Assessment of groundwater availability from recession flows and instream flow requirements of rivers in South Africa
Groundwater is an important resource for multiple uses in South Africa. However, setting limits to its sustainable abstraction while assuring basic human needs is a must. Due to prevalent data scarcity related to groundwater replenishment, which is the traditional basis for estimating groundwater av...
| Autores principales: | , |
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| Formato: | Informe técnico |
| Lenguaje: | Inglés |
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Water Research Commission
2015
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| Materias: | |
| Acceso en línea: | https://hdl.handle.net/10568/78429 |
| _version_ | 1855541809282809856 |
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| author | Ebrahim, Girma Yimer Villholth, Karen G. |
| author_browse | Ebrahim, Girma Yimer Villholth, Karen G. |
| author_facet | Ebrahim, Girma Yimer Villholth, Karen G. |
| author_sort | Ebrahim, Girma Yimer |
| collection | Repository of Agricultural Research Outputs (CGSpace) |
| description | Groundwater is an important resource for multiple uses in South Africa. However, setting limits to its sustainable abstraction while assuring basic human needs is a must. Due to prevalent data scarcity related to groundwater replenishment, which is the traditional basis for estimating groundwater availability, the present report presents a novel method for determining allocatable groundwater in quaternary catchment through information on streamflows. Using established methodologies for assessing baseflows, recession flows, and instream ecological flow requirements, the methodology develops a combined stepwise methodology to determine annual groundwater storage volumes in the catchments using linear reservoir theory, essentially linking low flows proportionally to upstream groundwater storages. The approach was trialled for twenty-one perennial and relatively undisturbed quaternary catchments with long-term and good streamflow records. Using the Desktop Reserve Model to estimate instream ecological flow requirements of the streams and equating these with ecological groundwater reserve, excess baseflows were converted into groundwater storages on an annual basis. Results show that groundwater development potential exists in nineteen of the catchments, with upper limits to allocatable groundwater volumes ranging from 0.01 to 1.58 MCM/yr over the catchments. With a secured availability of these volumes 75% of the years, variability between years is assumed to be manageable. A significant (R2 = 0.86) correlation between baseflow index and the drainage time scale for the catchments underscored the physical basis of the methodology and also enables the reduction of the procedure by one step, omitting recession flow analysis. The method serves as an important complementary tool for the assessment of the groundwater part of the Reserve and the groundwater directed measures. |
| format | Informe técnico |
| id | CGSpace78429 |
| institution | CGIAR Consortium |
| language | Inglés |
| publishDate | 2015 |
| publishDateRange | 2015 |
| publishDateSort | 2015 |
| publisher | Water Research Commission |
| publisherStr | Water Research Commission |
| record_format | dspace |
| spelling | CGSpace784292023-02-15T12:31:34Z Assessment of groundwater availability from recession flows and instream flow requirements of rivers in South Africa Ebrahim, Girma Yimer Villholth, Karen G. groundwater recharge groundwater water storage water availability water allocation water requirements stream flow flow rate rivers catchment areas drainage environmental flows rain multiple use ecological factors aquifers Groundwater is an important resource for multiple uses in South Africa. However, setting limits to its sustainable abstraction while assuring basic human needs is a must. Due to prevalent data scarcity related to groundwater replenishment, which is the traditional basis for estimating groundwater availability, the present report presents a novel method for determining allocatable groundwater in quaternary catchment through information on streamflows. Using established methodologies for assessing baseflows, recession flows, and instream ecological flow requirements, the methodology develops a combined stepwise methodology to determine annual groundwater storage volumes in the catchments using linear reservoir theory, essentially linking low flows proportionally to upstream groundwater storages. The approach was trialled for twenty-one perennial and relatively undisturbed quaternary catchments with long-term and good streamflow records. Using the Desktop Reserve Model to estimate instream ecological flow requirements of the streams and equating these with ecological groundwater reserve, excess baseflows were converted into groundwater storages on an annual basis. Results show that groundwater development potential exists in nineteen of the catchments, with upper limits to allocatable groundwater volumes ranging from 0.01 to 1.58 MCM/yr over the catchments. With a secured availability of these volumes 75% of the years, variability between years is assumed to be manageable. A significant (R2 = 0.86) correlation between baseflow index and the drainage time scale for the catchments underscored the physical basis of the methodology and also enables the reduction of the procedure by one step, omitting recession flow analysis. The method serves as an important complementary tool for the assessment of the groundwater part of the Reserve and the groundwater directed measures. 2015 2016-12-21T06:31:23Z 2016-12-21T06:31:23Z Report https://hdl.handle.net/10568/78429 en Limited Access Water Research Commission Ebrahim, Girma Yimer; Villholth, Karen Grothe. 2015. Assessment of groundwater availability from recession flows and instream flow requirements of rivers in South Africa. Gezina, Pretoria, South Africa: Water Research Commission. 60p. (Water Research Commission Report KV 339/15) |
| spellingShingle | groundwater recharge groundwater water storage water availability water allocation water requirements stream flow flow rate rivers catchment areas drainage environmental flows rain multiple use ecological factors aquifers Ebrahim, Girma Yimer Villholth, Karen G. Assessment of groundwater availability from recession flows and instream flow requirements of rivers in South Africa |
| title | Assessment of groundwater availability from recession flows and instream flow requirements of rivers in South Africa |
| title_full | Assessment of groundwater availability from recession flows and instream flow requirements of rivers in South Africa |
| title_fullStr | Assessment of groundwater availability from recession flows and instream flow requirements of rivers in South Africa |
| title_full_unstemmed | Assessment of groundwater availability from recession flows and instream flow requirements of rivers in South Africa |
| title_short | Assessment of groundwater availability from recession flows and instream flow requirements of rivers in South Africa |
| title_sort | assessment of groundwater availability from recession flows and instream flow requirements of rivers in south africa |
| topic | groundwater recharge groundwater water storage water availability water allocation water requirements stream flow flow rate rivers catchment areas drainage environmental flows rain multiple use ecological factors aquifers |
| url | https://hdl.handle.net/10568/78429 |
| work_keys_str_mv | AT ebrahimgirmayimer assessmentofgroundwateravailabilityfromrecessionflowsandinstreamflowrequirementsofriversinsouthafrica AT villholthkareng assessmentofgroundwateravailabilityfromrecessionflowsandinstreamflowrequirementsofriversinsouthafrica |