Effects of Land Cover Change on Urban Floods and Rainwater Harvesting: A Case Study in Sharjah, UAE (original) (raw)
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MATEC Web of Conferences
The work presented in this article is an extension of an earlier study [1] in which runoff in the city of Sharjah, United Arab Emirates (UAE), was assessed for the period 1967-2010. In this study, the impacts of urban expansion on potential flooding, storage and water harvesting were assessed for the period 1976-2016 using rainfall data recorded during the same period. Sharjah is a generally a flat coastal city that is located in a dry hot region average rainfall of approximately 100 mm/y. Remote sensing and GIS techniques were used to assess the expansion of built areas in the city using multi-temporal Landsat satellite images. The built areas in the city increased during the study period by approximately four folds while the population increased by more than 10 folds. The study results demonstrate the historical increase in runoff potential, flooding potential and runoff coefficient and decline in water storage potential. The results are consistent with the observed incidence of significant local flooding episodes in urban areas during rainfall events. Furthermore, an assessment of potential urban water harvesting based on expansion of built areas in the city is provided and appropriate urban storm water management practices for the city are recommended.
Spatio-temporal analysis of urban growth and its impact on floods in Ajman City, UAE
Environmental Monitoring and Assessment, 2019
The negative consequences of urbanisation have been recently recognised despite the social and economic benefits it provides to the community. Effects of urbanisation include increases in surface runoff, frequency and magnitude of floods and urban water harvesting capacity. Accordingly, this study utilised multi-spectral and multi-resolution satellite images combined with field data to conduct a quantitative assessment of the impact of urbanisation on urban flooding for the period of 1975-2015 in Ajman City, United Arab Emirates (UAE). Results showed that urban areas in the city have increased by approximately 12-fold over the period 1975-2015, whilst the population increased by approximately 16-fold. Owing to a substantial increase in urbanisation (as impervious areas expanded), minimum precipitation to generate runoff in built areas dropped from approximately 16.37 mm in 1975 to approximately 13.3 mm in 2015, which caused a substantial increase in the surface runoff. To visualise the flooding potential, urban flooding maps were generated using a well-established decision analysis technique called Analytical Hierarchy Process. The latter adopted three thematic factors, namely excess rain, elevation and slope. Flooding potential was then found to have increased substantially, specifically in the downtown area. Finally, this study is expected to contribute highly to flood protection and sustainable urban storm water management in Ajman City. Keywords Urban growth. Flood mapping. Water harvesting. High-resolution images. Ajman. United Arab Emirates Environ Monit Assess
International journal of economic and environment geology, 2023
There is a growing threat of urban flooding, particularly in Pakistan that needs attention and requires effective management strategies. The chief trigger for urban flooding is the rapid and unplanned urbanization in areas where impermeable surface inhibits rainwater diffusion and changes the natural water flow. In many developed countries, a technique of rainwater harvesting is implemented as a sustainable strategy to manage urban stormwater. Most studies and projects chiefly focused on the potential use of the Rainwater harvesting technique for water conservation in arid and semi-arid climates. In the present work, GIS and remote sensing methodologies are utilized for the suitability of rainwater harvesting structures. This study was conducted in Lahore, the second most populated city of Pakistan and the capital of Punjab. Generally, the water harvesting technique depends on topographical areas with water accumulation, where there is an availability of open spaces in the form of green areas and barren lands, rainfall, drainage network density, and rainfall distribution, particularly in the urban environment. The SRTM DEM data were used for finding high water accumulated areas, and the Landsat OLI image is used to retrieve land use information i.e. vacant land and open green spaces, existing drainage network density, and rainfall distribution. All these layers were integrated through AHP to detect the potentially suitable sites for the construction of rainwater harvesting structures. Results concluded 94 suitable sites with categorization from highly to critically suitable for the construction of rainwater harvesting structures in which 6 were highly suitable areas in Data Gunj Bakhsh Town and Ravi Town. Besides, residential areas are having a maximum site suitability percentage, followed by roads, agricultural and open spaces in the area under consideration. Considering the suitable sites, further rainwater harvesting methods can be identified in the study area to alleviate urban flooding and improve the urban environment.
Impacts of urban growth on flood hazards in Makkah City, Saudi Arabia
academicjournals.org
Flash floods are the most dangerous type of natural disasters in arid regions, such as Saudi Arabia. The effects of urban growth, witnessed between 1990 and 2010, in Makkah city, Saudi Arabia, on runoff volume and peak discharge are investigated using the curve number (CN) flood-modelling methodology. Shapefiles of residential areas are compiled and integrated in a unique geographic information system (GIS) environment. Datasets of geological structures, soil types, and a digital elevation model (DEM) have been collected and utilized. Peak discharges have been computed on the wadi scale, while the total flood volume have been estimated on the sub-basin scale for residential subbasins in order to get a detailed view of urbanization impacts on flood hazards. The results obtained show that the residential regions of Makkah city have been increased, over the period 1990 to 2010, by 197%, while the total flood volumes have been enlarged by 248%. The spatial distribution of high-flood urban regions is mapped. Furthermore, the results show significant positive correlations between urbanization and both peak discharge and flood volume. Accordingly, these findings should be taken into account in future urbanization, sustainable development and flood management plans of Makkah metropolitan area.
This study investigates the impact of the October 2016 flash floods in urban areas located in selected catchments along the Nile Valley and Red Sea regions for the assessment and the proposal of feasible mit-igation measures. Optical and radar satellite images acquired before and shortly after flash flood events were analyzed to detect and map the active contributing channels, the interfering urban areas, the response of natural depressions and storage areas, and the conveying channels to the flash floods. The quantitative estimates of October 2016 flash floods parameters including total rainfall depths, the active channel cross-sectional areas, and the spatial extent of storage areas of the accumulated flood water were measured. Various hydrological parameters were extracted using the Digital Elevation Model (DEM) for the estimation of water volumes of largely inundated depressions. It was determined that the October 2016 flash floods were devastating in the Ras Gharib area; however, these floods were properly managed at both the New El Minya and New Qena urban areas. In contrast, the flash floods at the Al-Saaf and Atfih urban area require urgent mitigation measures given that wastewater depressions and sanitary facilities are prevalent in the downstream reaches of the studied drainage basins. Ó 2020 National Authority for Remote Sensing and Space Sciences. Production and hosting by Elsevier B. V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Flood hazards in an urbanizing watershed in Riyadh, Saudi Arabia
Geomatics, Natural Hazards and Risk, 2014
Riyadh, the capital of the Kingdom of Saudi Arabia, has experienced unusual levels of urbanization in the past few decades, making it one of the fastest growing cities in the world. This paper examines flood hazards in the rapidly urbanizing catchment of Al-Aysen in Riyadh. Remote sensing and geographic information system techniques were employed to obtain and prepare input data for hydrologic and hydraulic models, with the former based on the very popular curve number approach. Due to the limited nature of the rainfall data, observations from two rain gauges in the vicinity of the catchment were used to estimate design storms. The hydrologic model was run in a semi-distributed mode by dividing the catchment into many sub-catchments. The impact of urbanization on runoff volume and peak discharge resulting from different storms was investigated, with various urbanization scenarios simulated. Flood hazard zones and affected streets were also identified through hydrologic/hydraulic model simulation. The mismatch between administrative and catchment boundaries can create problems in flood risk management for similar cities since hydrologic processes and flood hazards are based on the hydrologic connectivity. Since flooding events impact the road network and create driving hazards, governmental decision-makers must take the necessary precautions to protect drivers in these situations.
Estimating urban flooding potential near the outlet of an arid catchment in Saudi Arabia
Geomatics, Natural Hazards and Risk, 2016
The aim of this study is to build a flood simulation model for the city of Hafr Al-Batin catchment area. The model consists of a hydrologic model, a hydraulic model and pre-and post-processing tools. A geographic information system-based modelling interface was used to pre-process the terrain and rainfall data and generate input files for hydrologic and hydraulic models. Soil map data, land cover map, land use map and digital elevation model was used to delineate the physical watershed's characteristics. The runoff estimation was based on the widely known Soil Conservation Service curve number approach. The hydrologic/hydraulic model simulations simulated the runoff hydrograph corresponding to different design storms and helped to delineate the resulting flood inundation maps. The results indicate good agreement between the delineated inundation map and the hazard map developed by the municipality. They also show that the location of the city complicates the runoff response for small storms creating two distinct peaks. The results of this study can be utilized for planning purposes and in the design of flood control structures as the study has estimated the runoff corresponding to different design storms and used hydraulics and geospatial data in delineating the flood zones.
The Assessment of Urbanization Effect and Sustainable Drainage Solutions on Flood Hazard by GIS
Sustainability
Rapid and uncontrolled changes in land use patterns due to urbanization negatively affect urban rainfall-runoff processes and flood hazard. In this study, a method that included different sustainable drainage solutions, such as green infrastructure (GI) usage for flood hazard mitigation with various scenarios on a geographic information system (GIS) platform within a 1653 ha catchment of the Kağıthane Stream in İstanbul, Turkey is presented. Developed scenarios are as follows: scenario one (SN1) is the current situation; scenario two (SN2) used green roof application for buildings and a permeable surface for roads; scenario three (SN3) used only green roof application for buildings; scenario four (SN4) used a rainwater barrel for collecting roof water, a swale canal for collecting road water, and added additional structures to open areas to observe urbanization; scenario five (SN5) considered multiple GI implementations; and scenario six (SN6) considered full urbanization. The resul...
Remote Sensing, 2020
Nowadays, geospatial techniques are a popular approach for estimating urban flash floods by considering spatiotemporal changes in urban development. In this study, we investigated the impact of Land Use/Land Cover (LULC) changes on the hydrological response of the Erbil basin in the Kurdistan Region of Iraq (KRI). In the studied area, the LULC changes were calculated for 1984, 1994, 2004, 2014 and 2019 using the Digital Elevation Model (DEM) and satellite images. The analysis of LULC changes showed that the change between 1984 and 2004 was slower than that between 2004 and 2019. The LULC analysis revealed a 444.4% growth in built-up areas, with a 60.4% decrease in agricultural land between 1984 and 2019. The influence of LULC on urban floods caused by different urbanization scenarios was ascertained using the HEC-GeoHMS and HEC-HMS models. Over 35 years, there was a 15% increase in the peak discharge of outflow, from 392.2 m3/s in 1984 to 450 m3/s in 2014, as well as the runoff volu...
2016
This study uses an integrated approach, bringing together geographic information system (GIS), remote sensing, and rainfall-runoff modeling, to assess the urbanization impact on flash floods in arid areas. Runoff modeling was carried out as a function of the catchment characteristics and the maximum daily rainfall parameters. Land-use types were extracted from the supervised classification of SPOT-5 (2010) and Landsat-8 (2015) satellite images and were validated during field checks. Catchment morphometric characteristics were carried out using the correlated Topaz and Arc-Hydro tools. Maximum floods of the catchment were evaluated by coupling GIS and remote sensing with Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) hydrologic modeling. Peak discharges were estimated, and the abstraction losses were computed for different return periods. The model results were calibrated according to actual runoff event. The research shows that rapid urbanization adversely affects hydrological processes, since the sprawl on the alluvial channels is significant. This reduces infiltration into the underlying alluvium and increases runoff, leading to higher flood peaks and volumes even for short duration low intensity rainfall. To retain a considerable amount of water and sediments in these arid areas, construction of small dams at the fingertip channels at the outlet of the lower order sub-basins is recommended.