Flooding is a natural phenomenon of the hydrological cycle, but it has become an urban concern in many cities around the world. Due to human intervention on the functioning of hydrosystems through infrastructure, the channelling of watercourses, the redirection of the flow and the inevitable extension of the urban landscape, floods have become a growing urban hazard. Several cities are currently facing very frequent flash floods. These floods are of various types and several factors are at the origin of their manifestation, which leaves its understanding and prevention for local stakeholders a long-term process that requires a colossal amount of work among several multidisciplinary researchers. Without denying the scientific consensus on the role of climate change, currently floods are largely caused by the senseless and irresponsible behaviour of humans. Among the cities in Saudi Arabia facing the risk of flooding is the city of Abha located in the southwest of the country, the focus of this research. It is subject to recurrent and devastating floods caused by several factors. Controversial topography, dissected orography, aggressive rainfall, accelerated and unregulated urban growth, and irresponsible human intervention are all factors that aggravate this problem. The resolution of this problem, or at least the minimization of its consequences, requires a rigorous and carefully studied approach. The appropriate knowledge by local stakeholders must be reinforced by a methodological and cartographic assessment of this phenomenon in order to mitigate its consequences. The main objective of this work is to make cartographic and methodological contributions to acquire additional knowledge on the flood hazard in the city of Abha through a statistical processing of rainfall data for the period 1978-2018, a mapping of the factors intervening on the runoff and its various behaviors and finally a synthetic analysis.

Climate change is a hot topic. All the research covering this subject confirms its veracity. Since the end of the 20th century, the Earth has been facing a climatic evolution that often results in a thermal rise and a regression of the rains, with clear trend to drought. In this research, we try, through the climatic data of the Ghardaïa station (Algeria), to confirm or remove this truth through a comparative statistical approach. To achieve this purpose, we compare the thermal and rainfall data for the period 1986 -2017 with those for the period 1913-38 at the three time scales (monthly, seasonal and annual). In this article, we will focus on three themes of great importance, the qualitative climatic evolution through the rise and fall for both parameters, the quantitative aspect of this evolution. Establish climate synthesis in order to determine the tendency to drought and / or humidity.