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and shelter needs of the fish. The construction of a hydraulic ecology index system for fish fattening area is the basis
for quantifying the functional characteristics of fish fattening area and deducing the suitable ecological flow for fatten‐
ing. This study considered the overall function of the fattening area and the spatial heterogeneity of water flow，five

types of hydraulic indicators，water depth，flow velocity，Froude number，velocity gradient and kinetic energy gradi‐

ent were selected as the hydraulic index layer，four types of habitat patches indicators，pool，rapids，riffle and slack‐
water were introduced as fattening habitat patches index layer，and four types of landscape indicators，percentage of

landscape，percentage of water area，shannon’s diversity index，and aggregation index were selected as the patch

landscape index layer. A total of 13 indicators in 3 layers，combined with their ecological significance for fish fatten‐

ing，were used to construct the index system of fish’s fattening area. A two-dimensional hydrodynamic model was
used to analyze the characteristics of the water flow in Ayu’ fattening area of Nanxi River and the appropriate ecologi‐
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cal flow for Ayu’ fattening. The study results indicate that with the change of flow，the area and distribution of habi‐
tat patch also changed. Around the flow of 89.09 m³/s，the different types of patches are distributed in interphase，

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with little variation in patch area ratio，resulting in the highest Shannon’ Diversity Index，which can be used as the

suitable ecological flow for Ayu fattening. The results can provide a scientific basis for protecting and restoring the
fish’ fattening area.
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Keywords：fish’ fattening area；habitat patches；index system；appropriate ecological flow

（责任编辑：尹 婧）
（上接第 1060 页）
Sediment-transport rating curves and their variation mechanisms in sandy reach of the
Jingjiang River before and after construction of the Three Gorges Reservoir

ZHOU Weixing，SUN Zhaohua，YANG Zhonghua，LI Zhiqing，AN Shanshan

（State Key Laboratory of Water Resources Engineering and Management，Wuhan University，Wuhan 430072，China）

Abstract：The sediment-transport rating curves （STCs）in the sandy reach of the Jingjiang River have varied signifi‐

cantly due to the construction of the Three Gorges Reservoir （TGR），impacting channel-floodplain deformation
dynamics. This paper examined the mechanisms underlying the variations in STCs influenced by TGR construction，
utilizing hydrological，sediment，and river topography data，and analyzed their implications for channel-floodplain

deformation. Main conclusions indicate that prior to TGR construction，the STC exhibited a downward deflection
above bankfull discharge. This phenomenon was attributed to predominance of wash load transported in the main

channel，which subsequently entered the floodplain as overbank flow and transformed into bed load. Following TGR

construction，the deflection of STC above bankfull discharge disappeared，revealing a critical characteristic under
low flow condition instead. Although overall channel-floodplain morphology and hydrodynamic regimes have not
changed significantly since TGR construction，the coarsening of sediment particle size has led to qualitative shifts in

sediment transport modes：from wash load to bed load above bankfull discharge，and from suspended load to bed load

during dry periods. Influenced by altered sediment transport regimes，the main channel experiences significant

scour，while sedimentation rates on the floodplain are markedly reduced. This understanding enhances our compre‐
hension of water-sediment transport mechanisms under both equilibrium and non-equilibrium conditions in a
dammed sandy river，as well as long-term evolutionary trends of river channel.

Keywords：sediment-transport rating curve；sediment transport mode；channel-floodplain deformation；Jingjiang

River；the Three Gorges Reservoir
（责任编辑：鲁 婧）
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