Southern Water (United Kingdom)

ABSTRACT This study explores the impact of climatic variability on groundwater storage dynamics in the Central Highlands of Vietnam, focusing on the Sesan and Srepok River Basins. Different from traditional analyses with groundwater levels, groundwater storage variations are derived here from (i) the G3P Gravity-based Groundwater Product based on satellite gravimetry with GRACE/GRACE-FO and (ii) a network of in-situ groundwater level observations converted to basin-average storage with lithology-dependent specific yield estimates. The results show the dominant impact of rainfall variability on groundwater storage variations. Beyond the seasonal scale, non-seasonal storage anomalies can primarily be explained by the accumulated rainfall and evapotranspiration of the previous 9 to 12 months. Weak correlations with ENSO variability indicate lower groundwater storage in the study area during El Niño periods. The evaluation by in-situ observations indicates reasonable performance of G3P for assessing the regional-scale groundwater storage dynamics in the Central Highlands of Vietnam.

This paper examines the balance of sovereignty and water basin community interest through the development of states’ extraterritorial duties regarding the right to water. It traces the evolving legal notions of jurisdiction and extraterritoriality, specifically through the extraterritorial human right to water within a transboundary context. Through theoretical and empirical analyses, the study summarises progress and challenges encountered by international human rights law and international water law. It also identifies potential pathways for advancing the respect, protection and fulfilment of extraterritorial human rights to water. Looking forward, integrating extraterritorial human rights obligations with international water law obligations may facilitate the mainstreaming of state extraterritorial duties with respect to water, providing increased protection for communities across transboundary watercourses.

The study has developed a set of criteria for assessing saltwater intrusion risk at commune level for Tien Giang province, a region with a relatively well-developed irrigation system, in three periods including present, 2030s and 2050s. The criteria for occurrence time of saltwater intrusion event have been added to show the impact of saltwater intrusion on agricultural production. The results show that the level of risk tends to increase from East to West, and the area at a very high level of risk gradually expands to the East over time. By 2050s, all communes in Tien Giang province show moderate to very high levels of risk due to saltwater intrusion. The study shows the influence of the irrigation system in reflecting the severity of saltwater intrusion in the area, through the opening/closing time of sluice gates, regulation systems of fresh water and the water storing capacity for production during saltwater intrusion event.

Flash flooding is among the most hazardous natural events in the US and globally. Hydrologic simulations are key tools for flash flood forecasting, particularly in poorly gauged or ungauged catchments, and infiltration models are a crucial component of any hydrologic simulation. Ideally, model parameters are calibrated based on observations. In practice, calibration and validation are often not possible due to a lack of observations. This paper contributes new guidance for parameter estimation of three infiltration models using plot-scale rainfall simulation. All three models, namely, initial-constant (IC), linear-constant (LC), and the Green-Ampt (GA) models, will be available in the next release of the widely used Hydrologic Engineering Center–Hydrologic Modeling System software. Results show that model parameters are sensitive to soil texture, antecedent moisture conditions, and the presence of a physical soil crust.

The growing need to access recycled water as a source for drinking water supply necessitates management of perceived risks. This study aimed to use quantitative microbial risk analysis (QMRA) to evaluate microbiological risks of indirect water recycling. Scenario analyses of risk probabilities of pathogen infection were conducted to investigate four key quantitative microbial risk assessment model assumptions: treatment process failure, drinking water consumption events per day, inclusion or exclusion of an engineered storage buffer, and treatment process redundancy. Results demonstrated that the proposed water recycling scheme could meet WHO pathogen risk guidelines of ∼10-3 annual risk of infection under 18 simulated scenarios.

The Casa Loma Siphon Barrel No. 1, as part of the Metropolitan Water District of Southern California's (Metropolitan's) Colorado River Aqueduct (CRA), is a 148-in. (3,759-mm) diameter concrete pipe that extends 5 miles and crosses the Casa Loma Fault Segment of the San Jacinto Fault Zone. This paper discusses the design, construction, repair, and seismic resilient design of this siphon over a time span of almost a century. Metropolitan's strategy to improve the seismic resilience includes: (1) geologic and geotechnical investigations for the siphon at the crossing of the Casa Loma Fault; (2) development of seismic design criteria that meet Metropolitan's performance objectives; (3) mitigation strategy and application of earthquake-resistant pipe joints; (4) modeling of pipeline and fault interaction; (5) development of detailed design; and (6) construction contract delivery and sequencing considerations. The retrofitted pipeline is anticipated to remain functional and operational during and following a design seismic event.

The wasp Scleroderma guani is an important parasitic natural enemy of a variety of stem borers such as longicorn beetles. Studying and clarifying the suitable area of this wasp plays an important role in controlling stem borers. Based on information about the actual distribution of S. guani and on a set of environmental variables, MaxEnt niche model and ArcGIS were exploited to predict the potential distribution of this insect in China. This work simulated the geographical distribution of potential climatic suitability of S. guani in China at present and in different periods in the future. Combining the relative percent contribution score of environmental factors and the Jackknife test, the dominant environmental variables and their appropriate values restricting the potential geographical distribution of S. guani were screened. The results showed that the prediction of the MaxEnt model was highly in line with the actual distribution under current climate conditions, and the simulation accuracy was very high. The distribution of S. guani is mainly affected by bio18 (Precipitation of Warmest Quarter), bio11 (Mean Temperature of Coldest Quarter), bio13 (Precipitation of Wettest Month), and bio3 (Isothermality). The suitable habitat of S. guani in China is mainly distributed in the Northeast China Plain, North China Plain, middle‐lower Yangtze Plain, and Sichuan Basin, with total suitable area of 547.05 × 104 km2, accounting for 56.85% of China’s territory. Furthermore, under the RCP2.6, RCP4.5, and RCP8.5 climate change scenarios in the 2050s and 2090s, the areas of high, medium, and low suitability showed different degrees of change compared to nowadays, exhibiting expansion trend in the future. This work provides theoretical support for related research on pest control and ecological protection.

Abstract This Scientific and Technical Report (STR) provides in-depth fundamentals and guidelines regarding Computational Fluid Dynamics (CFD) simulations of Water Resources Recovery Facilities (WRRFs) unit processes (e.g. headworks, aerobic and anaerobic biological reactors, settling tanks, disinfection). Each unit process is described with respect to: Literature review and process descriptionRelevant CFD concepts and modelling approachCase studiesFuture research needs CFD Modelling for Wastewater Treatment Processes also opens the discussion on two fundamental topics: experimental validation of CFD simulations, and the complementarity between CFD and Chemical Reaction Engineering approaches. This book is intended for undergraduate and graduate students majoring in fields related to wastewater treatment and/or fluid mechanics, as well as researchers and engineers who conduct research and practices in modelling such unit processes. Water resource recovery modelling is not just about lab-scale processes. Now and in the future it is about improving our understanding of (and designing better) full-scale facilities!

Incidental entrainment of fishes at large-scale state and federal water diversion facilities in the Sacramento-San Joaquin Delta, California, can trigger protective management actions when limits imposed by environmental regulations are approached or exceeded. These actions can result in substantial economic costs, and likewise they can affect the status of vulnerable species. Here, we examine data relevant to water management actions during January–June; the period when juvenile salmonids are present in the Delta. We use a quantile regression forest approach to create a risk forecasting tool, which can inform adjustments of diversions based on near real-time predictions. Models were trained using historical entrainment data (Water Years 1999–2019) for Sacramento River winter-run Chinook Salmon or Central Valley Steelhead and a suite of environmental and water operations metrics. A range of models was developed; their performance was evaluated by comparison of a quantile loss metric. The models were validated through examination of partial dependence plots, cross-validation procedures, and further evaluated through WY 2019 pilot testing, which integrated real-world uncertainty in environmental parameters into model predictions. For both species, the strongest predictor of loss was the previous week’s entrainment loss. In addition, risk increased with higher water exports and more negative Old and Middle Rivers (OMR) flows. Point estimates of loss were modestly correlated with observations (R2 0.4 to 0.6), but the use of a quantile regression approach provided reliable prediction intervals. For both species, the predicted 75th quantile appears to be a robust and conservative estimator of entrainment risk, with overprediction occurring in fewer than 20% of cases. This quantile balances the magnitude of over- and under-prediction and results in a low probability (< 5% of predictions) of unexpected high-take events. These models, and the web-based application through which they are made accessible to non-technical users, can provide a useful and complementary approach to the current system of managing entrainment risk.