TITLE:
Observed Meteorological Trends and Climate Variability in the Lake Babati Catchment, Tanzania
AUTHORS:
Moses N. Sulumbi, Lusajo H. Mfwango, Edmund Mutayoba
KEYWORDS:
Climate Variability, Mann-Kendall Trend Test, Standardized Precipitation Index, Unimodal Rainfall, Lake Babati, Tanzania
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.7,
July
28,
2026
ABSTRACT: Lake Babati is a shallow, semi-closed freshwater lake in Babati District, Manyara Region, north-eastern Tanzania, whose water storage is highly sensitive to climate variability. This study provides what is, to the authors’ knowledge, the first systematic station-based analysis of observed meteorological trends and rainfall variability for the Lake Babati catchment, using records from Babati meteorological station over the period 2006-2025. The Mann-Kendall (MK) trend test, Sen’s Slope Estimator, and the Standardized Precipitation Index (SPI) at 3-month and 12-month accumulation scales were applied to a complete dataset with no missing values. Mean annual rainfall was approximately 887 mm but showed extreme year-to-year variability, ranging from 600 mm to 1373 mm with a coefficient of variation of 22%. No statistically significant trend was detected in annual or seasonal precipitation, with all results interpreted as observed tendencies over the 2006-2025 period given the short record length. The monthly rainfall pattern reveals a single, nearly continuous wet season from October through May with no meaningful dry break in January and February, a pattern more accurately described as a modified unimodal regime than the conventional bimodal classification applied regionally. Annual maximum temperature (Tmax) and minimum temperature (Tmin) both showed weak, equally non-significant tendencies (p = 0.721 for both), with no meaningful change in the diurnal temperature range. SPI-12 analysis identified three multi-year drought periods (2006-2008, 2013-2016, and 2018-2019) and two wet spells (2020-2021 and 2024-2025). These findings establish a useful observational climate baseline for the catchment and provide the foundation for future hydrological modelling and water resources planning in Babati District.