潮滩沉积物含水量是表征潮滩地物信息的一个重要特征量,它影响着遥感提取潮滩地物信息的准确性。利用含水量-反射率指数衰减模式建立单波段模型,同时参考4种植被指数的形式构建含水量指数,建立适用于潮滩环境的含水量反演波段组合模型,实现了沉积物含水量的遥感反演。研究结果显示:对反射率数据利用干土反射率进行归一化处理后构建的NEWCI(Normalized Enhanced Water Content Index)归一化增强型含水量指数模型的含水量反演效果最佳。在含水量结果中,除了砂类别反演的确定性系数R2为0.675以外,粉砂、砂质粉砂、粉砂质砂、粘土质粉砂等4种沉积物类型反演的确定性系数均在0.83以上;当不考虑沉积物类型时,NEWCI指数模型的反演精度也达到0.8,RMSE为0.059,表明NEWCI指数模型对沉积物类型不敏感,且能够保持较高的含水量模拟精度,因而适合潮滩沉积物含水量的大范围预测。其反演结果可在潮滩地物信息遥感反演时有效削弱水分的影响,进而提高地物信息提取的效率。
Tidal flow is a periodic movement of unsteady and non-uniform,which has acceleration and deceleration process obviously,especially in coastal shallow waters.Many researches show that vertical distribution of tidal flow Reynolds stress deviated from linear distribution.The parabolic distribution of the tidal flow Reynolds stress was proposed by Song et al.(2009).Although the model fills better with field observations and indoor experimental data,it has the lower truncated series expansion of tidal flow Reynolds stress,and the description of the distribution is not very comprehensive.By introducing the motion equation of tidal flow and improving the parabolic distribution established by Song et al.(2009),the cubic distribution of the tidal flow Reynolds stress is proposed.The cubic distribution is verified well by field data(Bowden and Fairbairn,1952;Bowden et al.,1959;Rippeth et al.,2002) and experimental data(Anwar and Atkins,1980),is consistent with the numerical model results of Kuo et al.(1996),and is compared with the parabolic distribution of the tidal flow Reynolds stress.It is shown that this cubic distribution is not only better than the parabolic distribution,but also can better reflect the basic features of Reynolds stress deviating from linear distribution downward with the tidal flow acceleration and upward with the tidal flow deceleration,for the foundation of further study on the velocity profile of tidal flow.
