Top PDF Planning for robust water supply system investments under global change

Planning for robust water supply system investments under global change

Planning for robust water supply system investments under global change

Optimization driven models choose their own operating rules each time step depending on what is optimal based on an objective function, which can be a penalty function or economic benefit or cost, etc. These models are easier to build but can have difficulties representing complex operating. Such models include WATHNET (Kuczera, 1992), WRIMS (formerly CalSim) (Draper et al., 2004), and WEAP (SEI, 2016). The WATHNET model uses a network linear program (NetLP) to simulate the operation which searches for the minimum cost solution for distributing water through a network. It is relatively fast but requires extensive user input in input script format and only a simplified water system network representation. Its custom coding ability is also very limited. The WRIMS model utilizes a mixed-integer linear program to determine reservoir releases and water allocations at each time step. Instead of operating policies the user defines relative priorities for water allocation and storage. However, the weighted approach requires careful consideration to achieve desired outcomes and its runtimes are relatively slow. The WEAP model consists of a conceptual rainfall-runoff sub-model connected to an optimization sub-model that applies a mixed-integer linear programming routine to maximize demand satisfaction based on the water demand prioritization, supply preferences and environmental requirements, mass balances, etc. to allocate water. It features a GUI and provides a possibility to extend its functionality with user–defined variables and functions (in VBScript, JavaScript, Perl, or Python). Its main weaknesses in relation to the purpose of this study are license costs, slow runtime and the ability to represent only a simple linear operating rules.
Show more

174 Read more

Global Change and Water Resources Management

Global Change and Water Resources Management

Water resources managers are, first and foremost, technical and empirical pragmatists. The nature of their jobs forces them to be empiricists because they are directly accountable to the public for their decisions, both in operating projects and as part of the planning process. Virtually every major decision in the Corps is accomplished through a formal public participation process with extensive stakeholder involvement. The water resources profession incorporates a good deal of empirical science, along with a large dose of economics and social and environmental considerations that are tempered by politics and public values about the outputs, balance, and quality of services provided. It became evident in the two national conferences on “Climate Change and Water Resources Management” that the Corps helped organize in 1993 and 1997 that the subgroup of water managers (as distinct from academicians and researchers who attended) held the basic view regarding climate nonstationarity that was encapsulated by Matalas in his article (this issue). To whit: “claiming nonstationarity is not enough. It must be shown that the perceived nonstationarity is real enough and has a significant effect on the management of water systems.” They also adhere to the corollary (also by Matalas) which posits that the current analytical practices, represented by stochastic hydrology, “can accommodate the uncertainties in water supplies induced by global warming with the operational assumption of stationarity as meaningfully as with the assumption of
Show more

5 Read more

Adaptation planning under climate change uncertainty

Adaptation planning under climate change uncertainty

On the other hand, adaptation revolving around flexible pathways and diversifying strategies prevails in managerial and adaptation-based literature (Smit and Pilifosova, 2003) which recognises the importance of enhancing choices and general societal resistance to climate change. Concerning climate risk in water resources planning, soft strategies, which are flexible and reversible, rank high in the adaptation agenda (Hallegatte, 2009). These soft solutions enhance the complete supply/demand integrated system capacity to absorb and to cope with socio- economic shock cascading from climatic disturbance (Nowotny, 1999; Nowotny, 2003). While traditional emphasis has been on the supply and engineering side, there has been a gradual recognition of the need to include cultural and socioeconomic interactions. These interactions can be powerful in driving the demand side and dictating the efficiency of supply options. Given the current level of uncertainties, adaptation strategies have moved toward capacity strengthening rather than optimal decision making (Smit and Pilifosova, 2003; Wilby et al., 2009). This paradigm shift leads to a move from top-down to more adaptive management approaches in the planning process (Ingram et al., 1984; Gleick, 2000; Pahl-Wostl, 2007; Van der Brugge and Van Raak, 2007). Combining both of these stances, Wilby and Dessai () emphasised options improving scientific and climate risk information as well as other water management practices; they further proposed a framework of robust and ‘low regret’ adaptation by testing both hard engineering solutions and soft solutions against climate impact models, technical feasibility and socio-economic acceptability.
Show more

315 Read more

Robust Decision Making and Info-Gap Decision Theory for water resource system planning

Robust Decision Making and Info-Gap Decision Theory for water resource system planning

Several limitations affect the relevance of the results for real Thames region planning. The England and Wales water sector fol- lows a ‘twin-track’ approach including both supply augmentation and demand management (e.g. water conservation, increased effi- ciency, metering, leakage reduction, communication campaigns, etc.). Our study only considers supply augmentation schemes to balance supply and demand; further research will bring in demand management options. The flow perturbation factors are applied to the historical flow time-series and do not take into account possi- ble shifts in the hydrologic regime; they uniformly shift the inten- sity of flows (i.e. both low and high flows are equally augmented) and do not change the frequency or pattern of severe events ( Prud- homme et al., 2010 ). Furthermore, the scaling of the flow factors in the IGDT analysis results in a compression or extension of the range of seasonal ranges of flows resulting in a further departure from the historical flow hydrology regime. Further research into methods that produce hydrologically consistent future flow time series is recommended and would strengthen the validity of the IGDT and RDM analyses. Uncertainty about the reliability of the River Severn Transfer should be considered, but without a water resource model of that area we could not consider it in this study. This would add a further dimension of uncertainty and signifi-
Show more

16 Read more

Our global water towers: ensuring ecosystem services from mountains under climate change

Our global water towers: ensuring ecosystem services from mountains under climate change

While climate change will degrade the provision of some mountain ecosystem services, others – such as food production, carbon sequestration, watershed services, and recreation – may be enhanced; their development may help ensure future resilience. Linking payment for ecosystem services to climate change adaptation has not yet progressed greatly in mountain

8 Read more

The evolution of phenotypic plasticity under global change

The evolution of phenotypic plasticity under global change

Multigenerational exposure to global change scenarios only modified the level of plasticity of a single trait; juve- nile developmental rate, in the combined scenario after transplant to the control (as is indicated by the presence of the significant transplant by generation interaction; Table 1). After two generations (F3, F4) in which no plastic responses were observed following transplant, the rate of juvenile development in the new, control environment significantly decreased compared to the mean measured in the combined scenario. The slope of the reaction norm being three times steeper in F5 compared to F3 (Fig. 2b). Transplantation from ocean warming back to the con- trol significantly modified juvenile developmental rate and fecundity, but the effect of transplant did not change between generations (Table 1). On average, transfer from ocean warming to control resulted in a 5% decrease in Figure 1. Schematic diagram of the experimental design. Adult individuals of the polychaete worm
Show more

8 Read more

Planning water resource systems under uncertainty

Planning water resource systems under uncertainty

1981; Loucks and van Beek, 2005; Mays, 2005; Revelle, 1999). Such optimisation methods have known success but also have limitations including the difficulty of representing water system non- linearities, the diversity of discrete options and their potential to mask important performance trade-offs for real systems when the optimisation is performed over few objectives (Woodruff et al., 2013). Water systems often use non-linear rules and are frequently subject to nonlinear cost and benefit functions. Their complexity may mean that aggregation and simplification of performance measures are often required when using classical optimisation methods. Often minimising costs has been the sole objective with non-commensurable objects translated into costs. When classical optimisation methods address multiple objectives, the relative weightings of each of the objectives must be pre-assigned, or changed iteratively. In real systems planners seek to simultaneously minimise expenditures whilst maximising performance criteria such as reliability and ecological benefits. Given that the historical consensus view that the water planning problem is inherently multi-objective (Cohon and Marks, 1975; Haimes and Hall, 1977) it is critical to move beyond classical commensuration approaches that require a single common unit of measure (typically monetary). The interaction of multiple criteria in the context of investment opportunities has been long discussed in various fields (Brill et al., 1982; Major, 1969) and water is no exception (Maass et al., 1962). Water resource system simulators are able to incorporate non-linearities and explicitly calculate system performance using multiple criteria without the need to translate non- commensurable metrics into a single monetary metric. In combined multi-objective evolutionary optimisation and simulation, a water resource simulator acts as the objective function whose solution is the performance output of the model.
Show more

176 Read more

Influence of Climate Change on the Optimization of Water Supply Systems

Influence of Climate Change on the Optimization of Water Supply Systems

In the last decades, climate change is affecting several aspects of human and natural systems worldwide. Concerning water resources, the main impacts are related to the combined effect of temperature increase and changes in availability and distribution of precipitation, which affects both quantity and quality. The Mediterranean is potentially very sensitive to climate change. In Calabria (Southern Italy) the projected reduction suggests a particular care in matching water resource availability and needs. In this paper, the province of Crotone in Calabria was analyzed as a study case. This area is characterized by a sufficient availability of resources as a whole when compared with the needs of the users, but with an unbalanced distribution through its networks. This condition requires the identification of a resource allocation optimization solution. Using a least-cost optimization model, water resource optimization solutions were identified and compared starting from a review of the existing water supply systems, taking into account both current water availability and possible future availability due to climate change.
Show more

9 Read more

The capacity of refugia for conservation planning under climate change

The capacity of refugia for conservation planning under climate change

The degree to which the actual distribution of refugia corresponds with projected distributions will also depend on stochastic factors, especially the interacting influences of disturbance and climate change (Bradstock 2010). In Tasmania, the distribution of rainforest on nutrient-poor soils is related to topographic fire refugia, with topogra- phy mediating the fire–vegetation feedbacks that main- tain vegetation mosaics (Wood et al. 2011). The evolu- tionary impacts of fire in our case study have been partially incorporated into the results, because the dri- ving models of species richness and compositional dissim- ilarity implicitly account for intrinsic relationships between fire and environmental conditions (Bradstock 2010; Wood et al. 2011). Nevertheless, future fire regimes are likely to be quite different from those that currently prevail in the region, adding uncertainty to our projec- tions (Bradstock 2010). The flexible, multidisciplinary approach we propose above helps in quantifying the capacity of refugia, thereby facilitating their integration into conservation planning and modeling. Our case study demonstrates the utility of this framework for defining, identifying, and prioritizing refugia for conserving bio- diversity under rapid climate change.
Show more

7 Read more

Genetic-Algorithms-Supported Planning of Water-Supply Systems

Genetic-Algorithms-Supported Planning of Water-Supply Systems

Genomes (chromosomes) are made from units called genes, i.e. decision variables arranged in a linear succession where every gene controls the inheritance of one or several characteristics (Fig.2). In the case of water- supply systems, the decision variables can be the diameters of the pipes, the range of which can vary in accordance with supplier-fixed diameters. The genomes can be represented in a number of ways. The simplest approach uses binary encoding where each chromosome consists of a string of binary digits (sequences of ones and zeros). It is important to know which gene carries information about a certain decision variable. For example, the first gene in Fig. 2 controls the inheritance of the value for a tank’s elevation.
Show more

17 Read more

Robust Trajectory Planning for Robotic Communications under Fading Channels

Robust Trajectory Planning for Robotic Communications under Fading Channels

shadowing effects. In this article we will show how to design offline a robust reference trajectory under limited amount of information and high uncertainty about the wireless channel. This trajectory will allow the MR to reach the goal point and completely transmit the content of its buffer to the access point (AP) with a sufficiently high probability.

13 Read more

Robust Path Planning and Feedback Design under Stochastic Uncertainty

Robust Path Planning and Feedback Design under Stochastic Uncertainty

disturbances, are most naturally characterized using stochastic models. 5 With stochastic uncertainty, it is typically not possible to guarantee mission success, defined as reaching the goal region and avoiding all obstacles, since there is always a small probability that a very large disturbance will occur. We can, however, define robustness in terms of chance constraints. These require that mission failure occurs with at most a user-specified probability. Such constraints enable the operator to trade conservatism against performance; a plan with a very low probability of failure will typically require more fuel, or time, to complete. In this paper we are concerned with the problem of optimal chance constrained path planning with feedback design. That is, we would like to design a sequence of feedforward control inputs and a feedback controller that minimizes cost, such as fuel use, while ensuring that the probability of failure is below the required threshold. We are concerned with discrete-time linear systems; prior work showed that a UAV operating at a constant altitude as well as other autonomous vehicles can be approximated as such a system, subject to velocity and turn rate constraints. 6, 7 A number of recent articles have addressed parts of this problem, which we summarize
Show more

12 Read more

A simulation-based multi-criteria management system for optimal water supply under uncertainty

A simulation-based multi-criteria management system for optimal water supply under uncertainty

In contrast, a PWDN does not only overcome obstacles of traditional networks (i.e., open networks), but also provides considerable advantages in water distribution and allocation (Phocaides, 2000). By using a PWDN, water supply to consumers can be achieved with both sufficient discharge and pressure requirements. Due to the high efficiency of PWDN, water loss through conveying process caused by leakage and evaporation can be negligible. Consequently, with the same volume of withdrawn water more users may be supplied. In addition to their easier operation, maintenance, and management, PWDNs can overcome topographic difficulties. Moreover, they make it easier to establish water fees based on volume of consumed water by using water meter that aims to avoid uncontrolled water exploitation (Lamaddalena et al., 2005). Advances in manufacturing processes and constructing techniques have considerably reduced the capital investment compared to open canals (Mays, 2000).
Show more

189 Read more

A global assessment of the impact of climate change
on water scarcity

A global assessment of the impact of climate change on water scarcity

Direct comparisons of projected changes in exposure to water scarcity with other studies is not straightforward because of the application of different climate models, emissions and population scenarios, hydrological models, and measures of water scarcity. An additional issue that complicates inter-study comparisons is the spatial scale at which water scarcity is calcu- lated. We estimated watershed population exposure to water scarcity and aggregated this to the national scale and then to the regional scale. Alternative approaches have conducted analyses at the scale of individual grid cells (Oki and Kanae 2006; Vörösmarty et al. 2000), countries (Oki et al. 2001) and food production units (Kummu et al. 2010). While the above comparisons do not account for these differences, a tentative comparison can be made, however, with two studies that both used a previous version of the hydrological model we applied and a WCI threshold of 1,000 m 3 /capita/year to define water scarcity at the watershed scale (then aggre- gating to country and regional scales). Arnell (2004) calculated a global increase in exposure (in billions of people) by 2055 under A2 of 1.1 to 2.8, across 6 GCMS. Our estimates by 2050 under A2 are 0.7 to 4.7, across 21 GCMs. Arnell et al. (2011) used a “Reference” scenario that is comparable to A1B and calculated a global increase in exposure by 2050 of 0.5 to 1.5 billion across 4 GCMs. Our estimate under A1B is 0.5 to 3.1 billion, across 21 GCMs.
Show more

15 Read more

Global soil organic carbon removal by water erosion under climate change and land use change during AD 1850–2005

Global soil organic carbon removal by water erosion under climate change and land use change during AD 1850–2005

Despite all the differences between the studies that cou- pled soil erosion to the carbon cycle, they all agree that soil erosion by rainfall and runoff is an essential component of the carbon cycle. Therefore, to better constrain the land– atmosphere and the land–ocean carbon fluxes, it is neces- sary to develop new LSM-compatible methods that explic- itly represent the links between soil erosion and carbon dy- namics at regional to global scales and over long timescales. Based on this, our study introduces a 4-D modeling ap- proach that consists of (1) an emulator that simulates the car- bon dynamics like in the ORCHIDEE LSM (Krinner et al., 2005), (2) the Adjusted Revised Universal Soil Loss Equa- tion (Adj.RUSLE) model that has been adjusted to simulate global soil removal rates based on coarse-resolution data in- put from climate models (Naipal et al., 2015), and (3) a spa- tially explicit representation for LUC. This approach repre- sents explicitly and consistently the links between the pertur- bation of the terrestrial carbon cycle by elevated atmospheric CO 2 and variability (temperature and precipitation change),
Show more

22 Read more

Non-Uniformity of Water Demands in a Rural Water Supply System

Non-Uniformity of Water Demands in a Rural Water Supply System

the literature. In rural areas, in the case of or- chards, the hourly non-uniformity index accepts the values of N h =2.7–3.0, and in the case of daily non-uniformity, even N d =13–35 (Wichowski, 2005). In the case of individual farms, daily wa- ter consumption variability is N d =3.5, and hourly variability is N h =2.3–8.9 (Bergel, Kaczor, 2007). Podwójci’s studies from 2010 demonstrated that in the case of multi-family residential develop- ment, the daily non-uniformity index changed from 1.06 to 1.20, depending on the studied sys- tem. The hourly non-uniformity indices amounted to N h =1.7–2.22 for a weekday, and N h =1.65–1.94 for a weekend day (Podwójci, 2011). In the rural water supply systems they studied, Ogiołda and Kozaczek calculated the daily non-uniformity indices to be N d =1.3 or N h =1.7, and hourly non- uniformity to be N h =1.55 or N h =1.62 (Ogiołda, Kozaczek, 2013). Hourly non-uniformity in large cities like Kraków, within a single zone, ranges from 1.312 (Tuesday) to 1.769 (Monday). For the same zone in Kraków, daily non-uniformity over the years 2007–2012 ranged from 1.210 (Thurs- day) to 1.499 (Friday) (Płoskonka, Beńko, 2014). During the application of mathematical model- ing for the purposes of designing the water sup- ply network in Zator commune, the indices at the levels of N h =1.32 and N d =1.21 were adopted for the existing status, and for the prospective status accounting for the Economic Activity Zone (in- dustry), N h =1.65 and N d =1.2 (Wierzbicki, 2015). In the case of tourist locations, the ratio of maxi- mum daily water consumptions to mean water consumption in a month is also checked besides the daily non-uniformity determined for the day of maximum water consumption during the year (Usiudas, Filon, 2011).
Show more

7 Read more

Managing Global Food Supply Chain Risks: A Scenario Planning Perspective

Managing Global Food Supply Chain Risks: A Scenario Planning Perspective

Food is a fundamental requisite for human existence. An agrarian society shows the simplistic form of existence where agriculture forms the core of the society and is the prime means of support and sustenance. That, however, no longer remains the foundation of most of today’s developed economies where food chains are increasingly becoming complex and multi tiered. The chains start with agriculture and ends ultimately, with household consumption. But the numbers of entities between these ends encompass geographical, economic, political and social extremes. This compounded over uncertainty occurring from natural disasters, climate changes, epidemics and terrorist threats place the food supply chain in a particularly vulnerable position. The recent Chinese milk scare which left thousands of Chinese babies ill after consuming melamine tainted milk powder produced by the Chinese Sanlu Group required urgent action by New Zealand, United States and the European Union to issue product warnings to contain the spread of melamine related kidney failure amongst infants in other countries. The more recent case of Salmonella outbreak in America traced to peanut butter manufactured at the Peanut Corporation of America, a factory in Blakely, Georgia caused the immediate recall of 2100 products in 17 categories.
Show more

22 Read more

Global change in streamflow extremes under climate change over the 21st century

Global change in streamflow extremes under climate change over the 21st century

et al., 2013; Koirala et al., 2014). Additionally, Giuntoli et al. (2015) studied changes in frequency of streamflow ex- tremes and not magnitude/intensity. Change in frequency of extremes may be studied using the historical extreme thresh- olds/percentiles, which may come to occupy different points in the streamflow probability distribution under future cli- mate change. A study of change in a 100-year flood re- turn period in the last 3 decades of the 21st century com- pared to the last 3 decades of the 20th century, projected by 11 GCMs under various emission scenarios, shows in- creased flood frequency over south and southeast Asia, north- ern Eurasia, South America, and tropical Africa (Hirabayashi et al., 2013). Another similar study investigated changes in 5th and 95th percentiles of streamflow, projected by the same 11 GCMs (Koirala et al., 2014). However, both these studies used a single river routing model for simulating streamflow using the GCM inputs. However, a single multi-GCM, multi- GHM global analysis of projected changes in magnitude of streamflow (routed runoff) extremes under different warm- ing scenarios over the 21st century is not yet available. Here, we study changes in the magnitude of the 95th percentile of annual streamflow (P95) at the end of the 21st century (2070– 2099, 21C) compared to the end of the 20th century (1971– 2000, 20C), in which an increase may indicate a greater po- tential for flood events. We also study the change in the mag- nitude of the 5th percentile (P5), in which a decrease may in- dicate greater potential for drought events. We study changes in both extremes to understand the changes in streamflow distribution and simultaneous vulnerability profiles to differ- ent types of hydrological risk in different regions. We use daily streamflow simulations from 25 GCM-GHM combina- tions (5 bias-corrected GCMs and 5 GHMs) from the ISI- MIP. We analyze simulated streamflow in 21C in comparison with 20C. GHM-generated
Show more

12 Read more

A novel approach in robust group decision making for supply strategic planning

A novel approach in robust group decision making for supply strategic planning

Organizations of important industries require structured models for decision making. Such organizations have extensive supply networks with undetermined demands, which sometimes require significant changes in processes and rate of responding. In this study, a robust method based on TOPSIS decision making algorithm in a group form is proposed and its ability in military industry is evaluated. In addition to considering locational effect of responses, the proposed method can consider the deviation effect of responses on statistical analysis of decisions. In order to propose long time and medium time decision suggestions, the most important weak points are specified. In this regard, by interviewing with experts, important criteria related to such industries are determined and their related decisions are prioritized.
Show more

11 Read more

Analysis of the water supply-demand relationship in the Sinú-Caribe basin, Colombia, under different climate change scenarios

Analysis of the water supply-demand relationship in the Sinú-Caribe basin, Colombia, under different climate change scenarios

renewable water supply). According to predictions, by 2025, 5 billion people will be affected by water tension. At the same time, flooding may increase in frequency and magnitude in other regions as a result of the growing incidence of heavy rainfall events, which could in turn increase runoff and erosion, making these events negative factors for many industries and purposes (IPCC, 2001a). It is estimated that 65% of the world’s population impacted by natural events has been affected by hydrometeorological phenomena. According to the WMO (2004), during the period 1993-2002, hydrometeorological extremes affected 87% of the people impacted by disasters. Of deaths reported in the period, 52% were the result of drought, and 11% of floods.
Show more

14 Read more

Show all 10000 documents...