The carbon footprint associated with water management policy options in the Las Vegas Valley, Nevada

A system dynamics model was developed to estimate the carbon dioxide (CO2) emissions associated with conveyance of water from the water source to the distribution laterals of the Las Vegas Valley. In addition, the impact of several water management policies, including water conservation, reuse, and population growth rate change was evaluated. The results show that, at present, nearly 0.53 million metric tons of CO2 emissions per year are released due to energy use for water conveyance in distribution laterals of the Valley from Lake Mead, located 32.2 km (20 miles) southeast of the Las Vegas at an elevation of nearly 366 m (1200 ft) below the Valley. The results show that the reduction in per capita water demand to 753 lpcd by 2035 can lower the CO2 emissions by approximately 16.5%. The increase in reuse of treated wastewater effluent within the valley to 77 million cubic meters by 2020 results in the decrease of CO2 emissions by 3.6%. Similarly, change in population growth rate by ±0.5% can result in CO2 emissions reduction of nearly 12.8% by 2035 when compared to the current status

Modeling structural change in spatial system dynamics: A Daisyworld example

System dynamics (SD) is an effective approach for helping reveal the temporal behavior of complex systems. Although there have been recent developments in expanding SD to include systems' spatial dependencies, most applications have been restricted to the simulation of diffusion processes; this is especially true for models on structural change (e.g. LULC modeling). To address this shortcoming, a Python program is proposed to tightly couple SD software to a Geographic Information System (GIS). The approach provides the required capacities for handling bidirectional and synchronized interactions of operations between SD and GIS. In order to illustrate the concept and the techniques proposed for simulating structural changes, a fictitious environment called Daisyworld has been recreated in a spatial system dynamics (SSD) environment. The comparison of spatial and non-spatial simulations emphasizes the importance of considering spatio-temporal feedbacks. Finally, practical applications of structural change models in agriculture and disaster management are proposed

System Dynamical Simulation of Risk Perception for Enterprise Decision-Maker in Communication of Chemical Incident Risks

PresentationSystem Dynamical Simulation of Risk Perception for Enterprise Decision-Maker in Communication of Chemical Incident Risk

An integrated dynamical modeling perspective for infrastructure resilience

International audienceThis paper considers a dynamical way to connect resilience outcomes and processes by nesting process-based approaches inside a controlled dynamical system under resource constraints. To illustrate this, we use a dynamical model of electric power generation to show the complementary aspects of outcome, resources, and process-based approaches for analyzing infrastructure resilience. The results of this stylized model show that adaptation is the most influential process and that for monitoring to be efficient it must account for associated costs. Beyond these specific results, we suggest that nesting outcome- and process-based approaches within a dynamical controlled framework can be very useful and complementary for infrastructure managers and designers tasked with effectively allocating resources for enhancing system resilience

Simulation Modeling for Sustainability: A Review of the Literature

This article is a review of work published in various journals and conference proceedings on the topics of Simulation Modelling for Sustainability between January 2000 and May 2015. A total of 192 papers are reviewed. The article intends to serve three goals. First, it will be useful to researchers who wish to know what kinds of questions have been raised and how they have been addressed in the areas of simulation modelling for sustainability. Second, the article will be a useful resource for searching research topics. Third, it will serve as a comprehensive bibliography of the papers published during the period. The literature is analysed for application areas, simulation methods and dimensions of the triple bottom line model of sustainable development

Framework for assessing and improving the performance of recursive digital filters for baseflow estimation with application to the Lyne and Hollick filter

Baseflow is often regarded as the streamflow component derived predominantly from groundwater discharge. The estimation of baseflow is important for water supply, water allocation, investigation of contamination impacts, low flow hydrology and flood hydrology. Baseflow is commonly estimated using graphical methods, recursive digital filters (RDFs), tracer based methods, and conceptual models. Of all of these methods, RDFs are the most commonly used, due to their relatively easy and efficient implementation. This paper presents a generic framework for assessing and improving the performance of RDFs for baseflow estimation for catchments with different characteristics and subject to different hydrological conditions. As part of the framework, a fully integrated surface water/groundwater (SW/GW) model is used to obtain estimates of streamflow and baseflow for catchments with different properties, such as soil types and rainfall patterns. An RDF is then applied to the simulated streamflow to assess how well the baseflow obtained using the filter matches the baseflow obtained using the fully integrated SW/GW model. In order to improve the performance of the filter, the user-defined parameter(s) controlling filter operation can be adjusted in order to obtain the best match between the baseflow obtained using the filter and that obtained using the fully integrated SW/GW model (i.e. through calibration). The proposed framework is tested by applying it to a common SW/GW benchmarking problem, the tilted V-catchment, for a range of soil properties. HydroGeoSphere (HGS) is used to develop the fully integrated SW/GW model and the Lyne and Hollick (LH) filter is used as the RDF. The performance of the LH filter is assessed using the commonly used value of the filter parameter of 0.925, as well as calibrated filter parameter values. The results obtained show that the performance of the LH filter is affected significantly by the saturated hydraulic conductivity (Ks) of the soil and that calibrated LH filter parameter can result in significant improvements in filter performance. © 2012 Elsevier Ltd.L. Li, H.R. Maier, M.F. Lambert, C.T. Simmons, D. Partingto

A Methodology for Assessing Dynamic Resilience of Coastal Cities to Climate Change Influenced Hydrometeorological Disasters

Confronted with rapid urbanization, intensified tourism, population densification, increased migration, and climate change impacts, coastal cities are facing more challenges now than ever before. Traditional disaster management approaches are no longer sufficient to address the increased pressures facing urban areas. A paradigm shift from disaster risk reduction to disaster resilience building strategies is required to provide holistic, integrated, and sustainable disaster management looking forward. To address some of the shortcomings in current disaster resilience assessment research, a mathematical and computational framework was developed to help quantify, compare, and visualize dynamic disaster resilience. The proposed methodological framework for disaster resilience combines physical, economic, engineering, health, and social spatio-temporal impacts and capacities of urban systems in order to provide a more holistic representation of disaster resilience. To capture the dynamic spatio-temporal characteristics of resilience and gauge the effectiveness of potential climate change adaptation options, a disaster resilience simulator tool (DRST) was developed to employ the mathematical framework. The DRST is applied to a case study in Metro Vancouver, British Columbia, Canada. The simulation model focuses on the impacts of climate change-influenced riverine flooding and sea level rise for three future climates based on the results of the CGCM3 global climate model and two (2) future emissions scenarios. The output of the analyses includes a dynamic set of resilience maps and graphs to demonstrate changes in disaster resilience in both space and time. The DRST demonstrates the value of a quantitative resilience assessment approach to disaster management. Simulation results suggest that various adaptation options such as access to emergency funding, provision of mobile hospital services, and managed retreat can all help to increase disaster resilience. Results also suggest that, at a regional scale, Metro Vancouver is relatively resilient to climate change influenced-hydrometeorological hazards, however it is not distributed proportionately across the region. Although a pioneering effort by nature, the methodological and computational framework behind the DRST could ultimately provide decision support to disaster management professionals, policy makers, and urban planners

Modeling Socio-Hydrological Systems for Wastewater Reused Watersheds

학위논문 (박사)-- 서울대학교 대학원 : 생태조경·지역시스템공학부(지역시스템공학전공), 2014. 8. 박승우.본 연구에서는 유역 수문·수질 해석을 통해 하수재이용에 따른 관개용수에의 영향을 분석하고, 농업생산성과 환경성을 고려한 재이용수 관개 논의 적정 질소시비방법을 제안하고자 하였다. 또한, 시스템 다이내믹스를 이용한 사회-수문시스템 모델링과 과정 사회수문학의 인식틀을 통해 하수재이용에 따른 소규모 사회-수문시스템의 변화과정을 모의 및 분석하였다. SWAT 모형을 이용한 간접재이용에 따른 유역의 수문·수질 응답반응을 실측 수문 및 수질자료를 통해 보정 및 검정한 결과, 구축한 모형이 대상유역에서의 간접재이용 영향을 잘 해석할 수 있는 것으로 평가되었다. 검정된 모형을 이용하여 하수처리장의 유무에 따른 관개용수 취수지점에서의 하천유황 및 관개수질영향을 분석하였다. 하천유황은 하수처리장 방류수를 반영하여 증가하였으며, 갈수량으로 갈수록 하수처리장 방류수의 영향이 큰 것으로 분석되었다. 또한, 허용 가능한 총질소 농도와 농업용수 수질기준의 초과확률이 각각 60%와 40% 이상 증가하는 것으로 분석되어 하수처리장 방류수의 관개용수 수질에의 영향이 상당히 큰 것으로 평가되었다. DSSAT 모형을 이용한 하수재이용에 따른 질소시비방법 모의체계를 구축하였으며, 구축한 모형은 보정 및 검정기간 동안 실측 논벼 수확량을 잘 모의하는 것으로 나타났다. 적정 질소시비량을 관개수 총질소 농도 수준별로 모의한 결과 표준시비량 대비 20~50% 저감된 질소시비량에서도 목표 논벼 수확량을 생산할 수 있는 것으로 분석되었다. 질소시비방법에 대한 논벼 수확량의 민감도를 분석한 결과, 밑거름보다 새끼칠거름과 이삭거름에 더 민감한 것으로 나타났으며, 분시율을 조정함으로써 10~20 kg ha-1 정도의 추가적인 질소시비량 저감이 가능한 것으로 모의되었다. 수문시스템의 물리적 현상을 수식화한 결정론적 총괄형 수문시스템 부모형과 인구, 토지이용, 경제성, 그리고 기술 및 정책수준 등을 수식화한 사회시스템 부모형을 시스템 다이내믹스를 이용하여 하나의 사회-수문시스템 모형으로 구축하였다. 민감도 분석과 극한조건 시험, 그리고 SWAT 모형의 모의결과 및 실측 수문자료와의 비교를 통해 구축한 모형이 구조 건전성과 거동 객관성을 가진 것으로 평가되었다. 인구증가는 하수처리장 방류수를 통해 하천유량과 지하수위, 그리고 하수재이용량을 증가시키는 것으로 모의되었다. 농경지의 도시용지로의 토지이용 변화는 침투량과 농업용수 수요량을 감소시키고, 지하수 관개량의 감소로 지하수위를 상승시킬 수 있는 것으로 분석되었다. 목표 수리답률을 달성하기 위해 지하수 관개 비중을 높일 경우 지속가능하지 않은 지하수 이용이 발생할 수 있으며, 재처리수 관개량을 늘릴수록 목표 수리답률을 보다 빨리, 그리고 안정적으로 달성할 수 있는 것으로 모의되었다. 재처리수 관개시설에 대한 경제성 분석결과, 시설 규모가 작을수록 단위자본비의 영향이 증가하였으며, 재처리수 관개의 경제성에 단위자본비가 단위운영비보다 더 큰 영향을 미치는 것으로 분석되었다. 또한, 하천유지유량을 통한 하천수 취수 제한은 하천유량의 보전뿐만 아니라 보상적 지하수 관개 및 기저유출에 따른 상대적 하천유량의 감소와 사회적 기회비용 또한 야기할 수 있는 것으로 분석되었다. 하수처리장 방류수의 관개용수에의 영향과 대안적 질소시비 방법으로부터 지속가능한 대체수자원으로서의 하수처리수의 농업용수재이용을 위한 합리적인 관리방안을 마련할 수 있을 것으로 기대된다. 또한, 사회-수문시스템 모델링은 수자원 정책결정에 중요한 도구로 활용할 수 있으며, 소규모 사회-수문시스템의 인과관계에 대한 보다 상세한 통찰을 통해 과정 사회수문학의 방법론으로 사용할 수 있을 것으로 기대된다.목 차 초 록 ⅰ 목 차 ⅲ List of Tables ⅶ List of Figures ⅹ 제 1 장 서 론 1 1.1. 연구배경 및 목적 1 1.2. 논문구성 5 제 2 장 연구사 7 2.1. 하수처리수의 농업용수재이용 7 2.2. 수문모형과 하수재이용 유역 수문·수질 모의 9 2.3. 작물생육모형과 적정시비량 모의 11 2.4. 사회수문학과 시스템 다이내믹스 12 제 3 장 SWAT 모형을 이용한 유역 수문·수질 해석 16 3.1. SWAT 모형 16 3.2. 대상유역 및 입력자료 17 3.2.1. 대상유역 17 3.2.2. 수문 및 수질자료 19 3.2.3. 입력자료 22 3.3. 모형의 보정과 검정 28 3.3.1. 유출량 32 3.3.2. 유사량 39 3.3.3. 총질소 42 3.4. 관개용수 영향 분석 45 3.4.1. 하수처리장 방류수 46 3.4.2. 하천유량 49 3.4.3. 관개수질 53 3.4.4. 하수재이용량 56 3.5. 요약 및 결론 58 제 4 장 DSSAT 모형을 이용한 논벼 수확량 모의 60 4.1. DSSAT 모형 60 4.2. 시험포장 및 입력자료 62 4.2.1. 시험포장 62 4.2.2. 입력자료 63 4.3. 모형의 보정과 검정 68 4.3.1. 모형의 보정 68 4.3.2. 모형의 검정 71 4.4. 적정 질소시비 방법 모의 74 4.4.1. 질소시비량에 따른 논벼 수확량 75 4.4.2. 질소시비에 대한 논벼 수확량 민감도 78 4.4.2. 질소시비 분시율에 따른 논벼 수확량 80 4.5. 요약 및 결론 82 제 5 장 시스템 다이내믹스를 이용한 사회-수문시스템 모델링 84 5.1. 시스템 다이내믹스 86 5.2. 대상유역 및 입력자료 88 5.2.1. 대상유역 88 5.2.2. 입력자료 96 5.3. 사회-수문시스템 모델링 111 5.3.1. 문제정의 111 5.3.2. 인과지도 113 5.3.3. 수문시스템 부모형 116 5.3.4. 사회시스템 부모형 127 5.3.5. 사회-수문시스템 모형 146 5.4. 모형의 평가 155 5.4.1. 모형 건전성 156 5.4.2. 모형 객관성 166 5.5. 요약 및 결론 173 제 6 장 하수재이용에 따른 사회-수문시스템 해석 175 6.1. 시나리오 설계 176 6.2. 도시화 영향 분석 177 6.2.1. 인구증가 177 6.2.2. 토지이용 변화 184 6.3. 하수재이용 영향 분석 190 6.3.1. 수문시스템 190 6.3.2. 사회시스템 194 6.3.3. 경제성 분석 202 6.4. 하천유지유량 영향 분석 205 6.4.1. 기준유량의 산정 205 6.4.2. 수문시스템 206 6.4.3. 사회시스템 209 6.5. 사회-수문시스템 모델링의 함의 213 6.6. 요약 및 결론 215 제 7 장 종합결론 217 참고문헌 221 Abstract 242Docto

Combined Strategic-Tactical Planning for Facility Rehabilitation Using System Dynamics and Optimization

Rehabilitation programs are essential for efficiently managing large networks of infrastructure assets and sustaining their safety and operability. While numerous studies in the literature have focused on various aspects of infrastructure rehabilitation, such as rehabilitation processes, deterioration modeling, life cycle cost analysis, project financing, etc., limited efforts have investigated the overall dynamics among these functions and the development of holistic models that can analyze the long-term effect of different strategic policies and their impact on tactical rehabilitation decisions. To support strategic level of decision-making and long-term policy analysis, this research utilized System Dynamics (SD) to study the dynamic interactions among the deterioration, rehabilitation, and budgeting feedback loops. Model performance and suggested policies were also checked against reference modes and verified using various model testing methods to ensure adequacy. The proposed System Dynamics model was then expanded to incorporate four main modules including policy, physical condition, life cycle cost, and sustainability, for the purpose of backlog accumulation analysis. School building facilities were used as the focused asset domain of this study. After identification of key variables based on literature analysis, previous researches on school building facilitates, and experts’ opinion, the dynamic interactions were studied using causal loop diagraming (CLD) methods. The developed CLD was then mapped into a stock-and-flow simulation model incorporating the four integrated modules with all the underlying mathematical relationships. Numerous experiments with different policy scenarios were conducted to investigate the impact of various policies related to rehabilitation, budget distribution, government investment, and private financing. The simulation results clearly indicated that some of the commonly used policies such as condition-based prioritization methods can lead to significant long-term problems in terms of backlog, and showed that equal distribution of budget can be more effective. Simulation results also indicated that the use of private financing for backlog elimination need to be carefully analyzed to determine a proper payback scheme without a negative effect on long-term backlog projections. The SD Model was also adopted to provide optimum policy solutions in terms of the level of budget allocated to rehabilitation of exiting school buildings and construction of new facilities to accommodate future enrolment. The proposed model used facility condition index (FCI) as an industry standard to investigate facility performance and also a utilized a facility risk index (FRI) to account for the risk of failure. The model was used to investigate and compare the effect of using enrolment-based budgeting policies versus an optimized policy solution on a network of 438 elementary school buildings. Results clearly showed that the enrolment-based approach, which has been used by education ministries for a long time, could be significantly improved with the used of policy optimization. The policy solutions form the strategic-level analysis were used to create detailed tactical rehabilitation plans. To support the tactical level of decision-making this research investigated the performance of mathematical mixed integer programming and genetic algorithm (GA) optimization models to handle the large-scale tactical problems. First, various model formulations including an integer, a one-shot binary, and a year-by-year binary formulation were examined for their performance on large-scale problems. A year-by-year formulation was then selected for the network-level analysis and was used with GA-based optimization. To improve the performance of the GA-based model, a segmentation approach was used that was able to eliminate performance degradation, yet exhibited long processing time. Subsequently, an integer programming model was developed on the GAMS/CPLEX optimization tool that resulted in the best solution quality and fast processing time for very large-scale problems (e.g., 50,000 building components). The promising result of the proposed mathematical model was mainly attributed to the formulation of the optimization model, advancements in the used optimization tools, and the separation between project and network level analysis. Combination of the strategic and tactical models developed in this research provides a comprehensive and systematic framework for a combined analysis of rehabilitation plans at both strategic and tactical levels of facility management