Meng Jihua

A Global Crop Growth Monitoring System Based on Remote Sensing

Crop growth means the growth of cereal crop seedlings, as well as the status and trend of their growth. It has been one of the most important aspects of agricultural remote sensing in the last twenty years. Evaluation of crop growing condition in large scope before harvesting could be helpful for field management, as well as provide important information for early crop production estimation. For a country with a population of 1.2 billion it is important to know not only the domestic crop growth, but also the crop condition in other big agricultural countries that have food trade with China. This paper introduced the design, methods used and implementation of a global crop growth monitoring system, which satisfies the need of the global crop monitoring in the world. The system uses two methods of monitoring, which are real-time crop growth monitoring and crop growing process monitoring. Real-time crop growth monitoring could get the crop growing status for certain period by comparing the remote sensed data (NDVI, for example) of the period with the data of the period in the history (last year, mostly). The differential result was classified into several categories to reflect the condition at difference level of crop growing. This analysis result allows users to quickly assess how much and where conditions have either deteriorated, remained unchanged or improved. The crop growing process monitoring is the contrast between year and year for crop growth profile, which reflects the crop growing continuance at time during crop growing season. Time series of NDVI during the crop season are used and crop growth profiles are formed by getting statistical average of time series NDVI image for plowland in certain regions such as a state. Eigenvalues such as growing rate, peak value, average and so on were gotten from the crop growing profile to estimate crop growing status which concerns the whole growing process. Based on the above monitoring methods, we developed a crop growth monitoring system based on remote sensing, which provides a monitoring and analyzing environment for real-time crop growth monitoring and crop growing process monitoring to all the users. The system was developed in C/S pattern and includes five main functional modules, which are real-time crop growth monitoring module, crop growing process monitoring module, results visualization module, business management module and system configuring module. The structure and the function are particularly described in the paper. In the system, both real-time crop growth monitoring and crop growing process monitoring are carried out at three scales, which are state (province) scale, country scale and continent scale. While in most of the countries in the world the monitoring was carried out at country scale, monitoring in large agricultural countries such as USA, Canada, India, etc., was carried out at both state (province) scale and country scale. This can provide more detailed crop growth information in these countries. Much more macro crop growth information was supplied by running the system at continent scale such as North America, Europe, Africa and South East Asia, etc. Taken 10-day (16-day for MODIS) composite NDVI products of NOAA/AVHRR, SPOT/VEGETATION and MODIS as data source, the system has been run successfully for more than a year, which provides decision-supporting information on crop condition to more than a dozen of ministries and commissions in China.

Ecology and environment information system for Yangtze Three Gorges Project with remote sensing and GIS

Three Gorges Project is a great water resource project. After the project is completed, it will partially change Yangtzes water regime and affect ecology and environment of region along Yangtze River, from reservoir region, middle reaches, lower reaches to estuary. As a result, it is of great significance to monitor Yangtzes ecology and environment element, which take place since 1996 with 19 themes over the whole river. This paper introduces the ecology and environment information system for Three Gorges Project. The architecture and working principles of the system is introduced firstly. Then, system functions and key implementation technology are stated. The system is unique and complicate mainly because its monitoring contents are wide, which cover water pollution, agricultural ecology, terraneous ecology, hydrophytic ecology, local climate, social environment and so on. The application of the system will provide decision support for sustainable development of Yangtzes drainage area.

Study on the changing trend of ecological environment of the Tarim River's main stream area based on remote sensing

The Tarim River is the longest continental river in China, and also one of the longest rivers in the world. The ecological environment of Tarim River drainage area has been gradually deteriorating in recent twenty years. By using 1 km NDVI data from Advanced Very High Resolution Radiometer (AVHRR) and introducing an integrated vegetation index to the region of interest, conclusion was gotten that the whole ecological environment of the Tarim River drainage area is deteriorating rapidly and the ecological environments of upper, middle and down streams are changing differently. While the ecological environment of the upper stream is meliorating slowly, the ecological environment of middle stream is maintaining its actuality and the ecological environment of the down stream is deteriorating rapidly. After we analyzed the causes of the changes by using the monitoring data of the river discharge from hydrographic stations in the research area, practical suggestions were made for improving the ecological environment in the aspects of water conservancy developments, the exploitation of water resources, etc.