Since the 1980s,the robust economic growth of China has prompted extensive land reclamation projects along its coastline,notably affecting local hydrodynamics and resulting in ecological repercussions.Using a nearshor...Since the 1980s,the robust economic growth of China has prompted extensive land reclamation projects along its coastline,notably affecting local hydrodynamics and resulting in ecological repercussions.Using a nearshore finite volume ocean model,we constructed a hydrodynamic model for Shacheng Bay,a southeastern coastal region with a winding and narrow entrance.We examined the hydrodynamic changes and mangrove dynamics over the past 36 years and the relationship between hydrodynamic alterations and mangrove degradation.Simulation results reveal that extensive reclamation projects between 1984 and 2000 weakened the current in Shacheng Bay,leading to decreased water exchange capacity and a significant reduction in mangrove area from 0.3 to 0.06km^(2).During this period,over 37% of mangrove degradation was ascribed to time-changing hydrodynamic variables without the direct influence of land reclamation.The results also highlight the changes in local hydrodynamics and water exchange patterns that adversely influenced mangrove growth.From 2000 to 2020,there were minimal coastline changes in Shacheng Bay,demonstrating reduced land reclamation activities.This stopped the further weakening trend of the currents,with a slight increase during ebb tides,while the residual current continued to weaken due to the decreasing tidal prism and water exchange capacity.The mangrove area partially recovered during this period,expanding from 0.06 to 0.11 km^(2),predominantly in new areas instead of where mangroves disappeared from 1984 to 2000.This work underlines the intricate relationship between land reclamation,hydrodynamics,and mangrove ecosystems,underscoring the need for sustainable coastal development strategies.展开更多
文摘针对室内全球导航卫星系统(Global navigation satellite system,GNSS)信号受遮挡时,农用车辆协同定位精度低、稳定性差、信号丢包等问题,本文开展面向超宽带(Ultra-wideband,UWB)调频技术的室内外农用车辆协同定位算法研究。首先,搭建三基站多边测距定位模型,实现主基站绝对位置标定以及辅助基站绝对位置坐标的变换求解;其次,提出全质心加权最小二乘的高速双边双向(Weighted least squares high double sided two-way ranging,WLS-HDS-TWR)农机协同定位算法,基于泰勒级数展开的WLS估计算法,求解主车位置。同时,提出面向室内环境的多状态基站组合的UWB定位模块布设模式,并验证其可行性;通过飞行时间法(Time of flight,TOF)获取主从车距离信息,融合GNSS标定位置信息、主车坐标信息以及测距信息,实现主从车协同定位。最后,基于Prescan/Simulink搭建联合仿真平台,验证提出算法的可靠性;通过农用履带车辆开展室内及室外协同定位实车试验,试验结果表明:全质心WLS-HDS-TWR协同定位算法可有效解决室内GNSS信号缺失问题,室内环境下,定位精度较HDS-TWR及全质心LS-HDS-TWR算法分别提高26.98%和22.03%,满足智能农机协同定位作业需求。
基金supported by the National Key R&D Program of China(No.2022YFD2401304)。
文摘Since the 1980s,the robust economic growth of China has prompted extensive land reclamation projects along its coastline,notably affecting local hydrodynamics and resulting in ecological repercussions.Using a nearshore finite volume ocean model,we constructed a hydrodynamic model for Shacheng Bay,a southeastern coastal region with a winding and narrow entrance.We examined the hydrodynamic changes and mangrove dynamics over the past 36 years and the relationship between hydrodynamic alterations and mangrove degradation.Simulation results reveal that extensive reclamation projects between 1984 and 2000 weakened the current in Shacheng Bay,leading to decreased water exchange capacity and a significant reduction in mangrove area from 0.3 to 0.06km^(2).During this period,over 37% of mangrove degradation was ascribed to time-changing hydrodynamic variables without the direct influence of land reclamation.The results also highlight the changes in local hydrodynamics and water exchange patterns that adversely influenced mangrove growth.From 2000 to 2020,there were minimal coastline changes in Shacheng Bay,demonstrating reduced land reclamation activities.This stopped the further weakening trend of the currents,with a slight increase during ebb tides,while the residual current continued to weaken due to the decreasing tidal prism and water exchange capacity.The mangrove area partially recovered during this period,expanding from 0.06 to 0.11 km^(2),predominantly in new areas instead of where mangroves disappeared from 1984 to 2000.This work underlines the intricate relationship between land reclamation,hydrodynamics,and mangrove ecosystems,underscoring the need for sustainable coastal development strategies.
