LAUSR

15 The objective of the present study is to demonstrate the informative capacity of 16 the longitudinal anomaly of potential energy (LAPE) in the analysis of the magnitude 17 and spatiotemporal variability of estuarine processes. For this purpose, a LAPE balance 18 equation is formulated. The LAPE integrates and varies with the vertical and longitu19 dinal density distribution. The formulation is applied on a subtidal scale to each box or 20 stretch of the Guadalquivir River estuary, a narrow, highly turbid, weakly stratified, and 21 strongly anthropized estuary. Data recorded by a large network of monitoring stations 22 in 2008 and 2009 are used to quantify advective transports as well as the transports as23 sociated with longitudinal dispersion and vertical turbulent mixing in different hydraulic 24 regimes. In low-river flow conditions, (river flows Q < 40 m3s−1), the magnitude of LAPE 25 transports decreases upstream and varies locally, depending on neap-spring tidal cycles. 26 The direction of the net LAPE transport creates convergence zones that are particularly 27 consistent with maximum levels of estuarine turbidity. During high-river flows (Q > 400 m3s−1), 28 this convergence disappears and the maximum longitudinal density gradient moves to29 wards the mouth. More specifically, tidal pumping -induced LAPE governs during these 30 conditions and manages to compensate the sum of the mean non-tidal and dispersive and 31 differential advective LAPE transports. However, during the post-riverflood period, the 32 mechanisms controlling recovery downstream from the mouth are the longitudinal dis33 persive and differential advective LAPE transports. Furthermore, the convergence zone 34 reappears with a longitudinal gradient of the net LAPE transport that is even greater 35 than in low-river flow conditions. 36