scholarly journals Investigation and Simulation of Flood Inundation Hazard in Urban Areas in Iran

2020 ◽  
Author(s):  
Mohammad Rostami Khalaj ◽  
Hamzeh Noor ◽  
Ali Dastranj

Abstract Extensive impervious area and the man-made streams are the characteristics of urban areas. In recent years, rapid urbanization has led to change of rural areas into urban areas, and urban runoff will increase as the result of spread and growth of impervious areas. Land use changes, increasing urbanization, unauthorized construction, inefficiency of sewage system and increased impervious surface in urban areas have significant impacts on inundation hazard. Therefore, to manage urban areas and prioritize regions to inundation elimination problems, the area most affected by inundation should be determined. In this study, the Storm Water Management Model (SWMM) is used to simulate the rainfall-runoff in the study area. The simulated runoff in the SWMM model is used as input to the HEC-RAS model and determines inundation hazard zones for 5, 25 and 50 return periods. Then, six factors such as distance from the main channel, slope, land use, drainage density, the main channel slope and elevation were selected to determine inundation hazard map using Analytic Hierarchy Process (AHP). The results showed that the combined model (SWMM and HEC-RAS) was suitable to analyze urban inundation and determine inundation hazard zones on urban areas. Simulated results can be used to develop urban inundation hazard forecasts. In addition, the result of inundation hazard map indicates that 8.2 percent of the case study is determined as a high hazard zone.

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohammad Rostami Khalaj ◽  
Hamzeh Noor ◽  
Ali Dastranj

AbstractExtensive impervious area and the man-made streams are the characteristics of urban areas. In recent years, rapid urbanization has led to change of rural areas into urban areas, and urban runoff will increase as the result of spread and growth of impervious areas. Land use changes, increasing urbanization, unauthorized construction, inefficiency of sewage system and increased impervious surface in urban areas have significant impacts on inundation hazard. Therefore, to manage urban areas and prioritize regions to inundation elimination problems, the area most affected by inundation should be determined. In this study, the Storm Water Management Model (SWMM) is used to simulate the rainfall-runoff in the study area. The simulated runoff in the SWMM model is used as input to the HEC-RAS model and determines inundation hazard zones in 5, 25 and 50 return periods. Then, six factors such as distance from the main channel, slope, land use, drainage density, the main channel slope and elevation were selected to determine inundation hazard map using Analytic Hierarchy Process (AHP). The results showed that the combined model (SWMM and HEC-RAS) was suitable to analyze urban inundation and determine inundation hazard zones on urban areas. Simulated results can be used to develop urban inundation hazard forecasts. In addition, the result of inundation hazard map indicates that 8.2% of the case study is determined as a high hazard zone.


2018 ◽  
Vol 10 (11) ◽  
pp. 4287 ◽  
Author(s):  
Yantao Xi ◽  
Nguyen Thinh ◽  
Cheng Li

Rapid urbanization has dramatically spurred economic development since the 1980s, especially in China, but has had negative impacts on natural resources since it is an irreversible process. Thus, timely monitoring and quantitative analysis of the changes in land use over time and identification of landscape pattern variation related to growth modes in different periods are essential. This study aimed to inspect spatiotemporal characteristics of landscape pattern responses to land use changes in Xuzhou, China durfing the period of 1985–2015. In this context, we propose a new spectral index, called the Normalized Difference Enhanced Urban Index (NDEUI), which combines Nighttime light from the Defense Meteorological Satellite Program/Operational Linescan System with annual maximum Enhanced Vegetation Index to reduce the detection confusion between urban areas and barren land. The NDEUI-assisted random forests algorithm was implemented to obtain the land use/land cover maps of Xuzhou in 1985, 1995, 2005, and 2015, respectively. Four different periods (1985–1995, 1995–2005, 2005–2015, and 1985–2015) were chosen for the change analysis of land use and landscape patterns. The results indicate that the urban area has increased by about 30.65%, 10.54%, 68.77%, and 143.75% during the four periods at the main expense of agricultural land, respectively. The spatial trend maps revealed that continuous transition from other land use types into urban land has occurred in a dual-core development mode throughout the urbanization process. We quantified the patch complexity, aggregation, connectivity, and diversity of the landscape, employing a number of landscape metrics to represent the changes in landscape patterns at both the class and landscape levels. The results show that with respect to the four aspects of landscape patterns, there were considerable differences among the four years, mainly owing to the increasing dominance of urbanized land. Spatiotemporal variation in landscape patterns was examined based on 900 × 900 m sub-grids. Combined with the land use changes and spatiotemporal variations in landscape patterns, urban growth mainly occurred in a leapfrog mode along both sides of the roads during the period of 1985 to 1995, and then shifted into edge-expansion mode during the period of 1995 to 2005, and the edge-expansion and leapfrog modes coexisted in the period from 2005 to 2015. The high value spatiotemporal information generated using remote sensing and geographic information system in this study could assist urban planners and policymakers to better understand urban dynamics and evaluate their spatiotemporal and environmental impacts at the local level to enable sustainable urban planning in the future.


2020 ◽  
Vol 18 (11) ◽  
Author(s):  
Abdul Ghapar Othman ◽  
Nurul Hanisah Jizan

Urbanization is the process of transforming a characteristically rural society into an urban one. The urban population is growing at an increasing rate while the rural population is declining, giving rise to imbalances in the development between urban and rural areas. The government’s strategy is to distribute the development to the major settlement centres in the rural areas, which are experiencing the same effects of urbanization as the urban areas in terms of changes to the use of land, especially the reduction of agricultural land and the increase in built-up areas. This study used the method of overlay in GIS applications to investigate land use changes, the speed of urban expansion and direction of development that has taken place from the period 2001 to 2018 in the town of Kuala Nerang, Kedah. This town has undergone a change in its status from a main settlement centre to a district administrative centre. Agricultural lands, which were targeted for development in the rural areas, have been converted into built-up areas. The speed of urban expansion has been slow, although some areas have recorded a higher rate. The development is moving towards the west along the main road connecting the major towns in this part of the state. The functions of the district administrative centre have influenced land use changes.


2021 ◽  
Vol 19 (16) ◽  
Author(s):  
Abdul Ghapar Othman ◽  
Kausar Hj Ali ◽  
Wan Mohammad Fazil Asli

Urbanization process has a significant impact on land use planning. It not only affects major cities but also extends to small towns in rural areas where it has a significant role in providing urban services to rural communities. The expansion of urban areas also resulted in the loss of many agricultural lands as well as forests that are rich in natural resources. In both instances, the land use composition is substantially affected. This study uses a "mixed method approach" combining GIS spatial analysis and AHP technique to study land use changes, identify land use growth parameters, determine land use growth suitability areas and identify the direction of urban land use development. The study area is the town of Pendang, which is the main administrative centre for Pendang District, Kedah. The main findings of the study show that changes were not that significant during the period between 2005 to 2012. However, significant land use changes occurred during the period of 2012 to 2020, especially in agricultural land use, vacant land and even water bodies. These land use changes have contributed to the increase in built-up areas. The direction of development is seen heading north, south and southwest of the study area. Accessibility is a major factor influencing the growth of land use and development direction in the study area.


Land ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 57
Author(s):  
Fernando Allende Álvarez ◽  
Gillian Gómez-Mediavilla ◽  
Nieves López-Estébanez ◽  
Pedro Molina Holgado ◽  
Judith Ares Barajas

The present paper highlights the importance of hedgerows and enclosures in the mountains of Central Spain. Now, these landscapes have suffered profound variations in terms of agroforestry practices, especially in the Mediterranean mountains where the characteristic multifunctional has largely been lost. The article analyzes land uses changes, dynamics, and their morphological features between the first half of the 20th Century (1956) and the second decade of the present time (2019). The paper was divided into three sections. First, the identification of land uses using orthophotograph and aerial photograph; after that the info was checked with fieldwork. Eleven categories were identified according to the dominant use and land use changes and size of land parcels were taken into consideration. Second, the configuration and the information collected through the type and intensity of change in land uses made it possible to recognise and quantify their distribution and trend between these two dates. Also, the kernel density algorithm available in the Arcgis 10.5 software was used to obtain density and changes in land parcels. Finally, an overview is given of the main role that this agroforestry plays due to the social, ecological, and economic benefits that they provide for allowing sustainable development.


Insects ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 269
Author(s):  
Eleanor N. Field ◽  
Ryan E. Tokarz ◽  
Ryan C. Smith

The ecology and environmental conditions of a habitat have profound influences on mosquito population abundance. As a result, mosquito species vary in their associations with particular habitat types, yet long-term studies showing how mosquito populations shift in a changing ecological landscape are lacking. To better understand how land use changes influence mosquito populations, we examined mosquito surveillance data over a thirty-four-year period for two contrasting sites in central Iowa. One site displayed increasing levels of urbanization over time and a dramatic decline in Culex pipiens group (an informal grouping of Culex restuans, Culex pipiens, and Culex salinarius, referred to as CPG), the primary vectors of West Nile virus in central Iowa. Similar effects were also shown for other mosquito vector populations, yet the abundance of Aedes vexans remained constant during the study period. This is in contrast to a second site, which reflected an established urban landscape. At this location, there were no significant changes in land use and CPG populations remained constant. Climate data (temperature, total precipitation) were compiled for each location to see if these changes could account for altered population dynamics, but neither significantly influence CPG abundance at the respective site locations. Taken together, our data suggest that increased landscape development can have negative impacts on Culex vector populations, and we argue that long-term surveillance paired with satellite imagery analysis are useful methods for measuring the impacts of rapid human development on mosquito vector communities. As a result, we believe that land use changes can have important implications for mosquito management practices, population modeling, and disease transmission dynamics.


2019 ◽  
Vol 1 ◽  
pp. 1-1
Author(s):  
Roxanne Lai ◽  
Takashi Oguchi

<p><strong>Abstract.</strong> Changing land use is an increasingly important issue as human habits, behaviors, and needs change. There has been an increase in land and agricultural abandonment in some places of the world. In Japan, movement of the population from rural to urban areas have resulted in much land and agricultural abandonment. In 2016, a land ministry survey showed that 4.1 million hectares of land in Japan had unclear ownership, with farmland making up 16.9% of the total. As vegetation cover changes after land abandonment, this temporal and spatial effect may have important effects on geomorphic processes such as landslide susceptibility and landslide kinematics.</p><p>Here we track long-term land use changes over vegetated landslide areas of the Sanbagawa and Mikabu Belts of Shikoku Island, Japan. The Sanbagawa and Mikabu Belts are metamorphic belts that run across Southwest Japan, and are home to numerous large crystalline schist landslides, including the widely-studied slow but continuously moving Zentoku landslide. Villages and communities have been built on these landslide areas due to historical and cultural factors, as well as the fertility of the soil. Consequently, given the changing land uses including land abandonment in these landslide areas over time, we use long-term high-resolution land cover vegetation datasets to examine first the long-term land use changes, and then use statistical methods to explore their relationships with landslide susceptibility and kinematics. Mapping of spatial data and their analysis using GIS constitute a core part of the research. The results suggest interconnections between land use changes and land movement.</p>


2018 ◽  
Vol 7 (3.30) ◽  
pp. 497
Author(s):  
Nonik Eko Wahyuning Tiyas ◽  
Dwita Sutjiningsih

Jakarta is a lowland area with 40% of its territory at an elevation below the sea level so it is very vulnerable to flooding. One of out many causes floods in Jakarta is by the overflow of the Ciliwung River. The Ciliwung Watershed has a very strategic value in Indonesia because the Ciliwung River is one of thirteen rivers crossing the nation's capital. The rapid urbanization and population growth led to an increasing impervious area in the Ciliwung Watershed which resulted in a flood hydrograph change. This research aims to determine the influence of land use change, which is taking into account the spatial discretization and the riparian characteristic of Middle - Lower Ciliwung Sub-Watershed on flood hydrograph at Manggarai Weir. This research reviews the related literature on the implementation of HEC-GeoHMS version 10.1 developed by US Army Corps of Engineers (2013) to estimate the effect of land use change on flood hydrographs by taking into account the characteristics of the riparian described descriptively and present arguments to claim that the discretization spatial method can provide significantly more flood hydrographs results with existing conditions.  


2011 ◽  
Vol 50 (9) ◽  
pp. 1872-1883 ◽  
Author(s):  
Winston T. L. Chow ◽  
Bohumil M. Svoma

AbstractUrbanization affects near-surface climates by increasing city temperatures relative to rural temperatures [i.e., the urban heat island (UHI) effect]. This effect is usually measured as the relative temperature difference between urban areas and a rural location. Use of this measure is potentially problematic, however, mainly because of unclear “rural” definitions across different cities. An alternative metric is proposed—surface temperature cooling/warming rates—that directly measures how variations in land-use and land cover (LULC) affect temperatures for a specific urban area. In this study, the impact of local-scale (<1 km2), historical LULC change was examined on near-surface nocturnal meteorological station temperatures sited within metropolitan Phoenix, Arizona, for 1) urban versus rural areas, 2) areas that underwent rural-to-urban transition over a 20-yr period, and 3) different seasons. Temperature data were analyzed during ideal synoptic conditions of clear and calm weather that do not inhibit surface cooling and that also qualified with respect to measured near-surface wind impacts. Results indicated that 1) urban areas generally observed lower cooling-rate magnitudes than did rural areas, 2) urbanization significantly reduced cooling rates over time, and 3) mean cooling-rate magnitudes were typically larger in summer than in winter. Significant variations in mean nocturnal urban wind speeds were also observed over time, suggesting a possible UHI-induced circulation system that may have influenced local-scale station cooling rates.


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