Estimating shallow groundwater availability in small catchments using streamflow recession and instream flow requirements of rivers in South Africa

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cg.contributor.affiliationInternational Water Management Instituteen_US
cg.contributor.crpWater, Land and Ecosystemsen_US
cg.coverage.countrySouth Africaen_US
cg.coverage.iso3166-alpha2ZAen_US
cg.coverage.regionSouthern Africaen_US
cg.identifier.doihttps://doi.org/10.1016/j.jhydrol.2016.07.032en_US
cg.identifier.wlethemeManaging Resource Variability and Competing Useen_US
cg.identifier.wlethemeRegenerating Degraded Agricultural Ecosystemsen_US
cg.issn0022-1694en_US
cg.journalJournal of Hydrologyen_US
cg.volume541en_US
dc.contributor.authorEbrahim, Girma Yimeren_US
dc.contributor.authorVillholth, Karen G.en_US
dc.date.accessioned2016-09-26T04:54:18Zen_US
dc.date.available2016-09-26T04:54:18Zen_US
dc.identifier.urihttps://hdl.handle.net/10568/77131en_US
dc.titleEstimating shallow groundwater availability in small catchments using streamflow recession and instream flow requirements of rivers in South Africaen_US
dcterms.abstractGroundwater is an important resource for multiple uses in South Africa. Hence, setting limits to its sustainable abstraction while assuring basic human needs is required. Due to prevalent data scarcity related to groundwater replenishment, which is the traditional basis for estimating groundwater availability, the present article presents a novel method for determining allocatable groundwater in quaternary (fourth-order) catchments through information on streamflow. Using established methodologies for assessing baseflow, recession flow, and instream ecological flow requirement, the methodology develops a combined stepwise methodology to determine annual available groundwater storage volume using linear reservoir theory, essentially linking low flows proportionally to upstream groundwater storages. The approach was trialled for twenty-one perennial and relatively undisturbed catchments with long-term and reliable streamflow records. Using the Desktop Reserve Model, instream flow requirements necessary to meet the present ecological state of the streams were determined, and baseflows in excess of these flows were converted into a conservative estimates of allocatable groundwater storages on an annual basis. Results show that groundwater development potential exists in fourteen of the catchments, with upper limits to allocatable groundwater volumes (including present uses) ranging from 0.02 to 3.54 × 106 m3 a-1 (0.10–11.83 mm a-1) per catchment. With a secured availability of these volume 75% of the years, variability between years is assumed to be manageable. A significant (R2 = 0.88) correlation between baseflow index and the drainage time scale for the catchments underscores 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 Resource Directed Measures in South Africa and could be adapted and applied elsewhere.en_US
dcterms.accessRightsOpen Accessen_US
dcterms.bibliographicCitationEbrahim, Girma Y.; Villholth, Karen G. 2016. Estimating shallow groundwater availability in small catchments using streamflow recession and instream flow requirements of rivers in South Africa. Journal of Hydrology, 12p. (Online first). doi: 10.1016/j.jhydrol.2016.07.032en_US
dcterms.extentpp. 754-765en_US
dcterms.issued2016-10en_US
dcterms.languageenen_US
dcterms.licenseCC-BY-NC-ND-4.0en_US
dcterms.publisherElsevieren_US
dcterms.subjectgroundwater assessmenten_US
dcterms.subjectwater availabilityen_US
dcterms.subjectwater allocationen_US
dcterms.subjectwater storageen_US
dcterms.subjectcatchment areasen_US
dcterms.subjectriversen_US
dcterms.subjectstream flowen_US
dcterms.subjectmodelsen_US
dcterms.subjectaquifersen_US
dcterms.subjectrechargeen_US
dcterms.subjecthydrogeologyen_US
dcterms.subjectdrainageen_US
dcterms.subjectrainen_US
dcterms.subjectecological factorsen_US
dcterms.subjecttime series analysisen_US
dcterms.subjectuncertaintyen_US
dcterms.typeJournal Articleen_US

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