TY - JOUR
T1 - The physics behind Van der Burgh's empirical equation, providing a new predictive equation for salinity intrusion in estuaries
AU - Zhang, Zhilin
AU - Savenije, Hubert H.G.
PY - 2017/7/4
Y1 - 2017/7/4
N2 - The practical value of the surprisingly simple Van der Burgh equation in predicting saline water intrusion in alluvial estuaries is well documented, but the physical foundation of the equation is still weak. In this paper we provide a connection between the empirical equation and the theoretical literature, leading to a theoretical range of Van der Burgh's coefficient of 1ĝ•2 < K < 2ĝ•3 for density-driven mixing which falls within the feasible range of 0 < K < 1. In addition, we developed a one-dimensional predictive equation for the dispersion of salinity as a function of local hydraulic parameters that can vary along the estuary axis, including mixing due to tide-driven residual circulation. This type of mixing is relevant in the wider part of alluvial estuaries where preferential ebb and flood channels appear. Subsequently, this dispersion equation is combined with the salt balance equation to obtain a new predictive analytical equation for the longitudinal salinity distribution. Finally, the new equation was tested and applied to a large database of observations in alluvial estuaries, whereby the calibrated K values appeared to correspond well to the theoretical range.
AB - The practical value of the surprisingly simple Van der Burgh equation in predicting saline water intrusion in alluvial estuaries is well documented, but the physical foundation of the equation is still weak. In this paper we provide a connection between the empirical equation and the theoretical literature, leading to a theoretical range of Van der Burgh's coefficient of 1ĝ•2 < K < 2ĝ•3 for density-driven mixing which falls within the feasible range of 0 < K < 1. In addition, we developed a one-dimensional predictive equation for the dispersion of salinity as a function of local hydraulic parameters that can vary along the estuary axis, including mixing due to tide-driven residual circulation. This type of mixing is relevant in the wider part of alluvial estuaries where preferential ebb and flood channels appear. Subsequently, this dispersion equation is combined with the salt balance equation to obtain a new predictive analytical equation for the longitudinal salinity distribution. Finally, the new equation was tested and applied to a large database of observations in alluvial estuaries, whereby the calibrated K values appeared to correspond well to the theoretical range.
UR - http://www.scopus.com/inward/record.url?scp=85021863090&partnerID=8YFLogxK
UR - http://resolver.tudelft.nl/uuid:0e9813a1-667f-4e37-a76b-079c62974cb4
U2 - 10.5194/hess-21-3287-2017
DO - 10.5194/hess-21-3287-2017
M3 - Article
AN - SCOPUS:85021863090
SN - 1027-5606
VL - 21
SP - 3287
EP - 3305
JO - Hydrology and Earth System Sciences
JF - Hydrology and Earth System Sciences
IS - 7
ER -