scholarly journals Evaluation of nitrogen loading in the last 80 years in an urbanized Asian coastal catchment through the reconstruction of severe contamination period

Author(s):  
Kunyang Wang ◽  
Shin-ichi Onodera ◽  
Mitsuyo Saito

Abstract Most semi-enclosed seas have experienced severe eutrophication owing to high nutrient loading from rivers during rapid population growth periods. In Japan, the coastal areas of some megacities (e.g., Tokyo and Osaka) experienced considerable economic growth during the 1960s–1970s. Therefore, determining the amount of nutrient loading during this period is essential to undertake measures for the conservation of coastal environments. However, determining the nutrient loading that occurred several decades ago is generally difficult owing to lacking water quality records. In this study, the nitrogen loading in the Yamato River catchment, an urbanized coastal catchment in Asia, for 80 years from the 1940s to the 2010s is reconstructed using the Soil and Water Assessment Tool. We considered factors such as population growth, wastewater treatment plant (WWTP) construction, and changes in land and fertilizer usage in different urbanization stages. Results show that the total nitrogen loading in the catchment peaked in the 1970s at 6616 tons/year owing to untreated wastewater discharge and rapid increase in population growth. By reducing 57% of the nitrogen loading in the 2010s from the catchment, WWTPs have been instrumental in improving the water environment. The decrease in and integration of agricultural land has reduced nitrogen loading attributed to nonpoint sources; however, this reduction was not obvious because of the high fertilizer usage before the 2000s. Overall, the findings of this study provide a comprehensive understanding of the impact of rapid urbanization in an Asian coastal catchment on nitrogen loading during the high economic growth period in the past. This study will be useful for the long-term assessment of nutrient loading in other.

2015 ◽  
Vol 14 (3) ◽  
pp. 417
Author(s):  
Genius Murwirapachena ◽  
Courage Mlambo

Great inconsistencies have been observed in life expectancy dynamics in Zimbabwe over the past decades. Contradictions exist among Zimbabweans where some believe that people used to live longer during the colonial era than they live now. Such beliefs have been exacerbated by the recent economic woes that ensued in the country. Dynamics in the Zimbabwean life expectancy patterns have seen male Zimbabweans outliving their female counterparts since the year 2000. Such an alteration contradicts general world life expectancy trends where females commonly live longer than males. This paper analyses trends in the Zimbabwean life expectancy over the period 1970 to 2012. The ordinary least squares method is used to examine the impact of economic growth, inflation, increase in agriculture land, population growth and the dependency ratio on life expectancy in Zimbabwe. Empirical results from this study revealed that economic growth, inflation and population growth have a positive relationship with life expectancy while increases in both agricultural land and the dependency ratio have negative effects on life expectancy in Zimbabwe.


2009 ◽  
Vol 21 ◽  
pp. 49-55 ◽  
Author(s):  
Q. D. Lam ◽  
B. Schmalz ◽  
N. Fohrer

Abstract. The aims of this study are to identify the capacities of applying an ecohydrological model for simulating flow and to assess the impact of point and non-point source pollution on nitrate loads in a complex lowland catchment, which has special hydrological characteristics in comparison with those of other catchments. The study area Kielstau catchment has a size of approximately 50 km2 and is located in the North German lowlands. The water quality is not only influenced by the predominating agricultural land use in the catchment as cropland and pasture, but also by six municipal wastewater treatment plants. Ecohydrological models like the SWAT model (Soil and Water Assessment Tool) are useful tools for simulating nutrient loads in river catchments. Diffuse entries from the agriculture resulting from fertilizers as well as punctual entries from the wastewater treatment plants are implemented in the model set-up. The results of this study show good agreement between simulated and measured daily discharges with a Nash-Sutcliffe efficiency and a correlation coefficient of 0.76 and 0.88 for the calibration period (November 1998 to October 2004); 0.75 and 0.92 for the validation period (November 2004 to December 2007). The model efficiency for daily nitrate loads is 0.64 and 0.5 for the calibration period (June 2005 to May 2007) and the validation period (June 2007 to December 2007), respectively. The study revealed that SWAT performed satisfactorily in simulating daily flow and nitrate loads at the lowland catchment in Northern Germany.


2022 ◽  
Vol 14 (2) ◽  
pp. 667
Author(s):  
Andrés Estrada-Rivera ◽  
Alfonso Díaz Fonseca ◽  
Samuel Treviño Mora ◽  
Wendy Argelia García Suastegui ◽  
Edith Chávez Bravo ◽  
...  

Population growth, poorly planned industrial development and uncontrolled production processes have left a significant footprint of environmental deterioration in the Alto Atoyac watershed. In this study, we propose using the integrated pollution index (PI) to characterize the temporary variations in surface water quality during the rapid urbanization process in the municipalities of San Martín Texmelucán (SMT) and Tepetitla de Lardizabal (TL), in the states of Puebla and Tlaxcala, between 1985 and 2020. We assessed the correlation between the population growth rate and the water quality parameters according to the Water Quality Index (ICA). The contribution of each polluting substance to the PI was determined. The industry database was created and the increase in population and industry, and their densities, were estimated. The results indicated that the temporal pattern of surface water quality is determined by the level of urbanization. The water integrated pollution index (WPI) increased with the passage of time in all the localities: SLG 0.0 to 25.0; SMTL 25.0 to 29.0; SRT 4.0 to 29.0; VA 6.0 to 30.0; T 3.5 to 24.0 and SMA 4.0 to 27.0 from 2010 to 2020, respectively. The correlation coefficients between the five parameters (BOD5, COD, CF, TU and TSS) in the six localities were positive with the population. The values that showed a higher correlation with the population were: SLG (FC 0.86), SMTL (BOD5 0.61, COD 0.89, TSS 0.64) and SRT (TU 0.83), corresponding to highly polluted localities, which generates complex and severe environmental implications due to the unsustainable management of water resources. Achieving the sustainability of water in the watershed is a challenge that should be shared between society and state. This type of research can be a useful tool in making environmental management decisions.


2020 ◽  
Vol 8 (4) ◽  
pp. 73-80
Author(s):  
Assefa Ayele ◽  
Kassa Tarekegn

AbstractIn a country like Ethiopia where the vast majority of the populations are employed in agriculture, land is an important economic resource for the development of rural livelihoods. Agricultural land in peri-urban areas is, however, transformed into built-up regions through horizontal urban expansion that has an effect on land use value. In recent years Ethiopia has been experiencing rapid urbanization, which has led to an ever-increasing demand for land in peri-urban areas for housing and other nonagricultural activities that pervades agricultural land. There is a high demand for informal and illegal peri-urban land which has been held by peri-urban farmers, and this plays a vital role in the unauthorized and sub-standard house construction on agricultural land. This urbanization has not been extensively reviewed and documented. In this review an attempt has been made to assess the impacts of rapid urbanization on agricultural activities. Urban expansion has reduced the areas available for agriculture, which has seriously impacted upon peri-urban farmers that are often left with little or no land to cultivate and which has increased their vulnerability. Housing encroachments have been observed to be uncontrolled due to a weak government response to the trend of unplanned city expansion. This has left peri-urban farmers exposed to the negative shocks of urbanization because significant urbanization-related agricultural land loss has a positive correlation with grain production decrease. Appropriate governing bodies should control urban development in order to control the illegal and informal spread of urbanization on agricultural land that threatens food production.


2019 ◽  
Vol 1 (3) ◽  
pp. 71
Author(s):  
Muhammad Fajri Setia Trianto ◽  
Evi Yulia Purwanti

The economy that continues to grow has the impact of environmental damage. This study aims to prove empirically the Environmental Kuznets Curve (EKC) hypothesis by analyzing the relationship of economic growth with environmental damage as measured by GDP per capita, and CO2 emissions. The data used are secondary data in the form of data on GDP per capita, CO2 emissions, population growth, inflation, and control of corruption in 10 countries in the ASEAN region in 2002-2016. Data analysis using the Fixed Effect model. The results show that there is a relationship between economic growth and environmental damage that forms an inverted U curve. Economic growth will initially have a positive effect on environmental damage so that at a point of economic growth negatively affects environmental damage. By adding control variables: population growth, inflation and corruption, inflation and corruption positively impact environmental damage, while population negatively affect environmental damage.


2019 ◽  
Vol 4 (2) ◽  
pp. 136-144
Author(s):  
Divine Ndubuisi Obodoechi ◽  
Charles Uchenna Onuoha

This paper empirically investigates the relationship between economic growth and unemployment in Nigeria under the Okun’s Law framework. The Auto Regressive Distributed Lag model approach, the ARDL Bounds Test and Cointegration Test were employed in this paper. Economic Growth was also regressed on unemployment, log of industrial output, log of net foreign assets, log of foreign direct investment and population growth so as to know the impact of these variables on output. The research findings indicated that high the Okun’s specification does not hold in the Nigeria, the impact of economic growth on unemployment is negative and insignificant. We did however find that there is a positive impact of unemployment on economic growth, meaning that the phenomena of jobless growth may be in play in the economy. The Johansen Co-integration test failed to establish evidence of long run relationship between GDP, industrial output, unemployment, foreign direct investment net foreign assets and population growth. The ECM could not be employed because the variables were integrated of different orders. It was however found there exist a significant positive relationship between the aforementioned variables and GDP except for population growth. The government should consider the Industrial Sector as a priority sector in a bid for better economic growth and development. Population control measures should also be put in play to ensure that the population does not exceed the economic carrying capacity. The government should also play an important role in abating unemployment in the economy using direct and indirect schemes and strategies.


Author(s):  
Moh Sholichin ◽  
Tri Budi Prayogo

Lake Tondano is the largest natural lake in North Sulawesi, Indonesia, which functions as a provider of clean water, hydroelectric power, rice field irrigation, inland fisheries, and tourism. This research aims to determine the effect of land cover types from the Tondano watershed on the lake water quality. The Soil and Water Assessment Tool (SWAT) model was used to evaluate the rate of soil erosion and the pollutant load of various land types in the watershed during the last ten years. Rainfall data is obtained from two rainfall stations, namely Paleloan Station and Noonan Station. The model is calibrated and validated before being used for analysis. We use climatological data from 2014 to 2019. The process of the SWAT model calibration and validation was carried out with the statistical formulas of the coefficient of determination (R2) and Nash-Sutcliffe efficiency (NSE). The results show that the potential for pollution load from the Tondao watershed is organic N of 0.039 kg/ha and organic P of 0.006 kg/ha coming from the agricultural land. The results of this study conclude that the fertility conditions of Lake Tondano are at the eutrophic level, where the pollutant inflow is collected in the lake waters, especially for the parameters of total N (1503697.44kg/year) and total P (144831.36kg/year). The SWAT simulation results show deviation between the modeling and field data collected with the value of R2 = 0.9303, and the significant level ≤ 10.


2020 ◽  
Vol 12 (3) ◽  
pp. 1171 ◽  
Author(s):  
Hongyu Du ◽  
Fengqi Zhou ◽  
Chunlan Li ◽  
Wenbo Cai ◽  
Hong Jiang ◽  
...  

In the trend of global warming and urbanization, frequent extreme weather influences the life of citizens seriously. Shanghai, as a typical mega-city in China that has been successful in urbanization, suffers seriously from the urban heat island (UHI) effect. The research concentrates on the spatial and temporal pattern of surface UHI and land use. Then, the relation between them are further discussed. The results show that for the last 15 years, the UHI effect of Shanghai has been increasing continuously in both intensity and area. The UHI extends from the city center toward the suburban area. Along with the year, the ratio in area of Agricultural Land (AL), Wetland (WL), and Bare Land (BL) has decreased. On the contrary, Construction Land (CL) and Green Land (GL) have increased. The average land surface temperature (LST) rankings for each research year from high to low were all CL, BL, GL, AL, and WL. CL contributed the most to the UHI effect, while WL and GL contributed the most to mitigate the UHI. The conclusion provides practical advice aimed to mitigate the UHI effect for urban planning authorities.


2007 ◽  
Vol 2007 ◽  
pp. 1-4 ◽  
Author(s):  
Shane J. Prochnow ◽  
Joseph D. White ◽  
Thad Scott ◽  
Christopher Filstrup

The soil and water assessment tool (SWAT) is used to assess the influence of small upland reservoirs (PL566) on watershed nutrient yield. SWAT simulates the impact of collectively increasing and decreasing PL566 magnitudes (size parameters) on the watershed. Totally removing PL566 reservoirs results in a 100%increase in total phosphorus and an 82%increase in total nitrogen, while a total maximum daily load (TMDL) calling for a 50%reduction in total phosphorus can be achieved with a 500%increase in the magnitude of PL566s in the watershed. PL566 reservoirs capture agriculture pollution in surface flow, providing long-term storage of these constituents when they settle to the reservoir beds. A potential strategy to reduce future downstream nutrient loading is to enhance or construct new PL566 reservoirs in the upper basin to better capture agricultural runoff.


2019 ◽  
pp. 1-28
Author(s):  
Alberto Bucci ◽  
Lorenzo Carbonari ◽  
Giovanni Trovato

We provide aggregate macroeconomic evidence on how, in the long run, a diverse degree of complexity in production may affect not only the rate of economic growth, but also the correlation between the latter, population growth and the monopolistic (intermediate) markups. For a sample of Organisation for Economic Co-operation and Development (OECD) countries, we find that the impact of population change on economic growth is slightly positive. According to our theoretical model, this implies that the losses due to more complexity in production are lower than the corresponding specialization gains. Using a finite mixture model, we also classify the countries in the sample and verify for each cluster the impact that the population growth rate and the intermediate sector’s markups exert on the 5-year average real gross domestic product (GDP) growth rate.


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