Abstract
Globally, there are significant changes in the vegetation in and around major world cities due to the constant modification of the land surface and environmental conditions. The subtropical regions of Iraq, particularly Erbil, have experienced significant changes in the past 15 years due to the factors like urbanization and climate change , and this has had a strong implication on the vegetation dynamics in the region. The influences of the urban microclimate and human interference of vegetation has influenced the vegetation spatial distribution in the region. The research explores to detect the changes in vegetation cover around the city of Erbil’s using a combination of MODIS data between the years 2000 to 2015 and NDVI, EVI and time series analysis. The assertion was that human activities have impacted on the vegetation distribution around Erbil City in the past one and half decade. The changes experienced are as a result of massive urban construction works due to the expanding urban population and the high demand for housing units. The satellite MODIs images of the region were analyzed to determine the spatial vegetation distribution and variation to establish the key contributors to the changes in the relationship between wetness, bareness, real estate expansion and the vegetation index. The research shows that there is a significant change in vegetation cover due to the increased human activities in the region and in some areas near the city’s core there is a complete replacement of the natural vegetation. The results show that the heavily built-up areas had limited green areas in comparison with the non-urban areas around Erbil’s city. Over the study period, there was significant variation in terms of population distribution from the core towards the outer areas of the city. It is evident that human activities and urbanization have a negative impact on the overall population distribution patterns observed in an area. The results are consistent and synonymous with the predictions and forecasts made earlier that observed that the expansion of Erbil is likely to affect the vegetation distribution around the city.
Introduction
There is a significant difference between primary and secondary vegetation cover based on the characteristics of the study area. It is evident that urbanization is the major factor affecting the natural vegetation globally and as noted as the population continues to expand, there is an increase in demand for housing units (Busar & Hall, 2005). The expansion of the housing unit and the human activities modify the climate, which in turn affects vegetation dynamics in the area. Currently, the Erbil municipality has a population of 826,876 people and a density of 135.5 persons per km2 and the population is rapidly expanding (Merkel & Seeyan, 2014). The growing population has led to the expansion of other associated amenities like transport, schools and housing that have taken up most of the cities land area. The rapid expansion has caused human interference on the natural vegetation distribution dynamics around the city (Shove, 2010`). The surface cover around the city is shaped by the microclimate effect of urbanization like the process of heat absorption, wind diversion among other microclimate modifications cause by urbanization. The impact of these changing conditions is evident in the changing spatial distribution of vegetation in the study area. The climatic changes contribute to the change in the vegetation dynamics in the areas of interest and as a result, major urbanized cities have experienced sporadic changes in terms of land cover (Gaffin et al., 2008). On the contrary, the non-urbanized areas experience limited land cover changes due to the limited human activities.
Satellite images provide real-time data that can help detect changes within the environment; MODIS vegetation index product provides and accurate and composite information at different degree resolutions that can be important for vegetation change observation. The bands that can be important for the research include the Normalized Difference Vegetative index (NDVI) and the Enhanced Vegetative index (EVI) that are important resources for establishing the changes in the study area over time (Fortuniak, 2009). The data requested was based on the vegetation dynamics over the past years using the Terra EOS AM satellite, and it indicated the different land cover index on the land surrounding the study area over the study time. The imaging color differences show the different expansion rates and the relationship between vegetation cover and the land use patterns in Erbil (Rabia & Saeed, 2010). As noted, there are limited resources particularly secondary sources that have published about the overall vegetation indices and changes over time. Use of MODIS data will differentiate the annual differences between urban expansion and the vegetative indices over the years. The research aims to use the MODIS data to analyze the distribution patterns over a period of time, and this has influence the climatic patterns of the area. MODIS diagrams provide high-quality aerial images that are remotely sense by the satellites and interpretation of the images can provide important information that can be used for vegetation classification of any region in the world based on the global vegetation distribution patterns (Shove, 2010`). The correlation between the Normalized Difference Vegetation Index (NDVI values will provide a time series impression about the changes that have occurred on the land cover around the Erbil city over time. The variation in the land annual land cover will act as a confirmation of the impact of different urbanization on natural vegetation cover.
Research in the vegetative indices of the cities is necessary as limited work has been done regarding the issue and it is necessary for the patterns of the vegetative land cover in the subtropics to be traced so as to predict the future climatic patterns. Vegetation plays a major role in determining the climatic patterns of an area, and this reinforces the need for spatial vegetative structure mapping of the Erbil that is a case of a semi-arid climate.
Study area
The study was conducted in Erbil region to evaluate the effect of urbanization on the vegetation distribution in the outskirts of Erbil province. Erbil province of the oldest city in Iraq located to the North of Iraq and bordered Iran to the East. Precisely the coordinates of the study area i.e. between the longitude (430 52’ – 440 12’) E and latitude (360 16’ – 360 06’) N the city is an important administration center for Erbil province. From the Iraq, capital Bagdad the city is located 316 km to the north and approximately 80 km to the west of Mosul (Rasul, 2013). The city is connected with road networks to the west connecting the city to Mosul, Tikrit and all the way to Bagdad (Edwin & Bruce, 2010). The larger Erbil city encompasses the towns of Sulaymaniyah and the region of administered by the Kurdistan regional government. The region is predominantly mountainous in terms of the physical topography, and the East side of the town is hilly while the western part if relatively flat with city landscape is undulated. The topographical differences in the city have a significant effect on the vegetation distribution patterns within the city.
Figure 1: showing the study area location and boundaries note the Orange box denotes the study area.
The urban setting of Erbil city dates back to about 6000 B.C, and the city had been inhabited for longest time and consists of one of the oldest buildings in Iraq. The city remains one of the oldest commercial centers situated on the en route from Bagdad and such that merchants could meet in the city and trade. As noted earlier, the current population of Erbil City is of 826,876 people and a density of 135.5 persons per km2 the population has increased significantly over the recent years, and this has a significant implication on the infrastructural requirements within the city (Merkel & Seeyan, 2014). Ths study area according to the Koppen system of climatic classification it is a semi-arid region and the city is the subtropical area. The regions rainfall is unevenly distributed, and mainly the annual temperature is 21.180C and rainfall amount of 386 mm annually (Rasul, 2013). According to the Iraq meteorological department, July and August are the months when the region experiences highest temperatures while the wet months recorded are March and December. The land cover in Erbil depends on the seasonality and the amount of wet months experienced in the area. The distribution of vegetation is also dependent on the human factors like farming and cultivation on the outskirts of the city. As noted in the structural arrangement of the city most of the structures are made up of concrete, and this brings about a change in the temperature patterns within and around the city.
Methodology
The study area will cover the larger Erbil region that is located North of Iraq and as defined in physiographically in the introduction. The highest level above sea level is 426 m, and the study area had an undulating landscape. The research will rely on primary and secondary sources of information. The primary data that will be utilized in the research includes the MODIS 13Q1 satellite images from 2000 to 2015, and other methods that can be integrated include time series analysis of the vegetative changes over time. The image generated are moderate in resolution and will be obtained from Terra EOS AM satellite. The secondary data was obtained from the demographic census reports on the environment that are available in the department of Agriculture and in the environmental archives of the Erbil municipality. Also, maps were obtained from the census reports and master plan reports from the Governorate and municipality. The images used in the study are from MODIS13Q1 on vegetation indices at 250 pixels that consist of composite images. The point of in interest in the data is point Lat 36.177 and Long 44.058 between may 2000 to may 2015.
The composite images were obtained from the Terra EOS AM satellite and were processed based on the pixel means of the images. The images will be evaluated for accuracy and clarity the mapping images obtained can be used to determine the vegetation dynamics in the region. The images need to be analyzed and classified based on the global chart of climate and vegetation distribution (Shove, 2010`). The classification will also be determined by the habited, and inhabited parts will also be important in determining the vegetation distribution patterns in the region. As noted the Erbil region can only consist of two main land use categories that include the general urban area and the uninhabited area and as noted based on the available data and classification the non-urban areas are the areas likely to contain vegetation and open grazing land. The images collected were places and recreated suing a range of colors to indicate the distribution of both man-made and natural features around the city as shown in the image.
Figure 2: the sample is showing the Terra MODIS image showing distribution vegetation within the city.
Further to understand the current and future distribution patterns it is important that the research conducts data modeling and forecasting. Erbil’s City faces an uncertain future, and the implication of this is that the vegetation growth and distribution in the target are likely to experience different changes. Thus plotting the vegetation growth and development map can assist in the proves of determining the future if Erbil as a region in terms of environmental conservation. The evident dynamics are those of manmade and natural climate whereby most of the vegetation in the urban areas is planted vegetation. The projections of the land use through statistical evaluation and data forecasting technologies can give insight on the course of future land use patterns and the vegetative changes that can be anticipated in the future.
Data sources and processing
NDVI Time series
The NVDI times series show that singular values are mostly triggered by atmospheric factors present during the data collection process that can be identified with the declines and humps in the data. The research used maximum values to eliminate the negative interferences from the climatic conditions. The NVDI time series used to process the data comprised of 16-day composites and the Monthly NDVI was obtained, and extreme values were eliminated in the process. The data stabilization process is important because of the high rates of climatic variability in the time series and the bidirectional effect of the data collection process. The process of data collection is highly volatile and affected by many factors during the NDVI composting process. The NVDI data interpretation process involved the process of analyzing the color changes observed in the study area over time. It is important to note the color changes over time, principally, plants always absorb Red light, and this means that the near-infrared light can pass through the plant or is reflected back by vegetation. From the NVDI series, it is evident that the areas covered by vegetation appear bright and mainly near the infrared while the are lands show a red color in the images. The results extracted are shown in the images shown, the extraction shows that at current the total area to be 2, 7328 ha that is represented by bare land, poor vegetation in the peri-urban, moderate vegetation in the outskirts, dense vegetation, and very dense areas.
Figure showing the NVDI data of the study area note the blue and red regions of the city (2000).
Results
The date was obtained from the MODIS data that was collected in the study area Erbil at 5 ETMT+ that was acquired in the year 2005 at about 3:00 pm local time with a clear and observable atmospheric conditions and a clear sky. The image used for this result was obtained with the permission of NASA through their data sharing platform MODIS data sharing. The image of the negative dimensions of the common climatic conditions in the study region with a recorded temperature of 34 degree Celsius and a relative humidity of around 16 percent based on the information from the ministry of Agriculture and the municipality department of environment. The data provides the basic design and structure of the man-made and the natural features the map as shown in the proceeding maps. The common components in the data in the data include the roads, streets, street planning. The definite structure and arrangement due to planning have affected the distribution patterns of the region based on the Image generated as shown in the figure. The process shows a change in vegetation dynamics over the time period that shows that urbanization has an impact on the nature and type of vegetation in an area.
MODIS satellite information
The MODIS information captured reveals the atmospheric conditions that represent the MODIS satellite Imagery at 7 ETM+. The image presented some normal distortions in terms of geometric proportions, and pre-processing was necessary to rectify the errors in the images to avoid the errors (Haoughton & Maryland, 2010). The date processing involved delineating the different regions of the map and assigning the area specific vegetation cover. The maps were divided to indicate the vegetative distributions in the outer regions of Erbil city. This is shown in the different color distribution as shown in the NVDI diagrams (Gaffin et al., 2008). Describing the process of urbanization on a macro-scale, it is evident that the satellite images show a significant change in the spatial distribution of vegetation from 2000-2015. Through the data, it is possible to show the spatial patterns of urbanization. The Terra data showed that the urbanization process is Northern Iraq is growing very fast, and this is accompanying the general vegetation distributions. The areas showing the boundaries of Erbil city shows that the vegetation distribution in the area changed with the expansion of the city evident in the color change noted in the NVDI data.
The different vegetative cover in the Erbil region based on the differing climatic regions and the datum showed that the region is with the UTM one that is located 29N in the geospatial coordinate system. The regions identified indicate that the city comprises of an urban core region that is located in the city’s center, and there are chances of climatic modification due to the influences of the urban microclimate (Garcia & Tejeda, 2009). The development of microsystems has an influence on the development of vegetation and the amount of vegetation available within the city. As shown in the processes map the regions were marked with areas with sparse vegetation consisting of the core and commercial segments of the city, the region lacking vegetation that was mainly industrial and the areas with dense vegetation (Gaffin et al., 2008). The region identified are shown in the processed map shown below the color codes indicates the level of vegetation in the area.
The figure above show the spatial distribution of vegetation in Erbil over the years, and it is evident that the NVDI increased to a significance level of p=0.017 and a slope of about 0.0034. The value increased over the years 2000 to 2015 and the coefficient variation of 0.0032 and the standard deviation of 0.014 that is generally low. Over the years, the NDVI values increased significantly, and the high magnitude value at the start of 2000 and the low magnitude ate the end of 2015 shows as a significant change in vegetation distribution over the years. There is a large change in the values over the years, and this can be seen from the high value of the standard deviation.
According to the distribution patterns and trend indicated here shows that the slope of the NVDI changed over time. The areas showing negative or positive trends show the areas that experienced vegetation degradation. From the data, the deduction that can be made and this are the planar distribution that is shown by the virtual distribution patterns of the vegetation cover over a given period. The data shows that the linear expansion of the urban center has contributed to the planar decline in vegetation over the time. There is a correlation between the vegetation distribution pattern and urbanization in the city (Edwin & Bruce, 2010). The significance level is evident in the climatic change and the overall NVDI change that has occurred over time. This is shown in the partial correlation between the NVDI and climatic changes over time and climate is the basic factor that drives changes in the vegetation cover. The changes in spatial vegetation distribution pattern in the Nothern part of Iraq as shown in the time series is contributed to by the annual changes in temperatures.
The process of urbanization in the larger Erbil region shows the changes that can be caused by anthropogenic activities during the period of study. In the past 15 years in the larger Erbil, there has been a major change in terms of large-scale urbanization in the northern part of China. The change has been brought about by the need for houses and the large-scale inflow of population to cities like Erbil. The massive anthropogenic activities have contributed to the massive changes in vegetation in the study region. The variations in the vegetation cover in the urban regions is smoothing worth noting. There are factors that are worth noting in terms of the impact of urban expansion on the vegetation patterns as noted in the NVDI as shown in the figures (Garcia & Tejeda, 2009). The images show the impact of urban expansion on the vegetation density.
The NVDI changes between the years from 2000 to 2015 shows that the mean NVDI of the Erbil was 0.3585 in the outskirt areas of the city and 0.2365 in the core of the urban center. The difference in the mean between the urban and peri-urban areas show a huge difference of 0.122, and this means that there is a significant change in vegetation cover on the two regions. The difference shows high rates of anthropogenic activity in the Erbil city that in the outskirt regions of the city. The NVDI analysis shows that the vegetation density in the peri-urban areas increased significantly. The trend shows that human activities had a direct influence on the on the vegetation density in the study region. There are direct spatial changes in the population density between the urban and peri-urban areas.
Discussion
The images show the impact of the human activities on the vegetation distribution patterns in the study area. As noted in the population distribution patterns it is evident that with the expansion of the Erbil urban center there is a corresponding decrease in the natural vegetation. This is evident during the period of analysis between 2002 and 2015. Despite the demographic contributions, there is an issue of other natural factors like topography and climatic changes over time (Fortuniak, 2009). Climate and topographic features have an impact on the vegetation development in the target region. To understand the influences of the climate on the vegetation distribution pattern in the larger Erbil city, it is worth noting the temperature trends in the areas surrounding the city and how this influences the climatic patterns. The temperature differences have an impact on the UHI of the area, and this can promote vegetative growth.
The urbanization process during the period of the study showed that the NVDI values changed significantly given the difference in the mean NVDI values between the city’s core and the outskirts if the city. The NVDI values over the years show significant spatial variation and the differences in value showed that human activities (Busar & Hall, 2005). The core areas in the Erbil city shows increased human activity that has contributed to the low vegetative cover in the area. There is a negative effect of human activity on the overall vegetation index across time series, and this supports the conclusion that human activities and development have an influence on the vegetation dynamics in the study area across the time series. The extent of vegetation change across the time series indicates how human activities across the study period. The process of urban expansion and the corresponding human activities had a direct impact on the vegetation patterns in Erbil region (Busar & Hall, 2005). The activities have led to the steadily declining vegetation cover in the expanding urban areas of Erbil. The replacements of natural vegetation cover with buildings and other human developments that have changed the overall outlook of the landscape over time. The changes can be attributed to the changing climatic patterns as a result of urbanization. The changes observed in the last 15 years shows that Erbil area has changed significantly, and the regression analysis shows the difference in the overall urbanization and vegetation cover change.
Conclusion
The anthropogenic activities in the open lands between the Erbil city core and the outskirts of the city are the reason for the rapidly changing environmental conditions, and this is coupled with the climatic conditions. Human activity has the ability to change the overall vegetative and climatic structure within cities, and this can explain the reason for the drastic rate of change of the nature of vegetation cover in the region after the relocation of people to the new regions outside the city (Erik, 2006). The MODIS data analysis from the satellite images shows that the nature of vegetative cover largely depends on the settlement patterns and also the temperature. As noted the plotted areas with lower overall temperature have higher vegetative cover when compared to the regions with high temperatures (NASA, 2010). The fully vegetated MODIS model shows that the region vegetation can distribute in terms of parks that showed the high vegetative cover, household gardens shown by the frontal gardens and sparse population and lastly the industrial regions with no vegetation. Generally, human encroachment has had a significant impact on the vegetation distribution patterns and dynamics in the Erbil region and with the expansion of urbanization, it is likely that the city will completely occupy the area covered by the parks and vegetation.
Acknowledgement
I would like to express my gratitude to all the individuals who made significant contributions to the accomplishment of this work. I am particularly grateful for the assistance according to my by my colleagues who tirelessly provided me with the assistance I required particularly in data collection and interpretation and assisting me with the editorial work. I thank the NASA for allowing me to use the images from their satellite in justifying my research based on facts. Finally, I appreciate my collaborators whose significant contributions made this work a success.
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