intervals.Nitrogen consumption was 16%lower in CTJ plants than in CT plants.On the other hand,consumption of nitrogen was 28%higher in Dl_(50) plants than in Dl_(70) plants while it was 23%higher in Dl_(50) plants than in l_(100) plants.By grafting,the average amount of nitrogen content in seeds,pulps and peels for CTJ was 30,43 and 56%more than those of CT,respectively.The yield and the quality were not significantly affected by the deficit irrigation.In this respect,grafting of watermelon gave higher yield,but,it had a slight effect on fruit quality.The highest yield values of 16.90 and 19.32 kg plant^(-1) in 2008 were obtained with l_(100)and in CTJ plants,respectively.However,Dl_(50) treatment could be taken into account for the development of reduced irrigation strategies in semiarid regions where irrigation water supplies are limited.Additionally,the yield increased by applying CTJ treatment to the watermelon production.展开更多
The assessment of the impacts of converting natural wetlands to agricultural farms in Nyabugogo wetland was the main objective for this research. Considering the efficiency of agricultural activities management, opera...The assessment of the impacts of converting natural wetlands to agricultural farms in Nyabugogo wetland was the main objective for this research. Considering the efficiency of agricultural activities management, operation and their maintenance in Kigali is essential to reduce the increasing environmental pollution, to raise production and to search for a sustainable method of environmental conservation, this research assesses the pollutant removal efficiency of agriculture such as crops and animal residues in order to enhance the sustainable agriculture development mainly physico-chemical characteristics and some biological characteristics and based on the preliminary assessment and review of existing literature on agriculture management systems for water resources and other environmental conservation concerns in Kigali, the research aims at contributing to the search of an appropriate agriculture management that is more efficient in terms of the increase in productivity, hence contributing to environmental sustainability. Six sampling sites were chosen in Nyabugogo wetland that is Nyabugogo, Karuruma, Kabuye (2 destinations), and Nyacyonga (2 destinations). Nyabugogo and Karuruma in the rural area, and Nyacyonga in the urban area, were chosen for the investigation of fecal coliforms. On the two first locations, Nyabugogo (80 cfu/100ml) and Karuruma (40 cfu/100ml), the study found low but not insignificant results. This is related to the dispersion of habitation in rural areas. Total Dissolved Solid (TDS) ranged from 178.1 mg/l to 179.9 mg/l at Site 1 (dry season) and subsequent test (rainy season) results ranged from 178 to 200 mg/l. The results showed different TDS in different test areas. The TDS was as low as 145.4 mg/l in the surface water of SP4 and as high as 179.9 mg/l in SP1, and in the second survey, the minimum value was 140.3 mg/l and the maximum value was 285 mg/l in SP3. Because the high turbidity levels seen along the river, in the Nyabugogo catchment, erosion protection measures should be implemented, including the use of terraces where there is agricultural activity and tree plantations, particularly at Nyabugogo sites. As a result, the Nyabugogo Riverbanks must be preserved. It would cut down on the quantity of sediment that ends up in waterways.展开更多
The present paper sought </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">to</span&g...The present paper sought </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">to</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> assess some physico-chemical parameters above permissible guidelines of irrigation water standard, the study was carried during establishment of Ecotourism Park. The field survey design was used and it was accompanied </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">by</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> laboratory tests to analyze the levels of physico-chemical parameters in both seasons (dry season and wet seasons) for water bodies as well as groundwater. The physical chemical parameters analysed were Sodium Adsorption Ratio (SAR), Soluble Sodium Percentage (SSP) Magnesium Adsorption Ratio (MAR) Kelly Index (KI) Total Hardness (TH), pH, the Electric conductivity (EC), Total Dissolved Solids (TDS). Our analyzed samples fall</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">into permissible limit of irrigation water quality, the mean values of electrical conductivity were high. The knowledge from this study will be used in establishment of Nyandungu recreation park irrigating with water quality on gardens surrounding recreation park and local community.展开更多
Laboratory experiments were conducted in different sequence and thickness of the soil layers to investigate the effects of layered-textural soils on wetting patterns and water and nitrate distributions from a surface ...Laboratory experiments were conducted in different sequence and thickness of the soil layers to investigate the effects of layered-textural soils on wetting patterns and water and nitrate distributions from a surface point source under various combinations of application rate and applied volume. Three layered soils, including a sandy-over-sandy loam (SL), a sandy loam-over-sandy (LS), and a sandy loam-sandy-sandy loam (LSL), and two uniform soils (a uniform sandy loam and a uniform sandy soil) were tested. In the experiments, the application rate was varied from 0.69 to 3.86 L h-1 and the applied volume from 5.7 to 12.1 L. The experimental results demonstrated that the wetting patterns and water and nitrate distributions were greatly affected by the sequence and thickness of soil layers as well as the application rate and volume applied. An interface existing in the layered soils, whether a fine-over-coarse or a coarse-over-fine, had a common feature of limiting downward water movement and of increasing horizontal water movement. For the fine-over-coarse layered soils of LS and LSL, water and nitrate were uniformly distributed at a given depth in the top layer soil. For a coarse-over-fine layered soil of SL, however, water accumulated in the sublayer soil underneath the interface and a zone of lower nitrate concentration was observed. The effect of application rate on water distribution pattern was dependent upon soil layering. A minor influence of application rate on water distribution for the fine-over-coarse layered soils (LS and LSL) than for the uniform soils was found. To obtain a greater wetted depth through selecting the emitters having a smaller application rate, which is a common method in the system design for a uniform soil, may not be necessarily applied for the layered soils. Measurements of nitrate distribution showed that nitrate accumulated toward the boundary of the wetted volume for both the uniform and the layered soils. This suggests the importance of optimal management of drip fertigation because nitrate is susceptible to the movement out of the root zone by mismanagement of fertigation. The information obtained from this research is useful in the design, operation, and management of a drip fertigation system.展开更多
The van Genuchten (vG) function is often used to describe the soil water retention curve (SWRC) of unsaturated soils and fractured rock. The objective of this study was to develop a method to determine the vG model pa...The van Genuchten (vG) function is often used to describe the soil water retention curve (SWRC) of unsaturated soils and fractured rock. The objective of this study was to develop a method to determine the vG model parameter m from the fractal dimension. We compared two approaches previously proposed by van Genuchten and Lenhard et al. for estimating m from the pore size distribution index of the Brooks and Corey (BC) model. In both approaches we used a relationship between the pore size distribution index of the BC model and the fractal dimension of the SWRC. A dataset containing 75 samples from the UNSODA unsaturated soil hydraulic database was used to evaluate the two approaches. The statistical parameters showed that the approach by Lenhard et al. provided better estimates of the parameter m. Another dataset containing 72 samples from the literature was used to validate Lenhard's approach in which the SWRC fractal dimension was estimated from the clay content. The estimated SWRC of the second dataset was compared with those obtained with the Rosetta model using sand, silt, and clay contents. Root mean square error values of the proposed fractal approach and Rosetta were 0.081 and 0.136, respectively, indicating that the proposed fractal approach performed better than the Rosetta model.展开更多
This study evaluated the impacts of future climate change on the hydrological response of the Richmond River Catchment in New South Wales(NSW), Australia, using the conceptual rainfall-runoff modeling approach(the Hyd...This study evaluated the impacts of future climate change on the hydrological response of the Richmond River Catchment in New South Wales(NSW), Australia, using the conceptual rainfall-runoff modeling approach(the Hydrologiska Byrans Vattenbalansavdelning(HBV)model). Daily observations of rainfall, temperature, and streamflow and long-term monthly mean potential evapotranspiration from the meteorological and hydrological stations within the catchment for the period of 1972 e2014 were used to run, calibrate, and validate the HBV model prior to the streamflow prediction. Future climate signals of rainfall and temperature were extracted from a multi-model ensemble of seven global climate models(GCMs) of the Coupled Model Intercomparison Project Phase 3(CMIP3) with three regional climate scenarios, A2, A1 B,and B1. The calibrated HBV model was then forced with the ensemble mean of the downscaled daily rainfall and temperature to simulate daily future runoff at the catchment outlet for the early part(2016 e2043), middle part(2044 e2071), and late part(2072 e2099) of the 21 st century.All scenarios during the future periods present decreasing tendencies in the annual mean streamflow ranging between 1% and 24.3% as compared with the observed period. For the maximum and minimum flows, all scenarios during the early, middle, and late parts of the century revealed significant declining tendencies in the annual mean maximum and minimum streamflows, ranging between 30% and 44.4% relative to the observed period. These findings can assist the water managers and the community of the Richmond River Catchment in managing the usage of future water resources in a more sustainable way.展开更多
To determine the potential effects of climate change on crop phenological development and productivity,an integrated analysis was conducted based on the observed climatic and phenological records of Northeast China fr...To determine the potential effects of climate change on crop phenological development and productivity,an integrated analysis was conducted based on the observed climatic and phenological records of Northeast China from 1992 to 2012.A set of quality assurance procedures,including repeated record checks,agro-meteorological station selection,internal consistency checks,temporal outlier checks,spatial outlier checks,and interpolation of missing data,were designed and applied to the phenology datasets of spring maize and paddy rice.Our results indicated that almost all phenological dates of spring maize and paddy rice became increasingly delayed from 1992 to 2012.The duration of the growing season was prolonged,particularly for the grain-filling stage(GS3).The prolonged growing season was beneficial to productivity.For spring maize,the average precipitation during GS3 decreased at a rate of 27.46 mm/decade,and the annual accumulated temperature over 10°C increased at a rate of 31.07°C/decade.Farmers initiatively adjusted crop cultivars and selected drought-resistant crops to cope with the challenges of drought.展开更多
Conversion of forest land to farmland in the Hyrcanian forest of northern Iran increases the nutrient input, especially the phosphorus(P) nutrient, thus impacting the water quality. Modeling the effect of forest loss ...Conversion of forest land to farmland in the Hyrcanian forest of northern Iran increases the nutrient input, especially the phosphorus(P) nutrient, thus impacting the water quality. Modeling the effect of forest loss on surface water quality provides valuable information for forest management. This study predicts the future impacts of forest loss between 2010 and 2040 on P loading in the Tajan River watershed at the sub-watershed level. To understand drivers of the land cover, we used Land Change Modeler(LCM) combining with the Soil Water Assessment Tool(SWAT) model to simulate the impacts of land use change on P loading. We characterized priority management areas for locating comprehensive and cost-effective management practices at the sub-watershed level. Results show that agricultural expansion has led to an intense deforestation. During the future period 2010–2040, forest area is expected to decrease by 34,739 hm^2. And the areas of pasture and agriculture are expected to increase by 7668 and 27,071 hm^2, respectively. In most sub-watersheds, P pollution will be intensified with the increase in deforestation by the year 2040. And the P concentration is expected to increase from 0.08 to 2.30 mg/L in all of sub-watersheds by the year 2040. It should be noted that the phosphorous concentration exceeds the American Public Health Association′s water quality standard of 0.2 mg/L for P in drinking water in both current and future scenarios in the Tajan River watershed. Only 30% of sub-watersheds will comply with the water quality standards by the year 2040. The finding of the present study highlights the importance of conserving forest area to maintain a stable water quality.展开更多
<span style="font-family:Verdana;">In this study, the possibility of using corn cobs as an organic aggregate in producing lightweight concrete ha</span><span style="font-family:Verdana;&q...<span style="font-family:Verdana;">In this study, the possibility of using corn cobs as an organic aggregate in producing lightweight concrete ha</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> been investigated. First, some important physical properties of corn cob have been determined in the laboratory. These properties are as follows: weight to volume ratio (unit weight), water absorption rate and granulometric analysis. Later on, 4 concrete mixtures have been prepared according to </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">workability of concrete and standar</span><span style="font-family:Verdana;">d</span><span style="font-family:;" "=""><span style="font-family:Verdana;">s specified in Turkey. After that, unit weight, heat transmissibility coefficient and 28-day pressure strength of these 4 concrete samples have been determined using machines measuring these properties. The 28-day pressure endurance value has been found between 1.4 - 56.25 kgf/cm</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">,</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">heat transmissibility coefficient ha</span><span style="font-family:Verdana;">s</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> been found between 0.19 - 0.35 Kcal/m<span style="white-space:nowrap;">∙</span></span><span style="font-family:Verdana;">h<span style="white-space:nowrap;">∙</span><span style="white-space:nowrap;">˚</span>C and unit weight of samples have been found between 800 - 1520 kg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">. Lastly</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> these properties of concrete samples have been compared with other lightweight materials being used in </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">construction of buildings.</span>展开更多
Many empirical models have been developed to describe the soil water retention curve (SWRC). In this study, a fractal model for SWRC was derived with a specially constructed Menger sponge to describe the fractal scali...Many empirical models have been developed to describe the soil water retention curve (SWRC). In this study, a fractal model for SWRC was derived with a specially constructed Menger sponge to describe the fractal scaling behavior of soil; relationships were established among the fractal dimension of SWRC, the fractal dimension of soil mass, and soil texture; and the model was used to estimate SWRC with the estimated results being compared to experimental data for verification. The derived fractal model was in a power-law form, similar to the Brooks-Corey and Campbell empirical functions. Experimental data of particle size distribution (PSD), texture, and soil water retention for 10 soils collected at different places in China were used to estimate the fractal dimension of SWRC and the mass fractal dimension. The fractal dimension of SWRC and the mass fractal dimension were linearly related. Also, both of the fractal dimensions were dependent on soil texture, i.e., clay and sand contents. Expressions were proposed to quantify the relationships. Based on the relationships, four methods were used to determine the fractal dimension of SWRC and the model was applied to estimate soil water content at a wide range of tension values. The estimated results compared well with the measured data having relative errors less than 10% for over 60% of the measurements. Thus, this model, estimating the fractal dimension using soil textural data, offered an alternative for predicting SWRC.展开更多
Data from eleven meteorological stations in the Tianshan mountains and the north slope of west Kunlun mountains, and eighteen meteorological stations in the Kaidu-Kongque river, Akesu river, Kashiger river and Yankant...Data from eleven meteorological stations in the Tianshan mountains and the north slope of west Kunlun mountains, and eighteen meteorological stations in the Kaidu-Kongque river, Akesu river, Kashiger river and Yankant river oases were examined to assess the differences in changes in potential evaporation from 1960 to 2006 in the mountainous and oasis regions of the Tarim basin and the relationships of these changes to meteorological factors. The decreasing trends in potential evaporation were primarily due to the decrease in the aerodynamic terms in both the mountainous and oasis regions, but the trends in the oasis regions were more pronounced. Based on the complementary relationship between potential and actual evaporation, the decreasing trends in potential evaporation appeared to be related to the increasing trends in precipitation in the mountainous regions and the increasing trends in water consumption in the oasis regions, thus reflecting the different impacts of natural changes and anthropogenic influences.展开更多
Over the past decades,both agriculture and power systems have faced serious problems,such as the power supply shortage in agriculture,and difficulties of clean energy consump-tion in the power system.To address and ov...Over the past decades,both agriculture and power systems have faced serious problems,such as the power supply shortage in agriculture,and difficulties of clean energy consump-tion in the power system.To address and overcome these issues,this paper proposes an idea to combine smart agriculture and clean energy consumption,use surplus clean energy to supply agriculture production,and utilize smart agriculture to support power system with clean energy penetration.A comprehensive review has been conducted to first depict the roadmap of coupling a agriculture-clean energy system,analyze their feasibilities and advantages.The recent technologies and bottlenecks are summa-rized and evaluated for the development of a combined system consisting of smart agriculture production and clean energy consumption.Several case studies are introduced to explore the mutual benefits of agriculture-clean energy systems in both the energy and food industries.展开更多
Pedotransfer functions(PTFs) have been developed to estimate soil water retention curves(SWRC) by various techniques.In this study PTFs were developed to estimate the parameters(θ s,θ r,α and λ) of the Brooks and ...Pedotransfer functions(PTFs) have been developed to estimate soil water retention curves(SWRC) by various techniques.In this study PTFs were developed to estimate the parameters(θ s,θ r,α and λ) of the Brooks and Corey model from a data set of 148 samples.Particle and aggregate size distribution fractal parameters(PSDFPs and ASDFPs,respectively) were computed from three fractal models for either particle or aggregate size distribution.The most effective model in each group was determined by sensitivity analysis.Along with the other variables,the selected fractal parameters were employed to estimate SWRC using multi-objective group method of data handling(mGMDH) and different topologies of artificial neural networks(ANNs).The architecture of ANNs for parametric PTFs was different regarding the type of ANN,output layer transfer functions and the number of hidden neurons.Each parameter was estimated using four PTFs by the hierarchical entering of input variables in the PTFs.The inclusion of PSDFPs in the list of inputs improved the accuracy and reliability of parametric PTFs with the exception of θ s.The textural fraction variables in PTF1 for the estimation of α were replaced with PSDFPs in PTF3.The use of ASDFPs as inputs significantly improved α estimates in the model.This result highlights the importance of ASDFPs in developing parametric PTFs.The mGMDH technique performed significantly better than ANNs in most PTFs.展开更多
Many factors such as freeze-thaw(FT)cycle influence soil behavior.Application of soil amendments can play an important role on runoff time commencement(RT),volume(RV)and soil loss(SL)on soils subjected to FT cycles.Ho...Many factors such as freeze-thaw(FT)cycle influence soil behavior.Application of soil amendments can play an important role on runoff time commencement(RT),volume(RV)and soil loss(SL)on soils subjected to FT cycles.However,limited studies have been documented on this subject.The present study was therefore carried out under rainfall simulation circumstances to investigate the effect of different rates of zeolite ap-plication to control the effects of FT on basic hydrological variables such as runoff production and soil loss.Towards this attempt,the effect of application of different rates of 250,500 and 750 gm^(-2) of zeolite applied before,during and after the occurrence of FT cycle on RT,RV and SL was assessed in a completely randomized design.Treatments were set up in two categories viz.control(without zeolite application),and three rates and times of zeolite application in small 0.25 m-experimental plots in three replications.The results showed that application of zeolite had significant effects on hydrological behavior of soil induced by FT cycles.Ap-plication rate of 750 gm^(-2) prior to FT cycle increased RT and reduced RV and SL at rates of 644%,68% and 91%,respectively.The results also verified that zeolite could successfully mitigate the impacts of FT cycle on the main soil hydrological variables of soil profile induced by FT cycle.It is accordingly recommended to employ zeolite as an effective amendment to control soil erosion in steep and degraded rangelands where surface soil is exposed to rainfall and runoff.展开更多
Studying the impact of future climate change on the yield and quality of wheat in the Yellow River Basin(YRB)is both essential for rationalizing the utilization of climate resources and ensuring national food security...Studying the impact of future climate change on the yield and quality of wheat in the Yellow River Basin(YRB)is both essential for rationalizing the utilization of climate resources and ensuring national food security.In this study,we employed corrected refined meteorological grid data(30 km×30 km)generated by the Climate-Weather Research and Forecasting model under RCP8.5,coupled with the DSSAT-CERES-Wheat model to predict the impact of climate change on wheat phenology,yield,and grain nitrogen content(GNC)in the YRB from 2020 to 2050.According to the type of wheat variety and planting management in the YRB,we designed five wheat ecological regions(I-V).The results show that from 2020 to 2050,the agro-meteorological resource,involving temperature,solar radiation,and precipitation,would have an overall increasing trend during the wheat growth seasons in the YRB.The growth period of wheat was generally shortened by approximately 8 d,including 6 d less from sowing to anthesis,and 2 d less from anthesis to maturity.In general,the predicted wheat yield showed a decreasing trend in the YRB,with an average reduction of 0.19%over the period from 2020 to 2050 compared with the baseline period from 1975 to 2005,and the spatial variation in wheat yield change was considerably large.In the future,the Qing‒Zang Spring Wheat region(V)in the western part of the YRB would be the only region with a yield increase of 35.4%,whereas the Northern Spring Wheat region(I)in the northern part of the YRB would be the region exhibiting the greatest decrease of 9.9%.Moreover,compared with the baseline,the GNC would increase by an average of 2.3%in the YRB,with a significant increase in the southern and central parts during 2020-2050.The GNC increase in the Huang‒Huai Winter Wheat region(III)was the highest with a 12.5%increment,but the Qing‒Zang Spring Wheat region(V)is the only region where GNC would decline,with an average decrease of 18.9%.This study implies that wheat yield and GNC have a negative correlation constraint.In general,winter wheat yield is less affected by future climate change,and the GNC of winter wheat would increase more than that of spring wheat in the YRB.Tapping the potential pathway for the balance of yield and GNC improvements under future climate change needs more exploration in the future.For instance,appropriate adjustment of the irrigation and fertilizer schedules and regimes could be considered and recommended to ensure the simultaneous improvement of wheat yield and quality in the YRB.展开更多
With the impacts of rapid urbanization and climate change,the urban flood has increasingly become a major hazard risk faced by human being in recent decades.The catastrophic urban flood events appear every year in the...With the impacts of rapid urbanization and climate change,the urban flood has increasingly become a major hazard risk faced by human being in recent decades.The catastrophic urban flood events appear every year in the world,especially in Asia and Pacific region due to its geographical composition,density population and un-even economic and social development.To reduce the urban flood risk and enhance the resilience of vulnerable communities,especially coastal communities,the Members of ESCAP/WMO Typhoon Committee(TC)have made their great efforts including engineering and non-engineering measures based on their different national conditions.As a key part of non-engineering measures,it is recognized that improving urban flood monitoring and forecasting is a measure with high benefit related to cost on urban flood risk reduction.In recent years,TC Members enhanced their capacity building on urban flood monitoring,forecasting and simulation,inundation mapping,etc.In order to enhance the technical cooperation and exchange on this aspect,Typhoon Committee Working Group on Hydrology(WGH)conducted two projects on“Urban Flood Risk Management in Typhoon Committee Area(UFRM)”and“Operation System for Urban Flood Forecasting and Inundation Mapping(OSUFFIM)”in the past years.This paper generally reviewed the situation and causes of urban flood in TC region;briefly summarized the progresses and shortages on urban flood monitoring and forecasting in TC Members;and initially discussed the areas to be enhanced in future for improvement of urban flood monitoring,forecasting and simulation,and inundation mapping with up-to-date development of weather radar and satellite monitoring,image-based monitoring,information technology(IT),Internet of Things(IoT),big data and artificial intelligence(AI).展开更多
Evapotranspiration is an essential component of the hydrological cycle that is of particular interest for water resource planning.Its quantification is helpful in irrigation scheduling,water balance studies,water allo...Evapotranspiration is an essential component of the hydrological cycle that is of particular interest for water resource planning.Its quantification is helpful in irrigation scheduling,water balance studies,water allocation,etc.Modelling of reference evapotranspiration(ET0)using both gene expression programming(GEP)and artificial neural network(ANN)techniques was done using the daily meteorological data of the Pantnagar region,India,from 2010 to 2019.A total of 15 combinations of inputs were used in developing the ET0 models.The model with the least number of inputs consisted of maximum and minimum air temperatures,whereas the model with the highest number of inputs consisted of maximum air temperature,minimum air temperature,mean relative humidity,number of sunshine hours,wind speed at 2mheight and extra-terrestrial radiation as inputs and with ET0 as the output for all the models.All the GEP models were developed for a single functional set and pre-defined genetic operator values,while the best structure in each ANN model was found based on the performance during the testing phase.It was found that ANN models were superior to GEP models for the estimation purpose.It was evident from the reduction in RMSE values ranging from 2%to 56%during training and testing phases in all the ANN models compared with GEP models.The ANN models showed an increase of about 0.96%to 9.72%of R2 value compared to the respective GEP models.The comparative study of these models with multiple linear regression(MLR)depicted that the ANN and GEP models were superior to MLR models.展开更多
For granular materials,discrete element modeling is one of the best computer tools to simulate their behavior and interactions.A field experiment was carried out to evaluate the performance of disc furrow openers in p...For granular materials,discrete element modeling is one of the best computer tools to simulate their behavior and interactions.A field experiment was carried out to evaluate the performance of disc furrow openers in paddy soil.Discrete element simulation was done to develop a 3D DEM model for notched,toothed and double disc furrow openers using EDEM software.Hertz Mindlin contact model with bonding was applied for simulation to fulfill the obligations of the soil moisture and bonding between the cohesive particles.Simulated and field experimental data were compared to determine the applicability in the different working conditions.The results of the simulation validated the applicability of the Hertz-Mindlin contact model with bonding to simulate the no till paddy soil using an extremely narrow tillage tool.The calibrated value of normal and shear stiffness was 5×10^(7)N/m,and the calibrated value of bond normal and shear strength was 3×10^(7)Pa.The relative error(-1.7%to 20.6%)for the double disc furrow opener was lower as compared with that notch typed(29.2%to 44.4%)and toothed type(31.5%to 45.9%)furrow openers.展开更多
文摘The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K<sup>+</sup>), Magnesium (Mg2<sup>+</sup>), Sulphur (S), CN ratio and Sodium (Na<sup>+</sup>) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.
基金the University of cukurova,Turkey,for providing funding through the Scientific Research Projects of Qukurova University(ZF2006D16 and ZF2008BAP1)
文摘The aim of this study is to determine the effects of deficit irrigation on nitrogen consumption,yield,and quality in grafted and ungrafted watermelon.The study was conducted in Cukurova region,Eastern Mediterranean,Turkey,between 2006 and 2008,and employed 3 irrigation rates(full irrigation(l_(100)) with no stress,moderate irrigation(Dl_(70)),and low irrigation(Dl_(50));Dl_(70) and Dl_(50) were considered deficit irrigation) on grafted(CTJ,Crimson Tide+Jumbo) and the ungrafted(CT,Crimson Tide) watermelon.The amount of irrigation water(IR) applied to the study plots were calculated based on cumulative pan evaporation that occurred during the irrigation intervals.Nitrogen consumption was 16%lower in CTJ plants than in CT plants.On the other hand,consumption of nitrogen was 28%higher in Dl_(50) plants than in Dl_(70) plants while it was 23%higher in Dl_(50) plants than in l_(100) plants.By grafting,the average amount of nitrogen content in seeds,pulps and peels for CTJ was 30,43 and 56%more than those of CT,respectively.The yield and the quality were not significantly affected by the deficit irrigation.In this respect,grafting of watermelon gave higher yield,but,it had a slight effect on fruit quality.The highest yield values of 16.90 and 19.32 kg plant^(-1) in 2008 were obtained with l_(100)and in CTJ plants,respectively.However,Dl_(50) treatment could be taken into account for the development of reduced irrigation strategies in semiarid regions where irrigation water supplies are limited.Additionally,the yield increased by applying CTJ treatment to the watermelon production.
文摘The assessment of the impacts of converting natural wetlands to agricultural farms in Nyabugogo wetland was the main objective for this research. Considering the efficiency of agricultural activities management, operation and their maintenance in Kigali is essential to reduce the increasing environmental pollution, to raise production and to search for a sustainable method of environmental conservation, this research assesses the pollutant removal efficiency of agriculture such as crops and animal residues in order to enhance the sustainable agriculture development mainly physico-chemical characteristics and some biological characteristics and based on the preliminary assessment and review of existing literature on agriculture management systems for water resources and other environmental conservation concerns in Kigali, the research aims at contributing to the search of an appropriate agriculture management that is more efficient in terms of the increase in productivity, hence contributing to environmental sustainability. Six sampling sites were chosen in Nyabugogo wetland that is Nyabugogo, Karuruma, Kabuye (2 destinations), and Nyacyonga (2 destinations). Nyabugogo and Karuruma in the rural area, and Nyacyonga in the urban area, were chosen for the investigation of fecal coliforms. On the two first locations, Nyabugogo (80 cfu/100ml) and Karuruma (40 cfu/100ml), the study found low but not insignificant results. This is related to the dispersion of habitation in rural areas. Total Dissolved Solid (TDS) ranged from 178.1 mg/l to 179.9 mg/l at Site 1 (dry season) and subsequent test (rainy season) results ranged from 178 to 200 mg/l. The results showed different TDS in different test areas. The TDS was as low as 145.4 mg/l in the surface water of SP4 and as high as 179.9 mg/l in SP1, and in the second survey, the minimum value was 140.3 mg/l and the maximum value was 285 mg/l in SP3. Because the high turbidity levels seen along the river, in the Nyabugogo catchment, erosion protection measures should be implemented, including the use of terraces where there is agricultural activity and tree plantations, particularly at Nyabugogo sites. As a result, the Nyabugogo Riverbanks must be preserved. It would cut down on the quantity of sediment that ends up in waterways.
文摘The present paper sought </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">to</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> assess some physico-chemical parameters above permissible guidelines of irrigation water standard, the study was carried during establishment of Ecotourism Park. The field survey design was used and it was accompanied </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">by</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> laboratory tests to analyze the levels of physico-chemical parameters in both seasons (dry season and wet seasons) for water bodies as well as groundwater. The physical chemical parameters analysed were Sodium Adsorption Ratio (SAR), Soluble Sodium Percentage (SSP) Magnesium Adsorption Ratio (MAR) Kelly Index (KI) Total Hardness (TH), pH, the Electric conductivity (EC), Total Dissolved Solids (TDS). Our analyzed samples fall</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">into permissible limit of irrigation water quality, the mean values of electrical conductivity were high. The knowledge from this study will be used in establishment of Nyandungu recreation park irrigating with water quality on gardens surrounding recreation park and local community.
基金This work was financially supported by the National Natural Science Foundation of China （50579077） the Key Laboratory of Plant Nutrition and Nutrient Cycling, Ministry of Agriculture, China.
文摘Laboratory experiments were conducted in different sequence and thickness of the soil layers to investigate the effects of layered-textural soils on wetting patterns and water and nitrate distributions from a surface point source under various combinations of application rate and applied volume. Three layered soils, including a sandy-over-sandy loam (SL), a sandy loam-over-sandy (LS), and a sandy loam-sandy-sandy loam (LSL), and two uniform soils (a uniform sandy loam and a uniform sandy soil) were tested. In the experiments, the application rate was varied from 0.69 to 3.86 L h-1 and the applied volume from 5.7 to 12.1 L. The experimental results demonstrated that the wetting patterns and water and nitrate distributions were greatly affected by the sequence and thickness of soil layers as well as the application rate and volume applied. An interface existing in the layered soils, whether a fine-over-coarse or a coarse-over-fine, had a common feature of limiting downward water movement and of increasing horizontal water movement. For the fine-over-coarse layered soils of LS and LSL, water and nitrate were uniformly distributed at a given depth in the top layer soil. For a coarse-over-fine layered soil of SL, however, water accumulated in the sublayer soil underneath the interface and a zone of lower nitrate concentration was observed. The effect of application rate on water distribution pattern was dependent upon soil layering. A minor influence of application rate on water distribution for the fine-over-coarse layered soils (LS and LSL) than for the uniform soils was found. To obtain a greater wetted depth through selecting the emitters having a smaller application rate, which is a common method in the system design for a uniform soil, may not be necessarily applied for the layered soils. Measurements of nitrate distribution showed that nitrate accumulated toward the boundary of the wetted volume for both the uniform and the layered soils. This suggests the importance of optimal management of drip fertigation because nitrate is susceptible to the movement out of the root zone by mismanagement of fertigation. The information obtained from this research is useful in the design, operation, and management of a drip fertigation system.
基金Supported by the National Natural Science Foundation of China (Nos.50979106 and 50779067)
文摘The van Genuchten (vG) function is often used to describe the soil water retention curve (SWRC) of unsaturated soils and fractured rock. The objective of this study was to develop a method to determine the vG model parameter m from the fractal dimension. We compared two approaches previously proposed by van Genuchten and Lenhard et al. for estimating m from the pore size distribution index of the Brooks and Corey (BC) model. In both approaches we used a relationship between the pore size distribution index of the BC model and the fractal dimension of the SWRC. A dataset containing 75 samples from the UNSODA unsaturated soil hydraulic database was used to evaluate the two approaches. The statistical parameters showed that the approach by Lenhard et al. provided better estimates of the parameter m. Another dataset containing 72 samples from the literature was used to validate Lenhard's approach in which the SWRC fractal dimension was estimated from the clay content. The estimated SWRC of the second dataset was compared with those obtained with the Rosetta model using sand, silt, and clay contents. Root mean square error values of the proposed fractal approach and Rosetta were 0.081 and 0.136, respectively, indicating that the proposed fractal approach performed better than the Rosetta model.
文摘This study evaluated the impacts of future climate change on the hydrological response of the Richmond River Catchment in New South Wales(NSW), Australia, using the conceptual rainfall-runoff modeling approach(the Hydrologiska Byrans Vattenbalansavdelning(HBV)model). Daily observations of rainfall, temperature, and streamflow and long-term monthly mean potential evapotranspiration from the meteorological and hydrological stations within the catchment for the period of 1972 e2014 were used to run, calibrate, and validate the HBV model prior to the streamflow prediction. Future climate signals of rainfall and temperature were extracted from a multi-model ensemble of seven global climate models(GCMs) of the Coupled Model Intercomparison Project Phase 3(CMIP3) with three regional climate scenarios, A2, A1 B,and B1. The calibrated HBV model was then forced with the ensemble mean of the downscaled daily rainfall and temperature to simulate daily future runoff at the catchment outlet for the early part(2016 e2043), middle part(2044 e2071), and late part(2072 e2099) of the 21 st century.All scenarios during the future periods present decreasing tendencies in the annual mean streamflow ranging between 1% and 24.3% as compared with the observed period. For the maximum and minimum flows, all scenarios during the early, middle, and late parts of the century revealed significant declining tendencies in the annual mean maximum and minimum streamflows, ranging between 30% and 44.4% relative to the observed period. These findings can assist the water managers and the community of the Richmond River Catchment in managing the usage of future water resources in a more sustainable way.
基金financially supported by the National Basic Research Program of China(2010CB951501)
文摘To determine the potential effects of climate change on crop phenological development and productivity,an integrated analysis was conducted based on the observed climatic and phenological records of Northeast China from 1992 to 2012.A set of quality assurance procedures,including repeated record checks,agro-meteorological station selection,internal consistency checks,temporal outlier checks,spatial outlier checks,and interpolation of missing data,were designed and applied to the phenology datasets of spring maize and paddy rice.Our results indicated that almost all phenological dates of spring maize and paddy rice became increasingly delayed from 1992 to 2012.The duration of the growing season was prolonged,particularly for the grain-filling stage(GS3).The prolonged growing season was beneficial to productivity.For spring maize,the average precipitation during GS3 decreased at a rate of 27.46 mm/decade,and the annual accumulated temperature over 10°C increased at a rate of 31.07°C/decade.Farmers initiatively adjusted crop cultivars and selected drought-resistant crops to cope with the challenges of drought.
基金The Modares Tarbiat University of Iran funded this work
文摘Conversion of forest land to farmland in the Hyrcanian forest of northern Iran increases the nutrient input, especially the phosphorus(P) nutrient, thus impacting the water quality. Modeling the effect of forest loss on surface water quality provides valuable information for forest management. This study predicts the future impacts of forest loss between 2010 and 2040 on P loading in the Tajan River watershed at the sub-watershed level. To understand drivers of the land cover, we used Land Change Modeler(LCM) combining with the Soil Water Assessment Tool(SWAT) model to simulate the impacts of land use change on P loading. We characterized priority management areas for locating comprehensive and cost-effective management practices at the sub-watershed level. Results show that agricultural expansion has led to an intense deforestation. During the future period 2010–2040, forest area is expected to decrease by 34,739 hm^2. And the areas of pasture and agriculture are expected to increase by 7668 and 27,071 hm^2, respectively. In most sub-watersheds, P pollution will be intensified with the increase in deforestation by the year 2040. And the P concentration is expected to increase from 0.08 to 2.30 mg/L in all of sub-watersheds by the year 2040. It should be noted that the phosphorous concentration exceeds the American Public Health Association′s water quality standard of 0.2 mg/L for P in drinking water in both current and future scenarios in the Tajan River watershed. Only 30% of sub-watersheds will comply with the water quality standards by the year 2040. The finding of the present study highlights the importance of conserving forest area to maintain a stable water quality.
文摘<span style="font-family:Verdana;">In this study, the possibility of using corn cobs as an organic aggregate in producing lightweight concrete ha</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> been investigated. First, some important physical properties of corn cob have been determined in the laboratory. These properties are as follows: weight to volume ratio (unit weight), water absorption rate and granulometric analysis. Later on, 4 concrete mixtures have been prepared according to </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">workability of concrete and standar</span><span style="font-family:Verdana;">d</span><span style="font-family:;" "=""><span style="font-family:Verdana;">s specified in Turkey. After that, unit weight, heat transmissibility coefficient and 28-day pressure strength of these 4 concrete samples have been determined using machines measuring these properties. The 28-day pressure endurance value has been found between 1.4 - 56.25 kgf/cm</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">,</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">heat transmissibility coefficient ha</span><span style="font-family:Verdana;">s</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> been found between 0.19 - 0.35 Kcal/m<span style="white-space:nowrap;">∙</span></span><span style="font-family:Verdana;">h<span style="white-space:nowrap;">∙</span><span style="white-space:nowrap;">˚</span>C and unit weight of samples have been found between 800 - 1520 kg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">. Lastly</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> these properties of concrete samples have been compared with other lightweight materials being used in </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">construction of buildings.</span>
基金Project supported by the National Natural Science Foundation of China (Nos. 50479011 and 50279025).
文摘Many empirical models have been developed to describe the soil water retention curve (SWRC). In this study, a fractal model for SWRC was derived with a specially constructed Menger sponge to describe the fractal scaling behavior of soil; relationships were established among the fractal dimension of SWRC, the fractal dimension of soil mass, and soil texture; and the model was used to estimate SWRC with the estimated results being compared to experimental data for verification. The derived fractal model was in a power-law form, similar to the Brooks-Corey and Campbell empirical functions. Experimental data of particle size distribution (PSD), texture, and soil water retention for 10 soils collected at different places in China were used to estimate the fractal dimension of SWRC and the mass fractal dimension. The fractal dimension of SWRC and the mass fractal dimension were linearly related. Also, both of the fractal dimensions were dependent on soil texture, i.e., clay and sand contents. Expressions were proposed to quantify the relationships. Based on the relationships, four methods were used to determine the fractal dimension of SWRC and the model was applied to estimate soil water content at a wide range of tension values. The estimated results compared well with the measured data having relative errors less than 10% for over 60% of the measurements. Thus, this model, estimating the fractal dimension using soil textural data, offered an alternative for predicting SWRC.
基金Supported by the National Natural Science Foundation of China(Grant Nos.50579031,50721140161,5067908)the Key Projects of China in the National Science&Technology Pillar Program(Grant No.2006BAD11B08)
文摘Data from eleven meteorological stations in the Tianshan mountains and the north slope of west Kunlun mountains, and eighteen meteorological stations in the Kaidu-Kongque river, Akesu river, Kashiger river and Yankant river oases were examined to assess the differences in changes in potential evaporation from 1960 to 2006 in the mountainous and oasis regions of the Tarim basin and the relationships of these changes to meteorological factors. The decreasing trends in potential evaporation were primarily due to the decrease in the aerodynamic terms in both the mountainous and oasis regions, but the trends in the oasis regions were more pronounced. Based on the complementary relationship between potential and actual evaporation, the decreasing trends in potential evaporation appeared to be related to the increasing trends in precipitation in the mountainous regions and the increasing trends in water consumption in the oasis regions, thus reflecting the different impacts of natural changes and anthropogenic influences.
基金This work was supported by the New Century Higher Education Teaching Reform Project of Sichuan University under Grant SCU8007and the Inter-disciplinary Training Project for Talents of Sichuan University under grant SCUKG056.
文摘Over the past decades,both agriculture and power systems have faced serious problems,such as the power supply shortage in agriculture,and difficulties of clean energy consump-tion in the power system.To address and overcome these issues,this paper proposes an idea to combine smart agriculture and clean energy consumption,use surplus clean energy to supply agriculture production,and utilize smart agriculture to support power system with clean energy penetration.A comprehensive review has been conducted to first depict the roadmap of coupling a agriculture-clean energy system,analyze their feasibilities and advantages.The recent technologies and bottlenecks are summa-rized and evaluated for the development of a combined system consisting of smart agriculture production and clean energy consumption.Several case studies are introduced to explore the mutual benefits of agriculture-clean energy systems in both the energy and food industries.
基金Supported by the Bu Ali Sina University,Iran (No. 65178)
文摘Pedotransfer functions(PTFs) have been developed to estimate soil water retention curves(SWRC) by various techniques.In this study PTFs were developed to estimate the parameters(θ s,θ r,α and λ) of the Brooks and Corey model from a data set of 148 samples.Particle and aggregate size distribution fractal parameters(PSDFPs and ASDFPs,respectively) were computed from three fractal models for either particle or aggregate size distribution.The most effective model in each group was determined by sensitivity analysis.Along with the other variables,the selected fractal parameters were employed to estimate SWRC using multi-objective group method of data handling(mGMDH) and different topologies of artificial neural networks(ANNs).The architecture of ANNs for parametric PTFs was different regarding the type of ANN,output layer transfer functions and the number of hidden neurons.Each parameter was estimated using four PTFs by the hierarchical entering of input variables in the PTFs.The inclusion of PSDFPs in the list of inputs improved the accuracy and reliability of parametric PTFs with the exception of θ s.The textural fraction variables in PTF1 for the estimation of α were replaced with PSDFPs in PTF3.The use of ASDFPs as inputs significantly improved α estimates in the model.This result highlights the importance of ASDFPs in developing parametric PTFs.The mGMDH technique performed significantly better than ANNs in most PTFs.
文摘Many factors such as freeze-thaw(FT)cycle influence soil behavior.Application of soil amendments can play an important role on runoff time commencement(RT),volume(RV)and soil loss(SL)on soils subjected to FT cycles.However,limited studies have been documented on this subject.The present study was therefore carried out under rainfall simulation circumstances to investigate the effect of different rates of zeolite ap-plication to control the effects of FT on basic hydrological variables such as runoff production and soil loss.Towards this attempt,the effect of application of different rates of 250,500 and 750 gm^(-2) of zeolite applied before,during and after the occurrence of FT cycle on RT,RV and SL was assessed in a completely randomized design.Treatments were set up in two categories viz.control(without zeolite application),and three rates and times of zeolite application in small 0.25 m-experimental plots in three replications.The results showed that application of zeolite had significant effects on hydrological behavior of soil induced by FT cycles.Ap-plication rate of 750 gm^(-2) prior to FT cycle increased RT and reduced RV and SL at rates of 644%,68% and 91%,respectively.The results also verified that zeolite could successfully mitigate the impacts of FT cycle on the main soil hydrological variables of soil profile induced by FT cycle.It is accordingly recommended to employ zeolite as an effective amendment to control soil erosion in steep and degraded rangelands where surface soil is exposed to rainfall and runoff.
基金grateful for the research grants from the National Key Research and Development Program of China(2019YFA0607403)National Natural Science Foundation of China(51879277,41961124007,41675115)Science and Technology Innovation Project of CAAS(2018-2020).
文摘Studying the impact of future climate change on the yield and quality of wheat in the Yellow River Basin(YRB)is both essential for rationalizing the utilization of climate resources and ensuring national food security.In this study,we employed corrected refined meteorological grid data(30 km×30 km)generated by the Climate-Weather Research and Forecasting model under RCP8.5,coupled with the DSSAT-CERES-Wheat model to predict the impact of climate change on wheat phenology,yield,and grain nitrogen content(GNC)in the YRB from 2020 to 2050.According to the type of wheat variety and planting management in the YRB,we designed five wheat ecological regions(I-V).The results show that from 2020 to 2050,the agro-meteorological resource,involving temperature,solar radiation,and precipitation,would have an overall increasing trend during the wheat growth seasons in the YRB.The growth period of wheat was generally shortened by approximately 8 d,including 6 d less from sowing to anthesis,and 2 d less from anthesis to maturity.In general,the predicted wheat yield showed a decreasing trend in the YRB,with an average reduction of 0.19%over the period from 2020 to 2050 compared with the baseline period from 1975 to 2005,and the spatial variation in wheat yield change was considerably large.In the future,the Qing‒Zang Spring Wheat region(V)in the western part of the YRB would be the only region with a yield increase of 35.4%,whereas the Northern Spring Wheat region(I)in the northern part of the YRB would be the region exhibiting the greatest decrease of 9.9%.Moreover,compared with the baseline,the GNC would increase by an average of 2.3%in the YRB,with a significant increase in the southern and central parts during 2020-2050.The GNC increase in the Huang‒Huai Winter Wheat region(III)was the highest with a 12.5%increment,but the Qing‒Zang Spring Wheat region(V)is the only region where GNC would decline,with an average decrease of 18.9%.This study implies that wheat yield and GNC have a negative correlation constraint.In general,winter wheat yield is less affected by future climate change,and the GNC of winter wheat would increase more than that of spring wheat in the YRB.Tapping the potential pathway for the balance of yield and GNC improvements under future climate change needs more exploration in the future.For instance,appropriate adjustment of the irrigation and fertilizer schedules and regimes could be considered and recommended to ensure the simultaneous improvement of wheat yield and quality in the YRB.
文摘With the impacts of rapid urbanization and climate change,the urban flood has increasingly become a major hazard risk faced by human being in recent decades.The catastrophic urban flood events appear every year in the world,especially in Asia and Pacific region due to its geographical composition,density population and un-even economic and social development.To reduce the urban flood risk and enhance the resilience of vulnerable communities,especially coastal communities,the Members of ESCAP/WMO Typhoon Committee(TC)have made their great efforts including engineering and non-engineering measures based on their different national conditions.As a key part of non-engineering measures,it is recognized that improving urban flood monitoring and forecasting is a measure with high benefit related to cost on urban flood risk reduction.In recent years,TC Members enhanced their capacity building on urban flood monitoring,forecasting and simulation,inundation mapping,etc.In order to enhance the technical cooperation and exchange on this aspect,Typhoon Committee Working Group on Hydrology(WGH)conducted two projects on“Urban Flood Risk Management in Typhoon Committee Area(UFRM)”and“Operation System for Urban Flood Forecasting and Inundation Mapping(OSUFFIM)”in the past years.This paper generally reviewed the situation and causes of urban flood in TC region;briefly summarized the progresses and shortages on urban flood monitoring and forecasting in TC Members;and initially discussed the areas to be enhanced in future for improvement of urban flood monitoring,forecasting and simulation,and inundation mapping with up-to-date development of weather radar and satellite monitoring,image-based monitoring,information technology(IT),Internet of Things(IoT),big data and artificial intelligence(AI).
文摘Evapotranspiration is an essential component of the hydrological cycle that is of particular interest for water resource planning.Its quantification is helpful in irrigation scheduling,water balance studies,water allocation,etc.Modelling of reference evapotranspiration(ET0)using both gene expression programming(GEP)and artificial neural network(ANN)techniques was done using the daily meteorological data of the Pantnagar region,India,from 2010 to 2019.A total of 15 combinations of inputs were used in developing the ET0 models.The model with the least number of inputs consisted of maximum and minimum air temperatures,whereas the model with the highest number of inputs consisted of maximum air temperature,minimum air temperature,mean relative humidity,number of sunshine hours,wind speed at 2mheight and extra-terrestrial radiation as inputs and with ET0 as the output for all the models.All the GEP models were developed for a single functional set and pre-defined genetic operator values,while the best structure in each ANN model was found based on the performance during the testing phase.It was found that ANN models were superior to GEP models for the estimation purpose.It was evident from the reduction in RMSE values ranging from 2%to 56%during training and testing phases in all the ANN models compared with GEP models.The ANN models showed an increase of about 0.96%to 9.72%of R2 value compared to the respective GEP models.The comparative study of these models with multiple linear regression(MLR)depicted that the ANN and GEP models were superior to MLR models.
基金The authors are grateful for the support of the Key Research and Development Project(2016YFD0200708)the Key Research and Development Project(Modern Agriculture)of Jiangsu Province,China(BE2017354)National Science and Technology Support Program(2018BAD08B04).
文摘For granular materials,discrete element modeling is one of the best computer tools to simulate their behavior and interactions.A field experiment was carried out to evaluate the performance of disc furrow openers in paddy soil.Discrete element simulation was done to develop a 3D DEM model for notched,toothed and double disc furrow openers using EDEM software.Hertz Mindlin contact model with bonding was applied for simulation to fulfill the obligations of the soil moisture and bonding between the cohesive particles.Simulated and field experimental data were compared to determine the applicability in the different working conditions.The results of the simulation validated the applicability of the Hertz-Mindlin contact model with bonding to simulate the no till paddy soil using an extremely narrow tillage tool.The calibrated value of normal and shear stiffness was 5×10^(7)N/m,and the calibrated value of bond normal and shear strength was 3×10^(7)Pa.The relative error(-1.7%to 20.6%)for the double disc furrow opener was lower as compared with that notch typed(29.2%to 44.4%)and toothed type(31.5%to 45.9%)furrow openers.
