Taking a typical inland wetland of Honghe National Nature Reserve (HNNR), Northeast China, as the study area, this paper studied the application of L-band Synthetic Aperture Radar (SAR) image in extracting eco-hydrolo...Taking a typical inland wetland of Honghe National Nature Reserve (HNNR), Northeast China, as the study area, this paper studied the application of L-band Synthetic Aperture Radar (SAR) image in extracting eco-hydrological information of inland wetland. Landsat-5 TM and ALOS PALSAR HH backscatter images were first fused by using the wavelet-IHS method. Based on the fused image data, the classification method of support vector machines was used to map the wetland in the study area. The overall mapping accuracy is 77.5%. Then, the wet and dry aboveground biomass estimation models, including statistical models and a Rice Cloudy model, were established. Optimal parameters for the Rice Cloudy model were calculated in MATLAB by using the least squares method. Based on the validation results, it was found that the Rice Cloudy model produced higher accuracy for both wet and dry aboveground biomass estimation compared to the statistical models. Finally, subcanopy water boundary information was extracted from the HH backscatter image by threshold method. Compared to the actual water borderline result, the extracted result from L-band SAR image is reliable. In this paper, the HH-HV phase difference was proved to be valueless for extracting subcanopy water boundary information.展开更多
In this study,effects of elevated air temperatures on thermal and hydrologic process of the shallow soil in the active layer were investigated. Open-top chambers(OTCs)were utilized to increase air temperatures 1-2℃ i...In this study,effects of elevated air temperatures on thermal and hydrologic process of the shallow soil in the active layer were investigated. Open-top chambers(OTCs)were utilized to increase air temperatures 1-2℃ in OTC-1 and 3-5℃ in OTC-2 in the alpine meadow ecosystem on the Qinghai- Tibetan Plateau.Results show that the annual air temperatures under OTC-1 and OTC-2 were 1.21℃ and 3.62℃ higher than the Control,respectively.The entirely-frozen period of shallow soil in the active layer was shortened and the fully thawed period was prolonged with temperature increase.The maximum penetration depth and duration of the negative isotherm during the entirely-frozen period decreased, and soil freezing was retarded in the local scope of the soil profile when temperature increased.Meanwhile, the positive isotherm during the fully-thawed period increased,and the soil thawing was accelerated.Soil moisture under different manipulations decreased with the temperature increase at the same depth. During the early freezing period and the early fully- thawed period,the maximum soil moisture under the Control manipulation was at 0.2 m deep,whereas under OTC-1 and OTC-2 manipulations,the maximum soil moisture were at 0.4-0.5 m deep. These results indicate that elevated temperatures led to a decrease of the moisture in the surface soil.The coupled relationship between soil temperature and moisture was significantly affected by the temperature increase.During the freezing and thawing processes, the soil temperature and moisture under different manipulations fit the regression model given by the equationθV=a/{1+exp[b(TS+c)]}+d.展开更多
Focusing on sustainability of water resources and ecology in the complex karst critical zone, we illustrated functions of the hydro-geochemical analysis on hydrology from the aspects of connection and interaction amon...Focusing on sustainability of water resources and ecology in the complex karst critical zone, we illustrated functions of the hydro-geochemical analysis on hydrology from the aspects of connection and interaction among hydrology–vegetation–soils/rock fractures along the karst subsurface profile. We reviewed isotopic and geochemical interpretations on tracing water sources for plant uptake, quantifying watershed outlet flow composition and residence times, and evaluating long-term evolution among climate–landscape–hydrology in the karst critical zone. In this paper, the application of the hydro-geochemical analysis on the above aspects in the karst areas of southwest China was summarized.展开更多
Drought is usually supposed to be a rainfall deficiency problem. Most studies and practices to mitigate drought disaster are focusing on water development and irrigation, while neglecting that the agriculture system i...Drought is usually supposed to be a rainfall deficiency problem. Most studies and practices to mitigate drought disaster are focusing on water development and irrigation, while neglecting that the agriculture system is a compounded human-natural system. Drought situation and tendency is also driven by human coping strategies. This paper takes Hebei Province in north China as an example, studing the spirally interact process of drought resisting and hydrological ecological feedback. The result shows that large scale water projects construction facilitated irrigation. With improved irrigation, farmers enhanced multiple crop index and land-use intensity greatly and increased the sowing area of water consuming crop, winter wheat. At the same time, both crop yield and gross output are raising steadily. Water demand and depletion in agricultural system increase year by year. This gradually leads to highly dependent on over exploitation of water resources, especially overdraw of groundwater. The process deteriorated the stability of hydrological-ecological system and made the ecological environment drying up. Drying up environment is breeding greater vulnerability and risk of drought in the long term. For sustainable development, integrated drought risk management should be based on the balance between sustainable water supply and water demand. The key is to improve agricultural system＇s adaptive and resilient capacity to drought.展开更多
Water and soil conservation is an important part of eco-civilization con-struction. It is a major part of eco-construction and lifeline of social and economy development. Therefore, water and soil conservation is of g...Water and soil conservation is an important part of eco-civilization con-struction. It is a major part of eco-construction and lifeline of social and economy development. Therefore, water and soil conservation is of great significance in maintaining eco-safety. The research concluded status quo and characters of water and soil losses in China and analyzed water and soil conservation and construction of eco-civilization from the perspectives of water and soil conservation and con-struction of eco-civilization.展开更多
基金Under the auspices of National High Technology Research and Development Program of China (No. 2007AA12Z176)National Natural Science Foundation of China (No. 40771170)Natural Science Foundation of Beijing (No. 8082010)
文摘Taking a typical inland wetland of Honghe National Nature Reserve (HNNR), Northeast China, as the study area, this paper studied the application of L-band Synthetic Aperture Radar (SAR) image in extracting eco-hydrological information of inland wetland. Landsat-5 TM and ALOS PALSAR HH backscatter images were first fused by using the wavelet-IHS method. Based on the fused image data, the classification method of support vector machines was used to map the wetland in the study area. The overall mapping accuracy is 77.5%. Then, the wet and dry aboveground biomass estimation models, including statistical models and a Rice Cloudy model, were established. Optimal parameters for the Rice Cloudy model were calculated in MATLAB by using the least squares method. Based on the validation results, it was found that the Rice Cloudy model produced higher accuracy for both wet and dry aboveground biomass estimation compared to the statistical models. Finally, subcanopy water boundary information was extracted from the HH backscatter image by threshold method. Compared to the actual water borderline result, the extracted result from L-band SAR image is reliable. In this paper, the HH-HV phase difference was proved to be valueless for extracting subcanopy water boundary information.
基金founded by The National Science Foundation of China(No.40730634 andNo.40925002)
文摘In this study,effects of elevated air temperatures on thermal and hydrologic process of the shallow soil in the active layer were investigated. Open-top chambers(OTCs)were utilized to increase air temperatures 1-2℃ in OTC-1 and 3-5℃ in OTC-2 in the alpine meadow ecosystem on the Qinghai- Tibetan Plateau.Results show that the annual air temperatures under OTC-1 and OTC-2 were 1.21℃ and 3.62℃ higher than the Control,respectively.The entirely-frozen period of shallow soil in the active layer was shortened and the fully thawed period was prolonged with temperature increase.The maximum penetration depth and duration of the negative isotherm during the entirely-frozen period decreased, and soil freezing was retarded in the local scope of the soil profile when temperature increased.Meanwhile, the positive isotherm during the fully-thawed period increased,and the soil thawing was accelerated.Soil moisture under different manipulations decreased with the temperature increase at the same depth. During the early freezing period and the early fully- thawed period,the maximum soil moisture under the Control manipulation was at 0.2 m deep,whereas under OTC-1 and OTC-2 manipulations,the maximum soil moisture were at 0.4-0.5 m deep. These results indicate that elevated temperatures led to a decrease of the moisture in the surface soil.The coupled relationship between soil temperature and moisture was significantly affected by the temperature increase.During the freezing and thawing processes, the soil temperature and moisture under different manipulations fit the regression model given by the equationθV=a/{1+exp[b(TS+c)]}+d.
基金supported by the National Natural Scientific Foundation of China(No.41571130071)
文摘Focusing on sustainability of water resources and ecology in the complex karst critical zone, we illustrated functions of the hydro-geochemical analysis on hydrology from the aspects of connection and interaction among hydrology–vegetation–soils/rock fractures along the karst subsurface profile. We reviewed isotopic and geochemical interpretations on tracing water sources for plant uptake, quantifying watershed outlet flow composition and residence times, and evaluating long-term evolution among climate–landscape–hydrology in the karst critical zone. In this paper, the application of the hydro-geochemical analysis on the above aspects in the karst areas of southwest China was summarized.
基金Acknowledgments China National Natural Science Foundation （No. 41171402） and Doctoral Fund of Hebei Normal University （No. 103237）.
文摘Drought is usually supposed to be a rainfall deficiency problem. Most studies and practices to mitigate drought disaster are focusing on water development and irrigation, while neglecting that the agriculture system is a compounded human-natural system. Drought situation and tendency is also driven by human coping strategies. This paper takes Hebei Province in north China as an example, studing the spirally interact process of drought resisting and hydrological ecological feedback. The result shows that large scale water projects construction facilitated irrigation. With improved irrigation, farmers enhanced multiple crop index and land-use intensity greatly and increased the sowing area of water consuming crop, winter wheat. At the same time, both crop yield and gross output are raising steadily. Water demand and depletion in agricultural system increase year by year. This gradually leads to highly dependent on over exploitation of water resources, especially overdraw of groundwater. The process deteriorated the stability of hydrological-ecological system and made the ecological environment drying up. Drying up environment is breeding greater vulnerability and risk of drought in the long term. For sustainable development, integrated drought risk management should be based on the balance between sustainable water supply and water demand. The key is to improve agricultural system＇s adaptive and resilient capacity to drought.
基金Supported by the Twelfth Five-year-plan in National Science and Technology for the Rural Development in China(2011BAD31B01)~~
文摘Water and soil conservation is an important part of eco-civilization con-struction. It is a major part of eco-construction and lifeline of social and economy development. Therefore, water and soil conservation is of great significance in maintaining eco-safety. The research concluded status quo and characters of water and soil losses in China and analyzed water and soil conservation and construction of eco-civilization from the perspectives of water and soil conservation and con-struction of eco-civilization.
