Watershed Management Model Research Articles

Updating SWAT+ to Clarify Understanding of In‐Stream Phosphorus Retention and Remobilization: SWAT+P.R&R

AbstractEfforts to reduce riverine phosphorus (P) loads have not been as fruitful as expected or hoped. One reason for the failure of these efforts appears to be that models used for watershed P management have understated and misrepresented the role of in‐stream processes in shaping watershed P export. Here, we update the latest release of the Soil and Water Assessment Tool (SWAT+), a widely used watershed management model, to better represent in‐stream P retention and remobilization (SWAT+P.R&R). We add new streambed pools where P is stored and tracked, and we incorporate three new processes driving in‐stream P dynamics: (a) deposition and resuspension of sediment‐associated P, (b) diffusion of dissolved P between the water column and streambed, and (c) adsorption and desorption of mineral P. The objective of this modeling work is to provide a diagnostic tool that enables researchers to challenge existing assumptions regarding how watersheds store, transform, and transport P. Here, in a first diagnostic analysis, SWAT+P.R&R helps reconcile in‐stream P retention theory (that P is retained at low flows and remobilized at high flows) and a discordant data set in our validation watershed. SWAT+P.R&R results (a) clarify that the theorized relationship between P retention and flow is only valid (for this point‐source affected testbed, at least) at the temporal scale of a single rising‐or‐falling hydrograph limb and (b) illustrate that hysteresis obscures the relationship at longer temporal scales. Future work using SWAT+P.R&R could further challenge assumptions regarding timescales of in‐stream P legacies and sources of P load variability.

Mekânsal otokorelasyon ve kümeleme analizi yaklaşımı ile Göksu Çayı Havzası’nın (Sakarya Nehri Havzası) bütünleşik ve sürdürülebilir havza yönetim modeli

Doğal ve beşeri ortam koşullarının yoğun etkileşim halinde olduğu havzalarda birçok kapsamdaçeşitli modellerle yönetim çalışmaları uygulanmaktadır. Bu araştırmanın amacı, coğrafi çeşitliliği,etkileşimleri ve potansiyel riskleri barındıran Göksu Çayı Havzası’nın farklı değişkenler üzerindenmekânsal otokorelasyon ve kümeleme analizine dayalı havza yönetim modelinin oluşturulmasıdır.Coğrafi Bilgi Sistemlerinin (CBS) etkin kullanıldığı çalışmada, deterministik, kantitatif,korelasyon ve dağılış analizi yöntemleriyle çok basamaklı sistematik oluşturulmuştur. Havzanınbütün coğrafi unsurlarını, etkileşimleri, doğal dinamik işleyiş yapısını ortaya koymak ve ilişkiselolarak kümelenme dağılışını oluşturmak için birçok parametrenin analizleri ile dört ana değişken(alt model) üretilmiştir. Ana değişkenler, jeomorfolojik uygunluk-elverişlilik, yağış akış, çoklu-riskve arazi kullanım modellerinden oluşur. Her bir model karşılıklı olarak mekansal korelasyona tabitutulmuş ve havzanın kümeleme analizi dağılış verisi üretilmiştir. Beş farklı kümenin tespit edildiğiveri, sorun-risk potansiyeli ve sürdürülebilir-uygun kullanım potansiyeli açısından da analizedilmiştir. Daha sonra dağılış verisi, Lokal Moran’s I-Anselin testi ve Getis-Ord Gİ istatistiği ile anlamlılıkve kümelenme açısından test edilmiştir. Analizlerden, havzanın yüksek çerçevesini oluşturansahaların sürdürülebilir-uygun kullanım potansiyeline sahip kümelenme gösterdiği, İnegölOvası, Yenişehir kuzeyi ve Göksu Vadisi’nde sorun-risk potansiyeli yüksek kümelenmenin olduğutespit edilmiştir. Havzada sürdürülebilirliğin sağlanması için, ekolojik sahaların korunması, sel,taşkın, erozyon, heyelan tedbirlerin arttırılması, akarsulardaki su kalitesinin kontrol edilmesi veantropojenik baskı yoğunlaşmasının daha uygun alanlara yönlendirilmesi gerekmektedir.

Predicting soil depth in a humid tropical watershed: A comparative analysis of best-fit regression and geospatial models

As the climate changes, water scarcity is becoming a major global concern. The accurate prediction of soil depth is critical for hydrological modeling under different climate change scenarios for the effective management of humid tropical watersheds. This study determined the best-fit assumption-based (i.e., ordinary least square (OLS)) and assumption-relaxed (partial least squared, quantile, and elastic net) regression models, and compared them with geospatial models (ordinary kriging, universal kriging, regression kriging, and cokriging), for predicting soil depth in a 50 × 150 m humid tropical watershed. Soil depth, apparent electrical soil conductivity (ECa) at two depths of exploration (ECas, 0–0.5 m, and ECad, 0–1.6 m using a DUALEM-1S EC meter), slope gradient, and soil physical and chemical properties measured in-field or using soil samples (0–0.2 m), were determined at each sampling location. Multivariate regression models explained 86–89% of the variability in soil depth and had a comparative root mean square error (RMSE), Lin’s concordance correlation coefficient (LCCC), ratio of performance to deviation (RPD), and prediction error rate (PER) to corresponding ECad univariate models. ECad was a significant predictor in all models except the elastic net regression model. The cokriging model was superior to all regression and geospatial models with the lowest RMSE (0.04) and PER (10 %), and highest LCCC (0.99) and RPD (6.71), and can be used to accurately predict soil depth across the watershed, thereby improving hydrological models for watershed management in this and similar vulnerable humid tropical watersheds. Most interestingly, our results suggest that OLS models are in some cases robust enough to handle violations of their assumptions, implying that data transformation may not always be required for OLS regression. Therefore, it is recommended that the traditional workflow for OLS regression include a validation check using an assumption-relaxed model, the outcome of which would determine the necessity of data transformation.

Pi-VAT: A web-based visualization tool for decision support using spatially complex water quality model outputs

Effective watershed management and protection of water resources from non-point source pollution require identification, prioritization, and targeting of pollutant source areas. Process-based hydrology and water quality models are powerful heuristic tools for land and water resources managers. However, because of their complexity, such models are often under-utilized as management prioritization and planning tools. In this paper, we present a prioritization, interactive visualization, and analysis tool (Pi-VAT) that is programmed to synthesize multi-scenario, multi-watershed outputs from process-based geospatial models. We demonstrate the utility of Pi-VAT to examine simulated hydrologic, sediment, and water quality response at the hillslope/hydrologic response unit (HRU) scale. We apply Pi-VAT to output from multiple watersheds and for multiple management scenarios and treatments from two geospatial models for watershed management: Water Erosion Prediction Project (WEPP) and Soil & Water Assessment Tool (SWAT). Pi-VAT was developed using the Shiny web application framework for the R programming language. In a matter of minutes, Pi-VAT can synthesize overwhelming amounts of output from process-based models into information useful for land and water resources managers. We illustrate the use of Pi-VAT to interactively identify, quantify, and visualize areas that are most susceptible to disturbance under different scenarios and provide a synthesis approach based on land use, soil type, and slope steepness. This approach guides land and water resources managers in prioritizing the areas of the watershed that provide the maximum reduction in pollutant loads while treating the least amount of area. Pi-VAT provides a flexible reactive platform for the development of decision support tools based on process-based models intended for watershed management and research applications.

HAVZA YÖNETİMİNİN GELİŞİM EVRELERİ VE FARKLI MODELLERİ

Havza yönetimi, sınırlarını doğal ortam koşullarının belirlediği alandaki kaynaklarının kullanılması, korunması ve meydana gelebilecek risklerin, kirlilik ve sorunların önüne geçilmesini amaçlayan geleceğe dönük planlama çalışmalarıdır. Bu kapsamda çalışmanın amacını, havza yönetiminin tarihsel süreçte gelişim evrelerini, ortaya çıkan farklı uygulama modellerini ve Dünya ile Türkiye üzerinden örneklerle açıklayarak literatürdeki boşluğu doldurmak oluşturur. Suyun ana unsur olarak düşünüldüğü havzalar ilk olarak su, enerji temini ve tarımsal amaç kapsamında 20. Yy. başlarında ABD ve birkaç münferit ülke ile yönetim çalışmalarının yapıldığı alanlar olmuştur. İkinci Dünya savaşından sonra artan talepler neticesinde su potansiyeli, erozyon, mühendislik çalışmaları ve tarımsal üretime katkı odaklı devam eden havza yönetimi, bilimsel çalışmalar, uluslararası konferans ve sempozyum kararlarından etkilenerek değişime uğramıştır. Özellikle 1990’lı yıllardan itibaren çevre-doğa koruma, sürdürülebilirlik kavramları havza yönetiminde önemli yer edinmiş ve günümüze gelindiğinde bütüncül yaklaşım havza yönetimi çalışmalarının temelini oluşturmuştur. Bütüncül yaklaşımın en önemli çalışmalarından birini, AB’nin Su Çerçeve Direktifi kapsamında uygulamaya koyduğu nehir havzası yönetim sistemi meydana getirmektedir. Günümüzde teknolojik imkânlar, multidisipliner yapı, havza yönetiminde birçok farklı modelin uygulanmasını sağlamakta ve bütüncül anlayışa çeşitli bakış açıları ile destek olmaktadır. Ayrıca ekosistem, ekolojik, coğrafi, kantitatif, sürdürülebilir, katılımcı, risk ve afet analizleri gibi birden çok detayı inceleyen havza yönetim modellerinin varlığı, havzaların analizlerle karşılaştırılabilir olmasını ve uygulanması açısından en doğru yönetim planlamalarının ortaya koymasını sağlamaktadır.

Pengaturan Ideal tentang Pengelolaan Daerah Aliran Sungai di Indonesia (Studi di Sungai Serang Kabupaten Kulon Progo)

Watershed management is closely related to regulations on the affairs of local governance, water resources, spatial planning, as well as soil and water conservation. All forms of regulation relating to watershed management must be strictly regulated as the legal basis for watershed management in Indonesia. This study aims to identify, understand, and analyze the juridical constraints faced in managing watersheds in Indonesia and to analyze the ideal juridical regulatory model for watershed management in Indonesia. This research was conducted using normative juridical research, by focusing on testing the implementation of rules or norms in positive law. The results of the study show juridical constraints in watershed management in Indonesia relating to the Revocation and Substitution of the Water Resources Law; the lack of synchronization between the Water Resources Law, the Regional Government Law and the Soil and Water Conservation Law. Therefore, the authors formulate the ideal form of watershed management arrangements, among others by taking quick and effective steps through district / city regional policies while continuing to synchronize efforts through policies in the form of mandates and tasks of assisting watershed management sub-affairs .

Optimal multi-instrument management of interrelated resources and a groundwater dependent ecosystem

We develop and operationalize an integrated groundwater and watershed management model using data from the Kīholo aquifer on the west coast of Hawai'i Island. Results from a numerical simulation suggest that investment in fencing (passive management) is preferred to invasive species removal (active management) if we are limited to selecting a single conservation tool. However, using both instruments jointly increases net present value relative to using either instrument independently in most cases tested, and the additional benefit of invasive species removal increases as water becomes scarcer. The general results are largely insensitive to variations in the invasive species uptake rate and recharge benefits of fencing, and in all cases, use of both instruments reduces the loss resulting from the imposition of a safe minimum standard for groundwater-dependent ecosystems more effectively than either instrument alone.

A simulation-based bi-level multi-objective programming model for watershed water quality management under interval and stochastic uncertainties.

A simulation-based interval stochastic bi-level multi-objective programming (SISBLMOP) model was proposed in this research, through integrating the global nutrient export from watersheds model, interval parameter programming and stochastic chance-constrained programming into a general bi-level multi-objective programming framework. The SISBLMOP model can handle multiple uncertainties expressed as discrete intervals and probability density functions in both the simulation and optimization processes. System complexities, including the hierarchy structure of upper- and lower-level decision makers, can also be addressed in the model. The proposed model is applied to a real-world case study of the Xinfengjiang Reservoir Watershed in South China to identify the satisfactory implementation levels of multiple best management practices (BMPs). The model results show that multiple BMP schemes for water quality management can be obtained under different upper- and lower-level decision-making and risk-violation scenarios, reflecting the cooperation and gaming results of the two-level decision makers. Consequently, the corresponding BMP implementation costs are acceptable to both the upper- and lower-level decision makers. The model is widely applicable and can be effectively used for water quality management under multiple uncertainties and complexities.

Integration of SWAT and HSPF for Simulation of Sediment Sources in Legacy Sediment-Impacted Agricultural Watersheds.

A total maximum daily load for the Chesapeake Bay requires reduction in pollutant load from sources within the Bay watersheds. The Conestoga River watershed has been identified as a major source of sediment load to the Bay. Upland loads of sediment from agriculture are a concern; however, a large proportion of the sediment load in the Conestoga River has been linked to scour of legacy sediment associated with historic millpond sites. Clarifying this distinction and identifying specific segments associated with upland vs. channel sources has important implications for future management. In order to address this important question, we combined the strengths of two widely accepted watershed management models - Soil and Water Assessment Tool (SWAT) for upland agricultural processes, and Hydrologic Simulation Program FORTRAN (HSPF) for instream fate and transport - to create a novel linked modeling system to predict sediment loading from critical sources in the watershed including upland and channel sources, and to aid in targeted implementation of management practices. The model indicates approximately 66% of the total sediment load is derived from instream sources, in agreement with other studies in the region and can be used to support identification of these channel source segments vs. upland source segments, further improving targeted management. The innovated linked SWAT-HSPF model implemented in this study is useful for other watersheds where both upland agriculture and instream processes are important sources of sediment load.

Restructuring Integrated Watershed Management Models for the Federal Democratic Regime of Nepal

Recent political envision has redesigned the administrative units of Nepal into federal states with the aim of decentralizing the power to ensure the process of rapid sustainable development. As a consequence, all the public service agencies need to restructure their delivery units for achieving goals targeted by the newly adopted administrative regime plan. With the aim of recommending the best watershed management models for this changing context, this paper aims to review existing watershed management models applied in different continents like European union, African union and the United States where they have already adopted this watershed management plans into their federal states or countries union successfully. Although they are geographically distinct and economically advanced, the major approach adopted is a river basin approach with the clear legislative framework. This approach is highly succeeded between interstate (or between member countries) because of political or interstate commitments for the common pool resource water. Clear policies and commitments between member countries or interstate greatly improved the function of this mechanism. With the light of those experiences in the field of watershed management plan adopted in federal or union countries, river based integrated management plan balancing efforts between interstates seems best models in the world, and is also proposed for the new federal republic of Nepal.

Rainwater harvesting potential in a semiarid Southern California city

To determine the rainwater capture potential in a small residential city located in semiarid Southern California, a model of the city's existing storm drainage system was developed using a watershed management model based on the U.S. Environmental Protection Agency's storm water management model. The model analyzes the effect of (1) 2‐ and 10‐year 24‐h storms and (2) dry, average, and wet climatic conditions under five different scenarios, considering (1) single rain barrel, (2) 5 rain barrels, (3) 7 rain barrels, (4) 10 rain barrels, and (5) a storage tank in each residential lot. Results show that, due to its fixed capacity, rain barrel(s) can only save a limited amount of water. A storage tank per lot increases rainwater capture efficiency, which can collect 19% of city's annual reclaimed water volume in an average climatic year. However, storage tanks can only be cost‐effective to residents through financial supports from local agencies.

New methodology of evaluation of best management practices performances for an agricultural watershed according to the climate change scenarios: A hybrid use of deterministic and decision support models

Climate change is a primary driver that alters water pollution hotspots in watersheds, which complicates the use of Best management practices (BMPs) for diffuse pollution mitigation strategies. The objective of this study is to evaluate future changes in BMPs on total phosphorus (TP) loads to the river system, depending on climate change. Current weather data were collected from 2000 to 2010 and future weather data from 2040 to 2050 were obtained from regional climate model simulations based on Representative Concentration Pathways (RCP) 2.6, 4.5, and 8.5 scenarios. This study describes various BMP implementation plans at affordable cost that are adapted to different weather conditions, current (for 2000–2010) and future climate scenarios (for 2040–2050). The Soil and Water Assessment Tool (SWAT), i.e., one of the deterministic models for watershed management, was used to estimate total phosphorus (TP) removal efficiency of various types of BMP at two crop fields (rice paddy and soybean fields) in the Yeongsan River (YR) watershed of Korea. The Non-dominated Sorting Genetic Algorithm II (NSGA-II), i.e., one of the artificial intelligence (AI) models for decision support framework, was applied to obtain allow for trade-off analysis between two conflict objectives, the maximum TP load reduction against implementation costs. The SWAT simulation results showed that the model performance based on the Nash-Sutcliffe efficiency and percent bias was acceptable for simulating three parameters; daily flow discharge, monthly sediment loads, and TP loads in the river. As a result, monthly sediment loads and TP loads increase remarkably under all future climate change scenarios except for July, when a comparable amount of precipitation is recorded during the present and future conditions. New implementation of BMPs, therefore, will be required for future climate change scenarios to achieve 50% TP load reduction in the given watershed condition. Interestingly, parallel terraces which showed good efficiency in reducing TP loads at both fields under the current weather condition cannot be effective any more under the worst-case weather scenario in the future climate. In such a case, detention ponds can be proposed as BMP alternative to parallel terraces. Overall, this study not only demonstrates that watershed management plans using BMPs should be adjusted according to climate change scenarios, but also that the hybrid use of SWAT model and AI can help in refining existing and future BMPs at affordable cost.

Integrated watershed management through multi-level and stepwise optimization for allocation of total load of water pollutants at large scales

The contradictory problem between water quality-induced water shortage and shortage of water quantity has been increasingly emerging. This research aims to control the total pollutant discharge in a transboundary river basin, to improve the water environment, and enhance the capabilities of water resources management and decision-making. The organic connection between the control of total discharge quantity, the reduction of pollutant discharge, and the improvement of water environmental quality is established at large-scale from the perspective of comprehensive decision-making and management. In addition, this paper innovatively proposes a comprehensive watershed management model of multi-level and stepwise optimization for allocation of total load of water pollutants, which is integrated through the Gini coefficients method, the comprehensive weights method, and the minimal optimization model of environmental Gini coefficient. It is capable of optimizing distributions of total amount control of water pollutants in the whole basin and controlling units both spatially and temporally. The model is applied to the Songhua River basin to address the conflicts among regions’ environmental fairness and environmental sustainability. According to the optimization results based on the proposed model, the scheme for the total load allocation of water pollutants developed through optimization is consistent with the actual present situation of Heilongjiang section. Major dischargers like Harbin, Suihua, Qiqihar, and Daqing are mainly controlled, and the control units with a low discharge load were rationally controlled. The study has shown that the model was useful in providing decision-making support for water pollution total amount control of the Songhua River basin.

POLA DAN EVALUASI PENGGUNAAN LAHAN DI SEMPADAN SUNGAI CINANGKA, SUB DAERAH ALIRAN SUNGAI CIMANUK HULU (Pattern and evaluation of land use in Cinangka Buffer Zone, Upper Cimanuk Sub Watershed)

In general, watershed problems are caused by two factors namely natural factors such as rainfall, slopes and soil types and human factors such as policy and socio-economic factors. This study aims to evaluate the existing land use compared to Regional Spatial Planning of Garut in the buffer zone of Cinangka River, which is part of the Upper Cimanuk sub watershed. This research is expected to contribute to the watershed management knowledge and offer an alternative model for watershed management based on dynamic socio-economic conditions. Primary data collection was conducted through field surveys and interviews to the selected farmers whose land we re in the selected areas. The interviews were to find out the reasons for planting the chosen crops . An observation plot of 50 meters for each river boundary as long as 1 km, were made to evaluate the land use. T herefore, total area of observation was 100.000 m 2 or 10 hectare (ha). The study area is dominated by monoculture farming, which is 62% of the total area. Other land uses include bare land and shrubs (13.2%), agroforestry (12.3%), forest trees (trees & MPTS) (11.6%), and other types of land use (1%). The use of monoculture agricultur e in this area is not accordance to the Regional Spatial Plans (RTRW) of Garut Regency in 2011-2031, which allocate s the area of Cinangka sub watershed as community forest cultivation .

Mental Models of Soil Management for Food Security in Peri‐Urban India

Agricultural development during the Green Revolution brought India food sovereignty but food insecurity persists. Increased crop production was promoted without considering the more holistic impact on food security. Scientists, extension agents, and farmers have different perspectives on how soil health relates to food security. Understanding stakeholders’ perspectives is essential to improving extension communication and mitigating consequences. This study uses qualitative interviews to construct mental models of soil health for food security. The study site is a peri‐urban watershed, which is currently participating in the Integrated Farmer Participatory Watershed Management Model (IFPWM). Our study details and defines stakeholders’ mental models of soil health, soil nutrient management, soil sodicity, and food security. A triad belief held by farmers shows the strongly perceived causal relationship between soil health, plant health, and human health. Healthy soil produces healthy food and humans that eat such food will be healthy. Scientists only perceive one condition to achieving food security in the community—food quantity. However, all other stakeholders perceived another risk to food security—food quality. Eating poor quality food is perceived as linked to human health problems in the community. This research suggests the importance of including a fifth dimension of food security, cultural acceptability, within agricultural technology development and dissemination.

GWAM—An Institutional Model to Address Watershed Impacts from Urbanization: Field Validation

With the realization of the limitations to top-down and bottom-up watershed management approaches in addressing issues associated with urbanization, a conceptual framework for a hybrid approach that tries to effectively integrate the advantages of the two approaches while overcoming their respective limitations, grass root watershed management model (GWAM), was proposed and presented. This paper presents the details of implementation and validation of GWAM at Shawsheen River watershed in Massachusetts, USA. An investigation on the major components of GWAM, a common platform to conduct the management, a partnership of two major stakeholder groups from government and non-governmental organizations, and a facilitation mechanisms were carried out in detail to gain the needed understanding on structure, process and function of a successful GWAM. Also the decision making process in addressing three major urban watershed issues; flooding, habitat and aquatic life impairment, and bacterial impairment, were examined through a set of cyclic steps. Based on the lessons learned, GWAM was enhanced as a general hybrid model. The most important challenge in sustaining GWAM was to keep differently motivated stakeholders together. As revealed in the Shawsheen watershed, science should play a key role in keeping differently motivated stakeholders together by providing needed facts, understandings, data, and knowledge. When scientifically sound solutions are vetted through a process of public involvement that supports appropriate regulatory actions, the most effective environmental decisions can be made.

GWAM—An Institutional Model to Address Watershed Impacts from Urbanization: Conceptual Framework

The urbanization process exerts negative multidisciplinary impacts on the integrity of natural watershed conditions. These impacts are best analyzed and addressed with local inputs, as many of these are site specific and require consistent local monitoring along with appropriate policies and regulations from conventional governance in an interdisciplinary platform. With the realization of the limitations to top-down and bottom-up watershed management approaches in addressing issues associated with urbanization, a conceptual framework for a hybrid approach that tries to effectively integrate the advantages of the two approaches while overcoming their respective limitations, the Grass root Watershed Management model (GWAM), is presented in this paper. The model is to establish a self-sustaining and effective institutional forum that can be used in watersheds across geographical and political boundaries while accommodating the urbanization process. GWAM consists of three crucial components: a common platform, a partnership among major groups of stakeholders, and a facilitation mechanism to conduct the watershed management at local lever or grass-root level. With effective integration of the governmental agencies and institutes at the top with the local residents and non-governmental organizations at the bottom, the concept is that the hybrid approach can serve as a self-sustaining model in achieving effective management of urbanization impacts.

Multi-objective game theory model and fuzzy programing approach for sustainable watershed management

This study was carried out with the aim of feasibility evaluation of the application of multi-objective game theory and fuzzy programing approaches for settling balance between economic development and environmental impact as well as to facilitate the respective decision-makings in Zemkan basin, west of Iran. The bi-objectives of multi-objective game theory and fuzzy programing approaches are minimizing the destructive effects on the environment (less erosion and sediments) and maximizing the economical incomes resulted from different land uses (more net present value). Satellite images were used for recognition of different land uses and the areas of these land use. In this study, the environmentalists and Zemkan basin users were selected as environmental and economical players, respectively. The results reveal that Nash bargaining solution, which is the result of the multi-objective game theory model, differs from Pareto optimalities, obtained through the classical multi-objective model. Nash bargaining solution offered more satisfactory solutions based on decision-makers’ priorities. In addition, the overall results showed that the results of fuzzy programming approach were very close to the results of the multi-objective game theory model. Therefore, in both methods, the decision variables of semi-closed forest, open forest, non-irrigated agricultural lands and barren rocky lands were eliminated and the ones of rural areas, urban areas, and water body remained unchanged. The innovation of multi-objective game theory and fuzzy programing approaches, which can be understood and interpreted well by decision makers, is setting a kind of balance between economic and environmental concerns in watershed management. The results also show that multi-objective game theory and fuzzy programing approaches can be applied to many other issues concerning the environmental management. The upcoming researches can concentrate on developing a third objective like social concerns and accordingly tri-objective games would be applied instead of bi-objective ones.

Hurricanes and tropical storms: A necessary evil to ensure water supply?

AbstractSeveral parts of the globe including Southeast North America, the Caribbean, Southeast Asia, Australia, and China are often hit by hurricanes and tropical storms (HTSs), which can deliver a large amount of rainfall within a period of a few days. Although HTSs are mostly studied as disaster agents, considering that they occur during the period when water supply systems are generally depleted, it is important to ascertain their potential contributions toward sustaining water supply. Using the Lake Michie–Little River reservoir system that supplies water to the city of Durham (North Carolina) as a representative test case, we implemented an integrated watershed and reservoir management model, supported by publicly available observations, to evaluate the extent to which HTSs impact water storages. Results indicate that HTSs can have a significant impact on reservoir water storage, with their effects being felt for more than a year for some storms. The impact on reservoir water storage is identified to be primarily controlled by 3 factors, namely, streamflow response size from HTSs, storage in the reservoir right before the event, and streamflow succeeding the event response to HTS (henceforth referred as postevent streamflow). Although the impact of streamflow response size on water storage is generally proportional to its magnitude, initial water storage in the reservoir and postevent streamflow have a nonmonotonic influence on water storage. As all the 3 identified controls are a function of antecedent hydrologic conditions and meteorological forcings, these 2 factors indirectly influence the impact of HTS on water storage in a reservoir. The identification of controlling factors and assessment of their influence on reservoir response will further facilitate implementation of more accurate estimation and prediction frameworks for within‐year reservoir operations.

Australia & Brazil: Ampacet – masterbatch

Climate change is a primary driver that alters water pollution hotspots in watersheds, which complicates the use of Best management practices (BMPs) for diffuse pollution mitigation strategies. The objective of this study is to evaluate future changes in BMPs on total phosphorus (TP) loads to the river system, depending on climate change. Current weather data were collected from 2000 to 2010 and future weather data from 2040 to 2050 were obtained from regional climate model simulations based on Representative Concentration Pathways (RCP) 2.6, 4.5, and 8.5 scenarios. This study describes various BMP implementation plans at affordable cost that are adapted to different weather conditions, current (for 2000–2010) and future climate scenarios (for 2040–2050). The Soil and Water Assessment Tool (SWAT), i.e., one of the deterministic models for watershed management, was used to estimate total phosphorus (TP) removal efficiency of various types of BMP at two crop fields (rice paddy and soybean fields) in the Yeongsan River (YR) watershed of Korea. The Non-dominated Sorting Genetic Algorithm II (NSGA-II), i.e., one of the artificial intelligence (AI) models for decision support framework, was applied to obtain allow for trade-off analysis between two conflict objectives, the maximum TP load reduction against implementation costs. The SWAT simulation results showed that the model performance based on the Nash-Sutcliffe efficiency and percent bias was acceptable for simulating three parameters; daily flow discharge, monthly sediment loads, and TP loads in the river. As a result, monthly sediment loads and TP loads increase remarkably under all future climate change scenarios except for July, when a comparable amount of precipitation is recorded during the present and future conditions. New implementation of BMPs, therefore, will be required for future climate change scenarios to achieve 50% TP load reduction in the given watershed condition. Interestingly, parallel terraces which showed good efficiency in reducing TP loads at both fields under the current weather condition cannot be effective any more under the worst-case weather scenario in the future climate. In such a case, detention ponds can be proposed as BMP alternative to parallel terraces. Overall, this study not only demonstrates that watershed management plans using BMPs should be adjusted according to climate change scenarios, but also that the hybrid use of SWAT model and AI can help in refining existing and future BMPs at affordable cost.