Ismail Youssef

The spatiotemporal analysis of land use/land cover change and monitoring, modeling, and forecasting the future of land uses are considered challenges facing planners and decision-makers in developing countries. These challenges are increased in neighborhood areas surrounding large cities, which are known as the “rural–urban continuum”. These areas have become the preferred areas for resettlement for most urban residents. The objectives of the present study were to (1) monitor the land cover change in the rural–urban continuum axis between the Ar-Riyadh and Al-Kharj cities during the period 1988–2020, (2) simulate the future growth of land cover up to the year 2030 using the Cellular Automated Markov Model (CA-Markov), and (3) improve the ability of CA-Markov to predict the future by integrating multi-criteria analysis based on geographic information systems (GIS-MCA) and analytic hierarchy process (AHP) method. The results of the study revealed large changes in the land cover in the rural–urban continuum axis between the Ar-Riyadh and Al-Kharj cities. About 60 km² of agricultural land has been lost, with an average annual decrease of 2 km². The industrial and urban areas were increased with growth rate of 4%. There were five categories of spatial suitability, ranging between 32 and 86%, and 70% or higher is the recommended percentage for future land uses. The industrial use was the most likely land use in 2030, as it recorded an increase of 27.1 km² over the year 2020.

The management of land use in big cities and capitals and the surrounding adjacent urban aggregates is still of major importance in the field of urban development, especially in cities with populations of millions and various types of land uses and economic activities. The rural–urban continuum between the cities of Ar Riyadh and Al Kharj suffers from an unclear general land use trend, due to urban expansion at the expense of the agriculture lands, the imbalance of the population compound, the deterioration of the urban fabric, lack and poor distribution of services, and the dominance of industrial land use at the expense of other uses. These factors have led to an increase in environmental changes and loss of the environmental and ecological characteristics of this area between Ar Riyadh and Al Kharj. The present study aims at evaluating the land use suitability for urban development in the rural–urban continuum between Ar Riyadh and Al Kharj cities. This is achieved by using the GIS-based Multi Criteria decision Analysis (GIS-MCDA) on twelve various economic, environmental, urban, and law criteria. The weights of criteria were determined using the Analytic Hierarchy Process (AHP) method. The results of the spatial suitability map of the land use for sustainable urban development revealed that there are five categories of spatial suitability ranging in suitability from 32% to 86%. The recommended areas for sustainable urban development are those with a spatial suitability upwards of 70% in the rural–urban continuum corridor between Ar Riyadh and Al Kharj cities. The sustainable development in this corridor can be achieved by executing high priority projects that ensure and support the urban sustainable development plan through establishing four local urban development centers and upgrading four current villages to rural communities, aiming at strengthening the functional bonds between the rural communities and the local urban development centers. These projects will limit the sustainable urban development to specific areas without allowing random expansion, avoiding the urban conjugation of the two Ar Riyadh and Al Kharj cities through the connecting area between them.

Drainage basins in dry and semiarid environments are exposed to sudden, irregular flooding that poses a threat to urban areas and infrastructure. The associated risk is exacerbated by land use changes. Geomorphometric analyses of drainage basins based on geographic information systems (GIS) are essential tools for assessing conceptual flood hazards. Geomorphological data extracted from high-precision digital elevation models (DEMs) provide valuable information for modeling the geomorphic, surface classifications of the earth, and for flood hazard mapping. This study aimed to develop an integrative approach to the mapping of flood hazards along the Al-Shamal train pathway in the city of Qurayyat in the Kingdom of Saudi Arabia (KSA) using GIS and hazard modeling for geomorphological ranking. Furthermore, we propose strategic solutions to provide mitigation and protection from negative impacts with the aim of improving the level of awareness of flood geomorphology. The hazard model of geomorphological ranking was used in mapping and calculating the degree of hazards using 24 geomorphometric criteria. These criteria were divided into formal criteria, terrain criteria, and criteria related to the drainage network. The results of the study revealed that the drainage sub-basins are exposed to flood hazards along the Al-Shamal train pathway in the city of Qurayyat. The very high flood hazard constituted 4228.3 km², accounting for 70.3% and 65.7%, respectively, of the drainage basins of the wadis of Makhrouq and Bayer. The high flood hazard represented 61% (4712.4 km²) of the basin of the wadis of Sarmadaa. The medium flood hazard was concentrated in the drainage basin of the wadi of Hasidah, accounting for nearly 57.7% (1271.3 km²). The very low flood hazard was present in 46.5% of the drainage basin of the wadis of Hasidah Umm Nakhla, accounting for an area of 799.4 km². The methodology applied in this study can be used in the estimation of flood hazards in different drainage basins throughout Saudi Arabia and in similar arid regions.

Understanding the dynamics of floods in dry environments and predicting an accurate flood hazard map considering multiple standards and conflicting objectives is of great political and planning importance in the Kingdom of Saudi Arabia’s vision for the year 2030, in order to reduce losses in lives, property, and infrastructure. The objectives of this study are (1) to develop a flood vulnerability map identifying flood-prone areas along the Al-Shamal train railway pathway; (2) to forecast the vulnerability of urban areas, agricultural land, and infrastructure to possible future floods hazard; and (3) to introduce strategic solutions and recommendations to mitigate and protect such areas from the negative impacts of floods. In order to achieve these objectives, multicriteria decision analysis based on geographic information systems (GIS-MCDA) is used to build a flood hazard map of the study area. The analytic hierarchy process (AHP) is applied to extract the weights of eight criteria which affect the areas which are prone to flooding hazards, including flow accumulation, distance from the wadi network, slope, rainfall density, drainage density, and rainfall speed. Furthermore, the receiver operating characteristic (ROC Curve) method is used to validate the presented flood hazard model. The results of the study reveal that there are five degrees of flooding hazard along the Al-Shamal train path, ranging from very high to very low. The high and very high hazard zones comprise 19.2 km along the path, which constitutes about 26.45% of the total path length, and are concentrated at the intersections of the Al-Shamal train pathway with the Bayer and Al-Makhrouk wadis. Moderate, low, and very low flood severity areas constitute nearly 53.39 km, representing 73.55% of the total length (72.59 km) of the track. These areas are concentrated at the intersection of the Al-Shamal train track with the Haseidah Al-Gharbiyeh and Hsaidah Umm Al-Nakhleh wadis. Urban and agricultural areas that are vulnerable to high and very high flooding hazards are shown to have areas of 29.23 km² (22.12%) and 59.87 km² (46.39%), respectively.