Journal of Tropical Oceanography >
Characteristics of recent evolution in Qinzhou Bay influenced by human activities
Copy editor: LIN Qiang
Received date: 2019-01-23
Request revised date: 2019-02-23
Online published: 2019-11-26
Supported by
National Key Research and Development Project(2018YFC0407804)
National Natural Science Foundation of China(51779280)
Scientific and Technological Projects of Guangxi Water Resources Department(201602)
Copyright
Based on the underwater topographical data and remote sensing data from the 1980s, we analyze the characteristics of shoal-trough pattern change and erosion-siltation evolution in Qinzhou Bay under the influence of recent high intensity human activities. We also discuss the reasons from the aspect of dynamic geomorphology combining the methods of remote sensing, GIS, and numerical simulation. The results indicate that the Maowei Sea showed overall deposition, the siltation intensity of the shallow water area above the 2m isobath was significantly greater than that in the other areas, and the channel was characterized by erosion due to artificial sand mining and enhancement of tidal current. The outer bay was dominated by deposition, but its deposition rate was less than that of the inner bay. The scouring and silting characteristics of the shoal and trough were significantly different. The west channel, middle channel, and the side foreland were dominated by deposition, while Middle Shoal, East Channel were characterized by scour. Due to high intensity human activities, the flood and ebb tidal capacity of the Maowei Sea reduced 4.6% and 4%, respectively, which caused continuous deposit. The coastline in the middle of the outer bay has been pushed toward the sea significantly, which made the tidal current concentrated and increased velocity by 0.1~0.2 m·s -1, leading to the erosion of the Middle Shoal. The deepening of the East Channel made flow in the Middle Channel move to the East Channel, which made the Middle Channel shrink. The changes of the horizontal Kelvin number indicate that human activities have greater impact on the East and Middle channels of the outer bay. The stability of the East Channel is enhanced and the Middle Channel continues to shrink, while the stability of the West Channel remains basically unchanged.
YANG Liuzhu , YANG Liling , PAN Hongzhou , LIU Chaoqun , YU Fenghua . Characteristics of recent evolution in Qinzhou Bay influenced by human activities[J]. Journal of Tropical Oceanography, 2019 , 38(6) : 41 -50 . DOI: 10.11978/2019013
图8 2004—2014年间钦州湾冲淤速率分布 dm1、dm2为选取的横断面Fig. 8 The speed of scour and silting of the Outer Bay during 2004-2014 |
表1 钦州湾冲淤特征参数统计表Tab. 1 Statistics of erosion and deposition characteristics in Qinzhou Bay |
高程/m | 2009—2016茅尾海冲淤特征 | 高程/m | 2004—2014外湾冲淤特征 | ||||
---|---|---|---|---|---|---|---|
冲淤量/(×104m3) | 冲淤厚度/m | 冲淤速率/(m·a-1) | 冲淤量/(×104m3) | 冲淤厚度/m | 冲淤速率/(m·a-1) | ||
>0 | 1061.14 | 0.44 | 0.06 | -4~0 | 2741.52 | 0.32 | 0.03 |
-2~0 | 1514.04 | 0.27 | 0.04 | -7~-4 | 80.63 | 0.02 | 0.00 |
-4~-2 | 228.27 | 0.16 | 0.02 | -7~-12 | -748.99 | -0.30 | -0.03 |
-4~2 | 2803.44 | 0.29 | 0.04 | -12~0 | 2073.16 | 0.13 | 0.01 |
表2 2004—2014年间高强度人类活动下茅尾海涨落潮量变化统计Tab. 2 Change of tidal capacity caused by high intensity human activities during 2004—2014 |
观测断面 | 涨潮量/m3 | 变化率/% | 落潮量/m3 | 变化率/% | ||
---|---|---|---|---|---|---|
开发前 | 变化值 | 开发前 | 变化值 | |||
MWH1 | 123509 | -11149.2 | -9.03% | 99029.8 | -3548.03 | -3.58% |
MWH2 | 553833 | -15502.6 | -2.80% | 307062.7 | -17837.2 | -5.81% |
MWH3 | 1002491 | -19487.41 | -1.94% | 664348.3 | -18084.2 | -2.72% |
表3 开发前后主要深槽水平Keh变化情况Tab. 3 Change of horizontal Kelvin number before and after high intensity human activities |
U/(m·s-1) | B/m | H/m | Keh | |||||
---|---|---|---|---|---|---|---|---|
工程前 | 工程后 | 工程前 | 工程后 | 工程前 | 工程后 | 工程前 | 工程后 | |
西航道(dm1) | 1.20 | 1.15 | 1294.99 | 1252.38 | 9.27 | 9.28 | 0.20 | 0.19 |
西航道(dm2) | 1.09 | 0.98 | 1063.20 | 1086.81 | 9.43 | 9.18 | 0.15 | 0.14 |
中水道(dm1) | 1.27 | 1.02 | 636.87 | 1477.59 | 7.45 | 6.9 | 0.13 | 0.26 |
中水道(dm2) | 1.18 | 1.16 | 1018.49 | 3235.52 | 7.11 | 6.58 | 0.20 | 0.68 |
东航道(dm1) | 1.22 | 1.07 | 1197.43 | 894.67 | 11.14 | 13.45 | 0.16 | 0.08 |
东航道(dm2) | 1.06 | 0.97 | 1279.07 | 627.88 | 9.52 | 15.15 | 0.17 | 0.05 |
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