Water Outflow Research Articles

Fractal Characteristics of Water Outflows on the Soil Surface after a Pipe Failure

Water pipe failures result in real water losses in the form of water outflowing into the porous medium, such as the surrounding soil. Such an outflow may result in the creation of suffosion holes. The appropriate management of the water supply network may contribute to reducing the number of failures, but due to their random nature, it is not possible to completely eliminate them. Therefore, alternative solutions are being sought to reduce the effects of the failures. This article presents a fragment of the results from a broader scope of the research, which attempted to determine the outflow zone in relation to the fractal characteristics of water outflows. The research included the analysis of the actual geometric structures created by the water outflows, which were simplified into linear structures using isometric transformations. The structures were analyzed in terms of the parameters characterizing them, including their fractal dimensions. As a result, it was found that there was no relationship between the analyzed fractal parameters and the leakage area or hydraulic pressure in the water pipe. However, the influence of the number of points forming each linear structure on the analyzed parameters was shown. This allowed for the determination of further research aimed at estimating the size of the water outflow zone after the unsealing of an underground water supply pipe.

Virtual Water Embodied in Interregional Energy Trade in China: A City-Level Analysis.

Large volumes of water are used in energy production for both primary (e.g., fuel extraction) and secondary energy (e.g., electricity). In countries such as China, with a large internal trade in fuels and long-distance transmission grids, this can result in considerable water inequalities. Previous research focused on the water impacts of energy production at the national and provincial levels, which is too coarse to identify the spatial differences and make specific case studies. Here, we take the next step toward a spatially explicit economically integrated water-use for energy assessment by combining a bottom-up assessment approach with a city-level multiregional input-output model. Specifically, we examine the water consumption of energy production in China, distinguishing between water for primary and secondary energy at the level of coal mines, oil and gas fields, and power plants for the first time. Of the total energy-related freshwater consumption of 4.9 Gm3 in 2017, primary energy accounted for 19% (940 Mm3) and secondary energy accounted for 81% (3955 Mm3). Coal was the largest water consumer for both primary and secondary energy (540 and 3880 Mm3, respectively), with both oil (361, and 0.5 Mm3, respectively) and gas (7 and 69 Mm3, respectively) also consuming large amounts. Intercity virtual water, that is, water embodied in energy trade across cities, reached 54% (2.6 Gm3) of energy-related freshwater consumption. Across China, 32% of cities see a bilateral trade in secondary- and primary-energy-related virtual water (e.g., Daqing city exports virtual water embodied in primary fuel to other cities that is then used to produce electricity in those cities, part of which is used back in Daqing via transmission). For these 32% of cities, 73% export more virtual water than import and 27% import more virtual water than export. This study reveals significant differences in city-level virtual water patterns (e.g., scale and direction) between primary and secondary energy to provide information for cities about their virtual water inflow and outflow and the potential collaboration partners for water management.

Optimal operation of a hydropower plant in a stochastic environment

Given the currently changing climate conditions it is of primary importance to optimise the management of hydropower resources. This paper proposes a framework in a dynamic setting to determine the water outflow that maximises the value of a water resource for a given reservoir. The model includes two sources of uncertainty, the water inventory determined mainly by the water inflow and the electricity prices. It is implemented under the stochastic optimal control approach and calibrated using monthly data of reservoir characteristics from ResOpsUs. The results indicate that the inventory dynamics are specially important in valuing reservoir resources. The application of optimal management policies guarantees the long-term sustainability of the reservoir. The possible effects of climate change are considered in a sensitivity analysis to changes in the price and water inventory dynamics.

Repeated subglacial jökulhlaups in northeastern Greenland revealed by CryoSat

Abstract Surface height changes above three previously undetected subglacial lakes in northeastern Greenland are documented using CryoSat, DEMs and ICESat-2. Between 7 February and 6 March 2012, the central ice region (22.6 km2) above the largest lake dropped by ~37 m followed by a further drop of 12 m in the following 29 days. This implies a subglacial water outflow, or jökulhlaup, of at least 1 km3 at rates of hundreds of cubic meters per second. A comparable outflow occurred again between 23 July and 15 September 2019, with smaller outflows in the fall of 2014 and 2016. In contrast, a second smaller subglacial lake at a higher elevation had two subglacial outbursts of ~0.3 km3 in 2012 and 2019 but the lake filling was gradual and not strongly seasonal or episodic. Water remained in both lakes after the outflows but this may not be the case for the third smallest and lowest subglacial lake. While there appears to be some hydrological link between the three lakes, the flux of water moving under the ice in this area appears to be larger than would be expected from local summer melt. However, the source of the excess water remains uncertain.

Development and physical characteristics of the Irish shelf-edge Macnas Mounds, Porcupine Seabight, NE Atlantic

Modern cold-water corals (CWCs) occur in a wide range of water depths, with Desmophyllum pertusum being one of the most common species. Pleistocene, Holocene, and modern coral mound formation by living CWC reefs have previously been described in the Porcupine Seabight from water depths greater than 700 m in the vicinity of the transitional zone between the Eastern North Atlantic Water and Mediterranean Outflow Water. Here we document occurrence of fossil corals retrieved from two cores at 370 m depth in the Macnas Mounds, a relatively shallow occurrence for mounds on the Irish shelf-edge. Both cores feature D. pertusum restricted to the upper two metres, immediately overlying an erosive surface and a coeval major down-core change in grain size from sand to mud. Radiocarbon dating of coral specimens indicates the CWC mounds initiated 7.82 Cal ky BP. Our study unequivocally documents the existence of Holocene shelf-edge coral mounds in the eastern Porcupine Seabight and highlights the possibility of other occurrences of CWCs in similar settings elsewhere in the northeast Atlantic. Given that no living CWCs were encountered in the study area, we suggest that the area previously experienced more favourable conditions for CWC mound initiation and development along the shelf-edge margin, possibly due to differing conditions in the European Slope Current which flows northward along the continental slope from south of the Porcupine Bank to the Faroe-Shetland Channel.Graphical

Is water replenishment an effective way to improve lake water quality? Case study in Lake Ulansuhai, China

Lakes are an important component of the global water cycle and aquatic ecosystem. Lake water quality improvement have always been a hot topic of concern both domestically and internationally. Noncompliant outflow water quality frequently occurs, especially for lakes that rely mainly on irrigation return flow as their water source. External water replenishment to improve the water quality of lakes is gradually being recognized as a promising method, which however, is also a controversial method. Lake managers, in the case of constant controversy, hesitate about the appropriateness of lake water replenishing. Thus, taking Lake Ulansuhai in China as an example, this study aimed to construct a lake hydrodynamic and water quality model, under the constraint of multiple boundary conditions, that has sufficient simulation accuracy, and to simulate and analyze the changes in COD (Chemical Oxygen Demand) and TN (Total Nitrogen) concentrations in the lake area before and after water replenishment, and explore whether water replenishment was an effective method for improving lake water quality. The results showed that when the roughness value of Lake Ulansuhai was 0.02, the TN degradation coefficient K was 0.005/d, and the COD degradation coefficient K was 0.01/d; the simulation and measured values had the best fit, and the built model is reasonable and reliable can be used to simulate lake water quality changes. By external water replenishment lasting 140 days in the water volume of 4.925 × 108 m³, the COD and TN concentrations in Lake Ulansuhai could be stabilized at the Class V water quality requirement, which helped improve the self-purification ability of the lake area. Water replenishment was proved to be an effective method for improving the water quality of the lake, but water replenishment is only an emergency measure. Lake water replenishment is more applicable to areas with abundant water resources. External source control and internal source reduction of lake pollution and protection of lake water ecology are the main ways to improve lake water quality for water-deficient areas under the rigid constraints of water resources. In the future, key technologies for reducing and controlling pollution in irrigation areas, construction of lake digital twin platforms, and active promotion of lake legislation work should be the main research direction for managing the lake water environment.

An extended discontinuous deformation analysis for simulation of grouting reinforcement in a water-rich fractured rock tunnel

Grouting has been the most effective approach to mitigate water inrush disasters in underground engineering due to its ability to plug groundwater and enhance rock strength. Nevertheless, there is a lack of potent numerical tools for assessing the grouting effectiveness in water-rich fractured strata. In this study, the hydro-mechanical coupled discontinuous deformation analysis (HM-DDA) is inaugurally extended to simulate the grouting process in a water-rich discrete fracture network (DFN), including the slurry migration, fracture dilation, water plugging in a seepage field, and joint reinforcement after coagulation. To validate the capabilities of the developed method, several numerical examples are conducted incorporating the Newtonian fluid and Bingham slurry. The simulation results closely align with the analytical solutions. Additionally, a set of compression tests is conducted on the fresh and grouted rock specimens to verify the reinforcement method and calibrate the rational properties of reinforced joints. An engineering-scale model based on a real water inrush case of the Yonglian tunnel in a water-rich fractured zone has been established. The model demonstrates the effectiveness of grouting reinforcement in mitigating water inrush disaster. The results indicate that increased grouting pressure greatly affects the regulation of water outflow from the tunnel face and the prevention of rock detachment face after excavation.

Net Transport Patterns of Surficial Marine Sediments in the North Aegean Sea, Greece

The spatial distribution of sediments on the seafloor reflects the various dynamic processes involved in the marine realm. To analyze sediment transport patterns in the North Aegean Sea, 323 surficial samples were obtained and studied. The granulometry data revealed a diverse range of grain sizes of surficial sediments, ranging from purely sandy to clay. The predominant size classes were silt and muddy sand, followed by sandy silt and mud. However, there were very few samples that fell within the clay classes. The sorting coefficient ranged from 0.21 to 5.48, while skewness ranged from −1.09 to 1.29. The sediment transport patterns were analyzed based on the grain-size parameters (mean, sorting, and skewness). The results showed the variability of flow parameters involved in sediment distribution. River influx and longshore drift near the shoreline are the most significant factors affecting sediment transport. At the open sea, sediment distribution is mainly controlled by general water circulation patterns, especially by the outflow of low-salinity waters from the Black Sea through the Dardanelles and the Marmara Sea. The heterogeneity of sediment textural parameters across the study area suggests that seafloor sediments are further reworked in areas where water masses are highly energetic. It can be concluded that open sea water circulation controls sediment distribution patterns at the open shelf, while close to the coast, river discharge plays a key role.

Transformation of the atlantic water between svalbard and Franz Joseph Land in the late winter 2018–2019

An inflow of warm and salty Atlantic origin waters (AW) from the Nordic Seas to the Arctic Ocean interior is in the list of the major external factors, which control the hydrologic regime of the East-Atlantic sector of the Arctic Ocean. Rapid decay of the sea ice cover in 2000–2010s raised questions on the possible changes in the fate of the inflow under present ice-depleted conditions: whether warm and salty AW will cool and freshen slower (due to less ice to be melted underway), or intensified heat loss to the atmosphere through the open surface will lead to the faster AW cooling on shorter distance? We present rare hydrologic data, collected during the late winter 2019 in the international expedition “Transarktika-2019” in the northern part of the Barents Sea and at the adjoining continental slope of the Nansen Basin. On the basis of field data, supported by the oceanic reanalysis product and numerical modelling we have studied the transformation of AW on its transit between Svalbard and Franz Joseph Land. We show that the observed cooling and desalination of the fraction of AW over the continental slope around this area is controlled by lateral mixing with colder and fresher waters, outflowing from cross-slope canyons, which cut the continental slope: Kvitøya Trough, Franz Victoria Trough and probably, the British Channel. The obtained results demonstrate more intensive transformation of AW on this transit compared to previous studies. Possible explanations of this contrast, which are supported by the earlier studies, may include: the season of the survey when dense water outflow through canyons is at its maximum and gradual “atlantification” of the East-Atlantic sector of the Arctic Ocean, which favours intensification of dense water formation in winter polynyas under conditions of increased seasonality of sea ice. In the latter case, faster cooling and desalination of AW en route in this part of the Arctic Ocean may be considered as a reasonable hypothesis, provided the atlantification of the Nansen Basin is progressing.

Accumulation of Beryllium in Bottom Sediments of Rivers in the Kizelovsky Coal Basin

The studies have been carried out on the accumulation of beryllium in bottom sediments of the river. Kosva (Western Urals, RF), which receives acidic waters from 8 water outflows, characterized by a sulfate iron-calcium composition, high mineralization and a significant beryllium content. It is concluded that a river suspension of colloidal size acts as a sorption barrier for beryllium, transported with the flow of water and gradually settling at the bottom. It is noted that the aggregation of particles among themselves with the formation of a larger suspension leads to the fact that, with distance from the source of pollution, a gradual increase in the beryllium content in coarse water suspension is observed with a decrease in the total beryllium content in water. It is recommended that the identified features of beryllium migration and accumulation be taken into account when developing environmental protection measures for the ecological rehabilitation of the river Kosvy.

From Cut-in to Qanats - Ancient Groundwater Extraction Techniques

Where a hillside stratified aquifer intersects the earth surface, springs and outseeping are observed. Cutting into this zone, thus opening it by digging, allows to increase and capture water outflow. As a matter of principle this classical method for water extraction without pumping, which is still found in hilly rural regions today, was already used 3600 years ago by the Hittites to fill the ponds of their capital Hattuşa in Central Anatolia. The today sedimented reservoirs were dug downhill of groundwater bearing zones. Rising in winter, groundwater discharged into the ponds through alongside cuts. The Hittites avoided the risks of strongly varying surface flows by opening near-surface groundwater and stratum aquifers. Although hydraulic investigation based on in-situ measurement of groundwater level supports the short-term efficiency of the ponds in supplying water to the ancient city, at the long-term, the decline of the Empire was probably triggered by severe droughts expanded over years. This seems plausible as severe droughts are still being experienced. For a higher and more reliable water yield, the further development went from ’cutting’ in to ’penetrating’ into the aquifer with tunnel-like drain conduits which collected the water and conveyed it to settlements and irrigation schemes. The improved water extraction system, named qanats, appeared in Eastern Anatolia and Persia about 500 years after the abandon of Hattuşa. An example of a qanat system in western Iran is presented in this study with less emphasis compared to the cut-in yet representative enough to demonstrate its role in supplying water sustainably. We conclude that the ancient time thinking is the same as that of modern engineering, and the ancient time hydraulic works are fundamental for today's civil structures.

The ternary water cycle of ‘nature–society–trade’ in the inland arid areas

AbstractWater cycle is important for maintaining the dynamic balance of regional water resources. Here, based on the input–output water circulation flux accounting model, we take Xinjiang as a case area to empirically explore the mechanism of the ‘nature‐society‐trade’ ternary water cycle. The results show that the water transferred out was much larger than the transferred in in Xinjiang. The scale of water resources development and utilization and the social water cycle fluxes have been constantly expanding, but there was a mismatch between the hydrological system and the socio‐economic system in terms of water resource utilization. From 2007 to 2017, agriculture had always been the department with the largest amount of direct water consumption and virtual water transfer in Xinjiang, which mainly transferred virtual water to the light industry and service sector where the production of final products requires large amounts of agricultural products as raw materials or intermediate products. In Xinjiang, the virtual water transferred outside through trade in products and services was much larger than the virtual water transferred in from other regions, and it was thus always in a state of net virtual water outflow as a whole. In inter‐provincial trade of China, Xinjiang mainly transferred virtual water to areas with abundant water resources, developed economies and dense populations in eastern China. Lastly, we put forward targeted suggestions on the optimal allocation of water resources to promote the sustainable development of Xinjiang and we hope that our study will be instructive for water resources management in other arid inland river basins.

Accumulation characteristics and fate modeling of phthalic acid esters in surface water from the Three Gorges Reservoir area, China

Phthalic acid esters (PAEs) are a group of compounds widespread in the environment. To investigate the occurrence and accumulation characteristics of PAEs, surface water samples were collected from the Three Gorges Reservoir area, China. The total concentrations of 11 analyzed PAEs (∑11PAEs) in the collected water samples ranging from 197.7 to 1,409.3 ng/L (mean ± IQR: 583.1 ± 308.4 ng/L). While DEHP was the most frequently detected PAE, DnBP and DnNP were the most predominant PAEs in the analyzed water samples with a mean contribution of 63.3% of the ∑11PAEs. The concentrations of the ∑11PAEs in the water samples from the upper reaches of the Yangtze River were significantly higher than those from the middle reaches. To better understand the transport and fate of the PAEs, seven detected PAEs were modeled by Quantitative Water Air Sediment Interaction (QWASI). The simulated and measured values were close for most PAEs, and differences are within one order of magnitude even for the worst one. For all simulated PAEs, water and particle inflow were main sources in the reservoir, whereas water outflow and degradation in water were important removal pathways. The contribution ratios of different sources/losses varied from PAEs, depending on their properties. The calculated risk quotients of DnNP in the Three Gorges Reservoir area whether based on monitoring or simulating results were all far exceeded the safety threshold value, implying the occurrence of this PAE compound may cause potential adverse effects for the aquatic ecology of the Three Gorges Reservoir area.

Potential of a Charcoal Evaporative Cooling Chamber for Extending the Shelf Life of Vegetables


 
 
 There are wide varieties of vegetables in Sri Lanka. The ambient temperature and relative humidity have an impact on rate of vegetables deteriorate. Evaporative cooling is a well-known, cost- effective way to reduce postharvest lost in order to lower the temperature and increase the relative humidity. This research was done to create a charcoal cooling chamber for increase the shelf life of vegetables combining polythene packaging and active packaging additives. The study was carried out in wet zone, Sri Lanka with a sizable chamber made of coconut shell charcoal. A rectangular box made of chicken wire with a 1 m3 capacity serves as the evaporative cooling chamber. It made of chicken wire mesh with a hardwood frame. The walls filled with 50 mm thick coconut shell charcoal and a water outflow 8.33 ml/min for wetting the walls. Vegetable samples without any treatment were placed in the charcoal chamber along with vegetables wrapped in sealed polyethylene (gauge 300) with and without active packing components. With a control sample held in ambient settings, the treatments were put to the test four times over the course of nine days. Both unloading and loading situations were used to evaluate the performance of chamber. Temperature drops of 4° C on average and 2.07° C on average, respectively, were seen in dry and wet climate conditions. 92.49% on average was the cooling efficiency. Sealed polyethylene bags without active packaging components were found to be the best treatment when taking into account physiological weight loss and sensory tests. When compared to the control group on days 3, 6 and 9 physiological weight loss was considerably (P<0.05) less in the sealed polyethylene bags without active packing components. When compared to the control sample total soluble solid content less in sealed polythene bag. The sensory evaluation for the treatments inside the chamber was more acceptable than for the control. Vegetables can store fresh for up to three days in evaporative cooling chamber without packaging. These chambers can install vegetable stalls on the side of the roads in Sri Lanka for temporary purposes.
 Keywords: Charcoal, Evaporation, Shelf-life, Temperature, Vegetables
 
 

TRABECULECTOMY IN CLOSED ANGLE UVEITIS GLAUCOMA A CASE REPORT

Introduction : Glaucoma uveitis is caused by increased outflow resistance, which distorts the balance between water production and outflow. Trabeculectomy is better than LPI in controlling IOP in glaucoma uveitis
 Case Illustration : Male patient aged 45 years, came to the Eye Polyclinic at Serui Hospital with complaints of very painful right eye since 2 weeks ago, the patient also complained of being unable to see at all, red eyes, headache, stiff neck, nausea and vomiting. Ophthalmological examination reveal right eye vision no light perception (NLP), palpebral edema, spasm, conjunctival hyperemia, corneal edema, shallow anterior chamber angle, iris-corneal contact, negative pupillary reflex, total pupillary block, negative fundus reflex, schiotz IOP 81 mmHg.
 Discussion : The patient diagnosed as right eye acute glaucoma and treated with acetazolamide, timolol maleate eye drops, potassium aspar tablets, prednisolone acetate drops, diclofenac sodium drops in the right eye, paracetamol tablets, re-evaluate in 2 hours. The patient chose to be referred to a hospital in Surabaya. The patient came back with the same complaint and was treated the same as before, right eye surgery trabeculectomy + peripheral iridectomy with releaseable suture flap limbal base with controlled IOP results, releaseable suture sutures were removed in 2 weeks. Trabeculectomy of the uveitic eye is generally less successful because of accelerated wound healing by the postoperative fibrinous and cellular response. Antimetabolites such as 5FU and Mitomycin C are used to enhance the success of trabeculectomy in uveitis eyes (5FU, MMC). 95% success (IOP less than 21 mm Hg with 1 or no treatment) was achieved with MMC augmented trabeculectomy.
 Conclusion : Increased IOP due to pupillary block causes acute glaucoma with signs of high IOP, middilated pupils, decreased pupillary reflexes, and irregular shape, corneal epithelial edema, episcleral and conjunctival vascular congestion, shallow anterior chamber, small number of flares and cells.

TRABECULECTOMY IN CLOSED ANGLE UVEITIS GLAUCOMA A CASE REPORT

Introduction : Glaucoma uveitis is caused by increased outflow resistance, which distorts the balance between water production and outflow. Trabeculectomy is better than LPI in controlling IOP in glaucoma uveitis
 Case Illustration : Male patient aged 45 years, came to the Eye Polyclinic at Serui Hospital with complaints of very painful right eye since 2 weeks ago, the patient also complained of being unable to see at all, red eyes, headache, stiff neck, nausea and vomiting. Ophthalmological examination reveal right eye vision no light perception (NLP), palpebral edema, spasm, conjunctival hyperemia, corneal edema, shallow anterior chamber angle, iris-corneal contact, negative pupillary reflex, total pupillary block, negative fundus reflex, schiotz IOP 81 mmHg.
 Discussion : The patient diagnosed as right eye acute glaucoma and treated with acetazolamide, timolol maleate eye drops, potassium aspar tablets, prednisolone acetate drops, diclofenac sodium drops in the right eye, paracetamol tablets, re-evaluate in 2 hours. The patient chose to be referred to a hospital in Surabaya. The patient came back with the same complaint and was treated the same as before, right eye surgery trabeculectomy + peripheral iridectomy with releaseable suture flap limbal base with controlled IOP results, releaseable suture sutures were removed in 2 weeks. Trabeculectomy of the uveitic eye is generally less successful because of accelerated wound healing by the postoperative fibrinous and cellular response. Antimetabolites such as 5FU and Mitomycin C are used to enhance the success of trabeculectomy in uveitis eyes (5FU, MMC). 95% success (IOP less than 21 mm Hg with 1 or no treatment) was achieved with MMC augmented trabeculectomy.
 Conclusion : Increased IOP due to pupillary block causes acute glaucoma with signs of high IOP, middilated pupils, decreased pupillary reflexes, and irregular shape, corneal epithelial edema, episcleral and conjunctival vascular congestion, shallow anterior chamber, small number of flares and cells.

Study of the Influence of Operating and Geometric Parameters on the Critical Outflow of Subcooled and Boiling Water through Channels of Different Geometry

Study of the Influence of Operating and Geometric Parameters on the Critical Outflow of Subcooled and Boiling Water through Channels of Different Geometry

Hydrological effects of open ditch damming and controlled subsurface drainage in a Nordic agricultural field

Abstract Controlled drainage (CRD) is an agricultural water management practice designed to adjust the capacity of a drainage system under varying hydrological conditions. This simulation study aimed to quantify the potential of combining a controlled subsurface drainage (CS) with open ditch damming (CD) to manage the water table depth (WTD) and field water balance in Nordic conditions. Simulations with and without controlled drainage were run using a hydrological model that had been set up for a flat loamy field in Northern Ostrobothnia, Finland, for the period 2010–2021. All CRD scenarios reduced the probability of deep WTDs during growing seasons (May–Sep). The impact of CS on WTDs was greater and more uniform than CD. The CRD effects on water balance were seen in water outflow pathways, as CS reduced drain discharge while CD had the opposite effect. When both methods were applied simultaneously, annual evapotranspiration increased 5–12% compared with the free drainage scenario. The effects of CRD on evapotranspiration were greatest during the dry years indicating that CRD has potential to reduce drought in food production areas. None of the CRD scenarios could maintain optimal WTDs during the entire growing season, highlighting the complexity of optimizing field water management using CRD alone.

The transmission of isotopic signals from precipitation to groundwater and its controls: An experimental study with soil cylinders of various soil textures and burial depths in a monsoon region

The use of stable isotopic composition in groundwater as a paleoclimatic proxy assumes that the isotopic values in groundwater are inherited from the corresponding values in the source precipitation. However, several studies have observed that groundwater δ18O (δ18Og) is not always in accordance with the average δ18O of precipitation (δ18Op). The cause of this inconsistency is still the subject of debate. Significant reduced isotopic variability and potential deviations from precipitation to groundwater because of the aquifer itself (e.g., groundwater buried depths and soil texture) and external precipitation characteristics (e.g., rainfall intensity and duration) have been poorly quantified in terms of identifying the dominant factors. To investigate the controls on the transmission of isotopic signals from precipitation to groundwater, we present new stable isotope data for precipitation and groundwater from an experimental site using eight soil cylinders of different soil textures and burial depths in a monsoon region. We collected data at inter-event sampling intervals (30 min) during and after two heavy precipitation events (daily amounts higher than 10 mm). Our results demonstrated a significant disparity between the average isotopic values of heavy rainfall and light rainfall, despite both exhibiting decreasing isotopic patterns throughout the course of the rainfall event. Various degrees of attenuation of isotopic variations were found in outflow waters with different groundwater burial depths (GBDs) and soil textures after rainfall events. The isotopic variations were not synchronized with the outflow changes. Specifically, there were evident outflow lags in response to heavy rainfall, especially in the lysimeters with GBDs deeper than 0.5 m, while the greatest isotopic variation was observed in the early infiltrating stage. Redundancy analysis indicated that precipitation amount was the most important contributor to the outflow variation (∼51 %, p < 0.05), while GBD was the key factor for isotopic temporal variation (∼52 %, p < 0.05). These results concurred with the clustering of principal component analysis results. The mixing of soil water and heavy rainfall event components was observed in four lysimeters with mixing proportions fP varying in the range of 7 %–51 %, indicating the effective recharge from heavy rainfall. Soil evaporation was highlighted with samples located parallel to the local meteoric water line. It is recommended that groundwater isotopes in paleoclimatic studies are used with additional constraints that consider disproportionate recharge from intense rainfall, past chaotic fluctuations in groundwater dynamics, and distortions introduced by evaporation.

Assessment of Blue Water Migration and Efficiency in Water-Saving Irrigation Paddy Rice Fields Using the Water Flow Tracking Method

Although irrigation systems largely sustain global agricultural production, their efficiency is often alarmingly low. While irrigation water (blue water) is critical for the water-saving irrigation of rice with a high water demand, the process and efficiency of irrigation water utilization need clarification. In this study, we examined the three commonly used irrigation and drainage patterns (frequent shallow irrigation (FSI), wet and shallow irrigation (WSI), and rain-catching and controlled irrigation (RCI)) in rice fields. We developed a tracking method for irrigation water flow decomposition, which includes irrigation water evapotranspiration (IET), irrigation water drainage (IDR), irrigation water leakage (IPC), and irrigation water field residual (IRE). Using this method, we established an irrigation water efficiency evaluation index system and a comprehensive evaluation method. Our tracking method is relevant to describing the irrigation water performance under varying irrigation and drainage patterns. The results revealed that the average irrigation water input for the three irrigation and drainage patterns between 2015 and 2018 was roughly 312.5 mm, wherein IET accounted for 148 mm. However, more than 50% of the irrigation water outflow, comprising IDR, IPC, and IRE, exceeded the total amount of irrigation water input. The mean values of the gross irrigation efficiency (GIE), net irrigation efficiency (NIE), and effective consumption ratio (ECR) for all treatments in the three-year period were 0.63, 0.47, and 0.75, respectively. Additionally, the irrigation water use efficiency was significantly higher in dry years compared to wet years. The fuzzy composite rating values of the three irrigation and drainage models from 2015 to 2018 were RCI, WSI, and FSI, in descending order, under varying precipitation conditions. The RCI patterns maintained a high composite rating value (greater than 3.0) under different precipitation conditions. Previous efficiency calculations disregarded the blue–green water migration process and did not differentiate the blue–green water flow direction in agricultural fields, creating significant biases in the outcomes. This study’s method offers a new approach to evaluate the use of blue water resources in farmland.