Impact of extreme weather events on faecal sludge management based on standardized precipitation index in Dar es Salaam

In developing countries, climate variability poses significant challenges to urban water resource management and faecal sludge management, particularly in flood- and drought-prone areas. Inadequate consideration of climate variability in faecal sludge management planning has led to service disruptions in flood- and drought-prone urban areas. This study integrates multi-timescale climate trend analysis with faecal sludge management challenges, providing novel insights into climate-resilient sanitation strategies. The extreme climate events and their implications on faecal sludge management were assessed by applying the Standardized Precipitation Index (SPI) at multiple timescales (SPI-12, SPI-6, and SPI-3). The Mann-Kendall test and Sen's slope estimator were applied to analyse long-term trends and the magnitude of change at annual, seasonal, and monthly levels. Climate Hazards Group InfraRed Precipitation with Station rainfall data (1981-2021) from four stations were used, with validation conducted through Pearson correlation against observed data from Dar es Salaam International Airport. Results indicate increasing precipitation variability, with statistically significant positive trends in some seasons, particularly during the long rains. Extreme wet periods (2019-2020, SPI: 2.48-2.92) have increased flood risks, while severe droughts (2002-2003, SPI: -1.57 to -2.08) have exacerbated water scarcity, thereby impacting the reliability of faecal sludge management services. The Sinza River Catchment, a lowland urban area where over 99% of residents rely on onsite sanitation, remains highly vulnerable to climate extremes, causing pit latrine failures due to flooding and limited desludging options during droughts. Addressing these issues requires climate-resilient faecal sludge management strategies, including flood-resistant latrines, water-efficient sanitation technologies, and the integration of policy into urban resilience planning.