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Given the significant momentum of developing water quality models to simulate water quality variables and support decision-making, the literature recognizes the importance of addressing uncertainties embedded in the water quality models, such as inherent, parametric, and hydrological uncertainties. However, previous studies have not extensively examined the magnitude of hydrological events in terms of their intensity. Therefore, this paper aims to propose an adjusted Monte Carlo event-based scenarios framework that considers four scenarios (1- 35 years of flow rate records, 2- events with ARI ≤ 10 years, 3- events with ARI ≤ 5 years, 4- events with ARI ≤ 1) to evaluate hydrological variabilities and quantify embedded uncertainties. The study employs a Qual2k model that simulates five water quality variables in the Zaroub River, Iran, as a case study. The model's uncertainty boundaries are quantified using five statistical metrics: Plevel, ARIL, SU, CU, and EU. The study's findings reveal that when considering the flow rate time histories during extreme hydrological events, there is a significant increase in uncertainty in the water quality model, highlighting the challenge of incorporating various scenarios within the framework such as high computational demand, integrating different scenarios, sparse data, and its temporal resolution. On the other hand, reducing the ARI values of hydrological events not only minimizes the uncertainty boundaries but also improves the accuracy of the model simulations. These results underscore the critical importance of selecting hydrological scenarios based on the water quality variable under investigation. Furthermore, the proposed framework can be applied to any water quality model and water body. The study's outcomes suggest that the presented methodology reduces uncertainty and provides more reliable simulations for decision-making in water resources conundrums. [ABSTRACT FROM AUTHOR]

Leak detectability or leakage awareness refers to the capability of sensing losses from a water supply system. Several methods exist in the technical literature to tackle this problem, but only few address it with a state estimation approach. The aim of this paper is to present a new methodology that enables probabilistic assessment of the extent to which water loss could be detected using state estimation by only analysing a single hydraulic state, i.e. one time period. Significant leaks are sensed by identifying unusually high normalised state estimation residuals, which can be identified based on the largest normalised residual test. More specifically, the probability of detecting leaks is computed here by working with the multivariate distribution among measurements and estimates to take into account the noisy nature of measurements with an analytical approach rather than with sampling experiments, which are time-consuming. The methodology set out herein also provides a procedure to systematically assess the minimum leak that could be detected in different parts of the network for a specific measurement setting and operating condition. The method has been applied to a water transport network case study to show its potential and to highlight the usefulness of such a tool for practitioners. The limitations of such a methodology are also discussed, including its possible use for on-line leak detection strategies. [ABSTRACT FROM AUTHOR]

The inequity of water allocation in the Indus Basin by the rotational method has created conflicts of interest leading to water scarcity for irrigated agricultural land. The arid region of the basin is affected the most, which demands a new inventive way of managing water resources. Geo-informatics maps of the Bahawalnagar canal circle were prepared which show groundwater quality and depth to water table (DWT) for 2006 and 2016, crop evapotranspiration (ETc) by using product MOD16A2 for Kharif (April to September) 2017 and Rabi (October to March) 2017–18 cropping season. Results showed that groundwater quality is deteriorating and DWT is rising over 72% of the study area which leads to waterlogging and salinization. Surface water deficit filled through groundwater contribution is 53.66% and 39%, while ETc varies from 0.0 to 931 and 0.0 to 1979 mm/season for the Rabi and Kharif cropping seasons respectively. This paper presents the status of water balance and groundwater characteristics of the arid region of the Indus basin and recommends re-evaluation of the current water allocation system both within and between canal command areas, recommending that water allocation should be allocated as per crop water requirement and groundwater quality. A re-allocation of water-based on groundwater characteristics will not only mitigate waterlogging and soil salinity, which is a threat to the sustainability of agricultural land but also reduces the stress of inequities within the current rotational system. Implementation of this water allocation strategy will require long-lasting monitoring of groundwater quality at a different depth, a variation of depth to the water table, and estimation of crop evapotranspiration. [ABSTRACT FROM AUTHOR]

Society benefits from rivers in many aspects. To the extent of water resources management, one of the salient issues is that the social benefit of in-stream water quality improvements is often difficult to be quantified for possible cost justification in many water pollution control programs. The difficulties arise from that many service flows of water quality are not channelled through the market system to consumers and producers. With different socio-economic structures, such valuation could be even more challenging when taking river basins with low-income level into account. Recent advances in fuzzy set theory provide a germain insight to viewing the in-stream water quality as a kind of fuzzy resource due to varying awareness of the quality of life. This paper provides a technical analysis using the fuzzy contingent valuation mothod (FCVM) to value in-stream water quality improvements in terms of three fuzzy resources from aesthetic to recreational, and to ecological aspects. Traditional CVM may allow interest groups or affected parties to join and present a more flexible asset assessment with respect to the prescribed environmental features in the river corridor. Yet the FCVM provides a mechanism that lies in providing a mapping (via fuzzy set theory) from a survey of respondents’ valuation of subjective assessments of water quality into objective economic measures in terms of water quality parameters that management can more directly manipulate. With this new tool, the traditional CVM assessment outputs in a well-developed river basin may even lead to derive a simular valuaton function in a form of a regression equation in a developing river basin where the incme level is relatively low. As part of the sustainablity analysis basin wide, a case study in Taiwan showed that such effort may provide supportive information for cost benefit analysis in many water pollution control programs corresponding to different temporal and spatial scales. [ABSTRACT FROM AUTHOR]

Often there are a number of criteria that must be considered when evaluating water resource management options, for example both water quantity and quality issues. Each criterion generally requires a separate model to assess the outcomes from different possible scenarios. Each model will have its own uncertainties and limitations, and the combination of all of these considerations can make the identification of acceptable, let alone optimal, options difficult. In this work, a resources management problem to identify the optimal operation of a large drainage network to support ecosystems at a number of key wetlands has been considered. These ecological outcomes were assessed by the ability to deliver sufficient volumes of water below important salinity thresholds. It was found that even with an unknown volume of water available, the optimal operations of the drainage network were generally constant. For the majority of wetlands considered, the ability to supply sufficient water below a given salinity threshold was mostly insensitive to uncertainty in the contributing groundwater salinity. However, in some wetlands, water of desirable salinity levels was unlikely to be available for all scenarios at one target wetland, the variability in groundwater salinity considered had a large influence on the availability of water of suitable quality. This work highlights the importance of keeping the modelling objectives in mind when considering the outputs and uncertainties involved in integrated modelling assessment. [ABSTRACT FROM AUTHOR]