Han Y.,Beijing Forestry University |
Fan Y.,Chinese Academy of Agricultural Sciences |
Yang P.,China Agricultural University |
Wang X.,CAS Research Center for Eco Environmental Sciences |
And 4 more authors.
Geoderma | Year: 2014
This study provides a new understanding to sources of nitrogen (N), and may serve as a foundation for further exploration of anthropogenic effects on N inputs. Estimation of net anthropogenic nitrogen inputs (NANI) was based on an inventory of atmospheric N deposition, N fertilizer use, N in human food and animal feed, seeding N and N fixation. This study took a step forward to calculate NANI in detail on a regional scale, and analyzed its temporal variations and geographic differences. Over the past 28years, NANI increased significantly in Mainland China, from 2360kgNkm-2yr-1 to 5013kgNkm-2yr-1. On a geographical basis, NANI was higher in southeast where China's eight major watersheds are located than in northwest, and the largest NANI, 26160kgNkm-2yr-1, appeared in Shanghai. The administrative regions corresponding to Haihe watershed, Huaihe watershed and Tai lake watershed have the largest NANI. N input of fertilizer is the largest source of NANI, followed by atmospheric N deposition and N fixation. The primary factor in relation to the change in NANI is total population density, followed by cultivated land area and total grain yield. In those densely populated large cities and watersheds, reasonably allocating the social resources to reduce the existing population density is the most effective way to address the problem of high N inputs, while in those agriculture-dominated regions and watersheds, the most effective way for reducing NANI is to improve fertilizer utilization efficiency in agriculture. © 2013 Elsevier B.V.
Zuo C.-Q.,China Institute of Water Resources and Hydropower Research |
Zuo C.-Q.,Chinese Ministry of Water Resources |
Zhang G.-H.,China Irrigation and Drainage Development Center
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2012
Based on the kinematic wave theory, a basic equation has been deduced to describe the runoff generation on a slope under the condition of natural rainfall with different rainfall intensities. The equation can be numerically solved by applying the Preissmann format. The feasibility of the model is verified by field experimental data. The maximum deviation between calculated results and experimental data is within ±17%. Putting field testing rainfall information into the model set up in this paper, the processes of rain?fall under different rainfall intensity condition were simulated, which indicated that the start of runoff yield time in the ground covered and apply covered by Bahia grass is obvious later than that in the bare ground, and the peak flow was less than that in the bare ground in evidence, making out that the measures by covering and apply covering with Bahia grass have significantly effect on reducing and suspending peak flow effect.
Zheng J.,China Agricultural University |
Li G.-y.,China Agricultural University |
Han Z.-z.,China Irrigation and Drainage Development Center |
Meng G.-x.,China Institute of Water Resources and Hydropower Research
Mathematical and Computer Modelling | Year: 2010
A distributed hydrological cycle model of an irrigation district was developed based on the SWAT model (Soil and Water Assessment Tool) and an artificial-natural composite of the hydrological cycle was considered. The SWAT model was modified in the aspects of the extraction of ditches, distributed subbasins and hydrologic response units, and the calculation method of the crop's actual ET. The applicability of the model was validated in the Fenhe irrigation district. The information on hydrology, weather and water use from 1996 to 2001 in the Fenhe irrigation district was used to simulate and analyze the water balance. The sensitive parameters were estimated by En s, RE and R2. The model was further validated with the monthly flow data from 2002 to 2006. The results showed that the simulated results of two monitoring points meet the estimated requirements. The RE value of the average annual runoff at the Erba Station varied from -7.34% to 19.13% except a low RE value (-30.70%) in 2006. The RE of the average annual runoff at the Yitang station was from -17.21% to 9.86% with an exceptional RE value (-21.13%) in 2003. From the monthly simulated results, the R2 of the monthly runoff at the Erba and Yitang stations was 0.81 and 0.77, respectively. The En s of the monthly runoff was 0.72 and 0.65, respectively. A modified SWAT model was applicable for water balance simulation at the Fenhe irrigation district. © 2009 Elsevier Ltd. All rights reserved.
Ni W.,China Irrigation and Drainage Development Center
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2010
The main elements of the rural water conservancy are irrigation and drainage engineering, and rural water supply. The current work of rural water conservancy includes three main objectives, such as reinforce of dangerous reservoirs, safety of rural drinking water, and reform of water-saving irrigation for irrigation regions, which includes reform of water-saving irrigation for large and middle scaled irrigation regions, reform of large scaled pump stations for irrigation and drainage systems, construction of small scaled agricultural water conservancy projects, and water-saving irrigation etc. Progress of above situation was analyzed in this paper, which also included overview of rural water technology development, such as research progress of water-saving irrigation techniques, rural drinking water technology and their integration, and the rapid evaluation and software development of the modern irrigation region management, water resource management technology which based on crop evapotranspiration. After discussing the technology requirement and key areas of rural water conservancy, the author thinks that we should increase joint research, accelerate the transformation and promotion of research fruits, pay attention to the relationship between inputs and outputs. Suggestions for extension service of rural water conservancy should be focused on the increase of farmers' income and the improvement of their living conditions, increase the guidance, support of rural water-related key enterprises, accelerate the transformation of scientific and technological achievements, give full play to enterprises in the important role of technology promotion.
Zheng J.,China Agricultural University |
Li G.-Y.,China Agricultural University |
Han Z.-Z.,China Irrigation and Drainage Development Center |
Meng G.-X.,China Institute of Water Resources and Hydropower Research
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2011
A distributed hydro logical model was developed for piedmont irrigation district based on the SWAT model (Soil and Water Assessment Tool) and the artificial-natural effect on the hydrological cycle for this kind of piedmont irrigation district was considered. Based on the interference of artificial irrigation canal, drainage ditches and river, the SWAT model was modified in the aspect of extraction of ditches, division of distributed subbasins and hydrologic response units, as well as the method for calculating crop actual ET. The modified SWAT model was applied to the irrigation district of Fenhe River basin. The hydrology, weather and water use information from 1996 to 2001 of the irrigation district were used to simulate and analyze the water balance. The sensitive parameters were estimated. The model was further validated with the monthly flow data of 2002-2006, which attained excellent results. The simulated results of two monitoring points meet the estimated requirements, and SWAT model is applicable to the Fenhe irrigation district water balance simulation.