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Dong G.,CAS Institute of Remote Sensing | Dong G.,Yellow River Institute of Hydraulic Research | Yang S.,CAS Institute of Remote Sensing | Gao Y.,Upper and Middle Yellow River Bureau | And 3 more authors.
Environmental Earth Sciences | Year: 2014

Riparian zones act as important buffer zones for non-point source pollution, thus improving the health of aquatic ecosystems. Previous research has shown that riparian zones play an important role, and that land use has an important effect, on phosphorus (P) retention. A spatial basin-scale approach for analyzing P retention and land use effects could be important in preventing pollution in riparian zones. In this study, a riparian phosphorus cycle model based on EcoHAT was generated with algorithms from soil moisture and heat models, simplified soil and plant phosphorus models, plant growth models, and universal soil loss equations. Based on remote sensing data, model performance was enhanced for spatial and temporal prediction of P retention in the riparian zone. A modified soil and plant P model was used to simulate the soil P cycle of a riparian zone in a temperate continental monsoon climate in northern China. A laboratory experiment and a field experiment were conducted to validate the P cycle model. High coefficients of determination (R 2) between simulated and observed values indicate that the model provides reliable results. P uptake variations were the same as the net primary productivity (NPP) trends, which were affected by soil temperature and moisture in the temperate continental monsoon climate. Beginning in June, the monthly content increased, with the maximum appearing in August, when the most precipitation and the highest temperatures occur. The spatial distribution of P uptake rates from March to September showed that areas near water frequently had relatively high values from May to August, which is contrary to results obtained in March, April, and September. The P uptake amounts for different land uses changed according to expectation. The average monthly P uptake rates for farmlands and grasslands were more than those for orchards and lowlands, which had moderate P uptake rates, followed by shrubs and forests. The spatial distribution of soil erosion demonstrated that the soil erosion came primarily from high-intensity agricultural land in the western and central areas, while the northern and eastern study regions, which were less affected by human activity, experienced relatively slight soil erosion. From the point of view of P pollution prevention, the spatial structure of riparian zones and the spatial distribution of land use around the Guanting reservoir are thus not favorable. © 2014 Springer-Verlag Berlin Heidelberg.

He H.,Xian Jiaotong University | Wang H.,Xian Jiaotong University | Li H.,Upper and Middle Yellow River Bureau | Mei T.,Xian Jiaotong University | Xi M.,Xian Jiaotong University
Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University | Year: 2011

A mobility problem-Solving strategy (MSEN) to enhance network stability is proposed to address the low stability of communication in Mobile Ad Hoc network. The strategy obtains the stability of communication routes by detecting the relative rates, and computing the stability of links among nodes. Routes with high stability will be preferred to improve network reliability. The strategy focuses on the problem of stability declining caused by mobility of nodes, and uses the creative method of moving direction prediction to raise the stability of the network. Simulation results show that the method selects the communication link with higher stability. Comparisons with traditional methods show that the performance of communication delay time is reduced by about 1%, and the throughput is increased by about 5%.

Liu X.-Y.,Chinese Ministry of Water Resources | Wang F.-G.,Upper and Middle Yellow River Bureau | Yang S.-T.,Beijing Normal University | Li X.-Y.,Yellow River Institute of Hydrology and Water Resources | And 2 more authors.
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2014

The sediment reduction effect of level terrace in the Loess Plateau is likely to have been under-estimated before. By analyzing the water and sediment regulation mechanism of the terraces in the basin, it is realized that the level terrace can not only significantly reduce the sediment yield from itself, but also intercept the sediment yield from the upper area, and can achieve the valley sediment reduction by reducing runoff flowing from slope to valley. The sediment reduction potential of level terrace with ridges in watershed is up to 65 %. Based on the measured data of the third and the fifth sub-district of the loess hilly region in different periods, the sediment reduction effect of different scale level terraces is analyzed under average annual rainfall condition. The concept of terrace ratio is introduced to build the relationship between terrace ratio and sediment reduction magnitude, which can be used to quantitatively evaluate sediment reduction effect of level terrace on a large spatial scale, When the terrace ratio is less than 30%, the magnitude of sediment reduction is basically proportional to the terrace ratio; and when the terrace ratio is larger than 35 %, the sediment reduction effect is basically stable at about 90%. The flood sediment concentration reduction effect of level terrace is not very obvious; this characteristic can be used to measure the water-reducing effect of level terrace in the river basin.

Liu X.-Y.,Yellow River Conservancy Commission | Yang S.-T.,Beijing Normal University | Wang F.-G.,Upper and Middle Yellow River Bureau | He X.-Z.,Upper and Middle Yellow River Bureau | And 2 more authors.
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2014

The sediment yield of the Yellow River have been reduced sharply since 2000. Based on the remote sensing information and local investigation in the sandy region of the Loess Plateau, this investigation analyzes the quantity and quality of the current terrace, the status of shrubs-herbs-arbor vegetation in 2010-2013 and the restoration effect comparing with its natural period. Their sediment reduction calculation methods and procedures for the coexistence situation of the terrace and shrubs-herbs-arbor vegetation restoration were demonstrated in this paper. Under the average rainfall condition of years, the calculation result revealed that the sediment reduction capacity of the current terrace and shrubs-herbs-arbor vegetation at their 2010-2013 level is about 1.065 billion ton in the area of above Longmen, Zhuangtou of the Beiluo River, Hejin of the Fenhe River, Xianyang of the Weihe River and Zhangjiashan of the Jinghe River, which account for 60% of its original sediment yield. ©, 2014, China Water Power Press. All right reserved.

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