GIS-based spatio-temporal analysis of rainfall trends under climate change in different agro-ecological zones of Wolaita zone, south Ethiopia

Abstract

Understanding the spatiotemporal dynamics of climatic conditions within a region is paramount for informed rural planning and decision-making processes, particularly in light of the prevailing challenges posed by climate change and variability. This study undertook an assessment of the spatial and temporal patterns of rainfall trends across various agro-ecological zones (AEZs) within Wolaita, utilizing data collected from ten strategically positioned rain gauge stations. The detection of trends and their magnitudes was facilitated through the application of the Mann-Kendall (MKs) test in conjunction with Sen's slope estimator. Spatial variability and temporal trends of rainfall were further analyzed utilizing ArcGIS10.8 environment and XLSTAT with R programming tools. The outcomes derived from ordinary kriging analyses unveiled notable disparities in the coefficient of variability (CV) for mean annual rainfall across distinct AEZs. Specifically, observations indicated that lowland regions exhibit relatively warmer climates and lower precipitation levels compared to their highland counterparts. Within the lowland AEZs, the majority of stations showcased statistically non-significant positive trends (p > 0.05) in annual rainfall, whereas approximately two-thirds of midland AEZ stations depicted statistically non-significant negative trends. Conversely, over half of the stations situated within highland AEZs displayed statistically non-significant positive trends in annual rainfall. During the rainy season, highland AEZs experienced higher precipitation levels, while the south-central midland areas received a moderate amount of rainfall. In contrast, the northeast and southeast lowland AEZs consistently received diminished rainfall across all seasons compared to other regions. This study underscores the necessity for the climate resilient development and implementation of spatiotemporally informed interventions through implementing region-specific adaptation strategies, such as water conservation measures and crop diversification, to mitigate the potential impact of changing rainfall patterns on agricultural productivity in Wolaita.

Keywords: Agro-ecology; Kriging-interpolation; Mann-kendall; Rainfall; Sen's slope; Spatiotemporal analysis; Wolaita zone.

Fig. 1

Map of the study area.

Fig. 2

Methodological framework of the study.

Fig. 3

To estimate the weighted total rainfall for the region, Wolaita zone thiessen polygons are created from meteorological stations.

Fig. 4

The spatial and seasonal/annual rainfall distribution over Wolaita zone (1987–2021).

Fig. 5

Trends of annual rainfall across stations.

Fig. 6

The MK test revealed the spatial variance of rainfall trends at the 5 % significance level for the a) Annual, b) Belg, c) Kiremt, and d) Bega periods.

Fig. 7

The spatial variation of a) Annual; b) Belg; c) Kiremt and d) Bega timescales of rainfall trends identified by the MK test at 5 % significance level.