scholarly journals Water demand predictions for megacities: system dynamics modeling and implications

Water Policy ◽  
2017 ◽  
Vol 20 (1) ◽  
pp. 53-76 ◽  
Author(s):  
Huanhuan Qin ◽  
Ximing Cai ◽  
Chunmiao Zheng

Abstract Sustaining the water supply in megacities is an enormous challenge. To address this challenge, it is especially important to predict water demand changes in megacities. This paper presents a system dynamics model to predict the future water demands of different sectors considering multiple factors, including population, structure of the economy, and water supply and use technologies. Compared with traditional methods such as the time series method and structure analysis method, the proposed model takes into account the interconnections, non-linear relationships and feedbacks between the various factors in a systems context. The model is applied to Beijing, a megacity with a population over 20 million and very limited water availability. It is found that the total water demand is likely to increase by at least 36.1% (up to 62.5%) by 2030 compared with that in 2011, and the water deficits vary from −0.36 × 109 to 1.80 × 109m3 in 2030. In addition, scenarios are designed to account for impacts associated with economic development, climate change and inter-basin water transfers. It is shown that climate change may have a large impact on the water supply reliability in Beijing. The water shortage problems can be alleviated via inter-basin water transfers.

2020 ◽  
Author(s):  
Sleemin Lee ◽  
Doosun Kang

<p>Water resources are essential for human life and closely related to various social and economic factors (e.g. land use, population, economic development, environment, etc). Also, such human activities affect hydrological environment conversely. Thus, socio-hydrology interdisciplinary studies that consider both hydro-engineering and socio-economic behavior are needed. Multi-purpose dam is a large water infrastructure mitigating water-related disasters by flood control and stable water supply. However, the effectiveness of multi-purpose dam besides the disaster mitigation has not been well analyzed, such as the social and economic influence to downstream area. This study aims to understand the relationship between the socio- and hydrology-sectors and quantitatively analyze the effects of the multi-purpose dam in target area. The representative components of socio-sector are population, land use, GRDP (gross regional domestic product), and flood/drought damages, and the hydrology-sector includes dam inflow/outflow, precipitation, and water demand. A causal loop was developed to identify the causal relationship between the socio- and hydrology-components, and a socio-hydrology system model was constructed using a system-dynamics technique. Various climate and socio-economic scenarios were applied to analyze the future effects of the multi-purpose dam on the population, regional economy, water supply, and flood damage prevention of the target area. The constructed socio-hydrology model can be used in decision-making for efficient water management and water facility planning.</p><p> </p><p>Keywords: Climate change, Multi-purpose dam, Socio-hydrology, System-dynamics modeling</p><p>                                                                 </p><p>Acknowledgment: This study is supported by Korea Ministry of Environment (MOE) as “Graduate School specialized in Climate Change”.</p>


2021 ◽  
Author(s):  
Mehri Abdi-Dehkordi ◽  
Omid Bozorg-Haddad ◽  
Abdolrahim Salavitabar ◽  
Hugo A. Loáiciga

Abstract Inter-basin water transfers are widely implemented to counter the uneven geographical distribution of natural water sources. The Big Karun Basin, Iran, has long been of interest to water managers due to its discharge potential, and where several water transfer projects are operated or are under study. This study implements system dynamics modeling (SDM) to the Big Karun Basin consisting of 6 dams, 12 drinking and industrial consumers, 7 fish farmers, 31 agricultural consumers, 5 operational inter-basin water transfer projects, and 7 under-study inter-basin water transfer projects. SDM was applied considering existing inter-basin water transfers. The results show an average annual 8 to 10 billion cubic meters of water is transfered from the Karun River to the Persian Gulf. Part of this flow can be used to meet some of the water demands in the central and eastern basins of Iran subject to accurate social and environmental assessment of impacts. SDM modeling was also implemented accounting for all existing water transfers plus under-study water transfers. The results indicate the firm energy from hydropower produced by the Big Karun Basin system would decrease by 28% relative to existing water transfer conditions. This issue raises concerns given the Big Karun Basin contribution to electricity production Iran. The water supply to several sectors would be marginally impacted by future water tranfers, yet water quality would be compromised in some instances. Therefore, the Big Karun Basin water system was simulated considering inter-basin water governance based on hedging rules for the under-study water transfers. Results indicate the minimum demands of destination basins and source basin (drinking and industrial consumers) couldbe met, the hydropower energy could be generated with a high reliability when implementing inter-basin water governance. The results also indicate the firm energy from hydropower produced by the Big Karun Basin system would decrease by 12% relative to existing water transfer conditions and the vulnerability of the water system would decrease in terms of required quality for downstream demands and water users relative to the full-transfer water condition.


Author(s):  
T. Z. Saad Omer ◽  
S. E. Ahmed ◽  
A. Karimi

The Roseires-Sennar Dams System (RSDS) at lower part of Blue Nile River play a vital role in water supply to the irrigation schemes in Sudan. The existing rule curves for this system belong to 1925 and 1966 for Sennar and Roseires reservoirs, respectively. Introduction of new irrigation schemes, approved climate change impacts on Blue Nile River flow and upstream developments in Ethiopia as well as the heightening of the Roseires Dam from elevation 480 to 490 m.a.s.l have shown the RSDS is losing its efficiency in terms of fully supplying the water demands. The literature addresses the simulation of Roseires and Sennar dams, and tries to find the best coordinated rule curves through a limited number of operation rules to find optimal operating rules for reservoirs that minimize the impacts of new developments, water demand growth and climate change on water supply to various demands on Blue Nile River. Such decisions are locally optimal in best condition since they do not consider the storage and carry-over capability of reservoirs that can transfer the non-optimal (locally optimal) decisions to other time steps of planning horizon and creat shortages in other time steps. Therefore, aim of this research is to find optimal coordinating operation rules for Roseires and Sennar dams that through a non-linear multi-period optimization model that considers the conditions of climate change, flow regime and water demand as scenarios. Model is validated by comparison with observed reservoir operation during November 1999 till May 2000. Eighteen scenarios that cover the normal, dry and very dry flow regimes, along with three suggested crop patterns and climate change impact are analyzed. Results shows in normal conditions of flow, crop pattern 2 is the most recommended with more than 11 Billion USD marginal profit and fully supplying the water demand and 1530 GWh energy generation per annum. The coordinated rule curves have a totally different pattern of emptying and filling compared with existing ones. Rule curves change from one flow regime to another, which proves how change in conditions of the system has influence on optimal operation rules. Comparison of marginal profits with crop pattern 2 shows in three inflow conditions of normal, dry and very dry years multi-period optimization model could keep the marginal profits above 11 Billion USD, let’s say, 11,050, 11,056 and 11,042 Billion USD, respectively, which shows the robustness of model in dealing with all conditions and keeping the marginal profits not affected. However, the Roseires rule curves are different in these three condition, while Sennar rules curves are almost the same. Without climate change impact, model can manage to supply the water demands fully in all flow conditions. However, water supply reliability is affected by climate change with all crop patterns. Roseires-Sennar Dams system in a normal year under climate change can produce 10,688 Billion USD marginal profit and 1371 GWh per year energy. It shows that model could manage the system performance so that climate change decrease the marginal profit by 3.27%, while inflow is reduced by 25% and water demands and evaporation increased by 19%. Energy generation under climate change has decreased by 10.5%, which is the most affected sector. Crop pattern 2 and 3 are not suitable for climate change conditions since up to 65% deficit in water supply can happen if very dry year realizing with climate change. In very dry conditions crop pattern 1 is more suitable to be practiced.


2014 ◽  
Vol 14 (6) ◽  
pp. 1057-1066 ◽  
Author(s):  
Ying Xie ◽  
Xuyong Li ◽  
Chunsheng Yang ◽  
Yang Yu

Water shortage is a major problem in northern China, because of a huge population and rapid economic growth. Taking the Luanhe River Basin (LRB) as a study area, we set up a System Dynamics (SD) model of the basin for the period 2005–2010, and considered various important socioeconomic and environmental factors and their correlation. Significant trends for the period 2011–2030 were simulated and the water resource carrying capacity (WRCC) of the LRB and its trends over the next 30 years were analyzed. The results indicate a decreasing trend of WRCC in the basin and that current economic growth is not sustainable. The study investigated possible optimized allocation projects. The most apt project would involve a combination of strategies that could considerably increase the WRCC, reduce demand, and improve water quality.


2018 ◽  
Vol 10 (4) ◽  
pp. 938-952 ◽  
Author(s):  
Elham Ebrahimi Sarindizaj ◽  
Mahdi Zarghami

Abstract During the last decade, Urmia Lake has lost most of its surface area. As a result, finding management practices to restore the sustainable ecological status of Urmia Lake, the world's second largest hyper-saline lake, is imperative. In this study, the sustainability of different plans under climate change was assessed using system dynamics. The plans were evaluated with respect to sustainability criteria including reliability, resiliency, and vulnerability measures. According to the results due to different management practices, on average, water consumption should be reduced by at least 30% to restore the lake. The results revealed that only hybrid plans which incorporate multiple management practices, instead of focusing on just one approach, can be influential. Among the hybrid plans, that of increasing irrigation efficiency, reducing cultivated area, changing crop pattern, and inter-basin water transfer was identified as the most sustainable plan. About eight years after applying this plan, the lake will achieve its ecological level and will remain sustainable. Considering comprehensive factors, the proposed model can help watershed managers to take the necessary measures to restore this vital ecosystem. The results of this study can be applied to water resources systems with the same problem, especially those in semi-arid regions with multidisciplinary aspects.


2020 ◽  
Author(s):  
Majed Khadem ◽  
Richard Dawson ◽  
Claire Walsh

<p>Uneven distribution of water resources in the face of climate change and population growth is imposing increasing threats to communities as well as challenging decision-makers. Inter-basin water transfer (IBT) schemes have been appreciated as one of the common approaches to tackle this issue. This work presents a framework for climate impact assessment and feasibility study for IBTs. The framework investigates negative impacts of IBTs on the donor and receiving bodies. This is done by calculating hydrological drought risk and environmental risks to freshwater habitats under 1200 future climatic scenarios and two different transfer scenarios. 2.2 Km resolution time-series from UK’s Met Office most recent climate projection (UKCP18) is used as the input scenario and a water resources model developed at Newcastle University is implemented to determine allocation and calculate the above risk factors. This work considers transferring raw water from England’s water-rich North East to its water-stressed South East as the case study. This case was chosen because England, with no major IBT scheme, is experiencing challenges from more frequent climate change and increasing demand for water in London. Additionally, organisations such as National Infrastructure Commission (NIC) and Environment Agency (EA) have encouraged England’s water companies to consider IBT as one of the options to improve water supply resilience. In this study, we assess schemes to transfer water using the existing infrastructures of water companies located from North East to South East of England to minimise costs and environmental impacts. Results suggest that, under a wide range of future scenarios, meeting London’s annual water shortage through transfers from the North East during wet season of each year not only increases London’s water supply resilience but also boosts flood resilience in the North East donor basin while still meeting environmental requirements.</p>


2013 ◽  
Vol 16 (3) ◽  
pp. 710-730 ◽  
Author(s):  
Pao-Shan Yu ◽  
Tao-Chang Yang ◽  
Chen-Min Kuo ◽  
Shien-Tsung Chen

This paper aims to propose a decision support system (DSS) for evaluating the climate change impacts on water supply–demand and inundation; and assessing the risks for water shortage and inundation under future scenarios. The proposed DSS framework is universal and flexible, which comprises five modules integrated by a geographic information system platform, including the modules of (1) scenario rainfall and temperature projection under climate change, (2) impact assessment of water supply–demand, (3) impact assessment of inundation, (4) assessment of vulnerability and risk, and (5) adaptation strategy. A case study in southern Taiwan was performed to demonstrate how the DSS provides information on the climate change impacts and risks under future scenarios. The information is beneficial to the authorities of water resources management for understanding the spatial risks for water shortage and inundation, and planning suitable adaptation strategies for the locations with larger risks.


Agronomy ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1657
Author(s):  
Chul-Hee Lim

Climate change has inherent multidisciplinary characteristics, and predicting the future of a single field of work has a limit. Therefore, this study proposes a water-centric nexus approach for the agriculture and forest sectors for improving the response to climate change in the Korean Peninsula. Two spatial models, i.e., Environmental Policy Integrated Climate and Integrated Valuation of Ecosystem Services and Tradeoffs, were used to assess the extent of changes in agricultural water demand, forest water supply, and their balance at the watershed level in the current and future climatic conditions. Climate changed has increased the agricultural water demand and forest water supply significantly in all future scenarios and periods. Comparing the results with RCP8.5 2070s and the baseline, the agricultural water demand and forest water supply increased by 35% and 28%, respectively. Water balance assessment at the main watershed level in the Korean Peninsula revealed that although most scenarios of the future water supply increases offset the demand growth, a risk to water balance exists in case of a low forest ratio or smaller watershed. For instance, the western plains, which are the granary regions of South and North Korea, indicate a higher risk than other areas. These results show that the land-use balance can be an essential factor in a water-centric adaptation to climate change. Ultimately, the water-centric nexus approach can make synergies by overcoming increasing water demands attributable to climate change.


2021 ◽  
Vol 3 ◽  
Author(s):  
Pennan Chinnasamy ◽  
Aman Srivastava

Traditional tanks in arid regions of India have been working to address water demands of the public for more than 2000 years. However, recent decade is witnessing growing domestic and agricultural water demand coupled with rising encroachment and ignorance toward tanks; consequently, intensifying water shortage issues. While climate change is impacting at alarming rates, local agencies have forgotten these tanks that have aided in sustainable water supply solutions for decades apart from municipal water supply. This research, for the first time, estimates water supply-demand for an arid region in South India (Madurai) and lists out the benefits if tanks were managed and desilted. Exploratory investigations for documenting seasonal domestic and agricultural unmet water demand were conducted followed by their validation through ground-truthing across the study period 2002–2019. Results indicated high unmet domestic water demand, estimating ~73% [maximum 365 thousand cubic meters (TCM)] for summer (March to May) and ~33% (maximum 149 TCM) for winter (January and February), and high unmet agricultural water demand estimating ~90% (maximum 5,424 TCM) during North-East monsoon (October to December), and ~95% (maximum 5,161 TCM) during South-West monsoon (June to September). Erratic rainfall pattern was identified as a major cause for higher fluctuations in water availability inside tanks ranging 0–50%, while lack of ownership resulted in increased siltation load ranging 30–70% of the tank's volume. The study found that the major portion of the unmet water demand can be accounted for through rehabilitation of the tanks, as under the rehabilitated tank irrigation scenario the tank storage could attain 200–400% more water than the estimated agricultural water demand. It was concluded that if the cascade tanks were managed appropriately, they could have positive impacts by reducing floods and providing water for drought seasons.


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