Assessment of the Spatial and Temporal Characteristics of Rainfall and Temperature Over Sudd Wetland in South Sudan in a Changing Climate

Abstract

The Sudd wetland is the world’s largest floodplain area and is essential for livelihoods, economic income, and water resources for communities living in the surrounding area. The communities in this area have been using traditional knowledge to forecast or predict rainfall seasons as well as when to start fishing. Each year during the rainfall season, there is heavy flooding and displacement of humans and livestock among the communities in the Sudd wetland. Thus, this study provides better knowledge regarding the variability of past and future changes in climate extremes over Wetland. This dissertation aimed to determine the temporal-spatial characteristics of past, present and projected rainfall and temperature, to examine the anomalous rainfall-related floods over the Sudd wetland area. The data used is monthly CHIRPS V2.0 data for precipitation and ERA5 for temperature. The data was obtained from the University of California, Santa Barbara, and ECMWF. ERA5 and version two of CHIRPS data for 41 years cover the period from 1981 to 2022 by using Statistical methods (Mean, Coefficient of Variation and time series analysis). For the projection of precipitation and temperature used in CMIP6 model analysis for exploring future precipitation and temperature under three scenarios SSP1-2.6, SSP2-4.5, and SSP5-5.8 for near (2030-2059), and far future (2070-2099) relative to historical (1981-2010). The findings of this study show the annual rainfall in The Sudd wetland is above 650mm, and the June to September season is the wettest. the Sudd wetland region experienced a significantly increasing rainfall in August of more than 500mm. while December to February is the driest season recording less than 10 mm. The annual mean temperature was between 27.5 to 29 0C, March, April, and May (MAM) seasons were the warmer seasons, while the colder seasons were June to September (JJAS). The results of data analysis showed that all seasonal rainfall has lower variability except for the March to May (MAM) rainfall season is moderate 20 to 30 %. The Statistical trend analysis indicates slightly increasing trends of mean annual and seasonal rainfall over The Sudd wetland region. The temperature variability was lower variability and the trend analysis indicates increasing trends of mean annual and seasonal temperature over The Sudd region. The result of rainfall anomalies showed that from 1981 to 2020 the Sudd wetland had an above-normal precipitation associated with flood recorded over this region and experienced a significantly increasing trend. The result of the CMIP6 model, June to September has shown a significant increase in seasonal rainfall over the Sudd wetland under three scenarios. quantitively, SSP1-2.6

is projected to be 0.50(0.50), SSP2-45 is projected to be 0.70(1.25) and SSP5-85 is projected to be 1.10(3.33), while the annual and all seasonal mean temperatures for the future term 2030-2059 and 2070-2099 projected to increase under three scenarios over the Sudd wetland. Future studies on The Sudd Wetland, request additional research utilizing the ensemble means of several models' best performance over The Sudd Wetland.