Characteristics of trends and relationships among climate variables in Zambia
Date
2016
Authors
Mtonga, Christopher
Journal Title
Journal ISSN
Volume Title
Publisher
University of Zambia
Abstract
This study embarked on trend analysis to understand the relationship that exists in weather,
precipitation and river flow using time series data. The study area was the entire country of
Zambia. Secondary hydrological and weather data used was representative of the six catchment
areas of the country and the three agro-ecological zones. Weather records were obtained from
SWAT- soil, an internet based software that stores daily meteorological data across the globe from
1979 to 2009 were temperature was extracted and used as reference for weather data. For stream
flows, 40 hydrological gauge data sets were acquired from DWA for the same period across the
country. The hydrological data sets were then classified into clusters using the five indicators of
hydrologic alterations namely; the frequency of flows, the magnitude of flows, the duration of
flows, the timing of flows and the rates of change in flows. The metrics for these indicators of
hydrologic alterations were obtained using time series analysis (TSA) in river analysis package
(RAP). Stream-flows of each station were grouped in three clusters according to precipitation
patterns in agro-ecological zones and according to the area each stream drained. These clusters
were used together with the corresponding temperature data sets for trend analyses and linear
regressions. It was found that firstly, there was an upward trend in temperature across the clusters
for the temporal window period of the study. Secondly, temperature is a predictor of precipitation
and discharge in streams across the country based on the P values (0.10 – 0.50) and r2 values
(0.008 – 0.336) obtained from regression and trend analysis. This was observed in 39 hydrological
and meteorological gauge stations used. Thirdly, temperature predicts stream-flow in rivers with
large catchment areas (>40,000km2) across all agro-ecological zones and perennial rivers in Agroecological
zone III. It was further found that temperature does not predict stream-flow of
ephemeral streams based on the P values (>0.50) obtained on temperature-discharge relationship of
these streams. Based on the findings, it is concluded that temperature has been increasing with
time and that it predicts precipitation negatively across the agro-ecological zones in Zambia.
Climate variables are characteristic of increasing or decreasing trend in Zambia.
Description
Post Grad. Dip. in integrated Water Resources Management
Keywords
Climate Changes-Zambia , Precipitation Forecasting-Zambia