Climate Change and Disaster Risk Management

Time Series Analysis of Temperature and Rainfall in the Savannah Region in Togo, West Africa

2023-04-23T00:00:00Z

Time Series Analysis of Temperature and Rainfall in the Savannah Region in Togo, West Africa Yao, Komlagan Mawuli Apelete; Kola, Edinam; Morenikeji, Wole; Filho, Walter Leal This study investigates the trend in monthly and annual rainfall, and minimum and maximum temperature (Tmin and Tmax) in the Savannah region of Togo. The historical data of Mango and Dapaong weather stations from 1981 to 2019 were used. A serial correlation test was applied to all time series to identify serially independent series. A Non-parametric Mann–Kendall (MK) test was applied to serially independent series. The magnitude of the trend was calculated using the Sen’s slope (SS) method. For the data influenced by serial correlation, a modified version of the Mann–Kendall test was applied. An open-source library package was developed in the R language, namely, “mkmodified”. For annual rainfall, results showed a significant increasing trend at Dapaong (p < 0.05) and a non-significant decreasing trend at Mango (p > 0.05) at 95%. There was an increasing trend in the Tmin both at Mango and Dapaong. No statistically significant trend was found at Mango (p > 0.05), while at Dapaong (p < 0.05), a significant trend was found at 95%. Simlarly, there was a statistically increasing trend in the Tmax both at Mango and Dapaong. Rainfall in Dapaong has increased (5.50 mm/year) whereas in Mango, it has decreased (􀀀0.93 mm/year). Tmn increased by 0.04 and 0.008 C per year in Mango and Dapaong, respectively. Tmax increased by 0.03 and 0.02 C per year in Mango and Dapaong, respectively. A Rainfall Anomaly Index (RAI) was also used to present a temporal variation in rainfall; the historical series presented drier years. Many studies have analysed the trend of climate parameters in northern Togo, but none of them has specifically targeted the Savannah region that is considered the poorest region of the country. A Publication submitted to the West African Science Service Centre on Climate Change and Adapted Land Use, the Université de Lomé, Togo in partial fulfillment of the requirements for the requirements for the degree of Doctor of Philosophy Degree in Climate Change and Disaster Risk Management

Extreme Rainfall in Southern Burkina Faso, West Africa: Trends and Links to Atlantic Sea Surface Temperature

2023-01-31T00:00:00Z

Extreme Rainfall in Southern Burkina Faso, West Africa: Trends and Links to Atlantic Sea Surface Temperature Sougue, Madou; Merz, Bruno; Sogbedji, Jean Mianikpo; Zougmoré, François Understanding the space-time variations of extreme rainfall plays an important role in the management of water-related disasters in Sahel countries. This study investigates temporal changes in rainfall characteristics and explores the link between Atlantic Sea surface temperature and extreme rainfall in the southern part of Burkina Faso. We find substantial spatial heterogeneity in rainfall trends across the study area. In contrast to national and supra-national studies that found predominantly increasing trends in extreme rainfall, we detect more downward than upward trends, particularly for indices representing extreme rainfall. This difference is presumably a consequence of the high spatial variability in rainfall trends that can only be detected with sufficiently dense climate networks. We use the Poisson-General Pareto (Poisson-GP) distribution to quantify the frequency and intensity of extreme rainfall. Our comparison of the traditional, stationary Poisson-GP model with the nonstationary version where rainfall depends on Atlantic SST shows that the nonstationary model outperforms the traditional approach. This finding suggests that the assumption of stationary nature must be considered with care when modeling the frequency and intensity of extreme rainfall in the study area. Overall, our results suggest that the recent increase in flood disasters in Burkina Faso is rather caused by land use and land cover changes and population and urban growth and not by increasing rainfall extremes. A Publication submitted to the West African Science Service Centre on Climate Change and Adapted Land Use, the Université de Lomé, Togo in partial fulfillment of the requirements for the requirements for the degree of Doctor of Philosophy Degree in Climate Change and Disaster Risk Management

Evaluation of the Economic Impact of Coastal Erosion in Dakar Region

2023-09-12T00:00:00Z

Evaluation of the Economic Impact of Coastal Erosion in Dakar Region Pouye, Ibrahima; Adjoussi, Dieudonne´ Pessièzoum; Ndione, Jacques Andre; Sall, Amadou Besides the environmental impacts, climate change negatively affects the economic value of coastal zones. Coastal erosion, which is one of its impacts, causes damage to people living along the coast. The narrowing of the beach due to erosion leads to socio-economic damage by reducing the areas where economic activities are carried out. As a result, livelihoods, human settlements, and economic activities such as fishing, tourism, and industry are disrupted. The evaluation of the economic impacts of coastal erosion is timely and relevant. This study aims to economically investigate the most affected coastal areas in Dakar region in 2030 and 2040. It also allows for the identification of localities that need protective infrastructure to prevent economic losses from coastal erosion. The assessment is done by estimating the economic value of the beach using multilinear regression, an econometric forecasting model. Software such as R, Excel, ArcGIS, and Digital Shoreline Analysis System were used in this study. The results show that, due to coastal erosion, the district municipalities along the coast of Dakar will record a loss estimated at 38,507,856,000 FCFA in 2030 and 57,822,698,000 FCFA in 2040. The results of this study suggest that the parameters such as Beach Width, Lost Areas, Coastal Length, Dynamic Rate, Littoral Areas, Built Areas, Proximity to Town, Coastal Vulnerability Index, Number of Buildings, Number of Hotels, Number of Industries, Number of Fishing Points, and Road Length play an important role on littoral value. Coastal erosion will be among the most threatening disasters in the Dakar region if the “do nothing” option is adopted as an adaptation measure. A Publication submitted to the West African Science Service Centre on Climate Change and Adapted Land Use, the Université de Lomé, Togo in partial fulfillment of the requirements for the requirements for the degree of Doctor of Philosophy Degree in Climate Change and Disaster Risk Management

Topography, Slope and Geomorphology’s Influences on Shoreline Dynamics along Dakar’s Southern Coast, Senegal

2023-03-16T00:00:00Z

Topography, Slope and Geomorphology’s Influences on Shoreline Dynamics along Dakar’s Southern Coast, Senegal Pouye, Ibrahima; Adjoussi, Dieudonné Pessièzoum; Ndione, Jacques André; Sall, Amadou Among the impacts of climate change inWest Africa, coastal erosion is the most threatening disaster apart from floods and the increase in temperatures. The southern coast of the Dakar region, as part of the most threatened coastal zones in West Africa, records the most current coastal damages in Dakar due to its coastline dynamics and low-lying area. This paper investigates the influences of the topography and slope of the beach on shoreline dynamics using remote sensing, cartographic tools and statistical methods such as linear regression. It also states the important role of geomorphologic structures in shoreline dynamics. It was conducted in three littoral cells (Mbao, Bargny and Toubab Dialaw) along the southern coast of Dakar. It helps to understand better the role that topography, slope and geomorphology play in coastal dynamics. The Modified Normalized Difference Water Index (MNDWI) was employed to delineate the coastlines before computing the dynamic rate of the coastline using Digital Shoreline Analysis System (DSAS) software. After that, the topography and slope were determined using a digital elevation model (DEM). Then, the correlation between the coastline dynamic, topography and slope was analyzed using the coefficient of correlation and linear regression model. In the Mbao and Bargny littoral cells where the geomorphology is mostly dominated by soils little or not evolved in situ, there is a significant relationship between the coast line dynamic, topography and slope with a coefficient of correlation of about 0.63 and 0.87, respectively. The relationship is not significant in Toubab Dialaw, where the topography and slope are high, and the geomorphology is mainly characterized by a category of sandstone, with a coefficient of 0.15. We conclude that topography, slope and geomorphology play an important role in the shoreline dynamics in the study area. A Publication submitted to the West African Science Service Centre on Climate Change and Adapted Land Use, the Université de Lomé, Togo in partial fulfillment of the requirements for the requirements for the degree of Doctor of Philosophy Degree in Climate Change and Disaster Risk Management