Spatial and Temporal Variability in Hydro-Meteorological Selected Variable in the Southern Highlands, Tanzania

Abstract

Continuous decline of natural vegetation cover has been claimed to adversely affect trends of rainfall and streamflow in Kilolo District. This study analyzed the extent of rainfall characteristics, streamflow and runoff for the period 1972-2019 at Kilolo District. Data were collected from various sources and collated. Linear regression, descriptive statistics and trend analyses techniques were used to analyze rainfall variability. Non-parametric rank-based Mann-Kendall test employed to detect trends in annual and seasonal rainfall. Rainfall patterns in Iringa Airport, Maji, Mtera and Msembe stations closely resembled each other. Rainfall characteristics follow unimodal pattern with rainfall starting in November through May. Analyses of long-term annual rainfall records from the four stations show that rainfall in the Kilolo District is highly variable. It received an average of 706 mm yr^-1 with years of high rainfall above the mean, and years of low rainfall below the mean. There is a significant declining trend of streamflow recorded in rivers draining the district. Decline of natural forest, bushland and wetland converted into cropland and plantation has played a great role to reverse this negative trend. This study recommends that efforts should be geared towards land cover conservation in order to enhance rainfall availability and improved streamflow.