We provide a theoretical framework to analyze how climate change influences the Ganges and how this influence affects pollution in the river caused by tanneries in Kanpur, India. We focus on two tanneries, A $A$ and B, $B,$ that are situated on the same bank of the Ganges in Kanpur. Both produce leather and leather production requires the use of noxious chemicals. Tannery A $A$ is situated upstream from tannery B. $B.$ Tannery A's ${Atext{'}s}$ leather production depends on labor use but tannery B's ${Btext{'}s}$ leather production depends on labor use, the chemical waste generated by tannery A, $A,$ and the natural pollution absorbing capacity of the Ganges. In this setting, we perform four tasks. First, we construct a metric that measures the climate change induced mean reduction in the natural capacity of the Ganges to absorb pollution in the time interval [0,t]. $[0,{t}].$ Second, we use this metric and determine the equilibrium production of leather by both tanneries in the benchmark case in which there is no pollution. Third, we ascertain how the benchmark equilibrium is altered when tannery B $B$ accounts for the negative externality foisted upon it by tannery A. $A.$ Finally, we study the impact on leather production and on labor use when the two tanneries merge and then discuss the policy implications stemming from our research.
{"title":"Climate change and river water pollution: An application to the Ganges in Kanpur","authors":"A. Batabyal, K. Kourtit, P. Nijkamp","doi":"10.1111/nrm.12370","DOIUrl":"https://doi.org/10.1111/nrm.12370","url":null,"abstract":"We provide a theoretical framework to analyze how climate change influences the Ganges and how this influence affects pollution in the river caused by tanneries in Kanpur, India. We focus on two tanneries, A $A$ and B, $B,$ that are situated on the same bank of the Ganges in Kanpur. Both produce leather and leather production requires the use of noxious chemicals. Tannery A $A$ is situated upstream from tannery B. $B.$ Tannery A's ${Atext{'}s}$ leather production depends on labor use but tannery B's ${Btext{'}s}$ leather production depends on labor use, the chemical waste generated by tannery A, $A,$ and the natural pollution absorbing capacity of the Ganges. In this setting, we perform four tasks. First, we construct a metric that measures the climate change induced mean reduction in the natural capacity of the Ganges to absorb pollution in the time interval [0,t]. $[0,{t}].$ Second, we use this metric and determine the equilibrium production of leather by both tanneries in the benchmark case in which there is no pollution. Third, we ascertain how the benchmark equilibrium is altered when tannery B $B$ accounts for the negative externality foisted upon it by tannery A. $A.$ Finally, we study the impact on leather production and on labor use when the two tanneries merge and then discuss the policy implications stemming from our research.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43284056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The use of the difference between ecological footprint and biocapacity to evaluate the sustainable development of a country may be biased. Therefore, we discuss the nonlinear impact of the ecological footprint on biocapacity from the perspective of the self‐regulation capacity of the ecosystem, which provides a new perspective for evaluating the sustainability of a country. Using panel data of the G20 countries, this study establishes a panel smooth transition model with a continuous transition process, which abandons the constraints of linear models and agrees with the gradual characteristics of ecosystem evolution. The results show that: (1) For the G20 countries, the influence of ecological footprint on biocapacity presents an inverted “U” curve. (2) From the perspective of the degree of development of a country, the growth of the ecological footprint of a developing country will weaken its biocapacity, whereas that of a developed country will enhance its biocapacity. (3) Economic growth weakens biocapacity, and overheated economic growth may have an irreversible impact on the ecosystem. (4) Technological progress and population density growth will enhance biocapacity.
{"title":"Does ecological footprint affect biocapacity? Evidence from the experiences of G20 countries","authors":"Yongchang Shen, Shujing Yue","doi":"10.1111/nrm.12369","DOIUrl":"https://doi.org/10.1111/nrm.12369","url":null,"abstract":"The use of the difference between ecological footprint and biocapacity to evaluate the sustainable development of a country may be biased. Therefore, we discuss the nonlinear impact of the ecological footprint on biocapacity from the perspective of the self‐regulation capacity of the ecosystem, which provides a new perspective for evaluating the sustainability of a country. Using panel data of the G20 countries, this study establishes a panel smooth transition model with a continuous transition process, which abandons the constraints of linear models and agrees with the gradual characteristics of ecosystem evolution. The results show that: (1) For the G20 countries, the influence of ecological footprint on biocapacity presents an inverted “U” curve. (2) From the perspective of the degree of development of a country, the growth of the ecological footprint of a developing country will weaken its biocapacity, whereas that of a developed country will enhance its biocapacity. (3) Economic growth weakens biocapacity, and overheated economic growth may have an irreversible impact on the ecosystem. (4) Technological progress and population density growth will enhance biocapacity.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43093575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Agegnehu M. Gebre, Mulugeta Dadi Belete, M. Belayneh
Gully erosion is a serious environmental issue in Lake Hawassa Sub‐basin. It has affected a large portion of the catchment, and a large amount of sediment has been transported into the lake. This condition needs to be addressed. However, before conservation techniques are implemented, the gully systems should be mapped, their extent and changes over time need to be measured, and their capacity to produce sediment from their catchments should be determined. The objective of this study were, therefore, to map and analyse the change in gully erosion and quantify the sediment loading rate and sediment yield from the active and connected gullies in Lake Hawassa Sub‐basin using object‐based image analysis (OBIA) with high‐resolution SPOT 5 satellite image of the years 2011 and 2020. This method was integrated with field observation for mapping gully features of the study area, in comparison with automatic digitization carried out with the help of eCogenition Developer Version 9.1 and ArcGIS tools. Overall accuracy and Kappa coefficient were determined and were found to be 85.2% and 0.81, respectively, for the image of year 2020 and 81.1% and 0.76, respectively, for the image of year 2011. Based on the OBIA method, the extent of gullies (in area) were found to be 63.5 km2 in 2011 and 79.9 km2 showing a rapid increase between 2011 and 2020 (an increase of 16.4 km2 (24.4%) in the 10 years considered). The later result shows that 5.53% of the area of the Lake Hawassa Sub‐basin is affected by gully erosion. The maximum gully density in the study area was found to be 589 km/km2 in 2011 and this increased to 884 km/km2 in 2020. The sediment loading rate from the Lake's catchment was found to be in the range of 12.62 to 38.59 ton per hectare per year. The sediment yield from the Lake's catchment was 8.83 to 27.02 t/ha/year. The total annual volume‐based sediment yield at the Lake generated from the gully was 2.39 million cubic meter considering sediment delivery ratio of 70% for fully connected gullies. This result shows that 0.21% of the storage capacity of the Lake was being lost due to sedimentation from the gully system every year. From the result by dividing the total volume of the sediment by the surface area of the lake, one can see that a silt thickness of 2.51 cm was being deposited in the Lake every year.
{"title":"Object‐based image analysis (OBIA)‐based gully erosion dynamics, sediment loading rate and sediment yield study in Lake Hawassa Sub‐basin, Ethiopia","authors":"Agegnehu M. Gebre, Mulugeta Dadi Belete, M. Belayneh","doi":"10.1111/nrm.12368","DOIUrl":"https://doi.org/10.1111/nrm.12368","url":null,"abstract":"Gully erosion is a serious environmental issue in Lake Hawassa Sub‐basin. It has affected a large portion of the catchment, and a large amount of sediment has been transported into the lake. This condition needs to be addressed. However, before conservation techniques are implemented, the gully systems should be mapped, their extent and changes over time need to be measured, and their capacity to produce sediment from their catchments should be determined. The objective of this study were, therefore, to map and analyse the change in gully erosion and quantify the sediment loading rate and sediment yield from the active and connected gullies in Lake Hawassa Sub‐basin using object‐based image analysis (OBIA) with high‐resolution SPOT 5 satellite image of the years 2011 and 2020. This method was integrated with field observation for mapping gully features of the study area, in comparison with automatic digitization carried out with the help of eCogenition Developer Version 9.1 and ArcGIS tools. Overall accuracy and Kappa coefficient were determined and were found to be 85.2% and 0.81, respectively, for the image of year 2020 and 81.1% and 0.76, respectively, for the image of year 2011. Based on the OBIA method, the extent of gullies (in area) were found to be 63.5 km2 in 2011 and 79.9 km2 showing a rapid increase between 2011 and 2020 (an increase of 16.4 km2 (24.4%) in the 10 years considered). The later result shows that 5.53% of the area of the Lake Hawassa Sub‐basin is affected by gully erosion. The maximum gully density in the study area was found to be 589 km/km2 in 2011 and this increased to 884 km/km2 in 2020. The sediment loading rate from the Lake's catchment was found to be in the range of 12.62 to 38.59 ton per hectare per year. The sediment yield from the Lake's catchment was 8.83 to 27.02 t/ha/year. The total annual volume‐based sediment yield at the Lake generated from the gully was 2.39 million cubic meter considering sediment delivery ratio of 70% for fully connected gullies. This result shows that 0.21% of the storage capacity of the Lake was being lost due to sedimentation from the gully system every year. From the result by dividing the total volume of the sediment by the surface area of the lake, one can see that a silt thickness of 2.51 cm was being deposited in the Lake every year.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":"36 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42067705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Decision problems may be subject to objectives or constraints that make the formal model intractable. We propose an adaptive and pragmatic approach to address such nonstandard objectives or constraints, where these are first circumvented for feasibility, then accounted for through heuristics. One example is managing risk and resilience in a natural system facing uncertainty. Our procedure is exemplified in a predator‐prey fisheries system where a reference policy that maximizes expected profits implies a risk of prey stock collapse. The reference policy includes a no‐fishing section for the prey and harvest beyond myopic catch for the predator in parts of state space. We construct heuristic recovery plans, based on the reference policy, to reduce the risk of collapse by partly backing in the auxiliary objective. Under the heuristic policies, system resilience is enhanced with limited economic losses. Via Monte Carlo simulations, we calculate viability probabilities as measures of improved resilience and employ dynamic programming to assess value losses.
{"title":"Greed is good: Heuristic adaptations for resilience in renewable resource management","authors":"Yuanming Ni, L. Sandal, S. Kvamsdal","doi":"10.1111/nrm.12367","DOIUrl":"https://doi.org/10.1111/nrm.12367","url":null,"abstract":"Decision problems may be subject to objectives or constraints that make the formal model intractable. We propose an adaptive and pragmatic approach to address such nonstandard objectives or constraints, where these are first circumvented for feasibility, then accounted for through heuristics. One example is managing risk and resilience in a natural system facing uncertainty. Our procedure is exemplified in a predator‐prey fisheries system where a reference policy that maximizes expected profits implies a risk of prey stock collapse. The reference policy includes a no‐fishing section for the prey and harvest beyond myopic catch for the predator in parts of state space. We construct heuristic recovery plans, based on the reference policy, to reduce the risk of collapse by partly backing in the auxiliary objective. Under the heuristic policies, system resilience is enhanced with limited economic losses. Via Monte Carlo simulations, we calculate viability probabilities as measures of improved resilience and employ dynamic programming to assess value losses.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45783114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Arid and semiarid areas generally face problems of natural resource degradation. In this paper, two indicators are proposed to characterize the utilization of rainwater: rainwater resource utilization quantity (RRU, mm) and rainwater resource utilization rate (RRUR, dimensionless ratio). A spatiotemporal assessment model (rainwater utilization assessment [RUA] model) for the RRUR and its influencing factors is constructed. The RUA model is based on Soil and Water Assessment Tool and Geographically Temporal Weighted Regression. The Zuli River Basin, located on the Loess Plateau in China, was selected as the study basin. The results show that the annual averages of the RRU and RRUR are 164 mm and 0.44, respectively, in the study basin. The RRU ranged from 71.4 to 243.2 mm, and the RRUR ranged from 0.32 to 0.53 during the evaluation period. Eight explanatory variables were selected, of which the leaf area index (LAI) and rainfall had a significant positive effect on RRUR, but there was spatial and temporal variability in the effects. The forest rehabilitation and crop rotations that can increase the LAI can effectively increase the RRUR, which increased by 0.10 and 0.11, respectively, and the increase in RRU was at least 36.42 mm, with a water volume of 3.85 × 108 m3. The impact of grassland rehabilitation and parallel terracing on the RRUR was small. We found that there is an interval effect and a threshold effect on rainfall utilization in the basin. The interval effect causes the RRUR to fluctuate within a certain range for rainfall intervals of 300–400 or 400–500 mm (Zuli River Basin). Threshold effects can guide the determination of the potential for rainwater utilization in different areas to ensure that the RRUR can be effectively enhanced with management measures.
{"title":"Assessment model of rainwater resource utilization and influencing factors in arid and semiarid areas","authors":"Xingyuan Zhang, Fawen Li, Ximin Yuan","doi":"10.1111/nrm.12366","DOIUrl":"https://doi.org/10.1111/nrm.12366","url":null,"abstract":"Arid and semiarid areas generally face problems of natural resource degradation. In this paper, two indicators are proposed to characterize the utilization of rainwater: rainwater resource utilization quantity (RRU, mm) and rainwater resource utilization rate (RRUR, dimensionless ratio). A spatiotemporal assessment model (rainwater utilization assessment [RUA] model) for the RRUR and its influencing factors is constructed. The RUA model is based on Soil and Water Assessment Tool and Geographically Temporal Weighted Regression. The Zuli River Basin, located on the Loess Plateau in China, was selected as the study basin. The results show that the annual averages of the RRU and RRUR are 164 mm and 0.44, respectively, in the study basin. The RRU ranged from 71.4 to 243.2 mm, and the RRUR ranged from 0.32 to 0.53 during the evaluation period. Eight explanatory variables were selected, of which the leaf area index (LAI) and rainfall had a significant positive effect on RRUR, but there was spatial and temporal variability in the effects. The forest rehabilitation and crop rotations that can increase the LAI can effectively increase the RRUR, which increased by 0.10 and 0.11, respectively, and the increase in RRU was at least 36.42 mm, with a water volume of 3.85 × 108 m3. The impact of grassland rehabilitation and parallel terracing on the RRUR was small. We found that there is an interval effect and a threshold effect on rainfall utilization in the basin. The interval effect causes the RRUR to fluctuate within a certain range for rainfall intervals of 300–400 or 400–500 mm (Zuli River Basin). Threshold effects can guide the determination of the potential for rainwater utilization in different areas to ensure that the RRUR can be effectively enhanced with management measures.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42068508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. G. Villavicencio‐Pulido, V. Vázquez–Hipólito, G. J. García‐Cruz
In this work, we propose a socioecological model to describe the effects of visiting tourists in biological attractive sites. We model conditioned interactions between the forest resources and the wildlife with the tourists. This allows us to describe the net benefits–costs rates that the species and their habitats receive from the interaction with tourists. We show that when a scenario of sustainable tourism exists, it is always at risk. This occurs because there is at least a component of the socioecological system that can go to zero when the initial conditions belong to the basin of attraction of a border equilibrium. However, a sustainable equilibrium can be reached when the initial conditions belong to the basin of attraction of a positive attractor. The analysis of the model shows that increasing the tourism carrying capacities can lead to different dynamical patterns. Sometimes, these patterns describe scenarios of unsustainable tourism. When this is the case, by decreasing the negative impact due to the nature and wildlife‐based tourism industry, a tourism sustainability can be reached. Among the scenarios of unsustainable tourism, there are scenarios without wildlife and/or tourists or without both; scenarios in which the ecological and the social variable show sustained oscillations, or scenarios with chaotic patterns for these variables. We show numerical solutions of the model to display different scenarios when the touristic carrying capacities are varied.
{"title":"Catastrophic or sustainable scenarios might occur when the carrying capacities of a tourism‐based socioecological system vary","authors":"J. G. Villavicencio‐Pulido, V. Vázquez–Hipólito, G. J. García‐Cruz","doi":"10.1111/nrm.12365","DOIUrl":"https://doi.org/10.1111/nrm.12365","url":null,"abstract":"In this work, we propose a socioecological model to describe the effects of visiting tourists in biological attractive sites. We model conditioned interactions between the forest resources and the wildlife with the tourists. This allows us to describe the net benefits–costs rates that the species and their habitats receive from the interaction with tourists. We show that when a scenario of sustainable tourism exists, it is always at risk. This occurs because there is at least a component of the socioecological system that can go to zero when the initial conditions belong to the basin of attraction of a border equilibrium. However, a sustainable equilibrium can be reached when the initial conditions belong to the basin of attraction of a positive attractor. The analysis of the model shows that increasing the tourism carrying capacities can lead to different dynamical patterns. Sometimes, these patterns describe scenarios of unsustainable tourism. When this is the case, by decreasing the negative impact due to the nature and wildlife‐based tourism industry, a tourism sustainability can be reached. Among the scenarios of unsustainable tourism, there are scenarios without wildlife and/or tourists or without both; scenarios in which the ecological and the social variable show sustained oscillations, or scenarios with chaotic patterns for these variables. We show numerical solutions of the model to display different scenarios when the touristic carrying capacities are varied.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41847446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The KINEROS2 model was utilized for runoff simulation in the Dehgin catchment situated in the Hormozgan province of Iran. A parameter allocation procedure was used in lieu of parameter optimization. After parameter allocation, the model was able to adequately simulate hydrographs associated with high‐magnitude peak discharge events with the efficiency values between 0.011–0.83 for Nash–Sutcliffe and 0.36–0.98 for Kling–Gupta, but the model did not accurately simulate hydrographs corresponding to low‐magnitude peak discharge events. Although calibration after parameter allocation improved model performance with respect to the simulation of low‐magnitude discharge events, numerical values of the hydraulic conductivity and net capillary pressure as the most sensitive model parameters did not agree with parameters known to be reasonable in the region. So that the value of hydraulic conductivity was decreased from 61 to 55 mm/h in channels and from 3.7 to 1.7 mm/h in planes. The new values are physically reasonable but are not approximately the same as physical values associated with the regional and environmental context of the Dehgin catchment. In this case, the values of the evaluation criteria were obtained between −2.5 and 0.78 for Nash–Sutcliffe and 0.17 and 0.98 for Kling–Gupta. The results of using the HydroPSO package in R to automated calibration of the model, with the value of Nash–Sutcliffe between −0.63 and 0.43, indicated that autocalibration without intelligent and deliberate selection of parameters cannot accurately represent hydrological processes, and therefore should be avoided. Also, the results show that an understanding of the catchment environmental conditions and appropriate allocation of parameters is initially more effective as a first step of the modeling process and thereby contributes to a first‐order characterization of environmental conditions in the catchment.
{"title":"Parameter allocation approach for runoff simulation in an arid catchment using the KINEROS2 hydrological model","authors":"D. Ghonchepour, A. Bahremand, N. Kinar","doi":"10.1111/nrm.12364","DOIUrl":"https://doi.org/10.1111/nrm.12364","url":null,"abstract":"The KINEROS2 model was utilized for runoff simulation in the Dehgin catchment situated in the Hormozgan province of Iran. A parameter allocation procedure was used in lieu of parameter optimization. After parameter allocation, the model was able to adequately simulate hydrographs associated with high‐magnitude peak discharge events with the efficiency values between 0.011–0.83 for Nash–Sutcliffe and 0.36–0.98 for Kling–Gupta, but the model did not accurately simulate hydrographs corresponding to low‐magnitude peak discharge events. Although calibration after parameter allocation improved model performance with respect to the simulation of low‐magnitude discharge events, numerical values of the hydraulic conductivity and net capillary pressure as the most sensitive model parameters did not agree with parameters known to be reasonable in the region. So that the value of hydraulic conductivity was decreased from 61 to 55 mm/h in channels and from 3.7 to 1.7 mm/h in planes. The new values are physically reasonable but are not approximately the same as physical values associated with the regional and environmental context of the Dehgin catchment. In this case, the values of the evaluation criteria were obtained between −2.5 and 0.78 for Nash–Sutcliffe and 0.17 and 0.98 for Kling–Gupta. The results of using the HydroPSO package in R to automated calibration of the model, with the value of Nash–Sutcliffe between −0.63 and 0.43, indicated that autocalibration without intelligent and deliberate selection of parameters cannot accurately represent hydrological processes, and therefore should be avoided. Also, the results show that an understanding of the catchment environmental conditions and appropriate allocation of parameters is initially more effective as a first step of the modeling process and thereby contributes to a first‐order characterization of environmental conditions in the catchment.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43508631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Harald Bergland, P. Mishra, P. A. Pedersen, Arkadi Ponossov, J. Wyller
We analyze the impacts of pollution on fishery sector using a dynamical system approach. The proposed model presupposes that the economic development causes emissions that either remediate or accumulate in the oceans. The model possesses a block structure where the solutions of the rate equations for the pollutant and the economic activity act as an input for the biomass and effort equation. We also account for distributed delay effects in both the pollution level and the economic activity level in our modeling framework. The weight functions in the delay terms are expressed in terms of exponentially decaying functions, which in turn enable us to convert the modeling framework to a higher‐order autonomous dynamical system by means of a linear chain trick. When both the typical delay time for the economic activity and the typical delay time for the pollution level are much smaller than the biomass time scale, the governing system is analyzed by means of the theory for singularly perturbed dynamical systems. Contrary to what is found for population dynamical systems with absolute delays, we readily find that the impact of the distributed time lags is negligible in the long‐run dynamics in this time‐scale separation regime.
{"title":"Time delays and pollution in an open‐access fishery","authors":"Harald Bergland, P. Mishra, P. A. Pedersen, Arkadi Ponossov, J. Wyller","doi":"10.1111/nrm.12363","DOIUrl":"https://doi.org/10.1111/nrm.12363","url":null,"abstract":"We analyze the impacts of pollution on fishery sector using a dynamical system approach. The proposed model presupposes that the economic development causes emissions that either remediate or accumulate in the oceans. The model possesses a block structure where the solutions of the rate equations for the pollutant and the economic activity act as an input for the biomass and effort equation. We also account for distributed delay effects in both the pollution level and the economic activity level in our modeling framework. The weight functions in the delay terms are expressed in terms of exponentially decaying functions, which in turn enable us to convert the modeling framework to a higher‐order autonomous dynamical system by means of a linear chain trick. When both the typical delay time for the economic activity and the typical delay time for the pollution level are much smaller than the biomass time scale, the governing system is analyzed by means of the theory for singularly perturbed dynamical systems. Contrary to what is found for population dynamical systems with absolute delays, we readily find that the impact of the distributed time lags is negligible in the long‐run dynamics in this time‐scale separation regime.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41914899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present initiative study has been planned to develop a conceptual model for watershed resilience for which rare documents have been reported yet, particularly in developing countries where such studies are necessary. In this vein, different ecological, social, economic, and infrastructural and cultural key domains were applied for the modeling processes of watershed resilience for the Shazand Watershed in Iran. To this end, watershed resilience was firstly conceptualized according to the prevailing conditions for three periods 1986–1998, 1999–2008, and 2009–2016. Accordingly, the watershed health index was used for the ecological dimension, and 13, 8, and 13 criteria were consequently considered for social, economic, and infrastructural and cultural dimensions, respectively. The whole data required for the last three dimensions were collected through the distribution of questionnaires among the stockholders of the Shazand Watershed. The principal component analysis (PCA) method was used to weighting and prioritize the criteria and dimensions. The overall resilience index was ultimately calculated by aggregating all four dimensions using a geometric mean. The effect of each dimension on resilience was also assessed by applying multivariable regression. According to the resilience map of the period 2009–2016, 40%, 9%, 34%, and 17% of the Shazand Watershed has been classified as very low and low resilience, moderate, high, and very high resilience. This study showed that the resilience of the Shazand Watershed has improved over time. The necessity of resilience modeling for practical and integrated management of watersheds was also confirmed during the present research.
{"title":"Spatial and temporal zoning of watershed resilience using a multidimensional composition approach","authors":"P. Farzi, S. Sadeghi, M. Jomehpour","doi":"10.1111/nrm.12362","DOIUrl":"https://doi.org/10.1111/nrm.12362","url":null,"abstract":"The present initiative study has been planned to develop a conceptual model for watershed resilience for which rare documents have been reported yet, particularly in developing countries where such studies are necessary. In this vein, different ecological, social, economic, and infrastructural and cultural key domains were applied for the modeling processes of watershed resilience for the Shazand Watershed in Iran. To this end, watershed resilience was firstly conceptualized according to the prevailing conditions for three periods 1986–1998, 1999–2008, and 2009–2016. Accordingly, the watershed health index was used for the ecological dimension, and 13, 8, and 13 criteria were consequently considered for social, economic, and infrastructural and cultural dimensions, respectively. The whole data required for the last three dimensions were collected through the distribution of questionnaires among the stockholders of the Shazand Watershed. The principal component analysis (PCA) method was used to weighting and prioritize the criteria and dimensions. The overall resilience index was ultimately calculated by aggregating all four dimensions using a geometric mean. The effect of each dimension on resilience was also assessed by applying multivariable regression. According to the resilience map of the period 2009–2016, 40%, 9%, 34%, and 17% of the Shazand Watershed has been classified as very low and low resilience, moderate, high, and very high resilience. This study showed that the resilience of the Shazand Watershed has improved over time. The necessity of resilience modeling for practical and integrated management of watersheds was also confirmed during the present research.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43592830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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