Examining the implications of past and future extreme drought characteristics on grasslands in Kiruhura District

Abstract

Drought is one of the major challenges in achieving sustainable development with impacts including; disruptions in the ecosystems, water and food resources among others. Understanding drought dynamics is therefore vital for protecting lives, securing food and water, preserving ecosystems and building climate resilience. This study investigated the characteristics and implications of past and future extreme drought on grasslands, with an aim of contributing towards building drought resilience of the cattle keeping communities in Kiruhura District. Specifically, the objectives of the study included; (1) examining the past and future extreme drought characteristics, (2) examining the impact of past extreme drought on spatiotemporal distribution of grasslands and (3) examining the projected impact of future extreme drought on the temporal distribution of the grasslands. The research employed the Standardized Precipitation Index (SPI) to analyze past and projected drought conditions focusing on the duration, severity, and intensity of extreme drought events. The spatiotemporal changes in the Normalised difference vegetation index (NDVI) against the Standard precipitation index (SPI) were used to investigate the impacts of extreme drought on the grasslands. The results reveal that the grasslands were negatively impacted by extended extreme drought periods of 6 and 12 months. Both SPI indices had a statistically significant relationship shown by the Pearson moment correlation analysis. SPI6 and SPI12 having P-values of 0.0031 and 0.0022 respectively. In the future, under both SSP245 and SSP585 climate scenarios, the relationship between drought and NDVI was generally insignificant with Pearson moment correlation P-values between 0.33 - 0.84, way above the significance level of 0.05. Comparing the two projected climate scenarios, the implication of this relationship was much more pronounced under SSP585 as revealed by the time series analysis where NDVI showed to respond to longer – term droughts although not statistically significant. Drawing from the study conclusions including the grasslands being resilient to short-term extreme droughts but vulnerable to prolonged droughts and the fact that no extreme drought control on grassland cover was evident in future projections. The study recommended grassland management policies that emphasize adaptive strategies such as controlled stocking rates, pasture rotation, restoration of degraded grasslands, and protection of key dry season grazing reserves to reduce vulnerability to prolonged and severe droughts to enhance resilience.