UAV (unmanned aerial vehicle) remote sensing system has advantages of strong real-time, flexible and convenient, little influence by the external environment, and the ability to work full-time. It can go deep into the places safely and reliably which staff can hardly arrived. The remote sensing system can be in response to emergencies to gain first-hand information as quickly as possible and have produced a unique emergency response to acquire an important basis for overall decision-making. However, UAV remote sensing system was so fast, flexible, low flying to carry on quick response to acquire high-resolution images. In the Wenchuan Earthquake, UAV remote sensing was applied successfully to acquire first-hand earthquake damage information in the short time under cloudy and rainy conditions of Sichuan Province. The system flow of UAV remote sensing to extract information on damaged houses after earthquake was set up successfully. Moreover, UAV remote sensing had an important role in mapping of damaged buildings after earthquake. Rapid identification of mapping of damaged buildings after earthquake with UAV remote sensing techniques can be carried out. UAV remote sensing techniques could have greater potentials for disaster mitigation and management after earthquake.
The Tonle Sap Lake plays a very important role in regulating the downstream flood of the Mekong River. It is necessary to understand its temporal changes of water area of the lake and to analyze its relation with the flood processes of the Mekong River. Monthly water area from June 2013 to May 2014 were monitored based on the multi-temporal images of HJ-1 satellite in this paper. Normalized difference water index (NDWI) was used to extract the water area. It is found that the water area of the lake had a dramatic increase from September to December. Moreover, after reaching its maximum in December 2013, the water area quickly decreased by 11463km<sup>2</sup> in only half month time from December to January. It kept rather stable at a lower level from February to May in 2014. It is feasible, fast and reliable to monitor and analyze the change of lake water area based on remote sensing method with important application prospect.
The Tropical Rainfall Measuring Mission (TRMM) satellite rainfall data were assessed and calibrated using limited ground meteorological and hydrological data in Irrawaddy River basin, a watershed with complex terrain conditions but lack of data. A correction factor was determined to adjust TRMM data, taking basin water balance and terrain slopes into consideration. A distributed hydrological model SWAT was established and used to simulate the basin rainfall-runoff processes from 2001 to 2011, driven by the calibrated TRMM rainfall data series. Results show that, in a data scarce basin like Irrawaddy River basin, such a water balanced based TRMM data calibration method is suitable and reliable.
Remote sensing is one subject of the modern geomatics, with a high priority for practical applications in which cross time and space analysis is one of its significant features. Object recognition and/or parameter retrieval are normally the first step in remote sensing applications, whereas cross time and space change analysis of those surface objects and/or parameters will make remote sensing applications more valuable. Based on a short review on the historic evolution of remote sensing and its current classification system, the cross time and space features commonly existing in remote sensing applications were discussed. The paper, aiming at improving remote sensing applications and promoting development of the remote sensing subject from a new vision, proposed a methodology based subject classification approach for remote sensing and then suggest to establish the theory of cross time and space remote sensing applications. The authors believe that such a new cross time and space concept meets the demand for new theories and new ideas from remote sensing subject and is of practical help to future remote sensing applications.
Satellite remote sensing with a larger spatial coverage and high temporal resolution makes it possible to monitor precipitation distribution under extreme rainfall events. In this paper, the heavy rainstorm that occurred in Beijing on 21, July in 2012 was monitored using the TRMM and Fengyun precipitation data. Results indicate that: (1) these two kinds of satellite precipitation data are in good agreement with ground observed precipitation data, having a correlation coefficient of 0.9390 and 0.9846 and an underestimation of 14.42% and 19.86% respectively; (2) The moving track of this extreme rainstorm can be well detected, with the storm center and a heavy rain belt moving from southwest to northeast found; (3) 15 minutes interval between the two satellite data makes them complement each other, which enables the temporal frequency of the monitoring data further increased so as to get construction of the rainstorm processes improved.
Regional river basins, transboundary rivers in particular, are shared water resources among multiple users. The tempo-spatial distribution and utilization potentials of water resources in these river basins have a great influence on the economic layout and the social development of all the interested parties in these basins. However, due to the characteristics of cross borders and multi-users in these regions, especially across border regions, basic data is relatively scarce and inconsistent, which bring difficulties in basin water resources management. Facing the basic data requirements in regional river management, the overall technical framework for remote sensing monitoring and data service system in China’s regional river basins was designed in the paper, with a remote sensing driven distributed basin hydrologic model developed and integrated within the frame. This prototype system is able to extract most of the model required land surface data by multi-sources and multi-temporal remote sensing images, to run a distributed basin hydrological simulation model, to carry out various scenario analysis, and to provide data services to decision makers.
The relationship between crop ET(Evapotranspiration) and yield is the theory base of agricultural irrigation management. Research on the interval amount of suitable crop ET is the most important headline of irrigation planning and water resources allocation. This paper, on the basis of previous field research works, taking winter wheat as an example, firstly analyzed the rule of crop water consumption during the whole growing stage and the relationship between ET and biomass, water productivity. Then, the relationship models of ET-biomass and ET-water productivity at the whole growing stage were established in Beijing by using remote-sensing ET and biomass, and the suitable water consumption interval for the winter wheat under the condition of non-sufficient irrigation was deduced[300mm,408mm]. At the last, the application characteristics and the main influences on the models were discussed. The paper provides scientific basis and reference for further research on improving crop water productivity and yield under the condition of non-sufficient irrigation in Northern semi-arid region.
With the objective of understanding the potential and limitations of satellite precipitation products for hydrological studies, this article compares TRMM (Tropical Rainfall Measurement Mission) precipitation product with observed precipitation data and analyzes its impacts on the water balance of the Upper Heihe River basin in Northwest China. TRMM 3b42 daily precipitation data were used to run the SWAT (Soil and Water Assessment Tools) model for the period 1998~2000 after compared to gauged precipitations. Three stations were selected as the reference precipitation datasets. The results show that basin wide annual average precipitation relative error is only 8%, and TRMM monthly data performed relatively well with the correlation coefficients all above 0.85. Model results reveal that TRMM can reproduce the water cycle reasonably well at the basin scale and monthly time step.