•An optimization model of water-food-energy nexus of irrigated agriculture is developed.•Conflicts between economic benefits and environmental impacts are addressed.•Interactions among water, food ...and energy subsystems in an irrigated agricultural system are quantified.•Dual uncertainty of water availability is addressed.•The model is demonstrated to solve a real-world nexus management problem.
Irrigated agriculture is the primary user of world's fresh water resources on one hand and the producer of food to feed the world's growing population on the other hand. Water, food, and energy are intertwined in irrigated agricultural systems and an effective and coordinated management of the water-food-energy nexus is needed for the sustainable development of agriculture which is challenging because of large uncertainties involved therein. This paper developed an optimization model for the allocation of resources toward the sustainable management of agricultural water, food, and energy nexus under uncertainty. The model is capable of providing policy makers with the ability to determine optimal policy options among water, energy, and land resources to obtain the maximum system economic benefit and simultaneously minimize environmental impacts. The model is also capable of handling complex uncertainties of random boundary intervals. The model is demonstrated to solve a real-world nexus management problem in an irrigation district in northeast China. Results highlight the sensitivity of food production and environmental pollution to the utilization of water, energy, and land resources. The model is applicable for similar agriculture-centered regions with limited resources.
Meteorological drought is the fuse of hydrological drought, and understanding the propagation mechanisms from meteorological to hydrological drought is of great significance to the monitoring and ...prevention of hydrological drought. Besides the linear dependence, this study thoroughly investigated the propagation from meteorological to hydrological drought by introducing the nonlinear dependence with directed information transfer index (DITI) for the first time. In this study, the standardized precipitation index and the standardized runoff index were used to represent meteorological drought and hydrological drought, respectively. A new drought response time (DRT) evaluation system was constructed based on the maximum Pearson correlation coefficient and DITI, simultaneously considering the linear and nonlinear relationships between meteorological drought and hydrological drought. Moreover, the relationships of drought characteristics (duration and severity) between these two types of drought were established by using run theory and mathematical function, and the trigger thresholds from meteorological to hydrological drought were then determined. The results indicate that: (a) the effective drought propagation rate was mainly affected by the characteristics of meteorological drought events and the sensitivity of hydrological drought to meteorological drought; (b) the DRT in the Pearl River Basin (PRB) was mainly concentrated in 2–5 months, and the drought translation rate in the PRB was relatively large; and (c) the duration of hydrological drought events was longer in the sub‐regions with smaller meteorological drought trigger thresholds.
Key Points
Directed information transfer index was introduced in drought propagation study to build a new drought response time evaluation system for the first time
Trigger thresholds from meteorological to hydrological drought were determined by a drought propagation model
Sub‐regions with smaller meteorological drought trigger thresholds had longer durations of hydrological drought events
plays an important role in the mineralization of many metal ions, but it is unclear whether this fungus is involved in the mineralization of calcium carbonate. In this study,
was cultured under ...various conditions to explore its ability to perform microbially induced calcium carbonate precipitation (MICP). Organic acids, yeast extract, and low-carbon conditions were the factors influencing the biomineralization of calcium carbonate caused by
, and biomolecules secreted by the fungus under different conditions could change the morphology, size, and crystal form of the biosynthesized mineral. In addition, transcriptome analysis showed that the oxidation of organic acids enhanced the respiration process of yeast. This implied that
played a role in the formation of calcium carbonate through the mechanism of creating an alkaline environment by the respiratory metabolism of organic acids, which could provide sufficient dissolved inorganic carbon for calcium carbonate formation. These results provide new insights into the role of
in biomineralization and extend the potential applications of this fungus in the future.
Biochar as a soil amendment has attracted wide attention worldwide. However, the study of biochar on soil hydraulic properties during freeze-thawing remains insufficient. The purpose of this study ...was to determine the effect of straw biochar on soil water retention and soil hydraulic conductivity during a freeze-thaw period. Specifically, the effects of different biochar application rates (0, 30, 60, 90 and 120 t·hm−2) on the soil water characteristic curve (SWRCs), saturated hydraulic conductivity (Ksat) and hydraulic characteristic parameters were analysed through field trials. The response relationship between changes in the soil pore size and hydraulic characteristics was explored. The results showed that the combination of biochar amendment and freezing-thawing significantly increased the soil micro pore size (≥0.3–5 μm), soil voids (>100 μm) and total porosity (TP) and thereby improved the soil water retention capacity during the melting period. In addition, the use of biochar can promote the Ksat before and after freezing-thawing. However, increases in the carbon added during the melting period decreased the value of Ksat by 3.89%, 8.12%, 13.02% and 18.14% (p < 0.05) due to blockage of the soil pores by fine carbon particles. Compared with the control treatment, biochar significantly increased the field capacity (FC) and available water content (AWC) in soil. The largest relative change in the FC was obtained with an applied carbon amount of 60 t·hm−2, and this effect would improve the drought resistance capacity of the soil in the spring season. The excessive application of biochar led to an imbalance between the liquid and gas phases in soil, and thus, suggested biochar should not be applied in excess amounts to avoid negative effects on the soil structure. This study revealed the response mechanism of the hydraulic characteristics of the carbon-soil mixture during the freeze-thaw period and can provide a reference for the efficient utilization of soil water resources and the prediction of soil moisture in cold and dry areas.
•The changes of soil pore caused by biochar were discussed under freeze-thaw conditions.•The difference of soil water retention by biochar was discovered before and after freezing-thawing.•Effect of different pattern of carbon-soil mixtures on hydraulic conductivity during thawing period were explored.•The mechanism of biochar to soil hydraulic properties in cold and arid regions was proposed.
This study investigates the response mechanisms between soil water-heat transfer and environmental factors during freeze-thaw periods and establishes soil water-heat transfer functions in a cold ...region. Based on field-measured values of soil temperature and liquid-phase water content collected at an automatic weather station in the black soil area of the Songnen plain, the influence of the cumulative negative temperature on the soil freezing depth was analyzed under different snow cover conditions. A gray correlation analysis method was used to screen the environmental factors and determine those with the most influence on changes in soil water-heat transfer processes. Then, soil water-heat transfer functions were established between the selected environmental factors and soil temperature, the liquid-phase soil water content. The results showed that during the freezing and thawing period, snow cover hindered the effects of the cumulative temperature on the thickness of the frozen soil layer. Additionally, the time of occurrence of the maximum freezing depth under natural snow (NS), compacted snow (CS) and thickened snow (TS) treatments was delayed 7, 12 and 20 days, respectively, compared with that under bare land (BL). The correlation between atmospheric temperature, total radiation and soil temperature was relatively high, and this effect decreased with the increasing of snow cover. The main driving factors of variations in the liquid-phase water content were ambient humidity and saturated vapor pressure, and the effects of these factors decreased with increasing soil depth and snow cover thickness, similarly. In the active frozen layer, the correlation coefficients of the soil water-heat transfer functions were relatively high, and the function model can be tested by the significance (P < 0.05) test. However, the R2 values of functions below the active layer were relatively low, and the soil water-heat transfer in the area below the active layer was less affected by the environment. This study reveals the characteristics of energy transfer and mass transfer in a composite system of atmospheric factors and frozen soil under snow cover conditions. It provides a reference for accurate forecasting and the efficient utilization of soil water and heat resources in cold and arid regions.
•Snow reduces the effect of negative cumulative temperature on soil frozen layer.•Soil temperature is mainly driven by ambient temperature and net radiation.•Transfer functions are built to reflect the variation process of soil water-heat.•Snow inhibits the energy transfer in soil, affecting soil water-heat variation.
•Optimizing the conjunctive use of surface water and groundwater at the regional scale.•Promoting the economic benefits of water resource systems while considering the penalties and risks.•Reflecting ...uncertainties expressed as discrete intervals and probability distributions.•Obtaining various water planning alternatives under different climate change scenarios.
The shortage of water resources and the increasing competition among water users have highlighted the importance of the water allocation problem. Water availability is crucial for water resource allocation and changes frequently, leading to the necessity to predict available water. This paper develops a framework aimed to plan regional water allocations under different representative concentration pathways (RCP) scenarios using an interval parameter conditional value-at-risk (CVaR) two-stage stochastic programming model. This framework combines prediction and optimization to reflect climate change, the uncertainty of water system and the coordination between water resources allocation and risk. The feasibility and practicality of the framework are demonstrated by its application in a real-world case study in the Lower Songhua River Basin in northeast China. Comparison between the results of the developed model and actual conditions show that 11.61 × 108 m3 volume of water supply can be saved after optimization, indicating that the developed model tends to allocate water in a more efficient way. The ratio of surface water to groundwater is reduced from 2:1 to 1.62:1. The proposed model has practical relevance for saving water and alleviating groundwater overexploitation. The approach is applicable to most areas with severe water shortages and groundwater overexploitation, and decision makers can determine the appropriate options for water resources allocation based on risk preferences and actual conditions.
Freeze-thaw cycles (FTCs) affect the nitrogen cycling process in the non-growing season. To explore the effects of biochar application combined with soil moisture on nitrogen mineralization under ...FTCs, a laboratory FTC test of simulated soil columns was conducted. In this laboratory study, black soil from the Songnen Plain, China, was subjected to different biochar application rates (0%, 2% and 4%), moisture contents (15%, 20% and 25%) and numbers of FTCs (each FTC consisted of freezing at −20 °C for 48 h and thawing at 10 °C for 48 h). We explored the changes in soil moisture and aggregates as well as the effects of biochar application and different moisture contents on nitrogen availability under FTCs. The results showed that FTCs promoted the fragmentation and decomposition of soil aggregates, processes that are also related to the moisture content and biochar application rate. Moreover, the application of biochar increased the soil water holding capacity. The ammonium nitrogen and nitrate nitrogen contents in the soil first increased and then decreased during the FTCs and peaked after the third FTC. However, influenced by transfer and transformation processes, the inorganic nitrogen contents were higher than the initial levels after freezing and thawing. In addition, the content of ammonium nitrogen increased with increasing initial soil moisture content but decreased with increasing biochar application rate. However, the content of nitrate nitrogen increased with increasing initial soil moisture content and biochar application rate. Analysis of variance showed that FTCs and moisture content are the major driving factors that affect nitrogen mineralization (p < 0.05). This study provides guidance for the regulation of farmland soil nitrogen and the efficient utilization of agricultural resources in areas with seasonally frozen soil.
•Freeze-thaw cycle decreased the stability of soil aggregate.•Biochar inhibited the water migration, but improved soil nitrogen fixation ability.•Biochar promoted the increase of NO3−-N, but inhibited the increase of NH4+-N.•Freeze-thaw cycle and moisture content affected the N mineralization significantly.
•An evaluation system was constructed more in line with the water resource carrying capacity in the eastern region of the Heilongjiang Province.•The improved TOPSIS model adopts a new method of ...assigning weights.•It avoids the deviation caused by subjective factors in the traditional analytic hierarchy process.•It avoids the emergence of extreme weights using the anti-entropy weighting method.
Assessments and analyses of the water resource carrying capacity provide practical guidance for regional water resource planning and water resource management. The water resource carrying capacity index system and the corresponding level criteria are constructed from the perspective of the carrying capacity subsystem. Additionally, a water resource carrying capacity model is constructed using the improved TOPSIS method. Finally, a comprehensive evaluation and analysis of the water resource carrying capacity in the study area from 2009 to 2018 is conducted, with the eastern part of Heilongjiang as a case study. The results show that the combination of the improved AHP and the anti-entropy weighting method can avoid the bias caused by subjective factors in the traditional AHP and the bias caused by the randomness of data in the entropy weighting method, yielding accurate estimates of the water resource carrying capacity. A new method of assigning weights in TOPSIS models is developed. In addition, the water resource carrying capacity of the studied cities is generally in state III (Moderate) in the eastern region of Heilongjiang, and the multiyear average value obtained from the comprehensive evaluation is 0.4581. The Qitaihe and Hegang areas have higher water resource carrying capacities than other areas. Overall, water resource and societal factors have an obvious influence on the water resource carrying capacity in the eastern region of Heilongjiang, and these factors vary in different areas. The water supply modulus and proportion of water used for agricultural irrigation have the greatest effects on the water resource carrying capacity in the study area.
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•Spatiotemporal changes of snow cover and soil moisture in different land use types.•Relationship between different snow cover parameters and soil moisture.•Inferring soil moisture ...status based on snow cover.
To explore the impact of climate change on snow cover and spring soil moisture (SM) in areas with seasonally frozen soil, snow cover parameters and spring SM for different land use types in Northeast China are extracted based on remote sensing snow cover and SM products. Snow cover parameters include snow days (SD), first day of snow cover (FSD), last day of snow cover (LSD), maximum snow depth (MSD) and average snow depth (ASD). The spatiotemporal variations and correlations between snow cover parameters and spring SM for different land use types are analyzed. The results showed that the average spring SM for different land use types was ordered woodland > farmland > grassland, with obvious woodland and farmland increases. Woodlands had many SD and large snow depths (MSD and ASD) that eventually decreased. Farmland SM increased significantly in spring, which aided crop development. The decrease in grassland spring SM was not obvious, but the snow cover parameters of certain areas decreased notably. Snow cover significantly impacted farmland SM, and correlation coefficients were highest between all snow cover parameters and SM in spring. The correlations between grassland snow cover parameters and SM in April were higher than those in May, but woodland snow cover parameters and spring SM were not correlated. Among the five snow parameters, FSD had the lowest correlation with spring SM, and SD had the greatest impact on SM. These results show the significant relationship between snow cover and SM and reveal relevant patterns. As future climate warming may introduce drought risk to woodland and grassland areas, advance preparations should be made. Farmland areas will continue to maintain appropriate SM, which is beneficial for agricultural development.
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•Spring drought factors include snow cover, precipitation, temperature, and soil moisture.•Established a variance analysis projection pursuit model (ANOVA PPM)•ANOVA PPM achieves a ...balance between overall dispersion and local aggregation.
Due to the influence of snow cover and soil freeze–thaw processes in the early spring, the characteristics of spring drought in cold regions are different from those in other regions. This paper takes Qiqihar, a cold and semiarid grain production area in Northeast China, as the study area. Based on factors such as snow cover in the early spring period and precipitation, temperature, evapotranspiration, and soil moisture during the spring sowing period, a projection pursuit model with analysis of variance (ANOVA PPM) was used to analyze the spatiotemporal variation characteristics of regional spring drought. For the ANOVA PPM, based on the grouping of the projection points, local aggregation is measured by the mean square within groups, and overall dispersion is measured by the mean square between groups, thus achieving comparability and balance between overall dispersion and local aggregation. The spatial analysis of spring drought showed that, from a spatial perspective, there were significant spatial differences in spring drought in different subregions, and spring drought was closely related to latitude, with significant differences occurring at different latitudes. The northern region is relatively light, while the central and southern regions are more severe. From a temporal perspective, there are significant differences in spring droughts between different decades (1980 s, 1990 s, 2000 s and 2010 s). Overall, spring drought first intensifies and then decreases.
