ABSTRACT:On behalf of more populous and developed regions in China, urban agglomerations have become important carries loading active economic activities and generous social benefits, and experienced sharper population increase, which results in great threat on local eco-environment construction. Therefore, exact and detailed population monitoring and analyzing, especially on the long sequence and multi frequency, is of great significance. The nighttime light time-series (NLT) products has been proven to be one of the most useful remotely sensed imagery to acquire persons at 1 km *1 km scales. However, the existed problems, such as light saturation and blooming, greatly limit the accuracy of estimated results. Furthermore, it's difficult to spatialize population at km 2 level due to the lack of basic data in non-census years. In order to solve all problems mentioned above, the populous Pearl River Delta was selected as the study area. A new residential extent extraction index (REEI) was proposed to solve light saturation and blooming problems. Population spatialization methods in census and non-census years were applied to acquire detailed population distribution from 2000 to 2010. Results showed the feasibility of the proposed methods in this work. During the decade, population was denser in the central PRD and sparser in the eastern, western and northern PRD. The speed of population increase was various in nine cities, but faster in

ABSTRACT:Urban expansion has far-reaching influences on cultivated lands, and has a serious effect on grain output and safety. However, relatively little attention has been paid to monitor cultivated land losses through urban expansion over a long timeframe and multi-frequency, especially its differences on national scale systematically. In this work, the characteristics of Chinese cultivated land dynamics were described using annual occupied area per city, contribution rate of cultivated lands to urban expansion and the classification method of basic trend of cultivated land losses. Results indicate that: (1) in the past four decades, large amount of cultivated lands have been occupied during the urban expansion process, and have become the first land source for Chinese urban expansion. (2) Cultivated land loss among municipalities, provincial capitals and other cities was obviously different. The higher of cities' administrative level was, the more obvious of cultivated land loss in these cities appeared, and the earlier of acceleration loss stage of cultivated lands occurred. (3) Cultivated land loss in five population-size cities was unbalanced, representing obviously different loss process and contribution on urban expansion. The bigger of cities' population size was, the more obvious of cultivated land loss in these cities appeared, and the earlier of acceleration loss stage of cultivated lands occurred. (4) Cultivated land losses during urban expansion process were imbalanced in China, and were classified into seven trends. (5) Chinese cultivated land protection has been carried out from the awakening stage to the deep implementation stage.