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Domestic water use is one of India's primary water uses that also includes irrigation, industrial, and environmental water uses. However, there is a lack of reliable data that hinders the estimatio...

Rising population and industrialisation aided by technological advancements have resulted in increased industrial water demand in India. Industrial water demand accounts for about 8–10 % of the total water demand in the country. Although some national and international organisations report industrial water demand, there is a wide variation in data due to the scarcity of the reliable data and inconsistencies in the methods adopted for quantification. Rather than using these estimates, the census-based statistical data could provide better figures. Therefore, the present study aims to quantify industrial water demand by compiling census-based statistical data collected from various Governmental agencies in India. Based on census datasets collected at National and State Governmental institutions, this study develops a new model to estimate industrial water demand. Industrial water demand is estimated in this study at State and monthly scale from 1991 to 2010. The study models industrial water demand as a function of industrial production data, industrial survey components, and economic/technological development indicators. Principal component analysis is employed to reduce these large number of input variables to a smaller number of latent variables, which account for the variance in the input variables. The model results are cross-validated with industrial water demand data obtained from National Commission on Integrated Water Resources Development (NCIWRD). Country-level estimates are disaggregated to State-level water demand estimates based on number of industrial units in each State. These State-level results are verified against an independent census dataset on industrial water demand collected from State Governmental organisations. It is found that industrial water demand increased at a rate of 2% per annum during the period of analysis, which exceeds the increase rate of agricultural and domestic water demands during the same period.

Reliance on new and alternative water supply sources is a desirable option for upgrading existing and ageing urban water system infrastructure that is no longer able to cater for steadily increasing water demand. This transformation will increasingly involve the use of decentralised, more complex and energy intensive urban water systems. Modelling capability that takes a holistic systems approach to optimize the dynamic interactions between water and energy is needed to evaluate the performance of fit-for-purpose water supply systems for the urban sector. This paper presents a simulation-optimisation model to concurrently simulate and optimize an urban water supply system based on minimum energy use when water of alternative quality is supplied to different users on a 'fit-for-purpose' basis. The model uses a System Dynamics approach to simulate the energy use of different water supply systems in the form of stocks and flows combined with a Genetic Algorithm (GA) technique to optimize energy use while satisfying all the water demands. The comprehensive model framework is built on a Matlab/Simulink® platform. Life Cycle Energy Assessment (LCEA) is used to generate the embodied energy use variables which are input to the simulation-optimisation model. The model is sufficiently flexible to accommodate water supply systems of variable spatial scales and analyse water and energy use at variable time scales. The application of the modelling framework on the Aurora urban development estate, Australia, shows that the model produces essential information about the water supply and energy use intensity according to specified criteria.

Freshwater scarcity and unsustainable water use are just some of the growing concerns in many parts of the world. Increasing water demand accompanied by a changing climate can lead to unsustainable use of freshwater resulting in water scarcity. Several studies have quantified sustainable water use and water scarcity at a continental-to-global scale in the past. This review focuses on the large-scale water resources assessments and the methods by which sustainable water use and water scarcity are quantified. The review is structured based on a framework that comprises the main components of water demand and supply and other aspects of sustainable water use including virtual water trade and future projections of sustainable water use. The major components of water demand and supply in such assessments are increasingly derived from global earth system models and national-level census datasets. These assessments conclude that the selection of appropriate spatial and temporal scales is critical. The grid-based global earth system models enable better spatial resampling of water information across country/political boundaries. Similarly, by refining the temporal scale from annual (the most commonly used temporal scale of assessment) to monthly time steps, water scarcity is better captured due to the distinctive seasonality of water availability and demand. This paper also discusses the role of major drivers of water scarcity. Although both changing climate and increasing water demand contribute to water scarcity, the majority of the literature concludes that the demand-driven freshwater scarcity has a much greater impact than that induced by climate change.

From the 1980s, Indian summer monsoon rainfall (ISMR) shows a decreasing trend over north and northwest India, and there was a significant observed reduction in July over central and south India in 1982-2003. The key drivers of the changed ISMR, however, remain unclear. It was hypothesized that the large-scale irrigation development that started in the 1950s has resulted in land surface cooling, which slowed large-scale atmospheric circulation, exerting significant influences on ISMR. To test this hypothesis, a fully coupled model, the CESM v1.0.3, was used with a global irrigation dataset. In this study, spatially varying irrigation-induced feedback mechanisms are investigated in detail at different stages of the monsoon. Results show that soil moisture and evapotranspiration increase significantly over India throughout the summertime because of the irrigation. However, 2-m air temperature shows a significant reduction only in a limited region because the temperature change is influenced simultaneously by surface incoming shortwave radiation and evaporative cooling resulting from the irrigation, especially over the heavily irrigated region. Irrigation also induces a 925-hPa northeasterly wind from 30°N toward the equator. This is opposite to the prevailing direction of the Indian summer monsoon (ISM) wind that brings moist air to India. The modeled rainfall in the irrigated case significantly decreases up to 1.5 mm day-1 over central and north India from July to September. This paper reveals that the irrigation can contribute to both increasing and decreasing the surface temperature via multiple feedback mechanisms. The net effect is to weaken the ISM with the high spatial and temporal heterogeneity. © 2018 American Meteorological Society.

This paper analyses the impacts of various hybrid water supply systems, conceptualised as the combination of centralized and decentralized water supply systems, on wastewater and stormwater flows and contaminants. The analysis comprises of seven alternative scenarios: i) centralized only, ii) centralized along with recycled water, iii) centralized along with treated greywater, iv) centralized along with rainwater harvesting, v) centralized along with stormwater harvesting, vi) centralized along with greywater tanks and stormwater harvesting and vii) centralized along with rainwater harvesting and recycled water. The water, wastewater and stormwater flows and associated wastewater and stormwater quality parameters (TSS-Total Suspended Solids, TN-Total Nitrogen, TP-Total Phosphorous, BOD-Biochemical Oxygen Demand, COD-Chemical Oxygen Demand,) are modelled under various scenarios. The results are utilized to comparatively evaluate the impacts of different hybrid water supply options on stormwater and wastewater flows as well as contaminant loads. The study provides insights by quantifying the relative benefits and challenges of a series of strategies before implementation. Further, the quantification of flow and contaminants provided by this paper could help operationalize the better integration of hybrid systems by identifying risks associated with contaminant loads, and thus could inform improved sewerage and drainage design, operation and maintenance planning.

This research proposes a novel generic method for irrigation scheduling in a canal network to optimize multiple objectives related to canal scheduling (e.g. maximizing water supply and minimizing imbalance of water distribution) within multiple hierarchical layers (e.g. the layers consisting of the main canal, distributaries) while utilizing traditional canal scheduling methods. It is based on modularizing the optimization process. The method is theoretically capable of optimizing an unlimited number of user-defined objectives within an unlimited number of hierarchical layers and only limited by resource availability (e.g. maximum canal capacity and water limitations) in the network. It allows flexible decision-making through quantification of the mutual effects of optimizing conflicting objectives and is adaptable to available multi-objective evolutionary algorithms. The method’s application is demonstrated using a hypothetical canal network example with six objectives and three hierarchical layers, and a real scenario with four objectives and two layers.

Detailed prediction of end-use water demand at multiple spatial and temporal scales is essential for planning urban water supply using multiple water sources based on fit-for-purpose criteria. This paper presents the application of a stochastic model to predict urban residential end-use water demands at multiple spatial and temporal scales. The model includes an improved representation of spatial and temporal variability of urban residential water use by considering the effect of a significant number of water demand drivers such as household size, dwelling type, appliance efficiency, availability of water end-uses/appliances at dwellings, presence of children, presence of people at home, diurnal behavioral patterns and temperature. A stochastic approach is used to describe the variability of residential water demand that is not captured by these known explanatory variables. The model is validated against quarterly meter readings and hourly water use data. The validation of household water demand at a quarterly scale with billing data shows Correlation coefficients (R2) ranging between 90% and 96% and Nash-Sutcliffe coefficients ranging between 0.70 and 0.92 for the four seasons analyzed which, verifies the predictive capacity of the model. The model validation also demonstrates the statistical stability of the selected probability distributions used in modeling the unexplained behavior of urban residential water consumers. The hourly scale validation also demonstrates a satisfactory predictive capacity in predicting household water demand. This also evidences the effectiveness of the modeling approach to predict urban residential water demand at multiple temporal scales.

Detailed prediction of water demand by their end-uses at multiple scales is essential to support planning of Integrated Urban Water Management, an increasingly applied approach to deal with the problem of water scarcity. This paper presents an urban residential water demand modeling framework that can predict end-use water demand at multiple scales, especially at small scales with a robust explanatory capacity. This is achieved by integrating the complex water demand dynamics of urban residential water use and their underlying variables into a single model. The model described in this study can predict shower, toilet, tap, dishwasher, clothes washer, irrigation, evaporative cooler, bath, and other uses which account for the entire household water use. The model aims to predict water demand at multiple spatial (household/cluster/suburb) and temporal scales (hourly, daily, weekly and seasonal) by considering behavioral differences triggered by factors such as seasonality and presence of people at home. The model incorporates an improved representation of spatial variability by considering behavioral differences between customer groups, and improves the capability to deal with areas with different demographic and housing characteristics. This research confirms the capacity of stochastic modeling methods to represent unexplained behavior of water consumers.

A survey of 77 water practitioners within Melbourne, Australia, highlighted the lack of objectiveness within current risk scoring processes. Each water authority adopted similar processes, all of which adhere to the ISO31000 standard on Risk Management, and these were tested within this study to determine the &ldquo, objective&rdquo, nature of technical risk assessments such as these. The outcome of the study indicated that current risk measurement approaches cannot be seen as objective. This is due to the high variation in risk scores between individuals, which indicates a level of subjectivity. The study confirms previous research that has been undertaken in assessing the effectiveness of risk matrices. This research is novel in its testing of the water sector&rsquo, s risk measuring practices and may be of value to other industries that utilize similar risk approaches. This research posits whether this subjectivity is due to inherent bias of either a psychological or cultural risk nature that could produce the varied scores.

Increasing water reliability in a catchment requires reducing the total quantity of water available to users in some years in order to supply it in more years when its supply is constrained. Thus, the more reliable the supply the more water that needs to be withheld. Consequently, increased levels of water reliability to a catchment, which reduces the costs associated with an unreliable supply, often comes at an incremental increase in costs that researchers do not consider; that of the water foregone that could be have been used productively if the system had been run less reliably. In this paper the trade-offs between the costs of water foregone to maintain a level of reliability and the costs associated with an unreliable supply of water at different levels of reliability in an irrigation system are discussed. The concepts developed are applied to the irrigation sector in the Musi catchment in Andhra Pradesh, India from 2011 to 2040. In this catchment it was found that the costs of water foregone to increase reliability rise as the level of reliability rises, while the benefits generally fall. When the level of reliability exceeded approximately 85% (where water is so scarce that it is used on only the most valuable output), the costs of greater reliability exceed the benefits resulting in net losses to the system. These results were found to vary in each demand centre across the catchment. These results have implications for those considering innovations that improve the level of reliability in a catchment.

This research proposes A THEORETICAL FRAMEWORK based on model predictive control (MPC) for irrigation control to minimize both root zone soil moisture deficit (RZSMD) and irrigation amount under a limited water supply. We (i) investigate means to incorporate direct measurements to MPC (ii) introduce two Robust MPC techniques - Certainty Equivalence control (CE) and Disturbance Affine Feedback Control (DA) - to mitigate the uncertainty of weather forecasts, and (iii) provide conditions to obtain two important theoretical aspects of MPC - feasibility and stability - in the context of irrigation control. Our results show that system identification enables automation while incorporating direct measurements. Both DA and CE minimize RZSMD and irrigation amount under uncertain weather forecasts and always maintain soil moisture above wilting point subject to water availability. The theoretical results are compared against the model AQUACROP, weather data and forecasts from Shepparton, Australia. We also discuss the performance of Robust MPC under different water availability, soil, crop conditions. In general, MPC shows to be a promising tool for irrigation control. MPC is used to minimize both root zone soil moisture deficit and irrigation amount.System identification incorporates direct measurements to MPC enabling automation.Uncertainty in weather forecasts is mitigated using two modified Robust MPC approaches.Optimal operation can be guaranteed through the proposed method.Guaranteed operation above wilting point at all times subject to water availability.

In model-based irrigation control, the root zone soil moisture deficit (RZSMD) is maintained based on the water balance. To predict RZSMD in real-time, effective rainfall, irrigation and crop evapotranspiration need to be calculated online. Estimating the first two variables is more important yet tedious due to practical limitations of knowing the amount of water actually infiltrated into the soil. In order to solve this problem, we propose to apply system identification on water balance data to obtain a linear time series model. We further investigate how to carry out the modelling (i) under saturated conditions, (ii) when there is a rule-based irrigation control, and (iii) under measurement noise in the soil moisture readings. Using synthetic data we obtained a model fit above 80% in all cases. Additionally, we show the model optimality and applicability with an independent dataset, using residual tests. For two sets of field data, we observed model fits of 84% and 63%, and satisfaction in all residual tests. Simplicity in the model reduces calibration efforts whereas its linearity and adequacy recommend it for real-time irrigation control applications. In summary, the results indicate that a first order linear time series model based on system identification can successfully predict RZSMD in a real-time irrigation control system.

Rice is one of the major crops cultivated predominantly in flooded paddies, thus a large amount of water is consumed during its growing season. Accurate paddy rice maps are therefore important inputs for improved estimates of actual evapotranspiration in the agricultural landscape. The main objective of this study was to obtain flooded paddy rice maps using multi-temporal images of Moderate Resolution Imaging Spectroradiometer (MODIS) in the Krishna River Basin, India. First, ground-based spectral samples collected by a field spectroradiometer, CROPSCAN, were used to demonstrate unique contrasts between the Normalized Difference Vegetation Index (NDVI) and the Land Surface Water Index (LSWI) observed during the transplanting season of rice. The contrast between Enhanced Vegetation Index (EVI) and Land Surface Water Index (LSWI) from MODIS time series data was then used to generate classification decision rules to map flooded rice paddies, for the transplanting seasons of Kharif and Rabi rice crops in the Krishna River Basin. Consistent with ground spectral observations, the relationship of the MODIS EVI vs. LSWI of paddy rice fields showed distinct features from other crops during the transplanting seasons. The MODIS-derived maps were validated against extensive reference data collected from multiple land use field surveys. The accuracy of the paddy rice maps, when determined using field plot data, was approximately 78%. The MODIS-derived rice crop areas were also compared with the areas reported by Department of Agriculture (DOA), Government of India (Government Statistics). The estimated root mean square difference (RMSD) of rice area estimated using MODIS and those reported by the Department of Agriculture over 10 districts varied between 3.4% and 6.6% during 10 years of our study period. Some of the major factors responsible for this difference include high noise of the MODIS images during the prolonged monsoon seasons (typically June–October) and the coarse spatial resolution (500 m) of the MODIS images compared to the small crop fields in the basin. However, this study demonstrates, based on multi-year analysis, that MODIS images can still provide robust and consistent flooded paddy rice extent and areas over a highly heterogeneous large river basin.

This study presents a comprehensive review of the literature on implementation of various decentralized water systems along with centralized systems. The review highlights the benefits provided by these systems as well as various challenges posed associated with them. There are complex interactions involved within the water systems in an urban setting that are multidimensional and span over various aspects of water availability, quality, energy use, environmental, legal, economic, and social sectors. Although there are many economic, environmental, and social benefits associated with decentralized systems, there are some hidden challenges that are generally overlooked by planners and managers; these include the spatial integration of such systems, their energy intensity, social, economic, and environmental viability of these systems. Decisions to implement decentralized water systems require decision makers to consider economic, social, and environmental dimensions conjointly through an appropriate multicriteria decision analysis to select the hybrid water supply combination optimal for the given circumstances. The existing studies and tools are unable to address these factors using an integrated approach. So a holistic framework to evaluate and compare various water supply options in terms of energy use, social, economic, and environmental impacts is required to assess such systems in comprehensive manner. For further resources related to this article, please visit the WIREs website. Conflict of interest: The authors have declared no conflicts of interest for this article.

The reliance on groundwater for irrigation is increasing in Australia and India, which is causing concerns to policy makers about energy consumption and greenhouse gas (GHG) emissions. Therefore, it is important to quantify the GHG emissions of all components of the groundwater-based irrigation systems, over the entire life cycle to develop more environmentally friendly groundwater management strategies. This study identified and analysed energy use and GHG emissions associated with different components in the supply chain of groundwater-based irrigation systems. An existing GHG emissions and energy-accounting framework was adapted to enhance its capabilities by considering drilling techniques, water distribution and irrigation application methods. The results of this study highlighted that embodied and direct GHG emissions from drilling tube wells were higher in the Musi catchment, India, compared to South Australia. The study also highlighted that GHG emissions associated with water conveyance were higher for concrete and plastic-lined channels than unlined channels. Drip irrigation systems in both countries were found to have more GHG emissions than gravity-fed systems. Centre pivot systems were found to be emitting more than the drip systems in South Australia. We conclude that different components of the system have an impact on total GHG emissions and energy consumption for both countries. Any change in the most commonly used methods of drilling bore wells, water distribution in channels, and the irrigation methods, will have distinct impacts on energy consumption rates and GHG emissions. The developed conceptual framework provided a systematic complete analysis of the energy-consuming and GHG-emitting components associated with groundwater-based irrigation systems. Policy makers and decision makers may use the developed framework to compare different system components to develop strategies that have minimal impact on the environment. Copyright © 2015 John Wiley & Sons, Ltd. Resume Le recours a des eaux souterraines pour l'irrigation est en augmentation en Australie et en Inde, ce qui preoccupe les decideurs politiques sur la consommation d'energie et la production de gaz a effet de serre (GES). Par consequent, il est important de quantifier les emissions de GES de toutes les composantes des systemes d'irrigation base sur les eaux souterraines, sur le cycle de vie complet afin d'elaborer des strategies de gestion des eaux souterraines plus respectueuses de l'environnement. Cette etude a identifie et analyse la consommation d'energie et les emissions de GES associees aux differentes composantes de la filiere et de l'irrigation a base d'eaux souterraines. Un systeme de comptabilite des emissions reelles de GES et de l'energie a ete adapte pour renforcer leurs capacites en tenant compte des techniques de forage, de la distribution de l'eau et des methodes d'application de l'irrigation. Les resultats de cette etude ont mis en evidence que les emissions grises et directes de GES pendant le forage des puits ont ete plus elevees dans le bassin versant de Musi en Inde par rapport a ceux d'Australie du Sud. L'etude a egalement souligne que les emissions de GES liees a l'adduction d'eau etaient plus elevees pour les canaux revetus de beton ou doubles de plastique que les canaux non revetus. Les systemes d'irrigation goutte a goutte dans les deux pays emettent plus de GES que les systemes d'alimentation par gravite. Les systemes a pivot central emettent plus que les systemes de goutte a goutte en Australie du Sud. Nous concluons que les differentes composantes du systeme ont un impact sur les emissions totales de GES et la consommation d'energie pour les deux pays. Tout changement dans les methodes les plus couramment utilisees pour la realisation des puits de forage, la distribution de l'eau dans les canaux et les methodes d'irrigation, aura des effets distincts sur les taux de consommation d'energie et les emissions de GES. Le cadre conceptuel elabore permet l'analyse complete et systematique de la consommatrice d'energie et de composants emetteurs de GES associes a des systemes d'irrigation bases sur les eaux souterraines. Les decideurs et les gestionnaires peuvent utiliser le cadre elabore pour comparer les differentes composantes du systeme a developper des strategies qui ont un impact minimal sur l'environnement. Copyright © 2015 John Wiley & Sons, Ltd.

Dairy farmers in the southern Murray–Darling (M–DB) of Australia are considering subsurface drip irrigation (SDI) for pasture production in response to reduced water supply. Use of SDI in pasture production is a significant departure from previous SDI knowledge because in pasture irrigation (1) uniform moisture, nutrients and pasture growth is sought across the full paddock width, (2) the pasture is grazed by dairy cattle, and (3) is grown on duplex soils with distinctive hydraulic behaviour. A field experiment was conducted on two dairy farms with contrasting subsoil hydraulic characteristics to investigate the impact of SDI design (tape spacing) and operation (irrigation frequency) on pasture productivity and hydrology under grazed conditions. Treatments comprising of tape spacing (0.6, 1.0 and 1.4 m) and irrigation frequency (D or 4D) were imposed. SDI successfully supported contiguous perennial pasture under grazing during a period of drought. The impact of SDI design and operation on pasture accumulation and its spatial variability differed strongly between sites, reflecting soil hydraulic characteristics. Pasture composition and irrigation efficiency were insensitive to SDI design and operation at both sites. Water balance analysis indicated that deep percolation was the main pathway for water loss in SDI pasture production, though the dominance of this over surface runoff will be influenced by soil hydraulic properties. SDI can support grazed pasture production on the duplex soils of the southern M–DB; however, its performance may be insufficient to offset the high economic cost of SDI technology.

Water demand prediction by end-use at an appropriate spatial and temporal resolution is essential for planning water supply systems that will supply water from a diversified set of sources on a fit-for-purpose basis. Understanding seasonal, daily and sub-daily water demand including peak demand by end-uses is an essential planning requirement to implement a fit-for-purpose water supply strategy. Studies in the literature assume that all indoor water uses except evaporative cooler water use are weather independent and do not exhibit seasonal variability. This paper presents an analysis undertaken to examine seasonal variability of residential water end-uses. The analysis was repeated using two sets of data to ensure the validity of findings. The study shows that shower water use is significantly different between winter and summer, in addition to irrigation, evaporative cooler and pool water end-uses, while other water end-uses are not. Weather is shown to be a significant determinant of shower water use, in particular it affects shower duration which increases with lower temperature. Further analysis on shower water use suggests that it is driven by behavioural factors in addition to weather, thus providing useful insights to improve detailed end-use water demand predictions.

This paper presents a critical review of the physical impacts of decentralized water supply systems on existing centralized water infrastructures. This paper highlights the combination of centralized and decentralized systems, which is referred to as hybrid water supply systems. The system is hypothesized to generate more sustainable and resilient urban water systems. The basic concept is to use decentralized water supply options such as rainwater tanks, storm water harvesting and localized wastewater treatment and reuse in combination with centralized systems. Currently the impact of hybrid water supply technologies on the operational performance of the downstream infrastructure and existing treatment processes is yet to be known. The paper identifies a number of significant research gaps related to interactions between centralized and decentralized urban water services. It indicates that an improved understanding of the interaction between these systems is expected to provide a better integration of hybrid systems by improved sewerage and drainage design, as well as facilitate operation and maintenance planning. The paper also highlights the need for a framework to better understand the interaction between different components of hybrid water supply systems.

In India the stresses on water resource systems have increased, due in part to increased demand for scarce water supplies. Yet, what could be of greater concern is the potential long-run threats of climate change affecting supplies. Before thinking of a policy response to these long-run concerns, the impact of climate change on the reliability of water supply across a catchment needs to be gauged from both a physical and an economic perspective. Once these impacts are known, a more target approach to policy can be formulated. The aim in this research is to briefly present and comment on the results of an assessment of some these dynamic interacting forces across the Musi catchment in India. Of primary interest are the impacts of three different climate variants over the next 30 years have on the reliability of water supply (at the 70, 80 and 90% levels) across seven different agricultural zones in the Musi catchment in India. A hydro-economic modelling effort underlies these results (see Davidson et al forthcoming) which draws on a hydrologic analysis based on the Hadley climate model to model the surface and ground water in the catchment. This model then provides inputs into an allocation model (REALM), to assess the amount of water reliably supplied to different zones in the Musi catchment at different levels of reliability. These flows are ultimately valued to determine the economic consequences of different climate scenarios. In this study, the results are reported for four dryland regions (zones 1 to 4), an irrigation region (Musi Medium,) and two river diverters (the Musi Anicut and the Wastewater irrigation system). Unsurprisingly, from a physical perspective the region's most greatly affected are those heavily dependent on dryland agriculture, especially near Hyderabad City. This region is where the high value products (such as vegetables) are produced. These results imply that some caution should be exercised in choosing policies that allow for the adaptation of climate change, especially in the dryland zones.

This study investigates the variability of household water use in Melbourne with the aim of improving the current understanding of factors affecting residential water use. This understanding is critical to predicting household water demand, particularly at an appropriate spatial and temporal resolution to support Integrated Urban Water Management based planning and to improve the understanding on how different household water demands respond to demand management strategies. The study used two sets of data each collected from 837 households under significantly different water use conditions in the years 2003 and 2011. Data from each household consist of the household characteristics and quarterly metre readings. Ordinary Least Square regression analysis followed by detailed analysis of each factor was used to identify key factors affecting household water use. The variables studied are household size, typology of dwelling, appliance efficiency, presence of children under 12 years, presence of children aged between 12 and 18 years, tenancy, dwelling age, presence of swimming pool, evaporative cooler, and dishwasher. All of them except presence of children aged between 12 and 18 years, tenancy and dwelling age were identified as variables that contribute to the variability of household water use in Melbourne. The study also found that the explanatory capacity of these variables increases with decreasing water use. This paper also discusses the significance of the explanatory variables, their impact and how they vary over the seasons and years. The variables found in this study can be used to inform improved prediction and modelling of residential water demand. The paper also explores other possible drivers to explain residential water use in light of the moderate explanatory capacity of the variables selected for this study thus, provides useful insights into future research into water demand modelling.

A commonly accepted paradigm in environmental flow management is that a regulated river flow regime should mimic the natural hydrological regime to sustain the key attributes of freshwater ecosystems. Estimation of the environmental risk arising from flow regulation needs to consider all aspects of the flow regime when applied to water allocation decisions. We present a holistic, dynamic and robust approach that is based on a statistical analysis of the entire flow regime and accounts for flow stress indicators to produce an environmental risk time series based on the consequence of departures from the optimum flow range of a river or reach. When applied to a catchment, (Campaspe River, southern Australia) the model produced a dynamic and robust environmental risk time series that clearly showed that when the observed river flow is drawn away from the optimum range of environmental flow demand, the environmental risk increased. In addition, the model produced risk time series showing that the Campaspe River has reversed seasonal patterns of river flow due to water releases during summer periods, which altered the flow nature of the river. Hence, this resulted in higher environmental risk occurring during summer but lower in winter periods. Furthermore, we found that the vulnerability and coefficient of variation indices have the highest contributions to consequence in comparison to other indices used to calculate environmental risk.

Water supply and wastewater services incur a large amount of energy and GHG emissions. It is therefore imperative to understand the link between water and energy as their availability and demand are closely interrelated. This paper presents a literature review and assessment of knowledge gaps related to water–energy–greenhouse gas (GHG) nexus studies in an urban context from an ‘energy for water’ perspective. The review comprehensively surveyed various studies undertaken in various regions of the world and focusing on individual or multiple subsystems of an urban water system. The paper also analyses the energy intensity of decentralized water systems and various water end-uses together with the major tools and models used. A major gap identified from this review is the lack of a holistic and systematic framework to capture the dynamics of multiple water–energy–GHG linkages in an integrated urban water system where centralized and decentralized water systems are combined to meet increased water demand. Other knowledge gaps identified are the absence of studies, peer reviewed papers, data and information on water–energy interactions while adopting a ‘fit for purpose water strategy’ for water supply. Finally, based on this review, we propose a water–energy nexus framework to investigate ‘fit-for-purpose’ water strategy.

Modelling offers a time efficient and cost-effective approach to integrate and analyse different components of complex peri-urban hydroecological systems. This paper evaluates and applies a catchment water balance model (Peri-Urban SimHyd) developed to simulate the complete water cycle of the South Creek catchment, a complex peri-urban catchment in Western Sydney (Australia). Peri-Urban SimHyd combined the modelling of daily rainfall-runoff from both impervious and pervious surfaces with the modelling of monthly reticulated potable water supply, wastewater flows, and surface and groundwater extractions, to simulate the monthly water balance of the catchment. The model was successful (the Nash-Sutcliffe efficiency >0.68) in simulating the monthly total wastewater discharges and streamflows in the South Creek and its main tributary, the Eastern Creek, over a period of 15 years (1992–2006). The model performance was found to be suitable for simulating macro water balance and catchment yield but not for low streamflow hydrographs. Further, the model demonstrated its applicability in assessing the impacts of water cycle management strategies, i.e. ‘replacement flows’ and ‘water smart farms’ scenarios, on monthly and annual streamflows in the South Creek catchment. In general, Peri-Urban SimHyd has a generic structure and can be employed to assess impacts of various ‘what if’ scenarios on water cycle and streamflows in other peri-urban hydroecological systems.

Summary The aim in this paper is to assess the hydrological and economic impacts of deploying water in the political jurisdictions of the peri-urban South Creek catchment of Western Sydney. This catchment has been identified as the region in which the city of Sydney will grow into in the future, with a plan to move an extra one million people into the catchment in the next 25–30 years. In conjunction with this expansion, a plan exists to augment the existing water supply by treating waste water effluent, harvesting stormwater and improving irrigation efficiency, along with a strategy for saving water on farms. Water in this catchment is operated by and in the interests of society, where decisions on its allocation have a political perspective to them. However, the growth within this catchment and the water augmentation strategies are not split evenly amongst the political entities within this catchment, namely the Local Government Authorities. An integrated hydro-economic model segregated according to the political entities in the catchment is used in this study to address a range of water saving scenarios raised by stakeholders. The trade-offs inherent in all water allocation decisions on a regional basis are made transparent in this model and its political ramifications, defined as the impacts on different political regions, are identified. In analysing the measures designed to save water across the catchment, none resulted in a positive Net Present Value. Even just expanding the system to accommodate one million extra people resulted in significant economic losses. In addition, the impact of each measure in each political region was markedly different. The purpose of this study is to provide stakeholders in individual local government regions with evidence of the costs and impacts of rational decisions to change the management of water resources in South Creek catchment.

Irrigation underpins agricultural productivity. The purpose of irrigation is to match water supply to crop water demand. The effectiveness of irrigation depends on the quality of the timing and duration of watering events, also called irrigation scheduling. Most farmers use heuristic rules to determine irrigation events. This often leads to over-watering which results in lower crop yields and wasted water. By acquiring good estimates of a plant's water demand and local weather, it is possible to use optimization theory to compute an irrigation schedule that matches supply and demand thereby improving crop yields. Previous work has focused on scheduling irrigation over long time frames such as seasonal water allocations. Real-time irrigation scheduling, e.g. hourly or daily, has received little attention. Farmers rely on heuristic approaches implemented using simple spreadsheet tools to help them in this task. This approach cannot deal effectively with operational constraints and thereby results in poor performance. In this paper we develop a Model Predictive Control framework for real-time irrigation scheduling. The proposed formulation can take into account common operational constraints, including limitations on water availability as well as practical limits on the maximum or minimum amount of water that should be applied. We use measured climate data coupled with a simulation model to evaluate the proposed algorithm.

Summary In this paper an integrated model of the hydrological and economic impacts of deploying water within the political divisions in the South Creek catchment of the ‘peri-urban’ region of Western Sydney is presented. This model enables an assessment of the hydrological and economic merits of different water allocation-substitution strategies, both over the whole catchment and in each political region and jurisdiction within it, to be undertaken. Not only are the differences in the water allocated to each region and use revealed, but also the net present values associated with each use within each region. In addition, it is possible to determine measures of equity in water distribution using this approach. It was found that over a period from 2008 to 2031 the South Creek catchment in total would on average use approximately 50,600 ML of potable water a year, the vast majority of this is used in the two urban regions of Penrith and Blacktown. Agricultural water use was also greatest in these two regions. Over this period the allocation system was estimated to have a small net present value of approximately $A301 million and the Benefit-Cost ratio was estimated to be 1.06. The urban regions of Penrith and Blacktown and the rural region of Hawkesbury were estimated to have returned a net positive benefit of $A76 million, $A246 million and $A39 million (respectively), while water to Liverpool and Camden was delivered at a loss of $A7 million and $A52 million over the period assessed. It was found that across the catchment a fair degree of both physical and economic equity occurred between regions, with the exception of Liverpool, which was over endowed with water and paid a high cost for it.

In China, the allocation of water rights in river basins is customarily determined by annual mean volumes of water resources. However, seasonal variability of water availability should be considered for an effective and flexible allocation policy. This paper summarizes a framework for seasonal water allocation. It proposes a modified rule for seasonal water allocation on the basis of the traditional rule used in China and introduces a risk analysis model to assess the performance improvement of the proposed rule when dealing with hydrologic variability in the context of a water rights system. The framework and models were applied to the Shiyang River Basin, Gansu Province, China, and they indicated that seasonally allocated water under the modified rule is more stable and has a lower risk for water use than a rule based on annual mean volumes. This leads to more reliable supplies over the seasons and could provide an effective method for water rights operation in the Shiyang River Basin. It also p...

This paper presents a novel approach to real time automatic flood control in a managed river network that is subject to uncertain inflows. The proposed approach uses multiple models to represent inflows ranging from low to high flow. Optimal model selection is achieved in a minimum mean square error sense using a bank of Kalman filters to identify the most likely inflow characteristic. There are no a-priori probabilities assigned to the individual models. Model Predictive Control is used for water level controller design. Our Adaptive Multi Model Predictive Control (AMMPC) method is proposed as an alternative to existing techniques that also use multiple inflow models but with a-priori inflow model probabilities, either weighted or equally likely. The performance of the approach is demonstrated using a simulated river-reservoir model as well as using data collected at the Wivenhoe Dam during the 2011 floods in Queensland, Australia.

Designing sustainable urban development is a multi-dimensional and multi-disciplinary challenge that can benefit from next-generation modelling tools to achieve high performance outcomes and integrated assessments. This chapter presents and demonstrates the use of ‘MUtopia’, an information modelling platform for assessing alternative urban development scenarios. The use of the platform is illustrated through the application to a peri-urban development in the city of Melbourne, Australia. The modelling platform allows simulation of various transition and future scenarios at the precinct level. The platform is capable of extracting data to assist in developing and assessing the performance of different components (land use, individual buildings and infrastructure related to energy and water supply and use, waste management and transport systems) by taking advantage of the platform’s unique scalability. The selected case study is a 31.5 ha Parcel of land, a typical peri-urban development in Melbourne’s fringe located in West Cranbourne. A key aspect of the development is the design of a sustainable precinct that is affordable, provides a greater level of amenity and incorporates biolink corridors and natural open spaces critical to the preservation of native biodiversity. As a low rise suburban development this project presents a unique opportunity for the application of the MUtopia platform and to demonstrate how the tool can lead to optimum design parameters for achieving sustainable development. This chapter also describes how MUtopia can be used to optimise the selection and design of sustainable and resilient energy, water and waste infrastructure and its integration with existing infrastructure.

Changes in energy subsidies for Indian agriculture and the introduction of a carbon tax in Australia have the potential to impact on energy use practices in groundwater-irrigated agriculture in both countries. A general framework for the accounting of life cycle greenhouse gas emissions and life cycle energy consumption from groundwater-irrigated agriculture was developed using life cycle and supply chain analyses to examine the contributing aspects of groundwater irrigation to total associated greenhouse gas emissions and energy use. The framework then formed the basis of a greenhouse gas emission and energy accounting model that was simulated for the groundwater- dependent agricultural areas of the Musi catchment in India and the south-east region of South Australia. The region in South Australia was found to be emitting around twice the greenhouse gas of the Indian region per unit volume of water delivered, while emissions associated with operating electricity powered water pumps contributed more than 99.8% of modelled emissions in the south-east of South Australia and over 99.1% of emissions in the Musi catchment. Diesel powered water pump irrigation systems emitted the least total amount of greenhouse gas emissions per unit volume of water supplied, compared to grid electricity and diesel generator powered submersible water pump options. Copyright © 2012 John Wiley & Sons, Ltd. RESUME Les changements dans les subventions energetiques pour l'agriculture indienne et l'introduction d'une taxe carbone en Australie peuvent potentiellement impacter les pratiques d'utilisation de l'energie pour l'agriculture irriguee a partir des eaux souterraines, ceci dans les deux pays. Nous avons developpe un cadre general pour comptabiliser le cycle de vie des gaz a effets de serre et le cycle de vie de la consommation energetique de l'agriculture irriguee par des eaux souterraines. Pour cela nous avons analyse les cycles de vie dans la filiere de l'irrigation par des eaux souterraines en faisant ressortir les aspects qui contribuent au total des emissions de gaz a effet de serre et de consommation energetique. Ce cadre a forme la base d'un modele de comptabilite d'emission de gaz a effet de serre et de consommation energetique qui a ete applique a deux zones agricoles dependant des nappes souterraines, a savoir le bassin versant de Musi en Inde et la region sud-est de l'Australie du Sud. La region en Australie du Sud a ete jugee emettant environ deux fois plus de gaz a effet de serre que la region indienne par unite de volume d'eau livre, alors que les emissions associees au fonctionnement des pompes electriques representent plus de 99.8% des emissions modelisees dans le cas australien, et plus 99.1% des emissions dans le cas indien. Les pompes a moteur diesel ont emis la plus faible quantite totale des emissions de gaz a effet de serre par unite de volume d'eau fournie que les pompes immergees alimentees par le reseau ou des generateurs diesel (dans cet ordre). Copyright © 2012 John Wiley & Sons, Ltd.

Urban water managers around the world are adopting decentralized water supply systems, often in combination with centralized systems. While increasing demand for water arising from population growth is one of the primary reasons for this increased adoption of alternative technologies, factors such as climate change, increased frequency of extreme weather events and rapid urbanization also contribute to an increased rate of adoption of these technologies. This combination of centralized-decentralized water systems approach is referred to as “hybrid water supply systems” and is based on the premise that the provision of alternative water sources at local scales can both extend the capacity of existing centralized water supply infrastructures, and improve resilience to variable climatic conditions. It is important to understand, however, that decentralized water production and reuse may change the flow and composition of wastewater and stormwater, thereby potentially also having negative impacts on its effectiveness and performance. This paper describes a framework to assess the interactions between decentralized water supply systems and existing centralized water servicing approaches using several analytical tools, including water balance modelling, contaminant balance modelling and multi-criteria decision analysis. The framework enables the evaluation of impacts due to change in quantity and quality of wastewater and stormwater on the existing centralized system arising from the implementation of hybrid water supply systems. The framework consists of two parts: (1) Physical system analysis for various potential scenarios and (2) Ranking of Scenarios. This paper includes the demonstration of the first part of the framework for an area of Melbourne, Australia by comparing centralized water supply scenario with a combination of centralized water supply and reuse of treated waste water supply scenario.

Border-check irrigation is the predominant method of applying water to dairy pastures in Australia. Dairy pastures consume 40% of total irrigation water in Australia and, with irrigation water security in Australia under threat from climate variability/change and rising demands from other users, socio-economic pressure for water savings in the dairying sector are increasing. Currently, there are no simulation tools that successfully link factors controlling irrigation efficiency at the within-bay scale to management factors that drive economic water productivity (principally pasture growth, pasture consumption and animal production). A simulation framework was developed to connect a biophysical research model of weather-soil-plant animal interaction in dairy systems ('DairyMod') to a surface irrigation hydraulic model, SRFR (Simulation of basin, border and furrow irrigations). The connection enabled simulation of the effects of border-check irrigation scheduling and event management on irrigated pasture production systems. Modifications were made to DairyMod, in which the paddock surface was represented as a point, so that it could accommodate infiltration data in a one-dimensional form, from the surface irrigation model SRFR. Multiple simulations of DairyMod were run each representing different discrete spatial zones within an irrigation bay, and the SRFR routines connect each discrete spatial zone with information on the advance front water depth. Model integration and the workings of the integrated model are described, and the process used to verify the integrity of the data transferred between the two models is presented. Comparisons of data input and output parameters from the stand-alone models and the integrated model confirmed that the data transfer between the models within the integrated framework did not introduce new sources of errors. Preliminary output for a scenario involving three irrigation durations is also presented. The scenario represented a perennial ryegrass based pasture on a texture contrast clay loam soil over a period of 10 years using measured climate data. Model predictions agreed well with data reported in the literature for annual irrigation amounts and pasture growth. It was demonstrated that the integrated model could be used effectively to determine how pasture production varied with changes in irrigation management such as irrigation duration. A limitation of the integrated model was its dependence on two sets of infiltration models that were difficult to relate to each other.

There are pressures on existing centralized water infrastructures in urban centers which justify the search for alternatives. An increasingly important alternative is to shift from centralized to hybrid systems, often in response to climate variability and demographic changes. In a hybrid system, water is supplied and discharged through a mix of centralized and decentralized systems. There is usually no single objective that justifies the choice of hybrid water systems, but they typically are justified based on the consideration of a number of different criteria in order to evaluate the overall quality of service provision. The most important criteria include meeting water demand, as well as reducing demand for fresh water and instead using local alternative water supplies. Integration of multiple objectives to evaluate the hybrid water supply systems can be accomplished by multi-criteria decision aid techniques. This paper evaluates a number of hybrid water supply scenarios using a case study based on the Northern Growth Area of Melbourne, Australia. It uses the Preference Ranking Organization METHod for Enrichment Evaluations (PROMETHEE) and Geometrical Analysis for Interactive Decision Aid (GAIA), one of the multi-criteria decision-making methods through D-Sight software, to rank the hybrid water supply scenarios, and this ranking is validated by means of sensitivity analysis. The centralized system combined with stormwater harvesting and the centralized system combined with treated wastewater and rainwater tanks yielded the first and second most preferred scenarios, while the centralized water supply system combined with treated wastewater yielded the worst hybrid water supply option.

Many water resource investigations require an estimate of evaporation from water supply reservoirs. Despite its recognised limitations, the pan coefficient method for estimating reservoir evaporation is widely used in industry due to its moderate data requirements. This paper presents a framework to quantify the uncertainties associated with estimates of reservoir evaporation generated using the pan coefficient method. The uncertainties associated with each of the inputs are quantified using a combination of statistical techniques, including Bayesian statistics and subjective judgement; before being combined using Monte Carlo simulation. The framework is applied to three reservoirs in the Werribee River catchment, Australia. The 95% probability intervals surrounding the estimates of reservoir evaporation are as large as ±40% of the best estimate. The largest contributing factor to uncertainty is shown to be the estimation of pan evaporation at reservoirs without a climate station, followed by the uncertainty surrounding the annual pan coefficient itself. The assessment shows that the largest reductions in uncertainty can be achieved by installing an evaporation pan at the reservoir.

Human interventions often lead to unsustainable river systems. There is always a trade-off between level of socio-economic gains from consumptive use in the river system and the need to maintain the natural seasonality of river flows supporting the ecosystem function. In the case of the Murrumbidgee River, Australia, irrigation demand is concentrated in the summer season while natural inflows to the river occur during the winter season. The summer-dominated irrigation water demand has created environmental and supply problems by altering the natural flow regime. This paper presents a hydrologic assessment of a range of irrigation demand management options for improving the natural seasonality of the river flow. Among the possible alternatives, change of cropping pattern by achieving a better mix of summer and winter crops is recommended as the most feasible alternative, which can also save up to 211 million m3 of water yearly. This water can then be released during the winter time to augment the environmental flows of the river. Other irrigation demand management options explored in this paper include aquifer storage and recovery, on-farm and off-farm water savings and construction of intermediate surface water storages. Copyright © 2008 John Wiley & Sons, Ltd.

Significant increases in water diversion for irrigation and other uses have taken place worldwide throughout the twentieth century, often with negative consequences for environmental sustainability. In this paper a framework which can be used to undertake an assessment of this trade-off problem is presented. The framework aims to achieve a balance between water extractions for irrigation and other uses and environmental demand. It involves, among many factors, an understanding of the hydrological, environmental, economic and social consequences of diverting water. The research component of the framework comprises three key elements: water cycle analysis, economic analysis and social analysis. At the core of the water cycle analysis is the characterisation of the water stocks and flows in the systems and a modelling framework to analyse system responses to water-sharing policies and trade-offs between extractive and environmental uses. The economic analysis focuses on the valuation of water allocated to each use including the environment, whilst the social analysis is centred on the relative values used to balance water extractions for society's needs and the environment. This framework is illustrated with examples from the Krishna Basin in India and the Murray– Darling Basin in Australia. Copyright © 2009 John Wiley & Sons, Ltd.

Temporary water trading is an established and growing phenomenon in the Australian irrigation sector. However, decision support and planning tools that incorporate economic and biophysical factors associated with temporary water trading are lacking. In this paper the integration of an economic trading model with a hydrologic water allocation model is discussed. The integrated model is used to estimate the impacts of temporary water trading and physical water transfers. The model can incorporate economic and biophysical drivers of water trading. The economic model incorporates the key trade drivers of commodity prices, seasonal water allocations and irrigation deliveries. The hydrologic model is based on the Resource Allocation Model (REALM) framework, which facilitates hydrologic network simulation modelling. It incorporates water delivery system properties and operating rules for the main irrigation and urban centres in a study area. The proposed integration method has been applied to a case study area in northern Victoria, Australia. Simulations were conducted for wet and dry spells, a range of commodity prices and different irrigation distribution system configurations. Some example analyses of scenarios incorporating water trading were undertaken. From these analyses potential bottlenecks to trade that constrain the economic benefits from temporary water trading were identified. Furthermore, it was found that in certain areas of the system, trading can make impacts of long drought spells worse for water users, e.g. irrigators. Thus, the integrated model can be used to quantify short-term and long-term third party impacts arising from temporary water trading. These findings also highlight the need to link “paper trades” (estimated by economic models) to physical water transfers (estimated by biophysical models).

Irrigation and environmental sustainability in irrigated catchments have, to date, been managed as two competing enterprises under separate and divergent control. There is an increasing quest and support for a "harmonised" business approach to sustainable use of land and water resources to achieve enduring business partnerships in the water management. The "system harmonisation" approach seeks to identify business opportunities for irrigators to become an integral part of an expanding environmental services industry and in so doing support a truly sustainable and diversified irrigation business environment The system harmonisation framework involves an all-encompassing approach that combines research and business principles to achieve productive and environmental improvements at the catchment level. The framework involves five feasibility steps including three research components and a business analysis component leading to the formation of regional irrigation business partnerships (RIBPs). The system harmonisation process establishes the base physical, economic and social position of the region, identifies the key biophysical, economic, social, environmental or institutional pressure points in the system and the system constraints. Changes in these key pressure points need to be assessed and acted upon, in a comprehensive and systematic way, to enhance the multifunctional productivity of irrigation systems. Copyright © 2008 John Wiley & Sons, Ltd.

To keep pace with population and economic growth, the city of Hyderabad, India, will need to identify and develop new supply sources almost continually. Increasing population growth rate, declining surface water resources, overexploitation of groundwater, deterioration of ground water quality and poor sewage treatment are the major water-related issues in Hyderabad. This paper reviews the current situation facing policy makers who need to come to terms with the problem of restricted water supply and increasing demand in an urban centre such as Hyderabad, India. The City Water Balance model developed in this study can be used to analyse different scenarios that include water conservation, urban wastewater reuse and improvement of distribution and conveyance efficiency. Water conservation programs, which include a 5% conveyance efficiency improvement, reusing 90 million cubic metres (MCM) of urban runoff and adoption of water harvesting by 0.5 million households together with recycling 120 MCM of wastewater recycling wastewater would be sufficient to meet the water demand by 2031, if the population grows at a rate of 2.5%.

An indicator defined as a function of the to- tal water diversion through the Coleambally canal and the potential irrigation demand is selected to represent the sus- tainability of the irrigation water system in the Coleambally irrigation area, Australia. A simulation procedure using a system dynamics approach was developed to evaluate the in- dicator. The procedure includes water diversion assessment, potential crop water demand and total gross margin. Three cases of water supply options (surface water, ground water pumping and water trading), two cases of changes in the total agricultural area and three cropping pattern sce- narios were simulated to better understand their impact on sustainability. The simulated results indicate that increasing the agricultural area reduces the sustainability of the irriga- tion system because the demand of water increased despite in- crease in the gross margin. The scenarios show that imposed water trading and ground water pumping would considerably increase the supply system having a positive impact on the sustainability. The paper concludes that a multi-objective sustainability indicator taking account of economic and envi- ronmental issues could be more useful.

Regulation of river systems has led to the development of irrigated agriculture and other uses of this engineered additional water supply. One of the main environmental drawbacks from regulation of river systems has been a shift in the seasonality of flow of these rivers. One such river is the River Murray, Australia. A common concern for the River Murray is a decreased incidence of winter and spring flooding of floodplains. A lesser known problem is the increased incidence of unseasonal flooding of the Barmah-Millewa Forest (B-MF) around the Barmah Choke on the River Murray. These flood events have often been said to be created by ‘rain rejection events’. Rain rejection events are the rejection of advanced irrigation orders by irrigators due to rainfall on their properties meaning this previously requested water goes unutilised. This paper investigates the causes of unutilised irrigation orders (UIO) and takes a holistic view to investigate the variables affecting unseasonal flooding of the B-MF. It is concluded from this research that unseasonal flooding of the B-MF can be linked to UIO but there are other more significant factors; inflow from Ovens River particularly during December, River Murray flow at Albury and the available airspace in the River Murray at Tocumwal. UIO were found to be linked to the previous day’s UIO, rainfall and the advanced order volume placed four days prior.

Improving the efficiency of water allocation has long been recognised as a key problem for the water resources management decision-makers. However, assessing the efficacy of management decision is difficult due to the complexity and interconnectivity of water resource systems. For this reason, it is vital that robust modelling approaches are employed to deal with the feedback loops inherent in the water resource systems. Whilst many studies have applied modelling to various aspects of water resource management, little attention has been given to innovations in modelling approaches to deal with the modelling challenges associated with improving decision-making. The aim of this study is to apply a System Dynamics modelling approach to improve the efficiency of water allocation incorporating a myriad of irrigation system constraints. The system dynamic approach allows the different system components to be organised as a collection of discrete objects that incorporate data, structure and function to generate complex system behaviour. Through the application of a system dynamic approach, a robust model (named the Economical Reallocating Water Model (ERWM)) was developed which was used to examine the options of re-allocating water resources that minimize the water cost all over an irrigated agricultural area. The ERWM incorporated a wide range of complexities likely to be encountered in water resource management: surface and ground water sources, water trading between sources, system constraint such as maximum ground water pumping, rates, maximum

The Makkink evaporation equation has been applied worldwide to estimate potential evaporation based on measured or estimated radiation, and mean atmospheric temperature. The general form of the Makkink equation is similar to the well-known Priestley and Taylor (1972) evaporation, although Makkink proposed the equation nearly 2 decades earlier. The writers have examined 51 references that refer directly or through a secondary source to the Makkink equation, yet every reference the writers have sighted refers to Makkink (1957b) as the relevant reference. This reference is incorrect, as the Makkink equation is not mentioned therein. After an exhaustive library search and pursing other avenues through colleagues, the writers are convinced the correct reference is Makkink (1957a). de bruin (1981) cites Makkink (1960) in a discussion of methods to estimate reference crop evapotranspiration. Makkink (1957a) is written in the international language Esperanto, and researchers can use the Google Translate function to translate. The Makkink equation, as reported in Makkink (1957a), is

Basin irrigation layouts are used extensively for irrigation of various types of crops worldwide. Basin irrigation is characterised by ground levelled to zero slope in both directions and each unit enclosed by dykes. Single closed level basins and sequential multiple basin layouts offer potentially high uniformity of application, reduced runoff and low labour requirements. Several simulation models have been developed to study the flow processes involved during an irrigation event in basin irrigation to improve the design and operation of these basin layouts. These simulation models are based on governing equations in the form of the full hydrodynamic Saint–Venant equations or the simplified zero-inertia approximation (neglecting inertial terms). This paper reviews various simulation models that have been developed and discusses various issues involved in modelling of basin irrigation layouts. Application of these models for use in the design and management of basin irrigation layouts is also discussed. It is concluded that two-dimensional rather than one-dimensional models are required to simulate all the flow processes involved in irrigation events in basin systems due to the non-linear nature of flow over the basin. Inclusion of basin topography through soil surface elevation even in laser levelled basins improves the quality of simulation and prediction of performance parameters. The availability of accurate values of surface irrigation parameters such as Manning's roughness coefficient and infiltration coefficients for the empirical equations is often a problem in the application of these models.

Water markets have great potential to increase the efficiency of water use. However, the very process of transferring a water entitlement can result in third party effects. Specifically, there are three types of impact that can affect the entitlements of third party irrigators: volumetric reliability, delivery reliability and water quality effects. In each case, policy makers must decide whether they will try to prevent the impacts and whether they will force traders to internalise third party effects. Potential strategies range from non-interventionist options, such as restricting trade, to market interventions, such as exchange rates, which adjust traded entitlements to account for volumetric externalities.

Statements, such as those that suggest that all the world's population has a right to fresh potable water supplies or that those who polluted water should be made to clean it up, are usually made without recourse to the costs and benefits of segregating water according to its quality. The purpose in this paper is to demonstrate the value that economic thinking can add to issues surrounding water quality by addressing four key questions. First, who would benefit from differentiating water quality? Second, given the multitude of quality types that exist, is it possible to specify a finite set of manageable categories that can be assessed? Third, can the costs of treating water to change its quality be viewed in a logical manner? Finally, given that water quality changes as it is used, how can the effects of this change on other users be viewed? This study found that an economic approach adds significantly to conceptualizing these problems, however, an analysis of them is severely hampered by the la...

A crucial, yet little understood, element in the economic studies of irrigation is the role played by companies who manage the supply of water. Many of these companies are publicly managed as they have the potential to act as monopolists. Possibly as a consequence of their ownership structure, analysts have questioned the economic viability and management of these firms. The case is made that many of these companies do not run profitably, that they rely on government subsidies to survive, that they do not spend enough on maintenance and that they run down their capital base. The purpose in this paper is to specify the measures that allow analysts to examine the financial viability of a publicly owned irrigation management companies and to apply these to a scheme in Vietnam. Of concern and contention in any irrigation scheme is the price that a company should charge for water in order to recover costs in the short-run. It was found that the company under investigation could not operate without subsidies and did run down their assets. It was found that a great disparity exists between what the consumers were charged for water and what the company received for supplying it. To ensure the sustainability of the Irrigation Management Companies in long term, they may have to increase the water fee by 3.75 times the current rate set by the provincial government (US$ 20 per ha).