Net Water Research Articles

Comprehensive framework for interpretation of WaPOR water productivity

This study presents a comprehensive framework for analyzing water productivity products provided by the FAO Water Productivity Open-access portal (WaPOR), focusing on various crops cultivated in both rainfed and irrigated areas within a semi-arid basin in Iran. Two indices, namely Gross Water Productivity (GWP) and Net Water Productivity (NWP), were introduced to quantify water productivity across crop fields. However, these indices may mislead decision-makers, because they aggregate water productivity for all crops and exacerbate the challenges posed by water scarcity. Therefore, mapping crop types seems necessary to enhance the interpretation of these indices and develop a dimensionless index for comparing different crops. The results demonstrated a fundamental change when comparing dimensionless water productivity with GWP and NWP products. Surprisingly, some pixels initially exhibiting high water productivity ranked as low water-productive pixels based on the derived dimensionless index, and vice versa. Based on dimensionless indicators, rainfed crops, particularly rainfed cereals, ranked as the most water-productive crops. The areas with dimensionless values below 0.5 warrant heightened attention to curtail non-beneficial water consumption and elevate water productivity. This research emphasizes the significance of mapping cultivation types as supplementary layers to facilitate precise, data-driven decision-making and enable comparisons of crops based on dimensionless water productivity indices.

Response of photosynthetic characteristics and yield of grape to different CO2 concentrations in a greenhouse.

Due to the enclosed environment of greenhouse grape production, the supply of CO2 required for photosynthesis is often insufficient, leading to photosynthetic downregulation and reduced yield. Currently, the optimal CO2 concentration for grape production in greenhouses is unknown, and the precise control of actual CO2 levels remains a challenge. This study aims to investigate the effects of different CO2 concentrations on the photosynthetic characteristics and yield of grapes, to validate the feasibility of a CO2 gas irrigation system, and to identify the optimal CO2 concentration for greenhouse grape production. In this study, a CO2 gas irrigation system combining CO2 enrichment and gas irrigation techniques was used with a 5-year-old Eurasian grape variety (Vitis vinifera L.) 'Flame Seedless.' Four CO2 concentration treatments were applied: 500 ppm (500 ± 30 µmol·mol-1), 700 ppm (700 ± 30 µmol·mol-1), 850 ppm (850 ± 30 µmol·mol-1), and 1,000 ppm (1,000 ± 30 µmol·mol-1). As CO2 concentration increased, chlorophyll a, chlorophyll b, and carotenoids in grape leaves all reached maximum values at 700 ppm and 850 ppm during the same irrigation cycle, while the chlorophyll a/b ratio was lower than at other concentrations. The net photosynthetic rate (Pn) and water use efficiency (WUE) of grape leaves were the highest at 700 ppm. The transpiration rate and stomatal conductance at 700 ppm and 850 ppm were significantly lower than those at other concentrations. The light saturation point and apparent quantum efficiency reached their maximum at 850 ppm, followed by 700 ppm. Additionally, the maximum net photosynthetic rate, carboxylation efficiency, electron transport rate, and activities of SOD, CAT, POD, PPO, and RuBisCO at 700 ppm were significantly higher than at other concentrations, with the highest yield recorded at 14.54 t·hm-2. However, when the CO2 concentration reached 1,000 ppm, both photosynthesis and yield declined to varying degrees. Under the experimental conditions, the optimal CO2 concentration for greenhouse grape production was 700 ppm, with excessive CO2 levels gradually inhibiting photosynthesis and yield. The results provide a theoretical basis for the future application of CO2 fertilization and gas irrigation techniques in controlled greenhouse grape production.

Physiological adaptation of Cyperus esculentus L. seedlings to varying concentrations of saline-alkaline stress: Insights from photosynthetic performance

Soil salinization effects plant photosynthesis in a number of global ecosystems. In this study, photosynthetic and physiological parameters were used to elucidate the impacts of saline-alkaline stress on Cyperus esculentus L. (C. esculentus) seedling photosynthesis. The results demonstrate that salt stress, alkali stress and mixed salt and alkali stress treatments all have similar bell-shaped influences on photosynthesis. At low concentrations (0−100 mmol L−1), saline-alkaline stress promoted net photosynthetic rate, transpiration rate and water use efficiency in C. esculentus. However, as the treatments increased in intensity (100−200 mmol L−1), plant photosynthetic parameters began to decline. We interpreted this as the capacity of C. esculentus to improve osmoregulatory capacity in low saline-alkaline stress treatments by accumulating photosynthetic pigment, proline and malondialdehyde to counterbalance the induced stress – an adaptive mechanism that failed once concentrations reached a critical threshold (100 mmol L−1). Stomatal conductance, maximum photosynthetic rate and actual photosynthetic rate all decreased with increasing concentration of the stress treatments, and intercellular carbon dioxide showed a decreasing and then increasing trend. These results indicated that when the saline-alkaline stress concentrations were low, C. esculentus seedlings showed obvious adaptive ability, but when the concentration increased further, the physiological processes of C. esculentus seedlings were significantly affected, with an obvious decrease in photosynthetic efficiency. This study provides a new understanding of the photosynthetic adaptation strategies of C. esculentus seedlings to varying concentrations of saline-alkaline stress.

On the Layered Structure and Seasonal Variation of the Water Exchanges in the Sulawesi Sea Areas As Well As the Associated Dynamics

AbstractThe layered structure and seasonal variation of the water exchanges in the Sulawesi Sea areas, as well as the corresponding dynamics, are investigated using HYCOM data. A net inward water mass transport is identified in the upper and intermediate layers in the Sulawesi Sea and it is compensated by the net outward transport in the deep layer. As an important source of this net inward transport, the southward flow through the Sibutu Passage (denoted hereafter as Sibutu Flow) reaches 5.06 Sv in winter, accounting for ∼43% of the net inflow. However, it decreases substantially to 1.79 Sv in summer, accounting for only 12% of the inflow. Further analysis reveals that this Sibutu Flow modulates the seasonal variation of the corresponding outward flow at the Makassar Strait, the major exit of the water mass in the Sulawesi Sea. In winter, the enhancement of the Sibutu Flow associated with the greater intrusion of Kuroshio water into the Luzon Strait produces a stronger eastward pressure gradient force, suppressing the surface intrusion of the Mindanao Current. Conversely, this pressure gradient force weakens and shifts westward in summer, permitting a larger water intrusion from the eastern section. Given that the outward Makassar Flow is the main passage of the Indonesian Throughflow (ITF), our study highlights the essential role of the Sibutu Flow in modulating seasonal variabilities of the ITF via the Makassar Strait and, thus, the transfer of water masses and heat content between the Pacific and Indian Oceans.

Congo Basin Water Balance and Terrestrial Fluxes Inferred From Satellite Observations of the Isotopic Composition of Water Vapor

AbstractLarge spatio‐temporal gradients in the Congo basin vegetation and rainfall are observed. However, its water‐balance (evapotranspiration minus precipitation, or ET − P) is typically measured at basin‐scales, limited primarily by river‐discharge data, spatial resolution of terrestrial water storage measurements, and poorly constrained ET. We use observations of the isotopic composition of water vapor to quantify the spatio‐temporal variability of net surface water fluxes across the Congo Basin between 2003 and 2018. These data are calibrated at basin scale using satellite gravity and total Congo river discharge measurements and then used to estimate time‐varying ET − P over four quadrants representing the Congo Basin, providing first estimates of this kind for the region. We find that the multi‐year record, seasonality, and interannual variability of ET − P from both the isotopes and the gravity/river discharge based estimates are consistent. Additionally, we use precipitation and gravity‐based estimates with our water vapor isotope‐based ET − P to calculate time and space averaged ET and net river discharge within the Congo Basin. These quadrant‐scale moisture flux estimates indicate (a) substantial recycling of moisture in the Congo Basin (temporally and spatially averaged ET/P > 70%), consistent with models and visible light‐based ET estimates, and (b) net river outflow is largest in the Western Congo where there are more rivers and higher flow rates. Our results confirm the importance of ET in modulating the Congo water cycle relative to other water sources.

Responses of precipitation and water vapor budget on the Chinese Loess Plateau to global land cover change forcing

There have been notable changes in precipitation patterns on the Loess Plateau (LP) of China in recent decades, and numerous attribution studies have focused on sea surface temperature anomalies and atmospheric circulation changes induced by aerosols and greenhouse gases emission. However, the influences of global land use and land cover change (LULCC) as an important forcing factor in the climate system on regional precipitation remains poorly understood. In this study, we quantified the impacts of LULCC on precipitation and the water vapor budget in the LP region, utilizing data from LULCC forcing experiments conducted by the sixth phase of the Coupled Model Intercomparison Project (CMIP6). Although global LULCC forcing exerted a negative effect on long-term mean precipitation on the LP region from 1850 to 2014, the different response characteristics were detected during different time periods. The global LULCC caused a decrease of 14 mm in annual precipitation during the period of 1850–1960. Conversely, from 1961 to 2014, it led to an increase of 6.4 mm, which is largely attributed to the enhanced water vapor transport along the southern boundary and westerly belt of the LP region. Moreover, from the perspective of the net water vapor balance of the entire LP, although LULCC caused net water vapor export during both periods 1850–1960 and 1961–2014, the export during the latter period (0.20 × 104 kg s−1) was smaller than that during the former period (0.28 × 104 kg s−1), indicating that the global expansion of grassland and cropland, along with the continuous rise in the leaf area index from 1961 to 2014, contributed to retaining more water vapor within the LP, which in turn was more favorable for precipitation. These findings provide valuable insights into the reasons behind precipitation variations in the LP region, emphasizing that global vegetation restoration and greening play a significant role in improving precipitation in ecologically fragile areas.

Modelling the impacts of future droughts and post-droughts on hydrology, crop yields, and their linkages through assessing virtual water trade in agricultural watersheds of high-latitude regions

This study elaborates on the effects of future drought and post-drought conditions on the reliability of global breadbaskets. The study simulates agro-hydrological processes in the Nelson River Basin, a large agricultural watershed in western Canada that supplies food for over 170 countries globally. In temperate zones of higher latitudes, future climate change scenarios suggest that global breadbaskets will likely experience increased precipitation and higher crop yields (Y). This could be perceived as an increased export potential of food from these regions. However, projected drought events in the future can affect agro-hydrological processes, Y, and, therefore, export potentials during and following the drought events. Using a process-based agro-hydrologic model, this research examines the potential impacts of future agricultural droughts and post-drought conditions on hydrological water yield (WYLD), Y, and their linkages through assessing the net virtual water export (NVWE), the water embodied in the production of crops that are destined for export. The results indicate that long-term average Y, NVWE, and WYLD are expected to improve in the future. However, droughts will become more extreme in the future, leading to considerable reductions in Y, NVWE, and WYLD. During the post-drought period, the recovery time for WYLD is considerably longer than Y and NVWE across regions. The slow recovery of WYLD, following an agricultural drought, is related to crop water uptake, which can be controlled by optimization of the cropping pattern. The continuous loss of WYLD during and after prolonged and more frequent droughts in the future can significantly affect not only the environment and several economic sectors but also the irrigated crop production and export potential from these regions. This finding highlights the connections between local hydrology and global trade systems in agricultural watersheds of higher-latitude regions. Future adaptation measures, such as changes in cropping patterns, can preserve WYLD during and after droughts, supporting water and food security.

Design and fabrication of porous three‐dimensional Ag-doped reduced graphene oxide (3D Ag@rGO) composite for interfacial solar desalination

Solar-driven interfacial desalination technology has shown great promise in tackling the urgent global water scarcity crisis due to its ability to localize heat and its high solar-to-thermal energy conversion efficiency. For the realization of sustainable saline water desalination, the exploration of novel photothermal materials with higher water vapor generation and photothermal conversion efficiency is indispensable. In the current study, a novel 3D interconnected monolithic Ag-doped rGO network was synthesized for efficient photothermal application. The Ultraviolet–Visible-Near Infrared (UV–Vis-NIR) and FTIR analyses demonstrated that the controlled hydrothermal reduction of GO enabled the restoration of the conjugated sp2 bonded carbon network and the subsequent electrical and thermal conductivity through a significant reduction of oxygen-containing functional groups while maintaining the hydrophilicity of the composite photothermal material. In the solar simulated interfacial desalination study conducted using 3.5 wt.% saline water, the average surface temperatures of the 3D material increased from 27.1 to 54.7 °C in an hour, achieving an average net dark-excluded evaporation rate of 1.40 kg m−2 h−1 and a photothermal conversion efficiency of ~ 97.54% under 1 sun solar irradiance. In the outdoor real-world application test carried out, the surface temperature of the 3D solar evaporator reached up to 60 °C and achieved a net water evaporation rate of 1.50 kg m−2 h−1 under actual solar irradiation. The 3D interwoven porous hierarchical evaporator displayed no salt precipitation over the 54-h period monitored, demonstrating the promising salt rejection and real-world application potential for efficient desalination of saline water.

Spatiotemporal Evolution and Driving Factors of Ecosystem Supply and Demand Bundles: A Case Study in the Sichuan-Yunnan Ecological Buffer Area, China

Identifying the spatial characteristics of ecosystem service (ES) supply and demand is crucial for effective ecosystem management and restoration. Past related studies have primarily focused on balancing ES supply and demand and supply clustering, with less attention focused on the drivers of demand clustering and their spatial evolution. This study explored the spatiotemporal supply–demand dynamics in four crucial ecosystem services (ESs) in the Sichuan-Yunnan ecological buffer area region between 2005 and 2019, namely water yield, net primary production, soil conservation, and habitat quality. Self-organizing maps and geographical detectors were used to classify supply–demand ES bundles as their main drivers, respectively. The main results of the study included: (1) A decline in habitat quality, whereas net primary productivity, water yield, and soil conservation increased. However, there were increasing demands for habitat quality, water yield, and net primary productivity, despite the decrease in demand for soil conservation. (2) Demand for habitat quality was met by supply, whereas there were deficits in soil conservation, water yield, and net primary productivity, which contributed to the demand in the east exceeding that elsewhere. (3) The proportion of ES bundle 2 increased, whereas those of the remaining ES bundles declined. Similarly, the areas of ES demand bundles (ESDBs) 1 and 4 decreased, whereas those of 2 and 3 increased. While the spatial extent of the ESBs remained relatively stable, those of the ESDBs in the northern regions increased. Key factors influencing the spatial distribution of ES supply include human activities, population density, and precipitation, whereas land use, population density, and the human activity index primarily affect demand distribution. The results of this study can act as a reference for comprehensive regional ecosystem management.

Use of remote sensing, spatial and geophysical modeling, and real recharging capabilities to identify suitable areas for groundwater exploitation in dry coastal areas

Accurate identification of groundwater potential areas in arid regions is an important task for groundwater management and sustainability. As a result, this study used the innovative integration of remote sensing (RS), geographic information system (GIS), watershed modeling system (WMS), geophysical survey, and water mass balance equation to identify potential groundwater areas in the W. Dara, Eastern Desert, Egypt. A weighted spatial probability model (WSPM) of groundwater potential based on eight regulatory factors was implemented within ArcGIS software. Drainage density (DD), precipitation (P), net groundwater recharge (NGR), terrain slope (TS), lineament density (LD), lithologic group (LG), water quality (TDS), and depth to groundwater level (DGW) are the aspects considered. The Analytical hierarchy process (AHP) method was used to assign weights to these parameters, and their accuracy was estimated using the consistency ratio (CR). The resulting groundwater potential map classified W. Dara study area into five categories, ranging from very low to very high potential. A geophysical survey, in the form of Vertical Electrical Sounding (VES) and Transient Electromagnetic (TEM), was conducted along W. Dara to validate the results of the WSPM, which identified areas of high groundwater potential. The 1D inversion of VES/TEM shows that the central and western parts of W. Dara are considered the most promising areas for groundwater occurrence, and are located in areas of high and very high potential classes derived from WSPM. Moreover, the results of VES and TEM surveys showed that the proposed aquifers (Nubian Sandstone, Miocene, and Quaternary) in the study area are horizontally and vertically connected through a set of normal faults traversing NW-SE. Ten sites have been proposed for drilling additional exploitative wells in W. Dara area based on the WSPM and geophysical survey with the aim of sustainable development. Thus, the integrated techniques applied in this study proved effective in accurately determining the development strategy for arid and semi-arid coastal areas, especially those that suffer from scarcity of rainfall and increased agricultural reclamation requirements in remote areas.

Measuring the Gains and Losses of Virtual Water Flows in China’s Coastal Areas

The virtual water flow behind product trade provides researchers with ideas to alleviate water problems in China’s coastal areas, with accompanying resource and economic implications. This paper adopts a multi-region input–output model to calculate virtual water flows in coastal areas and analyses resource benefits and economic benefits, by combining the water stress index and shadow price, to measure gains and losses of virtual water flow. This study shows that (1) China’s coastal areas depends on external water supplies; (2) virtual water flows between coastal and inland areas generated 38.26 billion m3 of net scarce water savings and CNY 31,751 billion of net economic benefits, indicating that coastal areas benefited from virtual water flows from both resource and economic perspectives; (3) virtual water flows among coastal provinces and cities caused 11.10 billion m3 of net scarce water losses, but generated CNY 9784 billion of net economic gains, indicating that a further intensification of water stress in coastal areas, but such a virtual water flow pattern was beneficial from an economic perspective. This paper reveals the resource and economic impacts of virtual water flow at the national scale and among coastal provinces and cities and further proposes suggestions for promoting the beneficial flow of virtual water in coastal areas.

A role for subducting clays in the water transportation into the Earth’s lower mantle

Subducting sedimentary layer typically contains water and hydrated clay minerals. The stability of clay minerals under such hydrous subduction environment would therefore constraint the lithology and physical properties of the subducting slab interface. Here we show that pyrophyllite (Al2Si4O10(OH)2), one of the representative clay minerals in the alumina-silica-water (Al2O3-SiO2-H2O, ASH) system, breakdowns to contain further hydrated minerals, gibbsite (Al(OH)3) and diaspore (AlO(OH)), when subducts along a water-saturated cold subduction geotherm. Such a hydration breakdown occurs at a depth of ~135 km to uptake water by ~1.8 wt%. Subsequently, dehydration breakdown occurs at ~185 km depth to release back the same amount of water, after which the net crystalline water content is preserved down to ~660 km depth, delivering a net amount of ~5.0 wt% H2O in a phase assemblage containing δ-AlOOH and phase Egg (AlSiO3(OH)). Our results thus demonstrate the importance of subducting clays to account the delivery of ~22% of water down to the lower mantle.

Enhanced Prediction of Malignant Cerebral Edema in Large Vessel Occlusion with Successful Recanalization Through Automated Weighted Net Water Uptake

Malignant cerebral edema (MCE) is associated with both net water uptake (NWU) and infarct volume. We hypothesized that NWU weighted by the affected Alberta Stroke Program Early Computed Tomography Score (ASPECTS) regions could serve as a quantitative imaging biomarker of aggravated edema development in acute ischemic stroke with large vessel occlusion (LVO). The aim of this study was to evaluate the performance of weighted NWU (wNWU) to predict MCE in patients with mechanical thrombectomy (MT). We retrospectively analyzed consecutive patients who underwent MT due to LVO. NWU was computed from nonenhanced computed tomography scans upon admission using automated ASPECTS software. wNWU was derived by multiplying NWU with the number of affected ASPECTS regions in the ischemic hemisphere. Predictors of MCE were assessed through multivariate logistic regression analysis and receiver operating characteristic curves. NWU and wNWU were significantly higher in MCE patients than in non-MCE patients. Vessel recanalization status influenced the performance of wNWU in predicting MCE. In patients with successful recanalization, wNWU was an independent predictor of MCE (adjusted odds ratio 1.61; 95% confidence interval [CI] 1.24-2.09; P<0.001). The model integrating wNWU, National Institutes of Health Stroke Scale, and collateral score exhibited an excellent performance in predicting MCE (area under the curve 0.80; 95% CI 0.75-0.84). Among patients with unsuccessful recanalization, wNWU did not influence the development of MCE (adjusted odds ratio 0.99; 95% CI 0.60-1.62; P=0.953). This study revealed that wNWU at admission can serve as a quantitative predictor of MCE in LVO with successful recanalization after MT and may contribute to the decision for early intervention.

Regional Brain Net Water Uptake in Computed Tomography after Cardiac Arrest – A Novel Biomarker for Neuroprognostication

BackgroundSelective water uptake by neurons and glial cells and subsequent brain tissue oedema are key pathophysiological processes of hypoxic-ischemic encephalopathy (HIE) after cardiac arrest (CA). Although brain computed tomography (CT) is widely used to assess the severity of HIE, changes of brain radiodensity over time have not been investigated. These could be used to quantify regional brain net water uptake (NWU), a potential prognostic biomarker. MethodsWe conducted an observational prognostic accuracy study including a derivation (single center cardiac arrest registry) and a validation (international multicenter TTM2 trial) cohort. Early (<6 h) and follow-up (>24 h) head CTs of CA patients were used to determine regional NWU for grey and white matter regions after co-registration with a brain atlas. Neurological outcome was dichotomized as good versus poor using the Cerebral Performance Category Scale (CPC) in the derivation cohort and Modified Rankin Scale (mRS) in the validation cohort. ResultsWe included 115 patients (81 derivation, 34 validation) with out-of-hospital (OHCA) and in-hospital cardiac arrest (IHCA). Regional brain water content remained unchanged in patients with good outcome. In patients with poor neurological outcome, we found considerable regional water uptake with the strongest effect in the basal ganglia. NWU >8% in the putamen and caudate nucleus predicted poor outcome with 100% specificity (95%-CI: 86–100%) and 43% (moderate) sensitivity (95%-CI: 31–56%). ConclusionThis pilot study indicates that NWU derived from serial head CTs is a promising novel biomarker for outcome prediction after CA. NWU >8% in basal ganglia grey matter regions predicted poor outcome while absence of NWU indicated good outcome. NWU and follow-up CTs should be investigated in larger, prospective trials with standardized CT acquisition protocols.

Contribution of Recycled and External Advected Moisture to Precipitation and Its Inter‐Annual Variation Over the Tibetan Plateau

AbstractIn this study, we performed a high‐resolution simulation using the Weather Research and Forecasting model, integrated with water vapor tracers, covering the years 2005–2019. Our objective was to obtain deeper insights into the spatiotemporal dynamics of external advected and local evaporative water vapor, and to elucidate their impact on precipitation patterns across the Tibetan Plateau (TP). Our findings underscore that a significant proportion of TP's precipitation originates from external advected water vapor, primarily entering through the western and southern boundaries. During summer, stronger zonal and meridional water vapor transport, driven by prevailing westerly winds and the Asian monsoon, significantly influences seasonal and spatial precipitation variations. Additionally, we observed that the inter‐annual variation of precipitation is intricately linked to changes in the net water vapor influx, modulated by alterations in atmospheric circulation. We also analyze the Precipitation Recycling Ratio (PRR) which refers to the proportion of precipitation originated from local evaporative water vapor to the total precipitation, revealing distinctive elevation‐dependent variations aligned with grassland distribution. Notably, PRR exhibits asynchronous shifts with precipitation at different timescales, potentially linked to soil moisture‐precipitation feedback at intra‐annual scales. Moreover, the investigation highlights that inter‐annual variations in PRR are primarily linked to the inflow and outflow of water vapor as well as wind strength at 500 hPa, particularly prominent during colder seasons, while thermal factors carry comparable weight to dynamical factors in warmer seasons.

Cropping calendar, agroclimatic and agroecological zoning for rainfed maize (Zea mays L.) under different rainfall scenarios in a semi-arid region of Brazil

Context The productivity of crops is influenced by the available net water balance, which relies on a complex interplay of edaphic and climatic factors. In this sense, rainfall is the leading water input for crop growth and yield, especially in water-scarce regions under semi-arid climates worldwide. Aims This study aimed to define the optimum cropping calendar and the agroclimatic and agroecological zones for rainfed maize in the state of Ceará, which is predominantly located within the Brazilian semi-arid region, assuming different rainfall scenarios. Methods We considered the subdivision of the study area into eight homogeneous precipitation regions according to the regional rainfall pattern. The climatic water balance for each region over two decades was calculated from historical weather data series, assuming three rainy scenarios: dry, regular, and rainy. The agroclimatic zoning was defined through the crop water balance results, soil classification, land use and occupation, slope and temperature, weighted through a multi-criteria decision analysis based on the Analytic Hierarchy Process. Key results The recommended planting period was broader in rainy conditions. However, there may be some dry spells between two 10-day intervals of the calendar, which impair plant growth depending on their intensity. For the dry scenario, the agroclimatic zoning showed that the marginal water deficiency covered 96.55% of the study area. Conclusions Rainfed maize cultivated under the semi-arid climate of Ceará state is viable in rainy conditions, partially restricted in regular years, and not recommended in dry years. Implications This study emphasises the importance of climate monitoring in effective planning for rainfed maize cultivation in semi-arid regions.

Estimation of water consumption volume and water efficiency in irrigated and rainfed agriculture based on the WaPOR database in Iran

ABSTRACT To evaluate the WaPOR model across the entire country of Iran, initially, 16 provinces located in four different climatic regions were selected for calculating and comparing the evapotranspiration using both the FAO-56 method and the WaPOR approach. The comparison of 10-day evapotranspiration values obtained from the FAO56 method and WaPOR demonstrates that the WaPOR model exhibits the highest correlation with FAO-56 values in semi-arid regions, with an R2 = 0.95 and an RMSE = 0.43. The analysis of evapotranspiration variations indicates that the evapotranspiration in the Caspian Sea and Zagros foothill regions has experienced more significant changes from 2015 to 2022. The annual analysis of net blue water productivity demonstrates that the net productivity in rainfed lands strongly depends on the precipitation received. Also, considering the importance of investigating the accuracy of biomass estimation, the correlation between the accuracy of biomass estimation and actual evapotranspiration was examined in four Iran climatic regions. Using the WaPOR model provides acceptable results for water consumption management and assessment in different regions and climates of Iran, particularly in agricultural lands. The WaPOR model can serve as a guide for determining reliable values of evapotranspiration and planning related to water resources in the agricultural sector in Iran.

Asymmetric responses of summer soil moisture anomalies to the large-scale teleconnections on the Loess Plateau between 2000 and 2020

Soil moisture is a key regulator of hydrological cycle and is closely related to vegetation growth and climate changes, which is mainly replenished by summer precipitation on the Loess Plateau. However, the response of soil moisture content (SMC) anomalies during summer on the Loess Plateau to large-scale teleconnection remains unclear. Here, using the empirical orthogonal function (EOF) method, this study extracted a homogenized area with significant variability of normalized difference vegetation index (NDVI) (p<0.01), which was called sensitive areas for vegetation restoration (SAVR) of the Loess Plateau. Based on 1 km daily soil moisture dataset named SMCI1.0 at top 1 m, we demonstrated that there was an interannual fluctuation of summer SMC from 2000 to 2020 over the SAVR of the Loess Plateau. Spatially, SMC during summer in the SAVR of the Loess Plateau exhibited an enhanced regional difference characterized by ‘dry to drier and wet to wetter’. Importantly, abnormal SMC during summer in the SAVR of the Loess Plateau can been attributed to distinct circulation pattern and anomalous water vapor transport, which showed asymmetrical distributions between positive and negative anomalous years of summer SMC. Due to the activities of western Pacific subtropical high (WPSH) and low-pressure system around the Lake Baikal (an anomalous anticyclone prevailed over the western north Pacific), the positive (negative) anomalous years of summer SMC witnessed net water vapor influx (outflux) anomalies to the Loess Plateau compared to the climatology, corresponding to anomalous upward (sinking) motions, further leading to more (less) SMC in summer over the SAVR of the Loess Plateau, respectively. The conclusions of this study have implications for excavating early warning information of SMC anomalies and natural restoration sustainable management on the Loess Plateau.

White Matter Hyperintensity is Associated with Malignant Cerebral Edema in Ischemic Stroke Treated with Thrombectomy

BackgroundWhite matter hyperintensity (WMH) burden may lead to poor clinical outcomes after endovascular thrombectomy (EVT). But the relationship between WMH burden and cerebral edema (CED) is unclear.PurposeTo examine the association between WMH burden and CED and functional outcome in patients treated with EVT.Study TypeRetrospective.Subject344 patients with acute anterior circulation large‐vessel occlusion stroke who received EVT at two comprehensive stroke centers. Mean age was 62.6 ± 11.6 years and 100 patients (29.1%) were female.Field Strength/Sequence3T, including diffusion‐weighted imaging and fluid‐attenuated inversion recovery (FLAIR) images.AssessmentThe severity of WMH was evaluated using the Fazekas scale on a FLAIR sequence before EVT. The severity of CED was assessed using CED score (three for malignant cerebral edema [MCE]) and net water uptake (NWU)/time on post‐EVT cranial CT. The impact of WMH burden on MCE, NWU/time, and 3‐month poor outcome (modified Rankin scale &gt;2) after EVT were assessed.Statistical TestsPearson's chi‐squared test, Fisher exact test, 2‐tailed t test, Mann–Whitney U test, multivariable logistic regression, multivariate regression analysis, Sobel test. A P value &lt;0.05 was considered statistically significant.ResultsWMH burden was not significantly associated with MCE and parenchymal hemorrhage (PH) in the whole population (P = 0.072; P = 0.714). WMH burden was significantly associated with an increased risk of MCE (OR, 1.550; 95% CI, 1.128–2.129), higher NWU/time (Coefficient, 0.132; 95% CI, 0.012–0.240), and increased risk of 3‐month poor outcome (OR, 1.434; 95% CI, 1.110–1.853) in the subset of patients without PH. Moreover, the connection between WMH burden and poor outcome was partly mediated by CED in patients without PH (regression coefficient changed by 29.8%).Data ConclusionWMH burden is associated with CED, especially MCE, and poor outcome in acute ischemic stroke patients treated with EVT. The association between WMH burden and poor outcome may partly be attributed to postoperative CED.Level of Evidence3.Technical EfficacyStage 5.

Integrating hydrologic modeling and satellite remote sensing to assess the performance of sprinkler irrigation

ABSTRACT Improving irrigation water management is a key concern for the agricultural sector, and it requires extensive and comprehensive tools that provide a complete knowledge of crop water use and requirements. This study presents a novel methodology to explicitly estimate daily gross and net crop water requirements, actual crop water use, and irrigation efficiency of center pivot irrigation systems, by mainly utilizing the Sentinel-2 MultiSpectral Instrument (MSI) imagery at the farm scale. ETMonitor model is adapted to estimate actual water use (as the sum of canopy transpiration and evaporation of water intercepted by canopy and evaporation from soil) at daily/10-m resolution, benefiting from the high-resolution Sentinel-2 data and thus to assess the irrigation efficiency at the farm scale. The gross irrigation water requirement is estimated from the net crop water requirement and the water loss, including the water droplet evaporation directly into the air during application before droplets fall on the canopy and canopy interception loss. The method was applied to a pilot farmland with two major crops (wheat and potato) in the Inner Mongolia Autonomous Region of China, where modern equipment and appropriate irrigation methods are deployed for efficient water use. The estimated actual crop water use showed good agreement with the ground observations, e.g. the determination coefficients range from 0.67 to 0.81 and root mean square errors range from 0.56 mm/day to 1.24 mm/day for wheat and potato when comparing the estimated evapotranspiration with the measurement by the eddy covariance system. It also showed that the losses of total irrigated volume were 25.4% for wheat and 23.7% for potato, respectively, and found that the water allocation was insufficient to meet the water requirement in this irrigated area. This suggests that the amount of water applied was insufficient to meet the crop water requirement and the inherent water losses in the center pivot irrigation system, which imply the necessity to improve the irrigation practice to use the water more efficiently.