Description: Generally, the water distribution networks are designed for peak demands so that under normal operating conditions pressure is adequate to meet the nodal demand however, due to this, the pressure remains excessive when the consumption is low. This leads to huge water leakages and pipe bursts due to excess available pressure. These excess of pressure can be reduced by operating pressure reducing valves. Moreover, the pressure deficient conditions of water distribution network depends on many factors such as excess demand (i.e., fire fighting demand), location and elevation of nodes, location and pressure setting values of pressure reducing valve, ageing of pipes (i.e., increase the pipe roughness) etc. In exceptional situations, pressure deficient condition also may occur when there is a fire demand while pressure reducing valves are in operating condition. The available literature of the pressure deficient condition as well as optimal location, number and their pressure setting values of pressure reducing valves are analysed by mathematical programming or optimization methods. Normally, it is cumbersome to the field engineers to use the any toolkit utility functions. Hence in this study, the pressure deficient condition is analysed via the method of modified pressure-deficient network algorithm without using EPANET toolkit functions which are coupled with pressure reducing valve operation. A benchmark problem is analysed and compared for the proposed method. Further, a real water distribution networks is analysed introducing fire demand at junction/distribution node using fixed and diurnal nodal demand pattern coupled with and without pressure reducing valve operation in a single hydraulic simulation.

Description: A physical model that consisted of a glass reinforced plastic model, constructed to a 1:25,000 horizontal scale and with a 1:125 vertical scale of the Severn estuary was designed and fitted into a tidal basin at Cardiff University. The model, which was first of its kind, was used to conduct studies on the hydrodynamic (i.e. water levels and velocities) and solute transport processes in the estuary, with the latter being studied through dye tracer studies. This basin is particularly significant since in recent years the estuary has attracted a lot of attention, especially with the potential of renewable energy generation. Thus any studies that can help mimic the water behaviour in the estuary, and replicate conditions in the prototype, would help address the many concerns relating to tidal dynamics and water quality in the estuary. The physical model could not match the prototype exactly due to scaling and space constraints, however, the results obtained agreed well with field studies and other studies reported in the literature.

Description: The aim of this paper is to evaluate the economic efficiency of irrigated agricultural enterprises using a non-radial data envelopment analysis approach. While a number of studies have used radial measures based on data envelopment analysis to obtain efficiency scores for a given production technology, we calculate non-radial measures to understand the efficiency of using individual inputs employed in the production process. In particular, the measures of economic efficiency are decomposed into water use efficiency and managerial efficiency. This decomposition enables us to obtain an efficiency score for the use of water as an environmentally sensitive input in irrigated crop production systems. Treating water input in this way goes beyond traditional measurement of water use efficiency, as the calculated efficiency scores can be used as indicators of sustainability in terms of water withdrawals for irrigation purposes. The results show that the overall efficiency for the considered irrigated enterprises is quite high. This is in contrast to the findings on the water use efficiency scores, which are fairly low. This indicates that while Australian irrigated farms are comparatively more efficient in overall farm activity management, they are not very efficient in managing water resources. In turn, this threatens the sustainability of this industry. There is a substantial variation of water use efficiency scores across irrigated enterprises and across regions. Analysing these variations can provide important insights for current policy and for future efforts to improve water use efficiency that will lead towards more sustainable irrigation industry.

Description: Integrated water resources management provides an often-recommended governance framework to manage water resources in a sustainable way. The application of this framework on Transboundary Rivers brings additional challenges, which can be exacerbated due to climate changes and extremes (such as droughts). These changes affect the operation of water infrastructures and will affect water management practices. Thus, the understanding and development of adaptation measures (across socio-economic, environmental and administrative systems) are critical, mainly on drought prone transboundary river basins. The paper draws on research conducted to 1) assess climatic risks in those watersheds, 2) describe the challenges in water resources management in the context of climate change, and 3) draw lessons for improving the use of research-based information. Two case studies were selected, the Colorado River Basin (North America) and the Guadiana River (Iberian Peninsula), the latter of which in the context of the five river basins shared between Portugal and Spain. Research and experience in these Basins show that several paradoxes in multistate water management and governance across borders militate against the accurate assessment of socio-economic impacts and the effective use of scientific information for meeting short-term needs in reducing longer-term vulnerabilities. Lessons drawn from both studies, but not always learned in practice, abound. These lessons include an expanded use of incentives for improving collaboration, water-use efficiency, demand management and for the development of climate services to inform water-related management as new threats arise. Recommendations are established for more effectively linking risk assessment approaches with resilience strategies that are applicable in practice and available to decision makers in a changing climate.

Description: Finnish arable land is typically located on flat areas, where the fields are mostly drained and sub-drained to control the water tables. These areas are highly susceptible to nutrient loss, which affects the water quality of rivers and lakes. Therefore, it is very important to understand current landscape pattern and processes controlling water quality, not only identifying factors affecting it, but also identifying strategies and restoring areas for mitigation. We studied linkage of 21 years (1990–2011) of water quality (WQ) data from 16 agricultural watersheds, using landscape indices at three functional scales: watershed-wide, saturation-excess zone, and riparian zone (of varying widths). The hydro-biogeochemical functional areas of watershed were obtained by digital terrain analysis. Statistical analyses by generalized linear model and multivariate redundancy analysis indicated that the fraction of watershed in agricultural use was linked to most of the studied water quality variables. The relationships varied across the seasons: they were strongest during high flow periods (spring and autumn) when also highest nutrient losses occur. Total suspended sediment concentrations were linked to critical source areas. Riparian vegetation index was important explaining nitrate concentrations in autumn. Terrain-based mapping of hydro-biogeochemical functional areas provides a rapid identification of potential sites to mitigate diffuse nutrient pollution, particularly in riparian zones.

Description: The difficulty in measuring spring discharge in mountainous regions often leads to incomplete time series, which are of low importance. Instead, the complete time series enable tο draw secure conclusions from the study of hydrographs. This article presents an innovative version of Modkarst model, which was originally developed to simulate the function of brackish coastal karst springs. Its originality is also related to its ability to complete time series and to give estimates with respect to important parameters of the karst aquifers, such as the storage coefficient and the extent of a spring’s recharge area. The new model, based on the fast and slow flow concept, uses two tanks instead of three and an appropriate modified system of equations from the initial one. Its inputs are time series of daily rainfall, while the model fitting requires discharge values. Its application area, Louros River basin, is a mountainous area consisting of 10 significant springs with yields varying between 0.07 and 3.4 m 3 /s, each of which discharges a hydrogeological karst unit. The validation of the model was accomplished by testing the accuracy of its results against a complete time series. Additional outputs, such as the estimated physical parameters, coincide with the outcomes from the hydrogeological investigation, thus confirming indirectly the code’s accuracy.

Description: Desalination has proven to be a reliable and efficient water supply option in many countries, especially in times of water scarcity. However, high desalination costs and high prices for desalinated water (twice or three times higher than those from traditional water sources) have been hindering an uptake and the development of desalination in many countries. Applied desalination technology, capital and operational costs, production capacity, water salinity are just a few factors determining the final cost of desalinated water that varies considerably between $1.7–9.5/kgal ($0.45–2.51/m 3 ). The final prices for desalinated water and the related costs for local municipalities are among the most crucial determinants of the overall short- and long-term effectiveness of desalination processes. This paper provides an in-depth analysis on economics of desalination with country specific examples. It depicts a comprehensive picture of cost variability of desalinated water and points out challenges for cost-effective desalination in the future.

Description: Simulation is considered a fundamental component in research on management of water resources, which can provide information to decision makers. An integrated model is developed here for simulating water resource management. After analysis of influences on water use, this model was separated into seven main modules: Population, Economy, Land Change, Water Demand, Water Supply, Wastewater, and Water Quality. Relationships between and within the modules were formulated based on mathematical models. The model was run dynamically based on system dynamics. It was then used to successfully simulate water use in Laoshan District of China after validation and calibration by historical data, with small mean relative error (〈15 %) and great coefficient of determination (〉0.65). Three scenarios were analyzed to develop effective water use solutions to support development of socioeconomic and ecological health. The results show that integrated management toward improving water use efficiency and the water-resource use mix is an effective solution. And the integrated model developed here is useful for decision makers to simulate and analyze the scenarios for water resource management.

Description: Recent evidences of the impact of regional climate variability, coupled with the intensification of human activities, have led hydrologists to study flood regime without applying the hypothesis of stationarity. In this study, identification of nonstationarity was conducted in the form of both trend and change point in the mean of the annual maximum flood magnitudes, using Mann-Kendall and Pettitt test, respectively in Wangkuai reservoir watershed, China. The annual maximum flood series exhibited a significant decreasing trend, and the timing of change point was detected in 1979, which was consistent with the construction of large numbers of check dams and small hydraulic structures. A correlation test (Pearson correlation test) between large-scale oceanic-atmospheric patterns (El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), North Pacific Oscillation (NPO), North Atlantic Oscillation (NAO), Atlantic Oscillation (AO)) and annual maximum flood peaks was adopted to assess the climatic causes of nonstationary flood series. It was found that NPO, NAO and AO had significant correlations with flood peak, but ENSO and PDO could not explain the variations of flood peak. In the case of human-induced nonstationarity, we proposed 2 new indices to represent the effect of human activities on flood. The new indices were proposed based on the storage capacity and drainage area of the large numbers of check dams and small hydraulic structures which were estimated with no observed data. The identification of nonstationarity for flood series and the climatic and human-induced causes could provide useful information in nonstationary flood frequency analysis.

Description: The authors propose a measurement method that divides the depth of the soil sample in discrete regions to investigate soil water propagation dynamics using soil impedance measurements. Experiments were conducted on a cylindrical phantom using a clay loam soil sample (60 % clay, 21 % loam and 19 % sand). The resulting impedance changes represent the wetting front (WF) propagation process at the different measurement depths. The measured impedance data is used to A) show graphically the wetting front propagation process, obtain B) a 1st order model, C) an ARX1821 model of the impedance change as a function of the irrigation volume applied and D) estimating changes in water content using a neural network. The results indicate that the proposed measurement technique can be used to detect and predict the movement of liquid trough the soil sample. The neural network permits inferring the water content from impedance and soil-water mixture temperature values. Changes in soil impedance in each segment, due to the water propagating downwards through the soil sample, can be used to study the dynamics of the wetting front, irrigation scheduling and model improvement from physical data.