Decreasing Water Demand Research Articles

Balancing the carbon and water footprints of the Ontario energy mix

With climate change being the current most pressing environmental issue, clean energy projects are emerging with a focus on reducing our carbon footprint while meeting our energy demands. There are several intersecting challenges surrounding climate change, energy demand, and water scarcity. The movement towards a less carbon-intensive energy supply could result in an increase or decrease in water demand, depending on the choice of technology. Ontario has made great progress in mitigating climate change by phasing out coal from their energy supply mix and further changes are expected over the next decade as the province shifts towards more renewable generation. This shift, however, will significantly increase the amount of water consumed to fuel demand. Carbon and water footprints for Ontario’s energy supply mix, based on present day as well as on future projections, are presented. Cases studies illustrate how these footprints could change in likely, as well as extreme scenarios. Comparisons are also presented for California, where water scarcity is a more urgent concern. These findings stress the need for a balance between our water usage and carbon footprint and for a nexus approach to be in place to ensure a sustainable relationship between energy and water resources.

Maximizing Productivity and Reducing Environmental Impacts of Full-Scale Algal Production through Optimization of Open Pond Depth and Hydraulic Retention Time.

The ability to dynamically control algal raceway ponds to maximize biomass productivity and reduce environmental impacts (e.g., land and water use) with consideration of local constraints (e.g., water availability and climatic conditions) is an important consideration in algal biotechnology. This paper presents a novel optimization strategy that seeks to maximize growth (i.e., optimize land use), minimize respiration losses, and minimize water demand through regular adjustment of pond depth and hydraulic retention time (HRT) in response to seasonal changes. To evaluate the efficiency of this strategy, algal productivity and water demand were simulated in five different climatic regions. In comparison to the standard approach (constant and location-independent depth and HRT), dynamic control of depth and HRT was shown to increase productivity by 0.6-9.9% while decreasing water demand by 10-61% depending upon the location considered (corresponding to a decrease in the water footprint of 19-62%). Interestingly, when the fact that the water demand was limited to twice the local annual rainfall was added as a constraint, higher net productivities were predicted in temperate and tropical climates (15.7 and 16.7 g m(-2) day(-1), respectively) than in Mediterranean and subtropical climates (13.0 and 9.7 g m(-2) day(-1), respectively), while algal cultivation was not economically feasible in arid climates. Using dynamic control for a full-scale operation by adjusting for local climatic conditions and water constraints can notably affect algal productivity. It is clear that future assessments of algal cultivation feasibility should implement locally optimized dynamic process control.

Mecanismos poupadores de água como suporte ao planejamento urbano

This research evaluates the use of water saving equipment in vertical buildings, in order to minimize the impact of water demand increasing over five years. The area studied is a district of Campina Grande city (PB) named Catole. A survey was developed of some reducing devices that could contribute to the water demand decrease in the studied buildings. Water Demand Management recommends the use of water saving devices in buildings to decrease water consumption. The main goal was to evaluate the reduction of the water use caused by water savers in residential buildings and to try to establish parameters for the new buildings. Those parameters can be used for urban planning guidelines and laws to minimize water consumption. Therefore, four different types of water saving devices were selected and the economic and efficiency aspects of implementation were analyzed. Some scenarios were simulated for unfinished buildings (under construction) to evaluate the future water consumption. The results obtained show that the use of water saving devices can reduce water consumption in vertical buildings by 83.26%. Therefore, it has been concluded that it is possible to minimize the water scarcity problem using management tools that can contribute to rational use and also improve society’s awareness of natural resources in urban areas.

Wind effects on leaf transpiration challenge the concept of "potential evaporation"

Abstract. Transpiration is commonly conceptualised as a fraction of some potential rate, driven by so-called "atmospheric evaporative demand". Therefore, atmospheric evaporative demand or "potential evaporation" is generally used alongside with precipitation and soil moisture to characterise the environmental conditions that affect plant water use. Consequently, an increase in potential evaporation (e.g. due to climate change) is believed to cause increased transpiration and/or vegetation water stress. In the present study, we investigated the question whether potential evaporation constitutes a meaningful reference for transpiration and compared sensitivity of potential evaporation and leaf transpiration to atmospheric forcing. A physically-based leaf energy balance model was used, considering the dependence of feedbacks between leaf temperature and exchange rates of radiative, sensible and latent heat on stomatal resistance. Based on modelling results and supporting experimental evidence, we conclude that stomatal resistance cannot be parameterised as a factor relating transpiration to potential evaporation, as the ratio between transpiration and potential evaporation not only varies with stomatal resistance, but also with wind speed, air temperature, irradiance and relative humidity. Furthermore, the effect of wind speed in particular implies increase in potential evaporation, which is commonly interpreted as increased "water stress", but at the same time can reduce leaf transpiration, implying a decrease in water demand at leaf scale.

Fighting drought with innovation: Melbourne's response to the Millennium Drought in Southeast Australia

The Millennium Drought in Southeast Australia forced greater Melbourne, a city of 4.3 million people, to find innovative ways of increasing water supply and decreasing water demand. This article explores how water managers in Melbourne reacted to the crisis and evaluates the short‐ and long‐term impacts of their decisions. Reduced water demand occurred primarily through residential and industrial water conservation programs, restrictions, together with emergency reductions in the environmental release of water to streams. The city also experimented with using recycled water, in place of surface water, to support agriculture in the Werribee Irrigation District. Water pricing was not strengthened during the drought, and thus not regarded as a drought demand management tool, primarily because Melbourne water companies lacked independent price‐setting powers. Today, five years after the end of the Millennium Drought, gains in water conservation appear to be holding steady, but recycled water for irrigation has declined for various reasons. We contend that the Millennium Drought provided Melbourne with the opportunity to develop and implement a more integrated approach to water management. Many of the innovations it forged (e.g., distributed harvesting and use of stormwater) will continue to enhance the city's resilience to drought and reduce its vulnerability to climate variability for years to come. Nevertheless, a challenge going forward is how to sustain these achievements in light of anticipated population growth and continued climatic change. This challenge—coupled with Melbourne's successes—hold important lessons for water‐stressed cities around the world. WIREs Water 2015, 2:315–328. doi: 10.1002/wat2.1087This article is categorized under: Engineering Water > Planning Water Science of Water > Water Extremes

Predicting farmers’ water conservation goals and behavior in Iran: A test of social cognitive theory

Lack of water constrains the economic development of all countries in arid and semi-arid areas and is forecast to become an even greater problem in the near future. Given the complexity of the water scarcity problem, an emerging drought in Iran (the worst in 30 years) has become an increasingly important issue, making more sustainable water management a necessity. Government bodies involved in water resource management mainly concentrate on increasing water supply, while approaches to decreasing water demand receive less attention. Iranian water users have been slow to implement voluntary water conservation. Encouraging voluntary action requires an understanding of existing behaviors, and of how behavioral changes can be made. In this context, a study was carried out to identify the most prominent drivers of, and impediments to, water conservation, using social cognitive theory. A sample of 360 farmers living in western parts of Iran was selected through a multi-stage, stratified, random sampling method. Findings revealed that farmers’ intention to conserve water was predicted mainly by outcome expectancy and self-efficacy. Moreover, self-efficacy was the most important determinant of farmers’ actual behavior in conserving water.

Influence of the processed sunflower oil on the cement properties

Used oils (vegetable oil, animal oil, engine oil, etc.), which are essentially industrial wastes, have found application as secondary raw materials in some braches of industry. In particular, the only well-known and commonly-used way of utilizing wastes of vegetable oils is to apply them as raw materials in the production of biodiesel. The goal of the present study is to develop a conceptually new way of vegetable oil wastes utilization in the building industry. The test admixture D-148 was obtained from the processing of wastes of sunflower oil and it mainly consists of fatty acid diethanolamide. The test admixture was added to the cement system for the purpose of studying its influence on water demand, flowability, setting times, compressive strength and moisture adsorption. The test admixture D-148 at the optimal content 0. 2 weight % causes 10% decrease in water demand, 1.7 time increase in flowability (namely spread diameter), 23% increase in grade strength and 34% decrease in moisture adsorption. The results of the present investigation make it possible to consider the final product of the waste sunflower oil processing as multifunctional plasticizing-waterproofing admixture.

Transient Effects of Self-adjustment of Pressure Reducing Valves

Pressure control strategy through Pressure Reducing Valves (PRV) has been deeply investigated as management strategy, aimed at water leakages reduction avoiding very expensive pipe replacement programs. On the contrary, few experimental data are available in literature, with regard to PRV transient behavior in terms of its response to incoming pressure waves, as well as the time required for achieving the pressure set point. In this paper, the results of some experimental tests are presented. The PRV is installed in a single high density polyethylene pipe and transients are generated by operating the downstream end valve. Two types of tests are considered: a partial valve closure and opening simulating a water demand decrease and increase, respectively. The analysis of the experimental pressure traces points out the valuable effects of the PRV on transient characteristics with respect to the case of a partially closed in-line valve with a constant opening degree.

Sensitivity Analysis of Coupled Hydro-Economic Models: Quantifying Climate Change Uncertainty for Decision-Making

The paper assessed the sensitivity of an integrated hydro-economic model, to provide a quantitative range of uncertainty in the impacts of climate change on water balance components and water use in the agricultural sector of Apulia region located in a semi-arid Mediterranean climate area in southern Italy. Results show that the impacts of climate change are expressed in the future by an increase in the net irrigation requirements (NIRs) of all crops. Total cultivated land is reduced by 8.5 % in the future, and the percentage of irrigated land decreases from 31 to 22 % of total agricultural land. Reduction in the irrigated land, together with the variation in the cropping pattern and the adoption of the different irrigation techniques, led to a decrease in water demand for irrigation across the entire region. The sensitivity analysis shows that the groundwater recharge has the lowest correlation to climatic parameters. Results are addressed to the scientific community and decision makers to support the design of adequate adaptation policies for efficient water management under the severe drought conditions that are likely to occur in the region according to climate change projections.

Impact of oil prices, economic diversification policies and energy conservation programs on the electricity and water demands in Kuwait

This paper describes the influences of oil revenue and government's policies toward economic developments and energy efficiency on the electricity and water demands. A Kuwait-specific electricity and water demand model was developed based on historic data of oil income, gross domestic product (GDP), population and electric load and water demand over the past twelve years (1998–2010). Moreover, the model took into account the future mega projects, annual new connected loads and expected application of energy conservation programs. It was run under six circumstances representing the combinations of three oil income scenarios and two government action policies toward economic diversification and energy conservation. The first government policy is the status quo with respect to economic diversification and applying energy conservation programs. The second policy scenario is the proactive strategy of raising the production of the non-oil sector revenue and enforcing legislations toward energy demand side management and conservation. In the upcoming 20 years, the average rates of change of the electric load and water demand increase are 0.13GW and 3.0MIGD, respectively, per US dollar oil price increase. Moreover, through proactive policy, the rates of average load and water demand decrease are 0.13GW and 2.9MIGD per year, respectively.

Historic water consumptions and future management strategies for Haihe River basin of Northern China

With the growth of population and economy, water demand has increased significantly in all the over world. However, the water consumptions in Haihe River basin located in the Northern part of China has decreased in recent years. Haihe River basin, covers the provinces of Beijing and Tianjin and parts of other six provinces of China is considered as the center of politics, economics, and cultural of China. Therefore, decreasing water demand in Haihe River basin has attracted the attention of hydrologists and decision makers. A study has been carried out in this paper by using information entropy theory to understand the possible causes of changing water consumptions in Haihe River basin. Results show that entropy value of water consumption system of Haihe River basin has increased from 0.72 in 1980 to 0.91 in 2008. The balance degree of water consumptions has also increased from 0.68 in 1980 to 0.89 in 2008. The results indicate that the water consumption structure of the basin has become more stable with time. The dominance of agricultural water consumption has weakened, the industrial consumption has stabled, and the domestic and ecological water consumptions have increased. The study reveals that land conversion from agrarian to industrial and higher water efficiency in industrial production have reduced the total water consumption in the basin. Water management approaches base on total quantity control and quota management have been proposed in this study for further reduction of water demand in the basin.

Reduction of environmental and energy footprint of microalgal biodiesel production through material and energy integration

The life cycle impacts were assessed for an integrated microalgal biodiesel production system that facilitates energy- and nutrient- recovery through anaerobic digestion, and utilizes glycerol generated within the facility for additional heterotrophic biodiesel production. Results show that when external fossil energy inputs are lowered through process integration, the energy demand, global warming potential (GWP), and process water demand decrease significantly and become less sensitive to algal lipid content. When substitution allocation is used to assign additional credit for avoidance of fossil energy use (through utilization of recycled nutrients and biogas), GWP and water demand can, in fact, increase with increase in lipid content. Relative to stand-alone algal biofuel facilities, energy demand can be lowered by 3–14GJper ton of biodiesel through process integration. GWP of biodiesel from the integrated system can be lowered by up to 71% compared to petroleum fuel. Evaporative water loss was the primary water demand driver.

Water, climate change, and sustainability in the southwest

The current Southwest drought is exceptional for its high temperatures and arguably the most severe in history. Coincidentally, there has been an increase in forest and woodland mortality due to fires and pathogenic outbreaks. Although the high temperatures and aridity are consistent with projected impacts of greenhouse warming, it is unclear whether the drought can be attributed to increased greenhouse gasses or is a product of natural climatic variability. Climate models indicate that the 21st century will be increasingly arid and droughts more severe and prolonged. Forest and woodland mortality due to fires and pathogens will increase. Demography and food security dictate that water demand in the Southwest will remain appreciable. If projected population growth is twinned with suburb-centered development, domestic demands will intensify. Meeting domestic demands through transference from agriculture presents concerns for rural sustainability and food security. Environmental concerns will limit additional transference from rivers. It is unlikely that traditional supply-side solutions such as more dams will securely meet demands at current per-capita levels. Significant savings in domestic usage can be realized through decreased applications of potable water to landscaping, but this is a small fraction of total regional water use, which is dominated by agriculture. Technical innovations, policy measures, and market-based solutions that increase supply and decrease water demand are all needed. Meeting 21st-century sustainability challenges in the Southwest will also require planning, cooperation, and integration that surpass 20th-century efforts in terms of geographic scope, jurisdictional breadth, multisectoral engagement, and the length of planning timelines.

Water footprint analysis for the assessment of milk production in Brandenburg (Germany)

Abstract. The working group "Adaptation to Climate Change" at the Leibniz-Institute for Agricultural Engineering Potsdam-Bornim (ATB) is introduced. This group calculates the water footprint for agricultural processes and farms, distinguished into green water footprint, blue water footprint, and dilution water footprint. The green and blue water demand of a dairy farm plays a pivotal role in the regional water balance. Considering already existing and forthcoming climate change effects there is a need to determine the water cycle in the field and in housing for process chain optimisation for the adaptation to an expected increasing water scarcity. Resulting investments to boost water productivity and to improve water use efficiency in milk production are two pathways to adapt to climate change effects. In this paper the calculation of blue water demand for dairy farming in Brandenburg (Germany) is presented. The water used for feeding, milk processing, and servicing of cows over the time period of ten years was assessed in our study. The preliminary results of the calculation of the direct blue water footprint shows a decreasing water demand in the dairy production from the year 1999 with 5.98×109 L/yr to a water demand of 5.00×109 L/yr in the year 2008 in Brandenburg because of decreasing animal numbers and an improved average milk yield per cow. Improved feeding practices and shifted breeding to greater-volume producing Holstein-Friesian cow allow the production of milk in a more water sustainable way. The mean blue water consumption for the production of 1 kg milk in the time period between 1999 to 2008 was 3.94±0.29 L. The main part of the consumed water seems to stem from indirect used green water for the production of feed for the cows.

Impact of decreasing water demand on bank filtration in Saxony, Germany

Abstract. Bank filtration has been of great importance to the drinking water supply in Germany for many decades. The water quality of pumped raw water from bank filtration sites depends to a high degree on the water quality of the infiltrating surface water and the landside groundwater, the mixed portion of both, as well as the flow and transport conditions in the aquifer. Following the improvement of river water quality and a drastic decrease in water demand during the last 20 years in Germany, the influence of landside groundwater quality has become more important for the raw water quality of waterworks relying on bank filtration. The hydrogeologic analysis of three bank filtration sites in Saxony and the management of abstraction rates and well operation in response to fluctuating water demand are discussed.

Goal Based Water Conservation Projections to Decrease Water Demand in Miami, Florida

Goal Based Water Conservation Projections to Decrease Water Demand in Miami, Florida

상수관망시스템에서의 장기간 모의를 위한 동역학적 모형의 개발

본 연구에서는 점진적인 유량 및 압력이 변화하는 상수관망에서 Rigid Water Column Theory를 이용하여 정상모형의 확장기간 모의해석보다 정확하고 수충격 해석보다는 계산비용 및 노력 측면에서 효율적으로 장시간 부정류 해석 모형을 개발하였다. 개발된 모형을 이용하여 실제관망에 대하여 24 시간 열 수요량을 고려한 부정류 해석 및 밸브폐쇄로 인한 수충격해석 모의에 적용하였고 해석 결과는 다음과 같다. 24 시간 일변화 모의의 경우에 수요량이 증가할 경우 모든 관로에서 압력감소가 나타났으며 수요량이 감소할 경우 압력증가가 나타났다. 그리고 일 수요량의 변화에 따라 나타난 절점에서의 유량 및 압력 변화폭은 각 절점마다 다르고 수요량과 유량의 변화양상이 반대로 나타나는 관로도 발생하고 있으며 KYPIPE2의 결과와 본 모형의 유량 및 압력차이도 발생하고 있어 상수관망의 동역학적 해석의 필요성이 대두되었다. 밸브폐쇄로 인한 수충격모의에 본 모형이 적용되었을 때 본 모형은 유체의 압축성을 무시함으로 인해 밸브 완전 폐쇄와 동시에 압력과 유량의 변화가 전 관망에 발생하였고 수충격모형은 유체의 탄성으로 인해 발생된 압력파의 도달시간이 필요함으로 압력과 유량변화가 지체되어 나타났으나 전체적인 변화양상 및 변화폭의 크기 등은 유사한 경향을 나타내어 본 모형의 적용성을 입증하였다. 본 연구에서 개발된 프로그램은 장기간 점진적인 관로 부정류를 비교적 정확하게 해석할 수 있을 것으로 판단되며 이를 이용하여 관로내 오염물의 확산해석, 수요량을 고려한 절점에서의 압력제어 및 누수저감, 장기간 관로내의 유량 및 압력 변화를 고려한 관망관리 등의 분야에서 효율적으로 이용될 수 있을 것으로 기대되었다. In this study, a long-term unsteady simulation model has been developed using rigid water column theory which is more accurate than Extended-period model and more efficient comparing with water-hammer simulation model. The developed model is applied to 24-hours unsteady simulation considering daily water-demand and water-hammer analysis caused by closing a valve. For the case of 24-hours daily simulation, the pressure of each node decreases as the water demand increase, and when the water demand decrease, the pressure increases. During the simulation, the amplitudes of flow and pressure variation are different in each node and the pattern of flow variation as well as water demand is quite different than that of KYPIPE2. Such discrepancy necessitates the development of unsteady flow analysis model in water distribution network system. When the model is applied to water-hammer analysis, the pressure and flow variation occurred simultaneously through the entire network system by neglecting the compressibility of water. Although water-hammer model shows the lag of travel time due to fluid elasticity, in the aspect of pressure and flow fluctuation, the trend of overall variation and quantity of the result are similar to that of water-hammer model. This model is expected for the analysis of gradual long-term unsteady flow variations providing computational accuracy and efficiency as well as identifying pollutant dispersion, pressure control, leakage reduction corresponding to flow-demand pattern, and management of long-term pipeline net work systems related with flowrate and pressure variation in pipeline network systems

Influence of furnace bottom ash on properties of concrete

Furnace bottom ash (FBA) is a by-product from thermal power plants. Unlike its companion, pulverised fuel ash (PFA), FBA has coarse particle size, higher water absorption and usually no pozzolanic effect. Therefore, it is dumped in landfill sites. Past recycle attempts of FBA have been mainly focused on using it in blocks, highway embankments, subgrades, sub-bases and structural fills. However, this may still be a source of environmental contamination by way of leached trace elements. A previous investigation carried out by the authors has indicated that FBA would be a potential fine aggregate in concrete. The effects of FBA on workability, compressive strength, permeability, depth of carbonation and chloride transport of concrete were further investigated and the results are reported in this paper. The natural sand was replaced with FBA by 0, 30, 50, 70 and 100% by mass, at fixed free water–cement ratios of 0·45 and 0·55 and a cement content of 382 kg/m3. The results indicated that the workability of the concrete increased with an increase in replacement level of natural sand with the FBA. Most of the FBA concrete was lower in compressive strength than the control that was manufactured with the natural sand up to an age of 28 days for both the water–cement ratios, but most of the FBA concretes were comparable with that of the control concrete at 365 days. The air permeability, water absorption and the carbonation rate at the age of 365 days were higher than those of the control concrete. However, the chloride transport coefficient decreased with the increase of the replacement level of natural sand with FBA up to 50% and it increased beyond this replacement level for both the water–cement ratios. Further investigation is required to assess whether properties of concrete could be improved by taking account of the decrease in water demand of the FBA concrete while determining the water–cement ratio of the mix.

Influence of furnace bottom ash on properties of concrete

Furnace bottom ash (FBA) is a by-product from thermal power plants. Unlike its companion, pulverised fuel ash (PFA), FBA has coarse particle size, higher water absorption and usually no pozzolanic effect. Therefore, it is dumped in landfill sites. Past recycle attempts of FBA have been mainly focused on using it in blocks, highway embankments, subgrades, sub-bases and structural fills. However, this may still be a source of environmental contamination by way of leached trace elements. A previous investigation carried out by the authors has indicated that FBA would be a potential fine aggregate in concrete. The effects of FBA on workability, compressive strength, permeability, depth of carbonation and chloride transport of concrete were further investigated and the results are reported in this paper. The natural sand was replaced with FBA by 0, 30, 50, 70 and 100% by mass, at fixed free water–cement ratios of 0·45 and 0·55 and a cement content of 382 kg/m3. The results indicated that the workability of the concrete increased with an increase in replacement level of natural sand with the FBA. Most of the FBA concrete was lower in compressive strength than the control that was manufactured with the natural sand up to an age of 28 days for both the water–cement ratios, but most of the FBA concretes were comparable with that of the control concrete at 365 days. The air permeability, water absorption and the carbonation rate at the age of 365 days were higher than those of the control concrete. However, the chloride transport coefficient decreased with the increase of the replacement level of natural sand with FBA up to 50% and it increased beyond this replacement level for both the water–cement ratios. Further investigation is required to assess whether properties of concrete could be improved by taking account of the decrease in water demand of the FBA concrete while determining the water–cement ratio of the mix.

A study on the parameters affecting the properties of Portland limestone cements

In this paper the parameters affecting the properties of Portland limestone cements are investigated. Portland limestone cements of different fineness and limestone content have been produced by intergrinding clinker, gypsum and limestone. Two kinds of clinker of different chemical composition, mineralogical composition and strength development and three limestones, with different contents of calcite, dolomite, quartz and clay, have been used. It is concluded that the appropriate choice of the clinker quality, limestone quality, % limestone content and cement fineness can lead to the production of a limestone cement with the desired properties. Limestone cements, having up to 10% limestone content and fineness up to a limit value, develop almost the same compressive strength, as the corresponding pure cements. The limestone cements, generally have lower paste water demand than the relative pure cements and the water demand decrease is mainly affected by the clinker type and limestone quality. In any case the properties of the limestone cements are affected by the interaction of the two components rather than their individual properties.