Water Control Measures Research Articles

Physical simulation for water invasion and water control optimization in water drive gas reservoirs

The development of water drive gas reservoirs (WDGRs) with fractures or strong heterogeneity is severely influenced by water invasion. Accurately simulating the rules of water invasion and drainage gas recovery countermeasures in fractured WDGRs, thereby revealing the mechanism of water invasion and an appropriate development strategy, is important for formulating water management measures and enhancing the recovery of gas reservoirs. In this work, physical simulation methods were proposed to gain a better understanding of water invasion and to optimize the water control of fractured WDGRs. Five groups of experiments were designed and conducted to probe the impacts of the distance between the fractures and the gas well, the drainage position, the drainage timing and the aquifer size on the water invasion and production performance of a gas reservoir. The gas and water production and the internal pressure drop were monitored in real time during the experiments. Based on the above experimental works, a theoretical analysis was conducted to quantitatively evaluate the performance of the gas reservoir recovery via the gas well production performance, water invasion, dynamic pressure drop and residual gas and water distribution analysis. The results show that when the fracture scale was appropriate, a gas well drilled close to a fracture (Experiment 1-3) or a high-permeability formation could also produce gas and achieve drainage efficiently. The recovery factor of Experiment 1-3 reached 62.5%, which was 24.6% and 21.1% higher than those of Experiments 1-1 and 1-2, respectively, which had wells drilled in low-permeability areas. Draining water near an aquifer can effectively inhibit water invasion during the early stage of gas recovery. The setup in Experiment 2-1 effectively inhibited water invasion and avoided the formation of water-sealed volumes of gas to recover 30% more gas than recovered with that of Experiment 1-1 without drainage wells. A shorter distance between the drainage well and the aquifer increased the drainage capacity and decreased the gas production capacity, respectively (Well 2 at Point A vs Point B). A larger aquifer had a lower gas recovery, which reduced the economic benefit. For example, due to an infinitely large aquifer, the reserves in Experiment 4-1 were developed by a single well, the gas recovery was only 33.4%. These research results are expected to be beneficial for the preparation of development plans and the optimization of water control measures for WDGRs.

Identification model of water inrush source based on statistical analysis in Fengyu minefield, Northwest China

Rapid and effective identification of water inrush source is an important guarantee for mine safety production. Hydrogeochemical theory has been applied in coal mining and water prevention and control, but its application scale and coverage are limited. The main reason is that the existing research is mostly based on conventional hydrochemical indicators, and less applied in trace elements and environmental isotopes. In order to explore the evolution mechanism of water inrush in well field and realize the accurate identification of water inrush source, this paper takes Fengyu well field in Shuozhou City, Shanxi Province, China, as the research object. Based on the test results of conventional hydrochemistry, trace elements, and environmental isotope indexes of each aquifer, the hydrogeochemical distribution and evolution law of each aquifer in a minefield are analyzed. Combined with cluster analysis, principal component analysis, and Bayesian stepwise linear discriminant method, the discrimination model of mine water inrush source is established. The results show that, with the gradual increase of aquifer depth, the total dissolved solids (TDS) of water samples showed a decreasing trend; HCO3− is dominant in all aquifers, which may be the result of mixing after water inrush in each aquifer; the content of trace elements in underground aquifer of minefield can be summarized as three principal components of groundwater overflow, river recharge, and dissolution. The distribution of Shanxi water, Taiyuan water, and Ordovician water conforms to the height effect and temperature effect; the established discrimination model of water inrush source in minefield can effectively discriminate water inrush source. The calculation process is simple and the model structure is stable, which is worthy of promotion and application. The research results can provide a scientific basis for the development of water control measures (draining, depressurization, and plugging) in minefields.

Institutional constraints to groundwater resource management in arid and semi-arid regions: a Straussian grounded theory study

As institutions are key pillars of groundwater resource management (GRM) it is important to determine the institutional constraints to GRM. This study used qualitative research methods to identify such constraints in western Iran. The participants were 37 key informants involved in GRM in Khorramabad county, including experts, representatives of relevant authorities, and members of local institutions. Snowball sampling was used to select the sample. Participants underwent in-depth individual interviews that were documented and transcribed for qualitative analysis. Open coding revealed 260 codes and 54 subcategories relevant to institutional constraints to GRM, which were further classified using axial coding. Using selective coding, a storyline was created, detailing the relationships among several of the categories, subcategories, and concepts. The results showed that the main phenomenon is “institutional structural and functional weakness”. Some conditions are contextual and allow the phenomenon to occur and some conditions have affected it. Regarding the contextual conditions, some cultural elements act as barriers to GRM. The inability of institutions involved in GRM to deal with unauthorized actors because of legal weakness (in both formulation and enforcement) also affects the phenomenon. In addition, weak organizational management due to centralized planning and complex bureaucracy affect the phenomenon. This research on causal conditions also indicates that groundwater exploitation in the form of drilling unauthorized wells and engaging in unplanned and unauthorized extraction is the most important cause of the phenomenon. The most important strategy of the institutions to overcome the phenomenon is to implement water engineering and control measures.

Effect of soil and water conservation measures on the reduction of runoff and sediment load in a loess hilly-gully region

Soil and water conservation are important measures in regulating runoff and sediment load on the Loess Plateau. Information on how land use and land cover changes, especially the implementation of the soil and water loss control project, can affect the sediment load dynamics and hydrological variables is important since large-scale eco-environmental governance programs are being implemented. In this study, an improved double mass curve and the decomposition method were used to assess the effects of different soil and water control measures on runoff and sediment load in the Lvergou, which is a small basin on the Loess Plateau in China, based on 60 years of data. We conclude that the total precipitation (<i>P</i>) was not statistically significantly different (<i>p</i> &gt; 0.05), whereas heavy rain increased significantly (<i>p</i> &lt; 0.01). Annual runoff (<i>R</i>) and sediment load (<i>S</i>) decreased significantly from 1954 to 2010, with abrupt changes in 1990 and 1986. Sensitivity analysis indicates that <i>P</i> is more influential than temperature (<i>T</i>) in affecting <i>R</i> and <i>S</i>. This study indicates that soil and water conservation are the strongest contributors to reducing annual runoff and sediment load, with their contributions reaching 84.2% and 91.1%, respectively, while the remaining percentage was caused by climate variations. Among all soil and water conservation measures, the runoff and sediment load in the basin were most sensitive to the terrace. There were obvious changes in the rainfall-flood and rainfall-sediment relationships due to extreme rainfall conditions. Compared with historical extreme rainfall events, the decreases in flooding and sediment load in the river basin after 2000 under similar rainfall and intensity conditions were obvious. This result further indicates that the implementation of soil and water conservation measures plays an important role in reducing flooding and sediment load in this region by changing the water-sediment relationship during extreme rainfall. These results can provide important an reference for understanding the causes of sharp decrease of water and sediment in the Loess Plateau basin.

Quantitative Characterization of Overburden Rock Development Pattern in the Goaf at Different Key Stratum Locations Based on DEM

The overburden rock mining fissures are the main cause of coal spontaneous combustion, gas pooling, and mine water inrush caused by goaf air leakage. Rapid and accurate determination of the development and evolution law of mining fissures have great significance for the application of coal spontaneous combustion prevention and control, gas disaster prevention and control, and water damage prevention and control measures. In this paper, a preliminary judgment of the development height of the water‐conducting fracture zone is made based on the theoretical analysis, and the physical model size of the numerical simulation is determined according to its judgment result. It is judged that the development height of its water‐conducting fracture zone is between 49 and 64.2 m, which is in line with the actual results. Based on this, a three‐dimensional solid model was established in PFC (Particle Flow Code) software to analyze the fissure development pattern of the overburden rock and the development height of the water‐conducting fracture zone when the main key stratum of the rock seam is in different positions by simulating the excavation process of the coal seam. The results show that when the main key stratum is located in the “original crack belt boundary,” the development of water‐conducting fracture zone is significantly inhibited; when the main key stratum is located in the “original caving zone,” the water‐conducting fracture zone is fully developed, and the crack belt finally develops to the top of the model. In order to verify the accuracy of the numerical simulation, similar material simulation experiments were performed under the same scheme. The results are consistent with the numerical simulation conclusions, effectively verifying the accuracy of the numerical simulation. Finally, the extraction of porosity of the goaf was carried out based on numerical simulation, and the permeability zoning of the goaf was performed; the results show that the development of the water‐conducting fracture zone has a significant influence on the permeability of the mining area, and the more fully developed the fissure is, the greater is its permeability. In this paper, the fissure development law in the goaf under different key stratums is explored by various research stratums, and the results show a good consistency, which provides a scientific basis for the prevention and control of disasters such as water inrush and coal and gas outburst in mines, and provides theoretical guidance for safe mining.

Discussion on evaluation method of water energy in strong water drive gas reservoir

In the process of gas reservoir development, as the pressure of gas reservoir decreases, water will invade into the gas reservoir and form a certain scale of water body, so it is very necessary to know the water body energy correctly. This paper takes strong water drive gas reservoir as an example, and uses equation of state method, pressure drop curve method and material balance method respectively to complete the water body energy evaluation of this block, so as to find the water body energy evaluation method suitable for strong water drive gas reservoir, which plays an important role in implementing water control measures.

A calculation model for water breakthrough time of gas wells in gas reservoirs with edge water considering interlayer heterogeneity: A case study of the Lower Triassic Feixianguan gas reservoirs in the Puguang Gas Field

The existing models for calculating the water breakthrough time of gas wells in gas reservoirs with edge water ignore the effects of reservoir's interlayer heterogeneity, so their calculation results are more deviated from the actual water breakthrough time of gas wells. As a result, they cannot accurately and effectively guide the adjustment of gas well production system and the formulation of technical water control measures. In this paper, a water-flooding seepage experiment of parallel core was conducted by taking the gas reservoir with edge water of Lower Triassic Feixianguan Formation in the Puguang Gas Field of the Sichuan Basin as an example. Then, the effects of edge water inrush caused by the interlayer heterogeneity of reservoir on water breakthrough time of gas wells was analyzed by means of reservoir numerical simulation. Based on this, the inrush coefficient was introduced to characterize the interlayer heterogeneity of reservoir, and a model for calculating the water breakthrough time of gas wells in the commingled gas reservoir with edge water considering the influence of interlayer heterogeneity was established. Finally, five wells in the gas reservoir of Feixianguan Formation in the Puguang Gas Field were selected for case calculation. And the following research results were obtained. First, the interlayer heterogeneity of gas reservoir results in edge water burst. And the stronger the interlayer heterogeneity, the more severe the edge water coning and the sooner the water breakthrough. The water breakthrough time of gas wells depends on the water breakthrough time in the reservoir with the highest permeability. Second, a model for calculating the water breakthrough time of gas wells in the gas reservoirs with edge water considering the influence of reservoir interlayer heterogeneity is established based on the seepage theory. And the relative errors of its calculation results are in the range of −3.43–4.70%, which can satisfy the accuracy requirement of engineering errors. In conclusion, this newly established model can provide an effective method for accurately calculating the water breakthrough time of the gas well in the commingled gas reservoir with edge water. Furthermore, it is conducive to the adjustment of the production system of gas wells in the gas reservoir with edge water and the formulation of technical water control measures.

The Enhanced Management of Water Resources Improves Ecosystem Services in a Typical Arid Basin

Ecosystem services (ES) are essential for human well-being. However, few studies have investigated the optimization of the management of water resources based on trade-offs of ES in arid areas. In order to solve this problem, four important ES that affect the carbon cycle and water cycle were selected from the regulating ecosystem services (carbon storage (CAS), evapotranspiration (ET)), the supporting ecosystem services (soil drought index (TVDI)) and the provisioning ecosystem services (groundwater depth (GWD)) in arid areas. The spatiotemporal distribution of these four ES were quantitatively analyzed—using related models—in the Tarim River, situated in a typical arid inland basin, in 2000, 2010, and 2018, in order to determine the fundamental driving factors of change in ES. The results showed that CAS was mainly affected by changes in land use, while ET, TVDI, and GWD were mainly affected by changes in water volume. The unified management of water resources improved the regulating ecosystem services (an initial increase in CAS, followed by a decrease; ET continued to grow from 2000 to 2018), the supporting ecosystem services (TVDI was maintained at 0.69–0.74), and the provisioning ecosystem services (GWD rose 5.77% in 2000–2010, and stabilized at 3.05 m in 2018). The trade-off/synergy relationships of the four ES were further analyzed at different geographical scales through correlation analysis and the trade-off index (RMSD). In different river sections, the ES that affect carbon and water cycles were highly dependent on each other. In areas with high CAS, the groundwater depth was low, and the soil moisture and ET were high. With different land use types, there was a synergistic relationship between CAS and GWD in woodland and grassland areas, and between ET and GWD in farmland areas. This showed that there was still strong competition between natural vegetation and groundwater, represented by woodland and grassland, and the ineffective loss of water resources such as ET through expansion of farmland. Finally, this study innovatively incorporated the results of trade-offs of ES into water resource management. In order to reduce the trade-offs between ES, and to improve ES, to achieve the ecological protection and restoration of desert riparian forests, and to optimize the water resource management in arid areas, different ecological water regulation and control measures were proposed in the high-flow years and the low-flow years of arid areas. This study can provide important scientific references for the improvement of ES and the optimization of the management of water resources in other similar river basins in arid areas.

Hydrochemical Characteristics and Possible Controls of the Surface Water in Ranwu Lake Basin

To study the chemistry of surface water and potential control measures in the Ranwu Lake basin, 19 samples were collected from Ranwu Lake in 2019. Conventional hydrochemical techniques and statistical analysis methods (descriptive statistics, the Gibbs figure, ion ratio, Piper triangular diagrams) were applied to better understand the solute geochemistry and surface water hydrochemistry in the Ranwu Lake catchment. Surface water in the Ranwu catchment is slightly alkaline (pH of the samples ranged from 7.54 to 8.48 with an average value of 8.06). The concentrations of total dissolved solids (TDS) in the water range from 59.89 to 96.75 mg ·L-1 with an average of 79.98 mg ·L-1, the total dissolved solids of all samples are less than 100 mg ·L-1 and belong to fresh water. The TDS are dominated by Ca2+, Mg2+, HCO3-, and SO42- in the Ranwu Lake. The ion concentrations in the lake water samples are in the order of Ca2+ > Mg2+ > Na+ > K+. The concentrations of Na+and K+are very low. Ranging from 0.5 to 1.21 mg ·L-1, with an average value of 0.58 mg ·L-1, the equivalent concentration of Ca2+ accounts for 63.3% to 76.2% of total cations with an average value of 67.2%. The equivalent concentration of Mg2+ accounts for 23.4% to 36.2% of total cations with an average value of 31.4%. Ca2+ and Mg2+ account for 98.5% of total cations. The main anions were HCO3- and SO42-. The equivalent concentration of HCO3- accounts for 74.31% to 84.29% of total anions with an average value of 78.21%. The equivalent concentration of SO42- accounts for 9.59% to 19.37% of total anions with an average value of 15.34%. HCO3- and SO42- together account for 93.55% of total anions on average. All the water samples fall in the water-rock interaction field, which suggests that the weathering of rocks primarily controls the major ion chemistry of groundwater in this area. Solutes are mainly derived from carbonate weathering and silicate weathering. The role of cation exchange in the geochemical process of the lake and the influence of human activities on the lake are found to be weak.

Response Mechanism of Cotton Growth to Water and Nutrients under Drip Irrigation with Plastic Mulch in Southern Xinjiang

The effects of water and nutrient control measures on the cotton plant height, stem diameter, biomass, seed yield, and soil moisture under an irrigated plastic mulch production system were studied. Using field experiments in the 2018 cotton-growing season, 6 fertilization treatments (30-10.5-4.5 (N-P2O5-K2O), 24-8.4-3.6 (N-P2O5-K2O), 20-7-3 (N-P2O5-K2O), 16-5.6-2.4 (N-P2O5-K2O), 10-3.5-1.5 (N-P2O5-K2O), and 0-0-0 (N-P2O5-K2O) kg/mu) and 6 deficit irrigation treatments (40% PET, 60% PET, and 80% PET) were established at the cotton budding and flowering stages. Analysis of variance (ANOVA) (P&lt;0.05) was used to evaluate the significant differences among the treatments. The results showed that the effects of the water and nutrient control measures were obvious. The irrigation water use efficiency (IWUE) was the highest under the 80% deficit irrigation (T7) treatment at the flowering stage (2.62 kg/m3). Increases in cotton plant height and stem diameter were promoted by mild or moderate deficit irrigation at the flowering stage, but normal growth and development were affected by severe deficit irrigation at any growth stage. The growth indexes of cotton increased with increasing fertilization, but significant differences between each fertilization gradient were not obvious. At the same time, excessive fertilization not only had a positive effect on the LAI (leaf area index) and yield but also caused fertilizer waste and unnecessary cotton growth. The cotton seed yield and single boll yield reached their highest values (566 kg/mu) under the 1.2 times fertilizer treatment (T9), but the 0.8 times fertilizer treatment had the highest IWUE among the nutrient control treatments (1.91 kg/m3). Therefore, it is suggested that deficit irrigation at 60~80% of the potential evapotranspiration (PET) at the flowering stage and 16-5.6-2.4 (N-P2O5-K2O) fertilizer be applied as an optimal water and nutrient management strategy to maximize the seed cotton yield, IWUE, and overall growth and development of cotton.

Effects of Water Stress on Fluorescence Parameters and Photosynthetic Characteristics of Drip Irrigation in Rice

To study the effects of water stress on the fluorescence parameters and photosynthetic characteristics of rice under drip irrigation and mulching, so as to determine the response mechanisms to water stress during the tillering stage. A two-year trial was carried out at Shihezi University, China. Three water gradients were investigated. The results showed that the chlorophyll content (a + b), photosynthetic rate (Pn), and leaf area index (LAI) decreased with decreasing soil moisture content at the tillering stage. The chlorophyll content (a + b) and Pn in the flooding irrigation (CK) treatment were significantly higher than those in the stress treatments, and the chlorophyll content (a + b) and Pn in the W1 and W2 treatments were significantly lower than those in the other treatments. The maximum LAI of the CK, W1, and W2 treatments were similar, while the W3 produced lower values; stress treatment improved the ability of tillering in the early and middle stages, while the decrease in soil water content in the tillering stage resulted in a decrease in the final tillering rate; drought stress in the tillering stage resulted in decreased rice yields. The yield of the W1 and W2 treatments were similar, while that of the W3 treatment was seriously reduced. The main reasons for the reduction in yield was the significant decrease in the number of effective panicles, the seed setting rate, and a decrease in the 1000-grains weight. Water consumption in the stress treatments decreased by 51.69%–58.78% compared to the CK treatment; water-use efficiency in the CK treatment was only 0.25 kg·m−3, and the water-use efficiency of the stress treatments increased by 40%–72%. We should make full use of the compensation effect of drought stress in the water regulation of drip irrigation in covered rice and adopt the water control measure of the W2 treatment in the tillering stage. These measures are conducive to improving water-use efficiency and achieving the goal of high quality, high yield, and high efficiency.

Application of binary compound water control technology in the development of horizontal wells in offshore oil fields

Offshore A oil field is a typical bottom water reservoir with thin thickness of oil layer and large thickness ratio of water layer and oil layer. Due to its strong bottom water energy, serious non-homogenous and the impact of the bottom ridge, most of the horizontal well production segment is seriously water out.Based on interaction relationship between horizontal segment trajectory and oil and-water interface, the distribution and contrast of permeability along horizontal segment and the comprehensive analysis of production performance, this paper combines the characteristics of the residual oil distribution of typical wells and the mechanism of dual compound oil addition, and from the perspective of combining theory with the field creatively put forward the dual composite water control mode of first injecting gel segment plug and then injecting foam. then completed the design of dual compound water control mode and dosage of the typical well. After processing water control measures, the production data shows that the water content decreased significantly after opening the well, from 95.1% before water control to 80%, which was 15% lower. Also the oil production rate has a significant increase from 2.3t/d before water control to maximum to 9t/d after implementing control measures and cumulative oil increase is 550t with effective period of 135 days. The effect of oil and precipitation is obvious.

A parallel electric field penetration technique for identifying hazardous water sources beneath coal seam mining face floors

Abstract In this work, a highly applicable multi-channel parallel electric field penetration technique is proposed to facilitate identification of hazardous water sources beneath coal seam mining face floors. The effects of various parameters on the characteristics of the apparent resistivity curves of a spherical model were analyzed through numerical simulation. It was determined that the proposed technique was sensitive to several model parameters (resistivity, size and spatial location). In addition, physical model experiments were also performed. Resistivity was determined from a three-dimensional inversion of the measurements. The results showed that the proposed technique was highly effective in determining the electrical characteristics and spatial distribution range of the anomalous bodies in the physical model. An engineering application of the proposed technique further demonstrated its effectiveness and reliability. The proposed technique can provide a basis for formulating water disaster prevention and control measures for mining faces.

Spatiotemporal dynamics of cell abundance, colony size and intracellular toxin concentrations of pelagic and benthic Microcystis in Lake Caohai, China

Lake Caohai has experienced extensive Microcystis blooms in recent years, and to improve its water quality, the local government carried out a series of water control measures. To better understand the dynamics of both pelagic and benthic Microcystis and their characteristics in Lake Caohai, we conducted a 1-year investigation from December 2015 to December 2016 to gain a seasonal outlook on the distribution and dynamics of cell abundance, colony size and intracellular microcystins (MCs) of Microcystis. The results indicated that the Microcystis bloom occupied primarily the northeastern region and then moved gradually from lakeshore to lake center. The perennial southwesterly winds and the water inflow from northeast to southwest in Lake Caohai determined the spatiotemporal distribution of pelagic Microcystis. Benthic Microcystis was mainly distributed in the northeastern region in summer, occupied the lake center in autumn and then occupied the southeastern region in winter, determined by the sedimentation of pelagic Microcystis and the death of benthic Microcystis. Small colonies (20–60 μm) overwintered more easily in both water column and sediment. The concentrations of intracellular toxin of benthic Microcystis were observed to be significantly higher than those of pelagic Microcystis. This might be because Microcystis synthesized large amount of MCs to acclimate to an unfavorable benthic environment. This knowledge on the dynamics of Microcystis expands our understanding of mechanisms underpinning the formation of Microcystis blooms.

Formation mechanism and prediction method of water inrush from separated layers within coal seam mining: A case study in the Shilawusu mining area, China

Water inrush form separated layers (WIFSL) is one type of mine water disaster, threatening the safety of coal mines. A thorough understanding of WIFSL formation mechanisms is prerequisite for creating water control measures. In this study, the formation conditions of roof bedding separation, menacing bed separation water and formation conditions of WIFSL were examined. According to the composite beam theory, the traditional criterion for bed separation location is revised. Combining the Winkler foundation beam model, the mechanical model for bed-separation water hazard above the water-flowing fractured zone (WFFZ) was established, and the theoretical discriminant of the first and periodic WIFSL was deduced. In addition, the water inrush coefficient method was used to divide the WIFSL risk. The results of this study show that separation locations are controlled by a combination of lithology, rock thickness, and elastic modulus. The formation of bed separation water is restricted by the separation locations and recharge water source. The formation of WIFSL mainly depends on the strength and thickness of the protective layer, between the bed separation and the WFFZ, and the foundation coefficient of the fractured rock mass in the WFFZ. Taking Shilawusu coal mine, Dongsheng coalfield, Inner Mongolia autonomous region, China as the application examples, the risk of WIFSL within the mining area was predicted and classified. In addition, theoretical analysis and calculation of bed separation locations, foundation coefficient, and periodic inrush distance of WIFSL within the 06A working face were carried out, verifying the accuracy of the theoretical model and prediction method in this study.

Modeling Runoff and Nitrogen Loads From a Watershed at Different Levels of Impervious Surface Coverage and Connectivity to Storm Water Control Measures

AbstractUrban development of watersheds increases runoff and nitrogen loads by adding urban impervious surfaces and increasing the hydrologic connectivity of these surfaces to streams. Storm water control measures (SCMs) are designed to disrupt this connectivity by retaining water in biologically active depressions where nitrogen retention, transformation, and removal occur. This work applies a mechanistic, spatially distributed, hydroecological model (RHESSys) to a suburban watershed in Charlotte, NC, with 15% total imperviousness (TI) and 33% watershed area mitigated by SCMs. We developed emergent relationships between watershed‐scale predictors (TI and connectivity to SCMs) and water and nitrogen response variables (storm water runoff ratios and nitrogen load by species). Results showed that annual runoff ratios were insensitive to increases in connectivity to SCMs (varying by ~1% of rainfall) because SCMs did not substantially increase evaporation but that runoff ratios increased by an average 0.2% per 1% increase in TI due to decreases in transpiration in the watershed. Generally, nitrate loads increased with TI but decreased as more surfaces were mitigated by SCMs. However, these nitrate reductions corresponded to increased export of dissolved organic nitrogen and ammonium. Together, these results indicate that SCMs act as both removers and transformers of nitrogen at the watershed scale. SCMs showed a net assimilation of nitrogen in warm months and net release in cool months, which offset the timing of nitrogen export relative to inputs. This work highlights that using a hydroecological, process‐based model reveals both the emergent relationships between watershed condition and response and the processes controlling those relationships.

Integrating ecosystem services flows into water security simulations in water scarce areas: Present and future

Water resources are indispensable resources for human survival. Researchers have used different methods to evaluate regional water security situations to ensure sustainable development. However, existing water security assessment models focus on the current status of water security in a static state and do not introduce flow characteristics of water resources into regional water security assessments. On the other hand, the quality of water resources should be reflected in not only current water security situations but also change trends of water security. Therefore, this paper attempts to integrate ecosystem service flows into a water security simulation using a simplified service path attribution networks (SPANs) model. Simultaneously, by simulating future scenarios and comparing future and current water security statuses, this paper systematically evaluates regional water security status and provides water security management and control suggestions that meet the requirements of regional development. The results show that water security in Henan Province and Shandong Province is lacking, and water resource management and control measures need to be strengthened to improve the water security in these areas. The water security assessment framework established in this paper not only reasonably assesses the status of water security but also provides a development model that meets the needs of the study area through a multiple scenario analysis. This study provides a scientific basis for government departments to formulate water management policies.

Influence of reservoir heterogeneity on water invasion differentiation in carbonate gas reservoirs

Diversified heterogeneities tend to occur in carbonate gas reservoirs due to different scales and distribution densities of pores, vugs and fractures in reservoirs, and consequently the water invasion laws of gas reservoirs are more different. In this paper, the methods quantitatively describing the matching relationships between pores, vugs and fractures were improved based on full-diameter core digital processing and analysis so as to understand the heterogeneity of carbonate reservoirs and its influence on the water invasion laws of gas reservoirs and then predict the water invasion dynamics of gas reservoirs. Firstly, a new method to evaluate the contribution of microfractures to reservoir seepage capacity was established according to the analysis chart of percolation theory. Then, gas–water relative permeability and rock compressibility were measured by conducting gas/water seepage and fluid–solid coupling stress sensitivity experiments under the conditions of actual gas reservoir pressure and temperature. And accordingly the effects of various fractures and caves on the gas invasion laws of gas reservoirs were analyzed. Finally, the method to predict the differentiation characteristics of water invasion influence of the reservoirs with different types of physical properties was developed based on the water invasion characteristics of typical carbonate gas reservoirs in the Sichuan Basin. The following research results were obtained. First, in a broad sense, different types of carbonate reservoirs are classified as a triple continuum. The development of fractures speeds up the appearance of water invasion in gas reservoirs while the uniform development of caves slows down the appearance of water invasion effect. Second, the development of microfractures is a prerequisite for ultra-low porosity reservoirs to possess the ability of medium permeability or high permeability. The water invasion law in this case is obviously different from the channeling along large fractures or the water invasion in the network small fracture development belt. Third, the stress sensitivity of reservoir porosity in aquifer is the main source of formation water invasion energy. This characteristic is more prominent in the early stage of the exploitation of abnormal high pressure gas reservoirs. The research results have been applied to water invasion energy assessment, water invasion performance forecast and water control measure effectiveness prediction in a number of carbonate reservoirs in the Sichuan Basin. And they provide effective technical guidance for water invasion control in complex gas reservoirs and further understanding of water invasion differentiation laws.

From ‘Vilest Beverage’ to ‘Universal Medicine’: Drinking Water in Printed Regimens and Health Guides, 1450–1750

Abstract Historians tend to assume that in pre-modern Europe people avoided the water, as too unsafe, risky and generally unhealthy to drink. This assumption is clearly flawed: early modern Europeans knew, through experience, which waters were ‘best’ and to take certain precautions when it came to the consumption of water. Town councils enacted legislation to ensure water quality as well as more pro-active measures to keep water sources clean. Extensive and expensive water works in many larger towns and the presence of water-carriers suggests a demand for drinking water. And yet the history of both water control measures and drinking practices before the onslaught of Asian cholera and the bacteriological revolution in the nineteenth century have yet to be written. As a contribution towards filling this gap, this study seeks to understand the radically changing nature of medical advice on water consumption between 1450 and 1750, and what it can tell us about the place of water in early modern society. To do this, we consider printed dietary regimens and guides to good health and long life, a successful, varied and changing genre. They offer privileged access to the circulation of knowledge regarding water, in the context of the everyday regulation of food and drink in the maintenance of health. We explain why water went from being considered ‘the vilest of beverages’ in the mid-fifteenth century, the consumption of which, though necessary, had to be carefully regulated, to a ‘universal medicine’ three hundred years later, able to prevent and cure disease. In the process, wine gave way to water as the preferred healthy drink—at least, for medical authors. We relate the medical advice to the different local conditions (such as river water quality), practices (use of cisterns, boiling or filtering) and fashions (cold-drinking) discussed in the medical literature. If water’s very banality means that it is often invisible in the written evidence, the regimens provide ample evidence of the importance of drinking water and of changing attitudes and practices over the course of the early modern period.

Intelligent Evaluation System of Water Inrush in Roadway (Tunnel) and Its Application

The risk assessment of mine water inrush is a complicated theoretical and technical problem that concerns hydrogeology conditions, engineering geology, mining conditions, rock mechanics, etc. To address this problem, a software system for the risk assessment of mine water inrush was established. From the matter-element extension theory, combined with the entropy-weight method, a matter-element extension entropy-weight model was constructed to evaluate mine safety. Eleven indices were determined based on the principles of science, rationality, operability, and representation, and each index was quantitatively graded. This system had built-in abundant cases of typical mine water inrush so users could determine the value of the parameter according to the analogy of water inrush cases with similar conditions. Combined with the analysis of typical water inrush cases, a database of water control measures with a strong advisory function was established. Finally, through the case study of a typical mine, it was found that the results of this study agreed with the practical ones, indicating that this system could improve the accuracy and availability of the risk assessment of mine water inrush.