Long-term changes and variability in rainfall and streamflow in Luvuvhu River Catchment, South Africa
We investigated long-term changes and variability in daily rainfall and streamflow in the Luvuvhu River Catchment, South Africa. Changes and variability in rainfall and streamflow impact on available water resources and the allocation of these resources. Daily rainfall data for six stations and dail...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Academy of Science of South Africa
2015-07-01
|
| Series: | South African Journal of Science |
| Subjects: | |
| Online Access: | https://www.sajs.co.za/article/view/3702 |
| _version_ | 1819045118636720128 |
|---|---|
| author | John O. Odiyo Rachel Makungo Tinyiko R. Nkuna |
| author_facet | John O. Odiyo Rachel Makungo Tinyiko R. Nkuna |
| author_sort | John O. Odiyo |
| collection | DOAJ |
| description | We investigated long-term changes and variability in daily rainfall and streamflow in the Luvuvhu River Catchment, South Africa. Changes and variability in rainfall and streamflow impact on available water resources and the allocation of these resources. Daily rainfall data for six stations and daily streamflow data for four stations for the period 1920/1921–2005/2006 were grouped into cycles of 5 and 10 years. Daily means and standard deviations were computed for each cycle. Standard deviation was used to define the rainfall and streamflow variability. Linear regression was used to compute trends in 5- and 10-year average rainfall and streamflow and their standard deviations. Paired two-tailed t-tests (significance level of 0.05) were carried out to verify the spatial variability of rainfall and streamflow in the study area. Mann–Kendall and linear regression were used to determine trend analyses based on long-term annual rainfall and streamflow data. All but two rainfall stations showed decreasing trends in 5- and 10-year mean rainfall; 10-year mean daily rainfall showed decadal rainfall fluctuations. Contrasting trends were observed in 5- and 10-year mean streamflow, indicating that other factors such as anthropogenic activities and impoundments could be impacting on streamflow. Trend directions identified from Mann–Kendall and linear regression analyses of long-term annual rainfall and streamflow were similar to those identified by linear regression of 5- and 10-year mean daily rainfall. Results of paired two-tailed t-tests verified the spatial variability of rainfall and streamflow in the study area. We have shown that the variability of rainfall and streamflow has increased in the Luvuvhu River Catchment over the 86-year study period. |
| first_indexed | 2024-12-21T10:23:30Z |
| format | Article |
| id | doaj.art-35f6bbd9ed6b4ecfa2f8a2f5466fd745 |
| institution | Directory Open Access Journal |
| issn | 1996-7489 |
| language | English |
| last_indexed | 2024-12-21T10:23:30Z |
| publishDate | 2015-07-01 |
| publisher | Academy of Science of South Africa |
| record_format | Article |
| series | South African Journal of Science |
| spelling | doaj.art-35f6bbd9ed6b4ecfa2f8a2f5466fd7452022-12-21T19:07:23ZengAcademy of Science of South AfricaSouth African Journal of Science1996-74892015-07-011117/89910.17159/sajs.2015/201401693702Long-term changes and variability in rainfall and streamflow in Luvuvhu River Catchment, South AfricaJohn O. Odiyo0Rachel Makungo1Tinyiko R. Nkuna2Department of Hydrology and Water Resources, University of Venda, Thohoyandou, South AfricaDepartment of Hydrology and Water Resources, University of Venda, Thohoyandou, South AfricaDepartment of Hydrology and Water Resources, University of Venda, Thohoyandou, South AfricaWe investigated long-term changes and variability in daily rainfall and streamflow in the Luvuvhu River Catchment, South Africa. Changes and variability in rainfall and streamflow impact on available water resources and the allocation of these resources. Daily rainfall data for six stations and daily streamflow data for four stations for the period 1920/1921–2005/2006 were grouped into cycles of 5 and 10 years. Daily means and standard deviations were computed for each cycle. Standard deviation was used to define the rainfall and streamflow variability. Linear regression was used to compute trends in 5- and 10-year average rainfall and streamflow and their standard deviations. Paired two-tailed t-tests (significance level of 0.05) were carried out to verify the spatial variability of rainfall and streamflow in the study area. Mann–Kendall and linear regression were used to determine trend analyses based on long-term annual rainfall and streamflow data. All but two rainfall stations showed decreasing trends in 5- and 10-year mean rainfall; 10-year mean daily rainfall showed decadal rainfall fluctuations. Contrasting trends were observed in 5- and 10-year mean streamflow, indicating that other factors such as anthropogenic activities and impoundments could be impacting on streamflow. Trend directions identified from Mann–Kendall and linear regression analyses of long-term annual rainfall and streamflow were similar to those identified by linear regression of 5- and 10-year mean daily rainfall. Results of paired two-tailed t-tests verified the spatial variability of rainfall and streamflow in the study area. We have shown that the variability of rainfall and streamflow has increased in the Luvuvhu River Catchment over the 86-year study period.https://www.sajs.co.za/article/view/3702linear regressionMann–Kendalltrendsclimate changeLimpopo Province |
| spellingShingle | John O. Odiyo Rachel Makungo Tinyiko R. Nkuna Long-term changes and variability in rainfall and streamflow in Luvuvhu River Catchment, South Africa South African Journal of Science linear regression Mann–Kendall trends climate change Limpopo Province |
| title | Long-term changes and variability in rainfall and streamflow in Luvuvhu River Catchment, South Africa |
| title_full | Long-term changes and variability in rainfall and streamflow in Luvuvhu River Catchment, South Africa |
| title_fullStr | Long-term changes and variability in rainfall and streamflow in Luvuvhu River Catchment, South Africa |
| title_full_unstemmed | Long-term changes and variability in rainfall and streamflow in Luvuvhu River Catchment, South Africa |
| title_short | Long-term changes and variability in rainfall and streamflow in Luvuvhu River Catchment, South Africa |
| title_sort | long term changes and variability in rainfall and streamflow in luvuvhu river catchment south africa |
| topic | linear regression Mann–Kendall trends climate change Limpopo Province |
| url | https://www.sajs.co.za/article/view/3702 |
| work_keys_str_mv | AT johnoodiyo longtermchangesandvariabilityinrainfallandstreamflowinluvuvhurivercatchmentsouthafrica AT rachelmakungo longtermchangesandvariabilityinrainfallandstreamflowinluvuvhurivercatchmentsouthafrica AT tinyikornkuna longtermchangesandvariabilityinrainfallandstreamflowinluvuvhurivercatchmentsouthafrica |