Regional Water Research Articles

A distributed modeling approach to water balance implications from changing land cover dynamics in permafrost environments

There is 78 % permafrost and seasonal frozen soil in the Yangtze River’s Source Region (SRYR), which is situated in the middle of the Qinghai-Xizang Plateau. Three distinct scenarios were developed in the Soil and Water Assessment Tool (SWAT) to model the effects of land cover change (LCC) on various water balance components. Discharge and percolation of groundwater have decreased by mid-December. This demonstrates the seasonal contributions of subsurface water, which diminish when soil freezes. During winter, when surface water inputs are low, groundwater storage becomes even more critical to ensure water supply due to this periodic trend. An impermeable layer underneath the active layer thickness decreases GWQ and PERC in LCC + permafrost scenario. The water transport and storage phase reached a critical point in August when precipitation, permafrost thawing, and snowmelt caused LATQ to surge. To prevent waterlogging and save water for dry periods, it is necessary to control this peak flow phase. Hydrological processes, permafrost dynamics, and land cover changes in the SRYR are difficult, according to the data. These interactions enhance water circulation throughout the year, recharge of groundwater supplies, surface runoff, and lateral flow. For the region’s water resource management to be effective in sustaining ecohydrology, ensuring appropriate water storage, and alleviating freshwater scarcity, these dynamics must be considered.

Antarctic Bottom Water Warming, Freshening, and Contraction in the Eastern Bellingshausen Basin

AbstractAntarctic Bottom Water has been warming in recent decades throughout most of the oceans and freshening in regions close to its Indian and Pacific sector sources. We assess warming rates on isobars in the eastern Pacific sector of the Southern Ocean using CTD data collected from shipboard surveys from the early 1990s through the late 2010s together with CTD data collected from Deep Argo floats deployed in the region in January 2023. We show cooling and freshening in the temperature‐salinity relation for water colder than ∼0.4°C. We further find a recent acceleration in the regional bottom water warming rate vertically averaged for pressures exceeding 3,700 dbar, with the 2017/18 to 2023/24 trend of 7.5 (±0.9) m°C yr−1 nearly triple the 1992/95 to 2023/24 trend of 2.8 (±0.2) m°C yr−1. The 0.2°C isotherm descent rate for these same time periods nearly quadruples from 7.8 to 28 m yr−1.

Observed changes in the climate and snow dynamics of the Third Pole

The Third Pole (TP) is the world’s largest highland and has one of the biggest reservoirs of glacier ice mass and snow cover on the Earth. Three major Asian rivers (the Indus, Ganga and Brahmaputra) are nourished by the melting of glaciers and snow in Central Himalaya, which are inevitable for the socioeconomic sustainability and water security of South Asia. Here, we investigate the long-term (1980–2020) changes in snow depth and precipitation in TP, where major precipitation occurs in the form of rainfall in summer, and snowfall in winter and spring. The seasonal mean snow depth is deep (≥1 m) in winter and shallow (≤0.2 m) in summer. The average snowmelt and snow water equivalent are higher in the central and western Himalaya and Karakoram ranges in spring, which are the regions with most glaciers in TP. There is a significant positive trend in total precipitation, about 0.01–0.03 mm d−1 yr−1 in the central and eastern TP during the South Asian Summer Monsoon for the 1980–2020 period. Snowmelt is also increasing (>0.5 × 10−3 mm yr−1) in the western Himalaya during spring, which is consistent with the temperature rise (0.04–0.06 °C yr−1) there. In addition, there is a notable increase in the annual mean glacier melt (here, the water equivalent thickness) in TP (−1 to −5 cm w.e. yr−1), with its highest values in the eastern and central Himalaya (−3 to −5 cm w.e. yr−1), as estimated for the period 2003–2020. On top of these, by the end of the 21st century, the Coupled Model Intercomparison Project Phase 6 (CMIP6) projections show that there would be a significant decrease in snow depth and an increase in temperature of TP in all shared socioeconomic pathways (SSPs). Henceforth, the increasing trend in temperature and melting of snow/glaciers in TP would be a serious threat to the regional climate, water security and livelihood of the people of South Asia.

The role of regional water vapor dynamics in creating precipitation extremes

While sub-daily precipitation extremes cause flash flooding and pose risk to life, longer precipitation extremes threaten infrastructure such as water supply dams. Frequent storm or floods events replenish water supplies, ensuring the health of our ecosystems, while rarer larger storms or floods cause damage to property and life. These differing impacts depend on both storm rarity and duration and are largely dependent on coincident atmospheric water vapour. Using a novel metric that quantifies the extent of concurrency that exists between precipitation and total water vapour extremes, large regional variations are identified across the globe. Tropical regions such as Northeast Africa and South/East Asia consistently exhibit greater concurrency across all precipitation durations. In contrast, areas of the extra-tropics, such as the Mediterranean and Northwest Americas, show a rapid decline in concurrency with increasing duration. However, for rare events of long duration, non-tropical regions maintain high concurrency. With the link between climate change and increasing total water vapour well established, these results suggest that flood events will increase globally, with increases most apparent for longer and rarer events. This work underscores the need for tailored regional strategies in managing extreme precipitation and flood events in the future.

Nitrogen reduction by 20 % with green manure retention reduces soil evaporation, promotes maize transpiration and improves water productivity in arid areas

ContextThe contradiction between high agricultural yields and water resource shortages is becoming increasingly serious. Reducing nitrogen appropriately with green manure retention can ensure high agricultural yields, but it remains unclear whether it can optimize crop water consumption characteristics and improve water productivity (WPc). ObjectiveThis study aims to investigate the effect of green manure retention combined with nitrogen reduction on water use characteristics of maize and its potential mechanisms. MethodsA field experiment was conducted at Wuwei Oasis Agricultural Experimental Station in China from 2020 to 2022, with five treatments: (i) traditional nitrogen application with green manure retention (N100), (ii) nitrogen reduction by 10 % with green manure retention (N90), (iii) nitrogen reduction by 20 % with green manure retention (N80), (iv) nitrogen reduction by 30 % with green manure retention (N70), and (v) nitrogen reduction by 40 % with green manure retention (N60). ResultsThe results showed that compared with the N100 treatment, 0−50 cm maize root biomass (RB), biomass accumulation (BA), and canopy cover (CC) were not significantly reduced in the N80 treatment. This model ensured a stable grain yield (GY) and improved 0−50 cm soil water storage (SWS) by 7.1−13.1 %. It effectively suppressed soil evaporation (E), promoted maize transpiration (T), reduced maize evapotranspiration (ET) by 4.8 %, and increased WPc by 1.8−26.6 %. Structural equation modeling (SEM) suggests that RB was the most important factor for improving WPc. In addition, this system ensures that economic benefits did not decrease. ConclusionIt can be seen that nitrogen reduction by 20 % with green manure retention is a reasonable nitrogen fertilizer management system to alleviate the contradiction between high maize yield and water resource shortages in the region. ImplicationsThe results of this study provide valuable insights into alleviating the contradiction between agricultural production and regional water resource scarcity.

Alkali-activated geopolymers based on calcined phosphate sludges and metakaolin.

The extraction of phosphorite ore in Tunisia has resulted in the discharge of substantial amounts of phosphatic sludge into the region's water system. To mitigate this environmental issue and prevent heavy metal leaching, a geopolymerization process was employed using two types of Tunisian calcined phosphate sludges (Cal-PS1 and Cal-PS2) as substitutes for alkali-activated metakaolin. This study aimed to investigate and compare the physical and mechanical properties of the resulting geopolymers. The optimal substitution ratio of metakaolin with calcined phosphate sludge was determined to be 1.5, equivalent to 20 wt.% of calcined phosphate sludge. Compressive strength tests conducted after 28 days of curing revealed values of 37 MPa for Cal-PS1 specimens and 28 MPa for Cal-PS2 geopolymers while compressive strength of geopolymers soaked in water for 28 days showed a decrease with the addition of phosphate sludges. The specific surface areas of Cal-PS1 geopolymers ranged from 16.3 to 16.9 m2/g and from 17.62 to 18.73 m2/g for Cal-PS2 specimens exhibiting a mesoporous structure. The elasticity modulus of the geopolymers was found to increase with the increase of the apparent density of geopolymers and with the sludges content but it tended to be lower than the Portland cement elasticity modulus. Leaching test was conducted to evaluate the potential environmental applications of the geopolymers. This test demonstrated effective containment of heavy metals within the geopolymers' network, except for low levels of arsenic.

The use of thermal performance analysis to improve conservation management: The case of the invasive Red Sea swimming blue crab Portunus segnis

The latest report from the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) expresses concern over the global proliferation of non-native species (NIS) driven by increasing temperatures. In 2023, the invasive blue crab Portunus segnis in the Mediterranean experienced a significant range expansion due to warmer waters in northern and western regions. Recognizing thermal tolerance as crucial for conservation, this study, using the blue crab as a model, emphasized the importance of considering thermal metabolic performance in conservation efforts. In this study, we experimentally measured the metabolic performance of P. segnis at different temperatures (from 7 to 42°C) using an oxygen consumption measurement system. The thermal performance curve (TPC) of P. segnis rose from 0.016 ± 0.011 mgO2 h−1 gWW−1 (12°C) to 0.238 ± 0.011 mgO2 h−1 gWW−1 (34°C), and decreased beyond. Organisms succumbed at 7°C and 42°C. The TPC obtained was compared with 24 TPC models and the O’Neill regression was the best fitting model determining the minimum critical thresholds (CTmin) at 11.33°C and CTmax at 41.13°C. Using the TPC curve equation, we applied the curve to satellite Mediterranean temperature data for the year 2022 and for the future (RCP 4.5 and 8.5) to determine the current and future monthly distribution of favorable thermal habitats for P. segnis. Results anticipated the future expansion of the species along the Spanish, French, Italian, and Greek coasts of the Aegean Sea, providing maps to prioritize high-risk invasion areas. Additionally, in the areas where the species in currently present, results predicted a long-term persistence of the species. Understanding species' responses to temperature changes appears crucial for anticipating and addressing the impending expansion of invasive species, underscoring the urgency of nature conservation measures.

The Use of Weather, Water, Ice, and Climate (WWIC) Information in the Polar Regions: What Is Known after the Decadelong Polar Prediction Project?

Abstract The polar regions are facing a wide range of compounding challenges, from climate change to increased human activity. Infrastructure, rescue services, and disaster response capabilities are limited in these remote environments. Relevant and usable weather, water, ice, and climate (WWIC) information is vital for safety, activity success, adaptation, and environmental protection. This has been a key focus for the World Meteorological Organization’s (WMO) Polar Prediction Project (PPP), and in particular its “Societal and Economic Research and Applications” (PPP-SERA) Task Team, which together over a decade have sought to understand polar WWIC information use in relation to operational needs, constraints, and decision contexts to inform the development of relevant services. To understand research progress and gaps on WWIC information use during the PPP (2013–23), we undertook a systematic bibliometric review of aligned scholarly peer-reviewed journal articles (n = 43), examining collaborations, topics, methods, and regional differences. Themes to emerge included activity and context, human factors, information needs, situational awareness, experience, local and Indigenous knowledge, and sharing of information. We observed an uneven representation of disciplinary backgrounds, geographic locations, research topics, and sectoral foci. Our review signifies an overall lack of Antarctic WWIC services research and a dominant focus on Arctic sea ice operations and risks. We noted with concern a mismatch between user needs and services provided. Our findings can help to improve WWIC services’ dissemination, communication effectiveness, and actionable knowledge provision for users and guide future research as the critical need for salient weather services across the polar regions remains beyond the PPP. Significance Statement Every day, people in the Arctic and Antarctic use weather, water, ice, and climate information to plan and carry out outdoor activities and operations in a safe way. Despite advances in numerical weather prediction, technology, and product development, barriers to accessing and effectively communicating high-quality usable observations, forecasts, and actionable knowledge remain. Poorer services, prediction accuracy, and interpretation are exacerbated by a lack of integrated social science research on relevant topics and a mismatch between the services provided and user needs. As a result, continued user engagement, research focusing on information use, risk communication, decision-making processes, and the application of science for services remain highly relevant to reducing risks and improving safety for people living, visiting, and working in the polar regions.

Revealing the ongoing speleogenetic processes in an underwater cave through the application of natural radionuclides and stable isotopes: case study from the hypogene Buda Thermal Karst

The underwater Molnár János Cave in the hypogene Buda Thermal Karst system (Budapest, Hungary) provides a unique site to study the effects of flowing groundwater and the interplay of fluids of different origin. The aim of the present study is to characterize the groundwater in different parts of the cave with temporal resolution, hence describe the recent speleogenetic processes within the cave. This study uses natural radioisotopes (uranium, radium, and radon) besides stable isotope ratios of oxygen and hydrogen to identify the different fluid components. The results show that the majority of the cave is situated in the flow path of the intermediate flow system, discharging in the Boltív Spring. Thus, the dominant recent speleogenetic processes are connected to this lukewarm groundwater. In contrast to previous views, typical hypogene processes, such as mixing corrosion involving thermal waters, are restricted to a narrower area in the cave, to the contact zone of lukewarm waters and the warmer upper water layer around the largest partially air-filled chamber (Kessler Hall). The warmer water layer is the result of free convection. In the air-filled chambers condensation-corrosion might be active. However, its effect is limited to the largest room (Kessler Hall), as it is open to surface conditions. More active mixing corrosion probably occurs deeper, in the area of the Northeastern Margin Fault, which is indicated by the radon content in the Boltív Spring. Regarding the temporal processes, the main driving force can be linked to the water level fluctuations of the Danube, which regulates the discharge of the regional flow-related thermal water upwelling, thus affecting the mixing ratio of the lukewarm waters transported by the intermediate flow systems and the thermal waters, representing the regional flow path, including basinal components.

Integrated hydrological modeling and water resource assessment in the Mayurakshi River Basin: A comprehensive study from historical data to future predictions

This study employs the SWAT hydrologic model to integrate climatological and hydrological processes for an in-depth analysis of the Mayurakshi River Basin. Utilizing the Markov Chain Model, the study evaluates water availability, flow patterns, and the basin's response to various climatic and land-use scenarios. Over 30 years of daily observed river discharge data were rigorously calibrated, validated, and analyzed for uncertainty, with critical data from the Massanjore Dam and Tilpara Barrage gauge stations characterizing the river's hydrological behavior. The result suggests the watershed received an average annual precipitation of 1432.4 mm, with evapotranspiration accounting for 40% of total water loss (578.4 mm). Surface runoff constituted over 90% of the total discharge, highlighting its importance for agricultural practices, particularly during the dry season. However future projections (2021-2031) indicate a significant decrease in mean annual precipitation (1404.7 mm) and a drop in evapotranspiration (542.1 mm or 38% of mean precipitation), attributed to reduced vegetation cover and increased settlement, leading to enhanced surface runoff. By quantifying internal renewable blue water, evapotranspiration, and soil water, this research provides crucial data for long-term water resource planning and assessment. The findings are valuable for national, regional, and transboundary water management agencies, offering insights into sustainable water resource management under changing climatic and different land-use conditions.

Impacts of Moisture Advection Scheme on Precipitation in the Steep Topography Region between the Tibetan Plateau and the Sichuan Basin

Abstract Water vapor transport is a crucial process in modeling and can contribute to errors in precipitation forecasts. To investigate the sensitivity of precipitation to the moisture advection scheme, this study introduced the two-step shape-preserving advection scheme (TSPAS), which has been proven to improve precipitation simulation over steep topography at lower resolutions, into the Southwest Center Weather Research and Forecast (WRF)-based Intelligent Numerical Grid Forecast System (SWC-WINGS) at a convection-permitting resolution. According to experiments conducted throughout the summer of 2021, the precipitation over the eastern slope of the Tibetan Plateau (TP) is highly sensitive to the moisture advection scheme. TSPAS successfully improved precipitation over the eastern slope of the TP, especially for torrential rainfall. The fractions skill score (FSS) is improved by 0.075 (27.78%) for daily precipitation with a threshold of 100 mm. Compared with the experiment with the original WRF advection scheme, the TSPAS reduced the overestimation of precipitation in the topographic region and excessive water vapor transport in a low-level atmosphere. To understand the precipitation improvement contributed by the advection scheme, additional experiments were conducted for a particular precipitation process from two approaches: switching advection schemes during the rainfall evolution and updating the variables related to moisture advection individually. Results demonstrate that the precipitation improvement is mainly contributed by the moisture advection scheme before the precipitation. Among the different variables, the combination of wind and water vapor was the most influential factor causing the precipitation improvement under the TSPAS.

Sustainable Urban Clean Water Governance in Indonesia: Problems, Institutions, and Future Solutions

This study aims to explain the urban community-based clean water provision in Bandung City, in terms of general problems, institutional and governance aspects. Community-based clean water governance should be developed so that communities are independent and ready to produce clean water. When clean water is available, the time and money spent on obtaining clean water can be used for other more productive purposes and can improve community welfare. The method used in this research is a qualitative approach with a descriptive approach. Data collection was done through literature review, in-depth interviews and several site surveys. The results of this study indicate the low performance of Regional Water Supply Company in managing clean water supply and the absence of local regulations related to urban community-based clean water governance. In addition, the implementation of clean water provision in Bandung City has not integrated community-based governance. The conclusion of this research is that urban clean water governance in Bandung City and other cities in Indonesia using a community-based system for the current condition is very relevant. Furthermore, it is important to draft a local regulation on urban community-based water governance that aims to protect water resources as well as to create a clean and healthy environment, and sustainable.

Internal Waves Force Elevated Turbulent Mixing at Barkley Canyon

AbstractSubmarine canyons are hot spots for topography‐internal wave interactions, with elevated mixing contributing to regional water mass transport and productivity. Two velocity time series compare and contrast internal waves deep inside Barkley Canyon to a nearby site on the shelf‐break slope of the Vancouver Island Continental Shelf. Elevation of internal wave energy occurs near topography, up to a factor of 10 above the slope and 100 in the canyon. All frequency bands display strong seasonal variability but weak interannual variability. Diurnal (K1) energy is sub‐inertial, trapped along topography, and forced locally through barotropic motions. Both sites have high near‐inertial (NI) energy linked to wind events, though fewer events are observed deep inside the canyon. At the slope site, near‐inertial energy is attenuated with depth, while in the canyon it is amplified near the bottom. Freely propagating semidiurnal (M2) energy appears focused near critical shelf‐break and canyon floor topography, due to local and remote baroclinic forcing. The high‐frequency internal wave continuum has enhanced near‐bottom energy at both sites (up to 7 × the Garrett‐Munk spectrum), and inferred dissipation rates, ɛ, reaching 10−7 W kg−1 near topography. Dissipation is most strongly correlated with semidiurnal energy variability at both sites, with secondary contributors that are site dependent. Forcing power law fits are on the slope, and NI0.2 in the canyon. There is also a build‐up of “shoulder” energy (PSh) near the buoyancy frequency, with a power law fit to dissipation of PSh ∼ ɛ0.3 at both sites.

DEVELOPMENT OF A METHOD FOR INJECTING WATER INTO A RESERVOIR TO MAINTAIN RESERVOIR PRESSURE IN AN OIL FIELD

This article discusses a system for developing an oil reservoir using the pressure of regional waters. The system is used for reservoir-type oil deposits with natural water pressure or active elastic water pressure regime. It involves drilling out the deposit with production wells, locating them mainly in the purely oil part of the deposit in closed (“circular”) rows parallel to the internal oil-bearing contour. This includes oil deposits with effective reduced wear regimes of deposits with water-pressure and active elastic-water-pressure regimes. Waterflooding cannot be developed when the permeability of the formations is low. As a result, some deposits are being developed under modern conditions.

PENGARUH KOMPENSASI DAN PENGEMBANGAN KARIER TERHADAP RETENSI KARYAWAN PADA PERUMDA AIR MINUM TIRTA LATIMOJONG (PAMTL) KABUPATEN LUWU

This study aims to investigate the influence of compensation and career development on employee retention. Data were collected through questionnaire distribution using the Likert scale. The population consisted of employees from the Regional Water Utility Company Tirta Latimojong (PAMTL) in Luwu Regency. The variables studied included compensation and career development as dependent variables, and employee retention as the independent variable. The results indicate that both compensation and career development have a positive and significant impact on employee retention. This research contributes to understanding the factors influencing retention in the context of organizational management and provides insights for enhancing employee engagement and longevity within the organization.

Dynamic Monitoring of Poyang Lake Water Area and Storage Changes from 2002 to 2022 via Remote Sensing and Satellite Gravimetry Techniques

The monitoring of Poyang Lake water area and storage changes using remote sensing and satellite gravimetry techniques is valuable for maintaining regional water resource security and addressing the challenges of global climate change. In this study, remote sensing datasets from Landsat images (Landsat 5, 7, 8 and 9) and three Gravity Recovery and Climate Experiment (GRACE) and Gravity Follow-on (GRACE-FO) mascon solutions were jointly used to evaluate the water area and storage changes in response to global and regional climate changes. The results showed that seasonal characteristics existed in the terrestrial water storage (TWS) and water area changes of Poyang Lake, with nearly no significant long-term trend, for the period from April 2002 to December 2022. Poyang Lake exhibited the largest water area in June and July every year and then demonstrated a downward trend, with relatively smaller water areas in January and November, confirmed by the estimated TWS changes. For the flood (August 2010) and drought (September 2022) events, the water area changes are 3032 km2 and 813.18 km2, with those estimated TWS changes 17.37 cm and −17.46 cm, respectively. The maximum and minimum Poyang Lake area differences exceeded 2700 km2. The estimated terrestrial water storage changes in Poyang Lake derived from the three GRACE/GRACE-FO mascon solutions agreed well, with all correlation coefficients higher than 0.92. There was a significant positive correlation higher than 0.75 between the area and TWS changes derived from the two independent monitoring techniques. Therefore, it is reasonable to conclude that combined remote sensing with satellite gravimetric techniques can better interpret the response of Poyang Lake to climate change from the aspects of water area and TWS changes more efficiently.

Integrated assessment of crop planting suitability: A case study in the Hetao Irrigation District of China using HJ-1A/1B satellite data

The increasing demand for food due to population growth and climate change poses significant challenges to achieve the Sustainable Development Goal of zero hunger by 2030. A key aspect in overcoming these challenges is to determine appropriate planting patterns for various crops, aimed at enhancing regional-scale crop water productivity despite the constraints of limited water and land resources. Remote sensing data and models provide the possibility for accurately estimating water productivity of different crops on a regional scale, but studies on remote sensing-based assessments of regional crop water productivity and its applications in agricultural management are still limited. In this study, we present a satellite-based integrated approach to assess crop planting suitability based on regional crop water productivity estimation. Focusing on the Hetao Irrigation District (HID) in the upper Yellow River basin, a representative irrigation district in arid region of Northwest China, we first use remote sensing data (HJ-1A/1B) to estimate water productivity for the two major crops, maize and sunflower, within the HID from evapotranspiration and yield estimates. Additionally, we introduce a novel crop planting suitability index based on the frequency distribution of crop water productivity, facilitating the determination of appropriate crop planting patterns. Our findings reveal that Dengkou, the periphery of Hangjinhouqi, and the southern part of Linhe are optimal for maize cultivation, while Wuyuan and the northern part of Linhe are ideal for sunflower cultivation. This is attributed to higher water productivity levels for maize in Dengkou (2.46 kg/m³) and Linhe (2.15 kg/m³), and for sunflower in Wuyuan (0.86 kg/m³). Following the optimization of crop planting distribution, the average water productivity for maize and sunflower increases by 7.6 % and 5.0 %, respectively. The proposed method can be generalized to other regions, and the results offer valuable insights for local governments in decision-making to regulate cropping pattern and maximize regional crop water productivity.

Estimating crop evapotranspiration of wheat-maize rotation system using hybrid convolutional bidirectional Long Short-Term Memory network with grey wolf algorithm in Chinese Loess Plateau region

Accurate estimation of crop evapotranspiration (ET) is essential for the efficient utilization of agricultural water resources, crop production enhancement, and sustainable agricultural development. However, direct measurement of ET is highly expensive, intricate, and time-consuming, highlighting the imperative of establishing a novel model to accurately estimate ET in agricultural ecosystems. To address the above problems, this study proposed a novel model (GWA-CNN-BiLSTM), which incorporates Grey Wolf Algorithm (GWA), Convolutional Neural Network (CNN), and Bidirectional Long Short-Term Memory network (BiLSTM) as a hyperparameter adjuster, feature extractor, and regression component, respectively, to estimate ET built upon various input combinations comprising net solar radiation (Rn), vapor pressure deficit (VPD), average air temperature (Ta), soil water content (SWC), and leaf area index (LAI) about winter wheat-spring maize rotation system during 2012–2020 in the Loess Plateau. Besides, following a comparative assessment within GWA-CNN-BiLSTM, Convolutional Bidirectional Long Short-Term Memory network (CNN-BiLSTM), BiLSTM, Long Short-Term Memory network (LSTM), and Shuttleworth-Wallace (SW) models, the results revealed that GWA-CNN-BiLSTM under varied inputs obtained the superior performance, ranging from 0.562 to 0.957 in determination coefficient (R2), 8.4–41.5 % in relative root mean square error (RRMSE), 0.349 mm d−1 to 1.521 mm d−1 in mean absolute error (MAE), −3.26 % to 14.11 % in percent bias (PBIAS), and 0.820–1.091 in regression coefficient (b0), respectively. Moreover, while the accuracy of BiLSTM over LSTM was evident, its performance was notably improved by the incorporation of the CNN module. Additionally, LSTM-type models under complete input combination present better precision than SW by 29.7−51.4 % in R2, 44.2−76.1 % in RRMSE, and 33.6−63.4 % in MAE, respectively. Furthermore, the accuracy of all models under varied inputs exhibited excellence in winter wheat compared to spring maize, and corresponding improvements ranged 1.4−4.3 % in R2, 5.1−20.1 % in RRMSE, and 3.1−17.9 % in MAE, respectively. Besides, the meteorological factors (Rn, VPD, Ta) proved to be the most important inputs for ET estimation in winter wheat and spring maize. Wherein the importance of SWC exceeded that of LAI in winter wheat, while the opposite trend was observed in spring maize. In brief, GWA-CNN-BiLSTM is the highly recommended model to estimate ET of winter wheat-spring maize rotation system under diverse input data scenarios in the Loess Plateau, which can facilitate to offer valuable assistance in regional agriculture water management decisions.

Intelligent Water Quality Testing Device based on Internet of Things Technology

Water quality testing is an important environmental testing standard. However, at present, Internet of Things water quality testing products generally have problems such as single function, complex interface, and short sensor life. The design of this paper is a device with intelligent water quality detection technology, including the independent design of the sensor interface standard, the sensor automatic recognition, plug and play; The sensor is equipped with a lifting mechanical structure to avoid long-term soaking of the sensor and increase the service life of the sensor by 35%. At the same time, combined with intelligent Internet of Things, big data analysis and other technologies, help relevant departments to grasp water quality information in a timely and accurate manner, early warning and forecasting of major regional water pollution accidents, supervision of pollutant discharge, and implementation of control systems to provide help. It is mainly used to monitor the water quality data of small and medium-sized reservoirs, rivers and lakes to achieve intelligent management within the jurisdiction.

Source identification of spring water mass in the Southern Western Ghats of Kerala, India: Application of biogeochemical tracers

This study investigates the sources and formation of spring water in the southwestern coastal regions of the Indian subcontinent. It involves sampling and analysing spring water, groundwater, rainwater of the region and biogeochemical tracers. The springs of the region were found to be cold (27.2–29.5 °C), acidic (pH = 3.43–6.83), freshwater dominant (Cl− = 10.10 – 43.67 mg L−1), and moderately oxygenated (DO = 5.08–9.43 mg L−1). Using a binary mixing model with biogeochemical tracers (total alkalinity and Cl−), the study identified precipitation and groundwater as primary contributors, with sea water also influencing coastal springs. The binary model indicates a higher precipitation contribution (85–100%) to spring water compared to groundwater (0–68%). The basin-wise variability of contribution by different water masses evidenced spatial variation of precipitation is not only acting as the major driving force to build the spring water mass, it is also intricately linked with the geochemical factors controlled by the hydraulic gradient between spring and groundwater systems.