A thorough analysis on its natural environment as well as social economic status of the hilly-gullied loess region is presented. A small watershed, the dominant landscape unit of the region, has been singled out for f...A thorough analysis on its natural environment as well as social economic status of the hilly-gullied loess region is presented. A small watershed, the dominant landscape unit of the region, has been singled out for further and specific study on landscape pattern and function, its social and economic distinctions. The authors proposed several principles based on its eco-economic background study, which includes water balance and efficient use principle, co-development of grass and agro-forestry principle, location optimization principle. Integrated with detailed analysis of a small watershed, an eco-productive paradigm for the loess land's development based on a small watershed scale was worked out. It consists of circle pattern with villages at core for high efficient agriculture production, hierarchical pattern along the slope for eco-economic development, point-axis pattern for commodity production and circulation in small watersheds and core-margin pattern for exchanges among watersheds.展开更多
Soil Conservation Service (SCS) model, developed by U. S. Soil Conservation Service in 1972, has been widely applied in the estimation of runoff from an small watershed. In this paper, based on the remote sensing geo-...Soil Conservation Service (SCS) model, developed by U. S. Soil Conservation Service in 1972, has been widely applied in the estimation of runoff from an small watershed. In this paper, based on the remote sensing geo-information data of land use and soil classification all obtained from Landsat images in 1996 and 1997 and con-ventional data of hydrology and meteorology, the SCS model was investigated for simulating the surface runoff for single rainstorm in Wangdonggou watershed, a typical small watershed in the Loess Plateau, located in Changwu County of Shaanxi Province of China. Wangdonggou watershed was compartmentalized into 28 sub-units according to natural draining division,and the table of curve number (CN) values fitting for Wangdonggou watershed was also presented. During the flood period from 1996 to 1997, the hydrograph of calculated runoff process using the SCS model and the hydrograph of observed runoff process coincided very well in height as well as shape, and the model was of high precision above 75%. It is indicated that the SCS model is legitimate and can be successfully used to simulate the runoff generation and the runoff process of typical small watershed based on the remote sensing geo-information in the Loess Plateau.展开更多
Vegetation net primary productivity(NPP)is a sensitive indicator to characterize the response of terrestrial ecosystems to the climate change.Projections of the NPP changes of the Loess Plateau under future climate sc...Vegetation net primary productivity(NPP)is a sensitive indicator to characterize the response of terrestrial ecosystems to the climate change.Projections of the NPP changes of the Loess Plateau under future climate scenarios have great significances in revealing the interactions among terrestrial ecosystems and climatic systems,as well as instructing future vegetation construction of this region.Here,we carried out a case study on the Yangou watershed in the Loess Plateau.Using the vegetation-producing process model(VPP)established for such small watersheds,we simulated the NPP of the Yangou watershed under different scenarios of climate changes.The results showed that the NPP significandy increased with the precipitation increasing and evidently decreased with the temperature increasing where the climate change occurred in the whole year or in the summer half year.However,where the climate change occurred in the winter half year,the increased precipitation had little effect on the NPP,and the increased temperature significantly reduced the NPP.There were clear differences among the response sensitivities of different vegetation types with trees and shrubs were more sensitive to the changes in temperature and precipitation than crops and grasses.Currently,the most favourable climate change scenario to the NPP in the Yangou watershed was T0P15 under which the precipitation increased by 15%and the temperature did not changed,in the whole year;in the meantime,the most unfavourable climate change scenarios was T2P-15 under which the precipitation declined by 15%and the temperature increased by 2℃,in the whole year.展开更多
The paper analyzes the sediment source of watershed by means of studying watershed in westernShanxi of the Losses Plateau. On the basis of watersheds classification, 7 typical watersheds were chosen andobserved for 11...The paper analyzes the sediment source of watershed by means of studying watershed in westernShanxi of the Losses Plateau. On the basis of watersheds classification, 7 typical watersheds were chosen andobserved for 11 years. The result shows that the sediment at the small watershed mainly comes from gullies,which is 60% of the total sediment. Erosion modulus of valley (including gully head, gully bed, valley side)is 1.28~2.48 times as that of the area between channels(including hill slope and mound of the Loess Plateau).The main sediment source of slope erosion is cultivated land on slope without water and soil conservationmeasures.展开更多
文摘A thorough analysis on its natural environment as well as social economic status of the hilly-gullied loess region is presented. A small watershed, the dominant landscape unit of the region, has been singled out for further and specific study on landscape pattern and function, its social and economic distinctions. The authors proposed several principles based on its eco-economic background study, which includes water balance and efficient use principle, co-development of grass and agro-forestry principle, location optimization principle. Integrated with detailed analysis of a small watershed, an eco-productive paradigm for the loess land's development based on a small watershed scale was worked out. It consists of circle pattern with villages at core for high efficient agriculture production, hierarchical pattern along the slope for eco-economic development, point-axis pattern for commodity production and circulation in small watersheds and core-margin pattern for exchanges among watersheds.
基金Under the auspices of National Natural Science Foundation of China (No 40101005)
文摘Soil Conservation Service (SCS) model, developed by U. S. Soil Conservation Service in 1972, has been widely applied in the estimation of runoff from an small watershed. In this paper, based on the remote sensing geo-information data of land use and soil classification all obtained from Landsat images in 1996 and 1997 and con-ventional data of hydrology and meteorology, the SCS model was investigated for simulating the surface runoff for single rainstorm in Wangdonggou watershed, a typical small watershed in the Loess Plateau, located in Changwu County of Shaanxi Province of China. Wangdonggou watershed was compartmentalized into 28 sub-units according to natural draining division,and the table of curve number (CN) values fitting for Wangdonggou watershed was also presented. During the flood period from 1996 to 1997, the hydrograph of calculated runoff process using the SCS model and the hydrograph of observed runoff process coincided very well in height as well as shape, and the model was of high precision above 75%. It is indicated that the SCS model is legitimate and can be successfully used to simulate the runoff generation and the runoff process of typical small watershed based on the remote sensing geo-information in the Loess Plateau.
基金Key Research Program of the Chinese Academy of Sciences(KZZD-EW-04)West Light Foundation of the Chinese Academy of Sciences and Funds of State Key Laboratory of Loess and Quaternary Geology,Chinese Academy of Sciences(SKLLQG1123)
文摘Vegetation net primary productivity(NPP)is a sensitive indicator to characterize the response of terrestrial ecosystems to the climate change.Projections of the NPP changes of the Loess Plateau under future climate scenarios have great significances in revealing the interactions among terrestrial ecosystems and climatic systems,as well as instructing future vegetation construction of this region.Here,we carried out a case study on the Yangou watershed in the Loess Plateau.Using the vegetation-producing process model(VPP)established for such small watersheds,we simulated the NPP of the Yangou watershed under different scenarios of climate changes.The results showed that the NPP significandy increased with the precipitation increasing and evidently decreased with the temperature increasing where the climate change occurred in the whole year or in the summer half year.However,where the climate change occurred in the winter half year,the increased precipitation had little effect on the NPP,and the increased temperature significantly reduced the NPP.There were clear differences among the response sensitivities of different vegetation types with trees and shrubs were more sensitive to the changes in temperature and precipitation than crops and grasses.Currently,the most favourable climate change scenario to the NPP in the Yangou watershed was T0P15 under which the precipitation increased by 15%and the temperature did not changed,in the whole year;in the meantime,the most unfavourable climate change scenarios was T2P-15 under which the precipitation declined by 15%and the temperature increased by 2℃,in the whole year.
文摘The paper analyzes the sediment source of watershed by means of studying watershed in westernShanxi of the Losses Plateau. On the basis of watersheds classification, 7 typical watersheds were chosen andobserved for 11 years. The result shows that the sediment at the small watershed mainly comes from gullies,which is 60% of the total sediment. Erosion modulus of valley (including gully head, gully bed, valley side)is 1.28~2.48 times as that of the area between channels(including hill slope and mound of the Loess Plateau).The main sediment source of slope erosion is cultivated land on slope without water and soil conservationmeasures.
