| As well known to all, intertidal zone is affected constantly by tide and alternately undergoes exposure and submergence, thus it is very hard to monitor its topographic change by conventional survey methods due to the special geographical environment. Taking one piece of intertidal flat as study area, which is located at the south of dafeng port in Jiangsu province, statistic method was employed to construct reflectance-moisuture model and moisture-elevation model. Then moisture factor as bridge was used to acquire reflectance-elevation model. The main contents of this thesis are as follows:1.Based on spectral experiment and statistic analysis, we found one waveband centered at2220nm enjoys high correlation with moisture content and single-waveband model constructed via this sensitive band possesses potential to retrieve moisture content.Water abundance derived from remotely sensed imagery by linear spectral mixture model (LSMM) bears high correlation with moisture content as well and possesses the highest R square and lowest mean absolute error (MAE) and mean relative error (MRE). It also has been proved that LSMM method has a potential to reduce the influence of parent material from different soil types.2. After comparison constructed moisture content estimation models, both single-waveband model and LSMM model was employed to retrieve moisture content of intertidal zone via remotely sensed imagery. Both of that enjoys reasonable results in terms of the spatial distribution of moisture content in intertidal zone features the obvious layers, which are matched with the tidal recession lines.3. Based on moisture measurement in field, we found the moisture content definitely reduce with time gone, which means the stand point of our hypothesis can be confirmed and the method we used for acquiring elevation is acceptable.4. Through analyzing the relationship between retrieved moisture content derived from remotely sensed imagery, we found moisture content retrieved via single-waveband model has obvious correlation with elevation. After further analysis, we found slope was the main factor influencing above relationship, so two kinds of elevation estimation models were constructed, which are tide ditch model and non-tide ditch model.In this process, negtive correation between moisture content and elevation has been proved as well, which laid a great foundation to our theory.5. The reflecante-elevation models fitting tide and non-tide ditch were deduced via reflectance-moisture model and moisture-elevation model together, which can be employed to retrieve elevation of intertidal zone by remotely sensed imagery.6. In order to distinguish appropriate study area for two elevation retrieval models, the ration of the width of tide ditch and distance of bank slope was employed to define the radius which is a parameter will be used in buffer analysis. Through experiment we found when ratio equals2.5, generated buffer zone could be used to divide study area into reasonable pieces. Finally, the radius was defined as700m and the study area was divided into two parts via buffer zone, and then two elevation retrieval models were applied in divided parts respectively to generate elevation of intertidal zone.7. Through accuracy evaluation, we found non-tide ditch zone possessed much higher estimation result, the MAE was only9.6cm and MRE was only7.8%. On the contrary, tide ditch zone had a much lower estimation result, the MAE was28.8cm and MRE was39.25%. In the whole area, the accuracy of elevation estimation is accepted because the MAE was19.2cm cm and MRE was23.5%. |
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