Mehdi Ketabchy - Profile on Academia.edu (original) (raw)
Papers by Mehdi Ketabchy
Probabilistic Quantitative Precipitation Forecast for Flood Prediction: An Application
Journal of Hydrometeorology, 2008
This paper outlines a methodology to produce probabilistic quantitative precipitation forecasts b... more This paper outlines a methodology to produce probabilistic quantitative precipitation forecasts by means of a dedicated uncertainty processor for weather model output. The uncertainty processor is developed as a component of a Bayesian forecasting system for river flow prediction. In this context the quantitative precipitation forecast is envisaged as a mixed binary–continuous predictand. The processor is applied to the quantitative precipitation forecasts and to precipitation observations covering a 5-yr period, whereby the forecasted and observed relative air humidity are used as ancillary meteorological indicators. The application of the processor to the selected dataset highlights a significantly larger skill of the quantitative precipitation forecast in predicting event occurrence rather than event depth and provides an objective quantification of the forecast uncertainty. The methodology applied here remains restricted to small basins, in which spatial variability of precipita...
6 CP: 4.0×10 6 *based on Herb et al. 2010 and Rossman, 2009 **represents the current properties o... more 6 CP: 4.0×10 6 *based on Herb et al. 2010 and Rossman, 2009 **represents the current properties of roofs/pavement, or baseline scenario of pavements/roofs properties; ***RR: Residential Roof; CR: Commercial Roof; GR: Galvalume Roof; CP: Concrete Pavement ****H: Higher than baseline scenario; L: Lower than baseline scenario. ***** Scenario 10 represents assumption of 6-year concrete age, while scenario 9 assumed concrete pavement newly constructed.
Design Principles of Permeable Pavement in Pollutants Removal from Surface Runoff
Sustainability, 2021
Iran is suffering from a state of water bankruptcy. Several factors have contributed to the curre... more Iran is suffering from a state of water bankruptcy. Several factors have contributed to the current water resources bankruptcy, ranging from anthropogenic impacts, such as an inefficient agricultural sector and aggressive withdrawal of groundwater, to climatological impacts. This paper suggests that water resources mismanagement in Iran should be evaluated beyond the policy-makers decisions, as it recognizes that the bankruptcy has been intensified due to the structural and institutional form of the political system in Iran. This study discusses the roots of the water bankruptcy and identifies four major shortcomings caused by the political system: (1) the absence of public engagement due to the lack of a democratic and decentralized structure; (2) adopting ideological policies in domestic and foreign affairs; (3) conflicts of interest and the multiplicity of governmental policy-makers and sectors; and (4) a state-controlled, resource-dependent economy. Through the development of a ...
Implications and Symptoms: Role of the Water Governance Components in Iran on the Existing Water Bankruptcy
The effect of piping stream channels on dissolved oxygen concentration and ecological health
Environmental Monitoring and Assessment
The Effect of Piping Stream Channels on Dissolved Oxygen Concentrations and Ecological Health
SSRN Electronic Journal
An Overview on Geographic Information System (GIS) Application in Environmental Management, Case Study: Algae Growth Assessment in Tampa Bay
Today's world is the world of information and its optimal management. Since major parts of th... more Today's world is the world of information and its optimal management. Since major parts of the decisions adopted by managers and urban planners at a regional macro level are somehow related to a specific situation with a location-source nature, the existence of precise, reliable and timely geographical information and its optimal management is necessary; Therefore there are no other options than using novel mechanized tools and technologies such as Geographic Information System (GIS) for their purpose. GIS enables environmental planners and decision makers for a time-efficient and cost-effective analyses. One of the most important parts of water and environmental management is quality studies of water resources such as rivers, estuaries, lakes, etc. In quality discussions of lakes and bays, the phenomenon of algal growth is of particular importance. Here, Tampa bay which is the part of the Gulf of Mexico and adjacent to the State of Florida is selected as the study area. By GIS ...
Evaluating the Effects of Piped Lengths of Buried Channels on Temporal and Small-Scale Spatial Variations of Streams Dissolved Oxygen Dynamics
Sunlight plays an important role in regulating the nutrient cycle in streams. Throughout the year... more Sunlight plays an important role in regulating the nutrient cycle in streams. Throughout the years, more streams are buried to accommodate for residential or commercial facilities. This results in ...
The effects of land use characteristics on urban stormwater quality and watershed pollutant loads
Science of The Total Environment, 2021
Urban developments can result in higher runoff and nutrient loadings transported to downstream re... more Urban developments can result in higher runoff and nutrient loadings transported to downstream receiving waterbodies. While much effort has been made recently in watershed restoration in the U.S., a lack of recent runoff quality data limits the prediction capability of urban watershed models. The objectives of this study was to fill an existing information gap on how rainfall and land uses interact and affect such loadings. This study instrumented six coastal urban catchments, each dominated by a single land use. We measured total nitrogen (TN), total phosphorus (TP), total suspended solids (TSS), total Kjeldahl Nitrogen (TKN), ortho-P, and nitrate concentrations in runoff from 30 storm events over one year from six urban land uses, namely commercial, industrial, transportation, open space, low density residential, and high density residential. Results indicated that the median event mean concentrations (EMCs) for TSS, TP, and TN were 30 (19-34), 0.31 (0.26-0.31), and 0.94 (0.73-1.25) mg L-1, respectively. TSS EMCs from the open space and industrial land uses were significantly greater than other land uses; there were positive correlations between TN concentrations and imperviousness and between TP concentrations and turf coverage. Both the amount and intensity of rainfall positively influenced TSS concentrations in runoff regardless of land use. Using the collected data, this study developed a generic equation for predicting the loading of a pollutant as a function of rainfall depth. This equation was verified by comparing its predictions with the simulations of a sufficiently-calibrated water quality model in terms of TSS, TP, and TN loadings from various land uses in another coastal catchment for a period of ten years. Average TSS, TN, and TP loadings from the catchment were estimated to be 0.86, 0.03, and 0.01 kg ha-1 cm-1, respectively.
Environmental Modelling & Software, 2019
Hydrologic models such as the Storm Water Management Model (SWMM) and the Hydrologic Simulation P... more Hydrologic models such as the Storm Water Management Model (SWMM) and the Hydrologic Simulation Program-Fortran (HSPF) are widely used to evaluate the impacts of urban development on watersheds and receiving waters. We compare the ability of these two models at simulating streamflow, peak flow, and baseflow from an urban watershed. The most sensitive hydrologic parameters for HSPF were related to groundwater; for SWMM, it was imperviousness. Both models simulated streamflow adequately; however, HSPF simulated baseflow better than SWMM, while, SWMM simulated peak flow better than HSPF. Global Sensitivity Analysis showed that variability of streamflow for SWMM was higher than that of HSPF, while variability of baseflow for HSPF was greater than that of SWMM. Further, analysis of extreme storm events indicated that the runoff coefficient for SWMM was slightly greater than HSPF for recurrence intervals of 1, 2, 5, and 10-yr.; the opposite was the case for recurrence intervals greater than 10 yrs.
Science of The Total Environment, 2019
We assessed thermal mitigation practices (TMPs) applied to an urban watershed. • We used MINUHET,... more We assessed thermal mitigation practices (TMPs) applied to an urban watershed. • We used MINUHET, SWMM, and a hybrid model for the assessment. • A sensitive species, brook trout (Salvelinus fontinalis), was used as an indicator. • Enhanced forest canopy mitigated stream temperatures better than other TMPs. • The best mitigation strategy was a combined one, which reduced heat loads by 62%.
Science of The Total Environment, 2019
Runoff water quality from a container nursery was assessed. • SWMM characterized runoff quantity ... more Runoff water quality from a container nursery was assessed. • SWMM characterized runoff quantity and quality reasonably well. • Storm TSS EMCs were higher than irrigation EMCs, while TN and TP were comparable. • TSS, TN and TP storm loads were ≈900, 35 and 50 times greater than irrigation loads. • TSS, TN and TP mean annual loads were 11,100, 80.3, and 11.1 kg•ha -1 •yr -1 , respectively.
Environmental Science and Pollution Research, 2018
The passengers inside vehicles could be exposed to high levels of air pollutants particularly whi... more The passengers inside vehicles could be exposed to high levels of air pollutants particularly while driving on highly polluted and congested traffic roadways. In order to study such exposure levels and its relation to the cabin ventilation condition, a monitoring campaign was conducted to measure the levels inside the three most common types of vehicles in Tehran, Iran (a highly air polluted megacity). In this regard, carbon monoxide (CO) and particulate matter (PM) were measured for various ventilation settings, window positions, and vehicle speeds while driving on the Resalat Highway and through the Resalat Tunnel. Results showed on average in-cabin exposure to particle number and PM 10 for the open windows condition was seven times greater when compared to closed windows and air conditioning on. When the vehicle was passing through the tunnel, in-cabin CO and particle number increased 100 and 30%, respectively, compared to driving on highway. Air exchange rate (AER) is a significant factor when evaluating in-cabin air pollutants level. AER was measured and simulated by a model developed through a Monte Carlo analysis of uncertainty and considering two main affecting variables, vehicle speed and fan speed. The lowest AER was 7 h -1 for the closed window and AC on conditions, whereas the highest AER was measured 70 h -1 for an open window condition and speed of 90 km h -1 . The results of our study can assist policy makers in controlling in-cabin pollutant exposure and in planning effective strategies for the protection of public health.
Journal of Environmental Management, 2018
Urban development increases runoff temperatures from buildings and pavement, which can be harmful... more Urban development increases runoff temperatures from buildings and pavement, which can be harmful to aquatic life. However, our ability to predict runoff temperature as a function of land use is limited. This paper explores available tools for simulating runoff temperature with respect to brook trout (Salvelinus sp.), a sensitive species. The Minnesota Urban Heat Export Tool (MINUHET) and the Storm Water Management Model (SWMM) were applied to a 14.1 km 2 portion of the Stroubles Creek watershed near Blacksburg, Virginia for two summers. Streamflow, water temperature, and weather data were acquired from the Virginia Tech StREAM Lab (Stream Research, Education, and Management) monitoring stations. SWMM and MINUHET were calibrated and validated for streamflow, and stream temperature, respectively. The models were sensitive to imperviousness (SWMM-predicted streamflow) and dew point temperature (MINUHET-predicted water temperature). While the models output time-step was 15 min, the model performance in simulating streamflow was evaluated using Nash-Sutcliffe Efficiency (NSE) on hourly time-steps. NSE values were 0.67 and 0.65 for SWMM and 0.62 and 0.57 for MINUHET during the calibration and validation periods, respectively, indicating that SWMM performed better than MINUHET in streamflow simulation. Stream temperatures were simulated using MINUHET with NSE value of 0.58 for the validation period, demonstrating a satisfactory simulation of water temperature. Since SWMM is not capable of stream temperature simulation beyond simple mixing. Hydrologic and thermal outputs from SWMM and MINUHET were combined in a hybrid approach that emphasized the strength of each respective model, i.e. SWMM for runoff and streamflow and MINUHET for water temperature. Heat loads were simulated using the MINUHET and the Hybrid models; the Hybrid model (0.56) had a greater NSE than MINUHET (0.45) alone. MINUHET predictions indicated water temperatures would exceed the trout toxicity threshold of 21 °C during 39% and 38% of calibration and validation periods, respectively. Since the observed temperature exceeded the toxicity threshold 59% and 53% of the time for the calibration and validation periods, respectively, MINUHET was not a conservative predictor of the duration of temperatures exceeding the toxicity threshold value.
Modeling Near Factory Air Pollutants Levels by Aermod: Case Study of Abyek, Iran
Interciencia
RESUME La concentración de los contaminantes del aire en el ambiente es variable en función de di... more RESUME La concentración de los contaminantes del aire en el ambiente es variable en función de diferentes factores, incluyendo distancias de las fuentes principales. Industrias en las afueras son una de las con mucho más crucial fuentes de contaminantes del aire. Abyek es una de las fábricas de cemento más significativos situados en el centro de la carretera Teherán-Qazvin con la pila de emisión de PM10 hasta 70 g / s. Las concentraciones de PM10 se determinó en diferentes distancias de la fábrica luego se redactó la cifra entre la distancia y la cantidad de PM10. La figura gradiente de concentración mostró decaimiento exponencial, lo que demostró que aproximadamente el 50% de los contaminantes del aire se deterioró en las distancias entre 800 a 1000 m de la fábrica. Esto es seguido por que después de 1000 m de distancia de los contenidos y cantidad de partículas disminuyeron significativamente. La precisión de los datos se comprobó mediante el uso del modelo AERMOD. Entonces softwa...
Investigation of the effectiveness of landscape improvement on downstream flow hydrograph at different return periods
Landscape improvement activities such as increase of green spaces can be utilized as an effective... more Landscape improvement activities such as increase of green spaces can be utilized as an effective stormwater management approach for urban runoff control. However, the efficiency of this approach at different return periods is being questioned. This study investigates the impact of landscape improvement on downstream flow hydrograph at different return periods in an urban catchment. The investigation is performed on the case study of Darakeh River which is a highly urbanized catchment located in Tehran, Iran. The city adopts channel network system for runoff control without utilizing novel stormwater management approaches (e.g., Low impact development). Increase in impervious surfaces as a result of urban development has intensified the risk of flooding and caused frequent overflows of the drainage network in the city. With the city restrictions on channel capacity enhancement, a greener advanced developmet is now being desired. It is therefore crucial to clearly understand the impa...
Russland-Analysen, Dec 5, 2023
Trotz der Invasion Russlands in die Ukraine im Februar 2022 haben die Getreideexporte Russlands w... more Trotz der Invasion Russlands in die Ukraine im Februar 2022 haben die Getreideexporte Russlands weiter zugenommen. Allerdings sind die Risiken, die das tatsächliche russische Weizenexportangebot auf den internationalen Märkten kurzfristig bestimmen, erheblich gestiegen. So könnte der russische Weizenexport kurzfristig geringer ausfallen als erwartet, was die Weltmarktpreise vorübergehend in die Höhe treiben und die globale Ernährungssicherheit beeinträchtigen würde. Politische Risiken ergeben sich aus einem System dauerhafter Weizenexportbeschränkungen, einem inoffiziellen Mindestpreis für Weizenexporte und einer verstärkten staatlichen Kontrolle des Getreideexportsektors. Die Infrastruktur des Getreidehandels am Schwarzen Meer ist militärischen Risiken ausgesetzt, die zu einer vorübergehenden Unterbrechung der Exportversorgung führen könnten. Auch die zunehmende Volatilität des Rubel-Wechselkurses stellt ein weiteres Risiko für Russlands Getreideexporte dar. Länder mit einer hohen Abhängigkeit von Getreideeinfuhren aus Russland sollten Maßnahmen zur Stärkung der Resilienz des Getreidehandels gut abwägen, um ihre Ernährungssicherheit zu stärken. Vor der russischen Invasion in die Ukraine in 2022 hatten sich die Getreideexporte von Kasachstan, Russland und der Ukraine dynamisch entwickelt. Erst im Jahr 2000 wurden alle drei Länder zu Nettoexporteuren von Getreide. Parallel zum Aufstieg Russlands zum größten Weizenexporteur der Welt avancierte die Ukraine zu einem der größten Maisexporteure. Die Weizenexporte Kasachstans sind ebenfalls gestiegen, haben sich aber auf einem deutlich niedrigeren Niveau stabilisiert. Kasachstan ist jedoch einer der größten Weizenmehlexporteure der Welt. In den letzten Jahren überstiegen die Getreideexporte Kasachstans, Russlands und der Ukraine die Menge von insgesamt 100 Millionen Tonnen jährlich. Dies entspricht mehr als einem Viertel der weltweiten Getreideexporte von Weizen, Mais und Gerste (Grafik 1 auf S. 3). Russischer Weizen wurde hauptsächlich von Ländern im Nahen Osten und in Nordafrika (MENA) importiert, wobei Ägypten und die Türkei die wichtigsten Zielmärkte waren. In den letzten Jahren haben die russischen Exporte in Länder mit niedrigem Einkommen, z. B. in Subsahara-Afrika, die stark von Nahrungsmittelimporten abhängig sind, zugenommen (Heigermoser et al. 2022). Mit einem Anteil von 26 % an den Weizenimporten aller afrikanischen Länder wurde Russland zum Hauptlieferanten von Weizen für diese (Götz und Svanidze, 2023). Dabei überschneiden sich die Bestimmungsorte der Weizenexporte Russlands und der Ukraine weitgehend. Im Gegensatz dazu exportiert Kasachstan hauptsächlich Weizen in die Nachbarländer der Region, z. B. nach Usbekistan, Tadschikistan und Afghanistan. Seit dem Beginn des Krieges Russlands gegen die Ukraine haben die russischen Getreideexporte weiter zugenommen. Die Prognosen deuten darauf hin, dass Russland ein dominierender Weizenlieferant auf dem Weltmarkt bleiben wird. So prognostiziert das US-Landwirtschaftsministerium (USDA) für das laufende Wirtschaftsjahr 2023/24 einen weiteren Anstieg der russischen Weizenexporte von 47,5 (2022/23) auf 50 Millionen Tonnen, obwohl die russische Weizenproduktion von 92 auf 85 Millionen Tonnen zurückgeht. Dieser Anstieg ist u. a. auf den Verkauf höherer Endbestände aus der letzten Vermarktungssaison zurückzuführen. Die russischen Ausfuhren von Mais und Gerste werden dagegen konstant bleiben. Das USDA geht davon aus, dass die Weizen-und Maiserzeugung in der Ukraine auch im Fall eines anhaltenden Krieges 2023/24 im Vergleich zu 2022/23 leicht ansteigen wird. Dagegen könnten die Getreideexporte weiter zurückgehen. Es ist zu erwarten, dass die Getreideexporte der Ukraine nach Beendigung des Krieges wieder zunehmen. Dennoch könnte die Bedeutung von Getreide für die Agrarexporte der Ukraine abnehmen, sofern die Ausfuhren von Ölsaaten und Ölsaatenerzeugnissen, insbesondere Rapssaaten, Sonnenblumenöl und Ölsaatenschrote, weiter zunehmen. Diese Entwicklungen sind jedoch von der künftigen Situation der Exportlogistik der Ukraine abhängig.
Probabilistic Quantitative Precipitation Forecast for Flood Prediction: An Application
Journal of Hydrometeorology, 2008
This paper outlines a methodology to produce probabilistic quantitative precipitation forecasts b... more This paper outlines a methodology to produce probabilistic quantitative precipitation forecasts by means of a dedicated uncertainty processor for weather model output. The uncertainty processor is developed as a component of a Bayesian forecasting system for river flow prediction. In this context the quantitative precipitation forecast is envisaged as a mixed binary–continuous predictand. The processor is applied to the quantitative precipitation forecasts and to precipitation observations covering a 5-yr period, whereby the forecasted and observed relative air humidity are used as ancillary meteorological indicators. The application of the processor to the selected dataset highlights a significantly larger skill of the quantitative precipitation forecast in predicting event occurrence rather than event depth and provides an objective quantification of the forecast uncertainty. The methodology applied here remains restricted to small basins, in which spatial variability of precipita...
6 CP: 4.0×10 6 *based on Herb et al. 2010 and Rossman, 2009 **represents the current properties o... more 6 CP: 4.0×10 6 *based on Herb et al. 2010 and Rossman, 2009 **represents the current properties of roofs/pavement, or baseline scenario of pavements/roofs properties; ***RR: Residential Roof; CR: Commercial Roof; GR: Galvalume Roof; CP: Concrete Pavement ****H: Higher than baseline scenario; L: Lower than baseline scenario. ***** Scenario 10 represents assumption of 6-year concrete age, while scenario 9 assumed concrete pavement newly constructed.
Design Principles of Permeable Pavement in Pollutants Removal from Surface Runoff
Sustainability, 2021
Iran is suffering from a state of water bankruptcy. Several factors have contributed to the curre... more Iran is suffering from a state of water bankruptcy. Several factors have contributed to the current water resources bankruptcy, ranging from anthropogenic impacts, such as an inefficient agricultural sector and aggressive withdrawal of groundwater, to climatological impacts. This paper suggests that water resources mismanagement in Iran should be evaluated beyond the policy-makers decisions, as it recognizes that the bankruptcy has been intensified due to the structural and institutional form of the political system in Iran. This study discusses the roots of the water bankruptcy and identifies four major shortcomings caused by the political system: (1) the absence of public engagement due to the lack of a democratic and decentralized structure; (2) adopting ideological policies in domestic and foreign affairs; (3) conflicts of interest and the multiplicity of governmental policy-makers and sectors; and (4) a state-controlled, resource-dependent economy. Through the development of a ...
Implications and Symptoms: Role of the Water Governance Components in Iran on the Existing Water Bankruptcy
The effect of piping stream channels on dissolved oxygen concentration and ecological health
Environmental Monitoring and Assessment
The Effect of Piping Stream Channels on Dissolved Oxygen Concentrations and Ecological Health
SSRN Electronic Journal
An Overview on Geographic Information System (GIS) Application in Environmental Management, Case Study: Algae Growth Assessment in Tampa Bay
Today's world is the world of information and its optimal management. Since major parts of th... more Today's world is the world of information and its optimal management. Since major parts of the decisions adopted by managers and urban planners at a regional macro level are somehow related to a specific situation with a location-source nature, the existence of precise, reliable and timely geographical information and its optimal management is necessary; Therefore there are no other options than using novel mechanized tools and technologies such as Geographic Information System (GIS) for their purpose. GIS enables environmental planners and decision makers for a time-efficient and cost-effective analyses. One of the most important parts of water and environmental management is quality studies of water resources such as rivers, estuaries, lakes, etc. In quality discussions of lakes and bays, the phenomenon of algal growth is of particular importance. Here, Tampa bay which is the part of the Gulf of Mexico and adjacent to the State of Florida is selected as the study area. By GIS ...
Evaluating the Effects of Piped Lengths of Buried Channels on Temporal and Small-Scale Spatial Variations of Streams Dissolved Oxygen Dynamics
Sunlight plays an important role in regulating the nutrient cycle in streams. Throughout the year... more Sunlight plays an important role in regulating the nutrient cycle in streams. Throughout the years, more streams are buried to accommodate for residential or commercial facilities. This results in ...
The effects of land use characteristics on urban stormwater quality and watershed pollutant loads
Science of The Total Environment, 2021
Urban developments can result in higher runoff and nutrient loadings transported to downstream re... more Urban developments can result in higher runoff and nutrient loadings transported to downstream receiving waterbodies. While much effort has been made recently in watershed restoration in the U.S., a lack of recent runoff quality data limits the prediction capability of urban watershed models. The objectives of this study was to fill an existing information gap on how rainfall and land uses interact and affect such loadings. This study instrumented six coastal urban catchments, each dominated by a single land use. We measured total nitrogen (TN), total phosphorus (TP), total suspended solids (TSS), total Kjeldahl Nitrogen (TKN), ortho-P, and nitrate concentrations in runoff from 30 storm events over one year from six urban land uses, namely commercial, industrial, transportation, open space, low density residential, and high density residential. Results indicated that the median event mean concentrations (EMCs) for TSS, TP, and TN were 30 (19-34), 0.31 (0.26-0.31), and 0.94 (0.73-1.25) mg L-1, respectively. TSS EMCs from the open space and industrial land uses were significantly greater than other land uses; there were positive correlations between TN concentrations and imperviousness and between TP concentrations and turf coverage. Both the amount and intensity of rainfall positively influenced TSS concentrations in runoff regardless of land use. Using the collected data, this study developed a generic equation for predicting the loading of a pollutant as a function of rainfall depth. This equation was verified by comparing its predictions with the simulations of a sufficiently-calibrated water quality model in terms of TSS, TP, and TN loadings from various land uses in another coastal catchment for a period of ten years. Average TSS, TN, and TP loadings from the catchment were estimated to be 0.86, 0.03, and 0.01 kg ha-1 cm-1, respectively.
Environmental Modelling & Software, 2019
Hydrologic models such as the Storm Water Management Model (SWMM) and the Hydrologic Simulation P... more Hydrologic models such as the Storm Water Management Model (SWMM) and the Hydrologic Simulation Program-Fortran (HSPF) are widely used to evaluate the impacts of urban development on watersheds and receiving waters. We compare the ability of these two models at simulating streamflow, peak flow, and baseflow from an urban watershed. The most sensitive hydrologic parameters for HSPF were related to groundwater; for SWMM, it was imperviousness. Both models simulated streamflow adequately; however, HSPF simulated baseflow better than SWMM, while, SWMM simulated peak flow better than HSPF. Global Sensitivity Analysis showed that variability of streamflow for SWMM was higher than that of HSPF, while variability of baseflow for HSPF was greater than that of SWMM. Further, analysis of extreme storm events indicated that the runoff coefficient for SWMM was slightly greater than HSPF for recurrence intervals of 1, 2, 5, and 10-yr.; the opposite was the case for recurrence intervals greater than 10 yrs.
Science of The Total Environment, 2019
We assessed thermal mitigation practices (TMPs) applied to an urban watershed. • We used MINUHET,... more We assessed thermal mitigation practices (TMPs) applied to an urban watershed. • We used MINUHET, SWMM, and a hybrid model for the assessment. • A sensitive species, brook trout (Salvelinus fontinalis), was used as an indicator. • Enhanced forest canopy mitigated stream temperatures better than other TMPs. • The best mitigation strategy was a combined one, which reduced heat loads by 62%.
Science of The Total Environment, 2019
Runoff water quality from a container nursery was assessed. • SWMM characterized runoff quantity ... more Runoff water quality from a container nursery was assessed. • SWMM characterized runoff quantity and quality reasonably well. • Storm TSS EMCs were higher than irrigation EMCs, while TN and TP were comparable. • TSS, TN and TP storm loads were ≈900, 35 and 50 times greater than irrigation loads. • TSS, TN and TP mean annual loads were 11,100, 80.3, and 11.1 kg•ha -1 •yr -1 , respectively.
Environmental Science and Pollution Research, 2018
The passengers inside vehicles could be exposed to high levels of air pollutants particularly whi... more The passengers inside vehicles could be exposed to high levels of air pollutants particularly while driving on highly polluted and congested traffic roadways. In order to study such exposure levels and its relation to the cabin ventilation condition, a monitoring campaign was conducted to measure the levels inside the three most common types of vehicles in Tehran, Iran (a highly air polluted megacity). In this regard, carbon monoxide (CO) and particulate matter (PM) were measured for various ventilation settings, window positions, and vehicle speeds while driving on the Resalat Highway and through the Resalat Tunnel. Results showed on average in-cabin exposure to particle number and PM 10 for the open windows condition was seven times greater when compared to closed windows and air conditioning on. When the vehicle was passing through the tunnel, in-cabin CO and particle number increased 100 and 30%, respectively, compared to driving on highway. Air exchange rate (AER) is a significant factor when evaluating in-cabin air pollutants level. AER was measured and simulated by a model developed through a Monte Carlo analysis of uncertainty and considering two main affecting variables, vehicle speed and fan speed. The lowest AER was 7 h -1 for the closed window and AC on conditions, whereas the highest AER was measured 70 h -1 for an open window condition and speed of 90 km h -1 . The results of our study can assist policy makers in controlling in-cabin pollutant exposure and in planning effective strategies for the protection of public health.
Journal of Environmental Management, 2018
Urban development increases runoff temperatures from buildings and pavement, which can be harmful... more Urban development increases runoff temperatures from buildings and pavement, which can be harmful to aquatic life. However, our ability to predict runoff temperature as a function of land use is limited. This paper explores available tools for simulating runoff temperature with respect to brook trout (Salvelinus sp.), a sensitive species. The Minnesota Urban Heat Export Tool (MINUHET) and the Storm Water Management Model (SWMM) were applied to a 14.1 km 2 portion of the Stroubles Creek watershed near Blacksburg, Virginia for two summers. Streamflow, water temperature, and weather data were acquired from the Virginia Tech StREAM Lab (Stream Research, Education, and Management) monitoring stations. SWMM and MINUHET were calibrated and validated for streamflow, and stream temperature, respectively. The models were sensitive to imperviousness (SWMM-predicted streamflow) and dew point temperature (MINUHET-predicted water temperature). While the models output time-step was 15 min, the model performance in simulating streamflow was evaluated using Nash-Sutcliffe Efficiency (NSE) on hourly time-steps. NSE values were 0.67 and 0.65 for SWMM and 0.62 and 0.57 for MINUHET during the calibration and validation periods, respectively, indicating that SWMM performed better than MINUHET in streamflow simulation. Stream temperatures were simulated using MINUHET with NSE value of 0.58 for the validation period, demonstrating a satisfactory simulation of water temperature. Since SWMM is not capable of stream temperature simulation beyond simple mixing. Hydrologic and thermal outputs from SWMM and MINUHET were combined in a hybrid approach that emphasized the strength of each respective model, i.e. SWMM for runoff and streamflow and MINUHET for water temperature. Heat loads were simulated using the MINUHET and the Hybrid models; the Hybrid model (0.56) had a greater NSE than MINUHET (0.45) alone. MINUHET predictions indicated water temperatures would exceed the trout toxicity threshold of 21 °C during 39% and 38% of calibration and validation periods, respectively. Since the observed temperature exceeded the toxicity threshold 59% and 53% of the time for the calibration and validation periods, respectively, MINUHET was not a conservative predictor of the duration of temperatures exceeding the toxicity threshold value.
Modeling Near Factory Air Pollutants Levels by Aermod: Case Study of Abyek, Iran
Interciencia
RESUME La concentración de los contaminantes del aire en el ambiente es variable en función de di... more RESUME La concentración de los contaminantes del aire en el ambiente es variable en función de diferentes factores, incluyendo distancias de las fuentes principales. Industrias en las afueras son una de las con mucho más crucial fuentes de contaminantes del aire. Abyek es una de las fábricas de cemento más significativos situados en el centro de la carretera Teherán-Qazvin con la pila de emisión de PM10 hasta 70 g / s. Las concentraciones de PM10 se determinó en diferentes distancias de la fábrica luego se redactó la cifra entre la distancia y la cantidad de PM10. La figura gradiente de concentración mostró decaimiento exponencial, lo que demostró que aproximadamente el 50% de los contaminantes del aire se deterioró en las distancias entre 800 a 1000 m de la fábrica. Esto es seguido por que después de 1000 m de distancia de los contenidos y cantidad de partículas disminuyeron significativamente. La precisión de los datos se comprobó mediante el uso del modelo AERMOD. Entonces softwa...
Investigation of the effectiveness of landscape improvement on downstream flow hydrograph at different return periods
Landscape improvement activities such as increase of green spaces can be utilized as an effective... more Landscape improvement activities such as increase of green spaces can be utilized as an effective stormwater management approach for urban runoff control. However, the efficiency of this approach at different return periods is being questioned. This study investigates the impact of landscape improvement on downstream flow hydrograph at different return periods in an urban catchment. The investigation is performed on the case study of Darakeh River which is a highly urbanized catchment located in Tehran, Iran. The city adopts channel network system for runoff control without utilizing novel stormwater management approaches (e.g., Low impact development). Increase in impervious surfaces as a result of urban development has intensified the risk of flooding and caused frequent overflows of the drainage network in the city. With the city restrictions on channel capacity enhancement, a greener advanced developmet is now being desired. It is therefore crucial to clearly understand the impa...
Russland-Analysen, Dec 5, 2023
Trotz der Invasion Russlands in die Ukraine im Februar 2022 haben die Getreideexporte Russlands w... more Trotz der Invasion Russlands in die Ukraine im Februar 2022 haben die Getreideexporte Russlands weiter zugenommen. Allerdings sind die Risiken, die das tatsächliche russische Weizenexportangebot auf den internationalen Märkten kurzfristig bestimmen, erheblich gestiegen. So könnte der russische Weizenexport kurzfristig geringer ausfallen als erwartet, was die Weltmarktpreise vorübergehend in die Höhe treiben und die globale Ernährungssicherheit beeinträchtigen würde. Politische Risiken ergeben sich aus einem System dauerhafter Weizenexportbeschränkungen, einem inoffiziellen Mindestpreis für Weizenexporte und einer verstärkten staatlichen Kontrolle des Getreideexportsektors. Die Infrastruktur des Getreidehandels am Schwarzen Meer ist militärischen Risiken ausgesetzt, die zu einer vorübergehenden Unterbrechung der Exportversorgung führen könnten. Auch die zunehmende Volatilität des Rubel-Wechselkurses stellt ein weiteres Risiko für Russlands Getreideexporte dar. Länder mit einer hohen Abhängigkeit von Getreideeinfuhren aus Russland sollten Maßnahmen zur Stärkung der Resilienz des Getreidehandels gut abwägen, um ihre Ernährungssicherheit zu stärken. Vor der russischen Invasion in die Ukraine in 2022 hatten sich die Getreideexporte von Kasachstan, Russland und der Ukraine dynamisch entwickelt. Erst im Jahr 2000 wurden alle drei Länder zu Nettoexporteuren von Getreide. Parallel zum Aufstieg Russlands zum größten Weizenexporteur der Welt avancierte die Ukraine zu einem der größten Maisexporteure. Die Weizenexporte Kasachstans sind ebenfalls gestiegen, haben sich aber auf einem deutlich niedrigeren Niveau stabilisiert. Kasachstan ist jedoch einer der größten Weizenmehlexporteure der Welt. In den letzten Jahren überstiegen die Getreideexporte Kasachstans, Russlands und der Ukraine die Menge von insgesamt 100 Millionen Tonnen jährlich. Dies entspricht mehr als einem Viertel der weltweiten Getreideexporte von Weizen, Mais und Gerste (Grafik 1 auf S. 3). Russischer Weizen wurde hauptsächlich von Ländern im Nahen Osten und in Nordafrika (MENA) importiert, wobei Ägypten und die Türkei die wichtigsten Zielmärkte waren. In den letzten Jahren haben die russischen Exporte in Länder mit niedrigem Einkommen, z. B. in Subsahara-Afrika, die stark von Nahrungsmittelimporten abhängig sind, zugenommen (Heigermoser et al. 2022). Mit einem Anteil von 26 % an den Weizenimporten aller afrikanischen Länder wurde Russland zum Hauptlieferanten von Weizen für diese (Götz und Svanidze, 2023). Dabei überschneiden sich die Bestimmungsorte der Weizenexporte Russlands und der Ukraine weitgehend. Im Gegensatz dazu exportiert Kasachstan hauptsächlich Weizen in die Nachbarländer der Region, z. B. nach Usbekistan, Tadschikistan und Afghanistan. Seit dem Beginn des Krieges Russlands gegen die Ukraine haben die russischen Getreideexporte weiter zugenommen. Die Prognosen deuten darauf hin, dass Russland ein dominierender Weizenlieferant auf dem Weltmarkt bleiben wird. So prognostiziert das US-Landwirtschaftsministerium (USDA) für das laufende Wirtschaftsjahr 2023/24 einen weiteren Anstieg der russischen Weizenexporte von 47,5 (2022/23) auf 50 Millionen Tonnen, obwohl die russische Weizenproduktion von 92 auf 85 Millionen Tonnen zurückgeht. Dieser Anstieg ist u. a. auf den Verkauf höherer Endbestände aus der letzten Vermarktungssaison zurückzuführen. Die russischen Ausfuhren von Mais und Gerste werden dagegen konstant bleiben. Das USDA geht davon aus, dass die Weizen-und Maiserzeugung in der Ukraine auch im Fall eines anhaltenden Krieges 2023/24 im Vergleich zu 2022/23 leicht ansteigen wird. Dagegen könnten die Getreideexporte weiter zurückgehen. Es ist zu erwarten, dass die Getreideexporte der Ukraine nach Beendigung des Krieges wieder zunehmen. Dennoch könnte die Bedeutung von Getreide für die Agrarexporte der Ukraine abnehmen, sofern die Ausfuhren von Ölsaaten und Ölsaatenerzeugnissen, insbesondere Rapssaaten, Sonnenblumenöl und Ölsaatenschrote, weiter zunehmen. Diese Entwicklungen sind jedoch von der künftigen Situation der Exportlogistik der Ukraine abhängig.