Explore the vast range of titles available.

Many engineering construction projects entail excavations into water bearing substrates. The authors explain the drainage techniques required to lower groundwater sufficiently to allow projects to be undertaken with confidence.

Hurricane Ian rapidly intensified from Category 3 to 5 as it transited the wide West Florida Shelf (WFS). This is ascribed to heating by the anomalously warm shelf waters, despite the water depth being shallow when compared to the thicker, mixed layer areas of the deeper ocean. By examining temperature from long‐term moorings, we found that the sea surface and subsurface temperatures exceeded the climatologies by 1–2°C and 2–3°C, respectively. Additionally, these anomalously high temperatures in summer/fall of 2022 were related to the absence of Gulf of Mexico Loop Current interactions with the WFS slope at its “pressure point”. Without such offshore forcing to induce an upwelling circulation, the warmer waters on the shelf were not flushed and replaced by colder waters of deeper ocean origin. This work highlights the importance of subsurface temperature and ocean circulation monitoring on shallow continental shelves, which are largely overlooked in hurricane‐related ocean heat content observational programs. Plain Language Summary Rapid intensification of tropical cyclones can be fueled by upper ocean warm water. The favorable environment of high ocean heat potential is thought to be more likely during marine heatwaves. However, both the hurricane heat potential and marine heatwaves are primarily calculated from satellite‐derived sea surface data, with subsurface data largely overlooked due to lack of in situ measurements, particularly in coastal oceans where hurricanes may rapidly intensify before making landfall. Here we examine an unprecedented set of coastal ocean temperature records from long‐term (26 years) moorings on the wide West Florida Shelf for the cause of Hurricane Ian's rapid intensification to a Category 5 hurricane in 2022. We found that while sea surface temperatures exceeded their climatological mean values by 1–2°C in summer/fall of 2022, the subsurface temperature exceedances were even higher (2–3°C). These anomalously warm waters were further ascribed to a lack of a coastal ocean upwelling circulation due to the absence of offshore forcing by the Gulf of Mexico Loop Current. This work highlights the importance of subsurface temperature and current monitoring on shallow continental shelves, which are largely overlooked in hurricane‐related ocean heat content observing programs. Key Points Hurricane Ian (2022) rapidly intensified over a wide continental shelf with subsurface water 2–3°C warmer than climatology The anomalously warm water was related to the absence of Gulf of Mexico Loop Current interactions with the shelf slope Coastal ocean circulation and subsurface temperature monitoring is important for future hurricane intensification forecasts

This work was carried out for the determination of the water quality in the Talagang District of Pakistan, as water is essential for agriculture and drinking uses. This study aims to assess the water quality for irrigation, drinking, and health risks using the Water Quality Index (WQI) and Human Health Risk Assessment (HHRA) tools to identify regions with contaminated water, and to evaluate the associated risks. A total of 98 water samples were taken at various points from diverse sources such as hand pumps, streams, springs, dug wells, and tube wells for physio-chemical assessment. In the current study, the effectiveness of the irrigation water quality index (IWQI), human health risk assessment (HHRA), and water quality index (WQI) tools have been assessed. The characteristics of subterranean water are influenced by evaporation, ion exchange, rock-water interaction, and parent-rock weathering, as shown by the Piper and Gibbs diagram. According to the WQI results, the water quality is 20. 89% and 27.46% of the sample sites are moderate and poor, making them unfit for human intake. Based on HHRA, compared to adult males and females in the study area, children are deemed to be at a higher risk. A larger number of the sample localities are appropriate for irrigation purposes. The study assists in identifying contaminated regions and in monitoring newly implemented remediation actions to manage the source of contaminants in the study area.

In arid regions, groundwater is a vital resource that can also provide a long-term record of the regional water cycle. However, the use of groundwater as a paleoclimate proxy has been limited by the complex hydrology and the lack of appropriate chronometers to determine the recharge time without complication. Applying 81Kr, a long-lived radioisotope tracer, we investigate the paleohydroclimate and subsurface water storage properties of the Nubian Sandstone Aquifer in the Negev Desert, Israel. Based on the spatial distributions of stable isotopes and the abundance of 81Kr, we resolve subsurface mixing and identify two distinct moisture sources of the recharge: one recent (<38 ky ago) from the Mediterranean and the other 361 ± 30 ky ago from the tropical Atlantic, both of which occurred under conditions of low orbital eccentricity comparable to that of the present. The recent recharge provided by the moisture from Mediterranean cyclones can be attributed to the southward shift of the storm track during the Last Glacial Maximum, and the earlier recharge can be attributed to moisture from the Atlantic delivered as tropical plumes under a climate colder than the present. Furthermore, the residence time of the latter reveals that tectonically active terrain can store groundwater for an unexpectedly long period, likely due to strongly attenuated groundwater flow across the fault zones. With this tracer, groundwater can now serve as a direct record of paleoprecipitation over land and of subsurface water storage from the mid-Pleistocene and onward.

Field-based trials are crucial for successfully achieving the goals of plant breeding programs aiming to screen and improve the salt tolerance of crop genotypes. In this study, simulated saline field growing conditions were designed using the subsurface water retention technique (SWRT) and three saline irrigation levels (control, 60, and 120 mM NaCl) to accurately appraise the suitability of a set of agro-physiological parameters including shoot biomass, grain yield, leaf water relations, gas exchange, chlorophyll fluorescence, and ion accumulation as screening criteria to establish the salt tolerance of the salt-tolerant (Sakha 93) and salt-sensitive (Sakha 61) wheat cultivars. Shoot dry weight and grain yield per hectare were substantially reduced by salinity, but the reduction was more pronounced in Sakha 61 than in Sakha 93. Increasing salinity stress caused a significant decrease in the net photosynthesis rate and stomatal conductance of both cultivars, although their leaf turgor pressure increased. The accumulation of toxic ions (Na and Cl ) was higher in Sakha 61, but the accumulation of essential cations (K and Ca ) was higher in Sakha 93, which could be the reason for the observed maintenance of the higher leaf turgor of both cultivars in the salt treatments. The maximum quantum PSII photochemical efficiency ( / ) and the PSII quantum yield (ΦPSII) decreased with increasing salinity levels in Sakha 61, but they only started to decline at the moderate salinity condition in Sakha 93. The principle component analysis successfully identified the interrelationships between all parameters. The parameters of leaf water relations and toxic ion concentrations were significantly related to each other and could identify Sakha 61 at mild and moderate salinity levels, and, to a lesser extent, Sakha 93 at the moderate salinity level. Both cultivars under the control treatment and Sakha 93 at the mild salinity level were identified by most of the other parameters. The variability in the angle between the vectors of parameters explained which parameters could be used as individual, interchangeable, or supplementary screening criteria for evaluating wheat salt tolerance under simulated field conditions.

Intermittent rivers spread worldwide, but estimating them and their response to extreme climate conditions at the catchment scale, like prolonged drought, remains challenging. This study related river network dynamics to river‐groundwater interaction and investigated the response of wetted river network contraction and expansion to prolonged drought by coupling a fully distributed hydrological model (mHM) with a groundwater model (MODFLOW). The coupled model was applied to the Bode catchment (3,200 km2) in central Germany from 2000 to 2022, with 2018–2022 considered a prolonged drought period. Results demonstrated good model performance when evaluated using discharge, groundwater table depth, and sampling data of river dryness and wetness. Compared to the reference period 2004–2017, in the lower Bode, 7% of the total river length shifted from water gain to water loss due to prolonged drought. The total gross river gain from groundwater dropped by 17%, with the decline primarily occurring in small streams. Meanwhile, the total gross river loss declined by 9%, driven by reduced instream flow during prolonged drought. The annual mean wetted river network contracted by 140 km due to the prolonged drought, with extended drying and reduced rewetting on a seasonal scale. River persistence declined significantly due to prolonged drought, with around 130 km of intermittent river shifted to totally dry. Based on this coupling approach, this study highlights the impact of prolonged drought on wetted river network dynamics, which, mediated by groundwater dynamics and their memory effects, can significantly change water resource distribution, thereby affecting ecosystem health and water quality. Plain Language Summary Perodically flowing rivers are found all over the world, but predicting how they respond to extreme climate events like prolonged droughts is still difficult. This study looked at how the prolonged drought affect wetted river networks length, from the perspective of river‐groundwater interaction. By combining a hydrological model (mHM) with a groundwater model (MODFLOW), we simulated conditions in the Bode catchment in central Germany from 2000 to 2022, with emphasis on the 2018–2022 drought period. The results showed that the models performed well when compared to river flow, groundwater table depth, and river dryness/wetness data. During the prolonged drought, 7% of the river length in the lower Bode area shifted from water gain to loss. Groundwater contributions to the river decreased by 17%, and overall river loss dropped by 9% due to lower instream flows. The wetted river network shrank by 140 km, with reduced rewetting and extended drying periods. River persistence declined, with around 130 km of intermittent rivers drying out completely. This study highlights the significant impact of prolonged droughts on river networks, altering water distribution and affecting ecosystems and water quality. Key Points A coupled hydrological‐groundwater model was built and applied in Bode to assess wetted river network dynamics during prolonged drought Groundwater's capacity to buffer instream drought diminishes with decreasing stream order during prolonged drought Prolonged drought contracts river networks interannually, delaying rewetting and extending drying on a seasonal scale

Evaluation was carried out on the existing furrow irrigation system located in an open agricultural field within Hor Rajabh Township, south of Baghdad, Iraq (latitude: 33°09’ N, longitude: 44°24’ E). Two plots were chosen for comparison: treatment plot T1, which used subsurface water retention technology (SWRT) with a furrow irrigation system. While the treatment plot T2 was done by using a furrow irrigation procedure without SWRT. A comparison between the two treatment plots was carried out to study the efficiency of the applied water on crop yield. In terms of agricultural productivity and water use efficiency, plot T1 outperformed plot T2, according to the study’s final findings. Compared with plot T2, the rate of increase in the efficiency of water and crop yield were found to be 44.9% and 14.2%, respectively. Additionally, compared to plot T1, the rate of increase in the applied water in plot T2 was 26.8%. The efficiency of plot T1 is attributed to the usage of SWRT membranes beneath the plant’s root zone, which helped conserve water and nutrients, which affected crop yield and water consumption.

The interaction of riverine inputs and ocean current systems causes complex spatiotemporal variations in phytoplankton dynamics in marginal seas of the northwest Pacific Ocean, yet quantitative assessments of these variations and their causes remain limited. Here we evaluate phytoplankton biomass and community structure changes using lipid biomarkers, accompanying ocean circulation and nutrient variations in surface waters collected in spring and summer of 2017–2018 at 118 sites in the East China Sea off the Zhejiang coast. High biomass of diatoms, inferred from brassicasterol concentrations, shifted from the south in spring to the north in summer, while high dinoflagellate biomass, inferred from dinosterol concentrations, occurred mainly in the Changjiang (Yangtze) River plume and adjacent areas in both seasons. Seasonal variation in phytoplankton distribution was linked to the spatial extents of water masses such as the Changjiang Diluted Water (CDW) and the intrusion of the Kuroshio Subsurface Water (KSSW). A three end-member mixing model was applied to quantify water mass contributions. The results showed that an increase in the KSSW (from 0 to 40%) and a decrease in the CDW (from 100 to 20%) resulted in a significant (20%) increase in diatom proportions and a significant (20%) decrease in dinoflagellate proportions. Dinoflagellate proportions were highest in the CDW-dominated region, while diatoms and total phytoplankton biomass were higher in the CDW–KSSW mixing region and the KSSW-dominated region. This study highlights the dynamic response of the phytoplankton community to water mass changes in marginal seas that can aid coastal ecosystem management.

The regulating ways of different water masses affecting the locations and intensities of hypoxia zones were studied based on the time-space continuum data from August 2011 to 2013–2017. The 6-year distribution of the hypoxic area in the Changjiang Estuary (CE) and its adjacent waters show that the hypoxic area can be divided into two segments. The southern segment is out of the south branch of the CE, whereas the northern segment is in the junction zone between the South Yellow Sea and the CE. The two segments were divided along the 31.5°–32 °N latitude line. The northern and southern segments were dominated by the East China Sea shelf water (ECSSW) and Kuroshio subsurface water (KSW), respectively. When the KSW (salinity > 34) intrusion reached the east of 123 °E and south of 31 °N, hypoxia zones mainly occurred in the southern segment covered by the Changjiang Diluted Water (CDW), meanwhile the Yellow Sea cold water mass may emerge in the northeastern area. When the KSW intensely invaded westward to the region between 122° and 122.5°E and northward to 31.5°N or further north, hypoxia zones appeared in the northern segment. The strength of the KSW with low dissolved oxygen concentration is the basic driving factor for the hypoxia occurrence in the CE. Moreover, the stratification is crucial for the southern segment, whereas the organic matter decomposition is dominated for the northern segment, even with severe hypoxia across the sea surface in the study area.

Freshwater resources in coastal zones are limited while demands are high, resulting in problems like seasonal water shortage, overexploitation of freshwater aquifers, and seawater intrusion. Three subsurface water technologies (SWT) that can provide robust, effective, and cost-efficient solutions to manage freshwater resources in the subsurface are evaluated using groundwater modelling and validation at field-scale: (1) ASR-coastal to store freshwater surpluses in confined brackish-saline aquifers for recovery in times of demand, (2) the Freshkeeper to counteract salinization of well fields by interception and desalination of upconing brackish groundwater, and (3) the Freshmaker to combine ASR and Freshkeeper to enlarge the volume of natural freshwater lenses for later abstraction. The evaluation indicates that SWT can be used in various hydrogeological settings for various hydrogeological problems like seawater intrusion, upconing, and bubble drift during ASR and have significant economic benefits. Although only sporadically applied to date, we foresee that SWT will stimulate (cost-)efficient and sustainable exploitation of various freshwater sources (like groundwater, rainwater, treated waste water, surface water) in coastal zones. Prolonged SWT testing in the current pilots, replication of SWT in other areas worldwide, and the development of technical and non-technical support tools are required to facilitate potential end-users in investment decision making and SWT implementation.