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In this paper, the dynamic change of water surface area in Honghu Lake in recent 40 years based on remote sensing technique is introduced by using the multi-temporal remote sensing imagery including Landsat MSS, TM, ETM and HJ-1 CCD since 1970s. Meanwhile, the daily precipitation and evaporation data of Honghu meteorological station and the fishery production value of Jingzhou since 1970s were also collected to analyze the influence of climate change and human activities factors on the change of Honghu Lake's water surface area. The multiple regression analysis shows the influence coefficients of precipitation, precipitation days, evaporation and fishery production value for the water surface area of Honghu Lake are 0.7575", "-0.0035", "-0.0952 and -0.4761 respectively, which means climate factor is still the major factor on the change of Honghu Lake, while human activity should not be ignored.

Greenhouse gas concentration in the atmosphere has already grown continuously due to the usage of fossil fuels and other anthropogenic activities since industrial revolution. The improvement of greenhouse gas concentration maybe results in climate change and redistribution of water resources. So more and more attentions were paid to low-carbon or clean energy exploitation in order to meet the energy demand of economic and social development. Hydropower is an important clean energy which would not produce greenhouse gas directly. But the construction of dam maybe change regional climate, aquatic ecosystem and the distribution of carbon cycle in water body of reservoir. So greenhouse gas emission from freshwater reservoir was monitored and analyzed at the Shuibuya reservoir over the Qingjiang River Basin, China in this paper. The floating chamber was used to measure carbon dioxide and methane fluxes at the water-atmosphere interface of water body. All measurement points are distributed in the upstream, middle, tributary or bay, and drawdown zone of the Shuibuya reservoir respectively. Data analysis indicated that carbon dioxide fluxes at all measurement points were below 800 mg.m−2.d−1 and methane fluxes was below 8.0 mg.m−2.d−1 at Sep. 03, 2010. The navigated measurement showed the slightly improved trend of carbon dioxide and methane concentration from upstream to dams of the reservoir. So it is concluded that the Shuibuya reservoir releases carbon dioxide and methane to the atmosphere from water body at Sep. 3, 2010, but the emission amount is very small and could be neglected compared to lakes, wetland and other natural water body.

Soil moisture and vegetation index provides valuable information for surface water content and drought assessment with remotely sensed data. In this paper, a new drought monitoring method (MPDI1) with soil moisture and vegetation index is constructed in NIR-Red reflectance space. The relationship between MPDI1 and soil moisture is explored using satellite image and field measure data, and a comparison among MPDI1, the Perpendicular Drought Index (PDI), and the Modified Perpendicular Drought Index (MPDI) is also evaluated. Results indicate that the MPDI1 is highly accordant with the in-situ ground observation with the coefficient of determination (R2=0.4905) between MPDI1 and 5-20 cm mean soil moisture. Moreover, PDI, MPDI and MPDI1 provide quite similar spatial patterns for bare soil or lower vegetated surface, but MPDI1 demonstrates a better performance in measuring densely vegetated surface. This paper concludes that MPDI1 is a useful tool for surface drought estimation under complex underlying conditions.