TY - JOUR
T1 - Hydrograph separation using tracers and digital filters to quantify runoff components in a semi-arid mesoscale catchment
AU - Saraiva Okello, Aline Maraci Lopes
AU - Uhlenbrook, Stefan
AU - Jewitt, Graham P.W.
AU - Masih, Ilyas
AU - Riddell, Edward Sebastian
AU - Van der Zaag, Pieter
PY - 2018/5/15
Y1 - 2018/5/15
N2 - Chemical hydrograph separation using electrical conductivity and digital filters is applied to quantify runoff components in the 1,640 km2 semi-arid Kaap River catchment and its subcatchments in South Africa. A rich data set of weekly to monthly water quality data ranging from 1978 to 2012 (450 to 940 samples per site) was analysed at 4 sampling locations in the catchment. The data were routinely collected by South Africa's national Department of Water and Sanitation, using standard sampling procedures. Chemical hydrograph separation using electrical conductivity (EC) as a tracer was used as reference and a recursive digital filter was then calibrated for the catchment. Results of the two-component hydrograph separation indicate the dominance of baseflow in the low flow regime, with a contribution of about 90% of total flow; however, during the wet season, baseflow accounts for 50% of total flow. The digital filter parameters were very sensitive and required calibration, using chemical hydrograph separation as a reference. Calibrated baseflow estimates ranged from 40% of total flow at the catchment outlet to 70% in the tributaries. The study demonstrates that routinely monitored water quality data, especially EC, can be used as a meaningful tracer, which could also aid in the calibration of a digital filter method and reduce uncertainty of estimated flow components. This information enhances our understanding of how baseflow is generated and contributed to streamflow throughout the year, which can aid in quantification of environmental flows, as well as to better parameterize hydrological models used for water resources planning and management. Baseflow estimates can also be useful for groundwater and water quality management.
AB - Chemical hydrograph separation using electrical conductivity and digital filters is applied to quantify runoff components in the 1,640 km2 semi-arid Kaap River catchment and its subcatchments in South Africa. A rich data set of weekly to monthly water quality data ranging from 1978 to 2012 (450 to 940 samples per site) was analysed at 4 sampling locations in the catchment. The data were routinely collected by South Africa's national Department of Water and Sanitation, using standard sampling procedures. Chemical hydrograph separation using electrical conductivity (EC) as a tracer was used as reference and a recursive digital filter was then calibrated for the catchment. Results of the two-component hydrograph separation indicate the dominance of baseflow in the low flow regime, with a contribution of about 90% of total flow; however, during the wet season, baseflow accounts for 50% of total flow. The digital filter parameters were very sensitive and required calibration, using chemical hydrograph separation as a reference. Calibrated baseflow estimates ranged from 40% of total flow at the catchment outlet to 70% in the tributaries. The study demonstrates that routinely monitored water quality data, especially EC, can be used as a meaningful tracer, which could also aid in the calibration of a digital filter method and reduce uncertainty of estimated flow components. This information enhances our understanding of how baseflow is generated and contributed to streamflow throughout the year, which can aid in quantification of environmental flows, as well as to better parameterize hydrological models used for water resources planning and management. Baseflow estimates can also be useful for groundwater and water quality management.
KW - digital filters
KW - hydrograph separation
KW - runoff generation
KW - semi-arid catchment
KW - Southern Africa
KW - tracers
UR - http://www.scopus.com/inward/record.url?scp=85045729861&partnerID=8YFLogxK
U2 - 10.1002/hyp.11491
DO - 10.1002/hyp.11491
M3 - Article
AN - SCOPUS:85045729861
SN - 0885-6087
VL - 32
SP - 1334
EP - 1350
JO - Hydrological Processes
JF - Hydrological Processes
IS - 10
ER -