Applied Mechanics and Materials Vol. 737

Abstract: In this study, Soil and Water Assessment Tool (SWAT) model was used to simulate land-use change effects on water quantity in the upper Huaihe river basin above the Xixian hydrological controlling station with a catchment area of 10,190 km² by the use of three-phase (1980s、1990s、2000s) land-use maps, soil type map (1:200000), 1980 to 2008 daily time series of rainfall from the upper Huaihe river basin. On the basis of the simulated time series of daily runoff, land-use change effects on spatio-temporal change patterns of runoff coefficients and runoff modules were investigated. The results revealed that under the same condition of soil texture and terrain slope the advantage for runoff generation and the sensitivity of rainfall-runoff relationship to rainfall descended by farmland, paddy field, woodland.The outputs could provide important references for soil and water conservation and river health protection in the upper stream of Huaihe river.

Abstract: Through the water compensation models, the article studies the effect of water resources compensation policy on the upstream and downstream areas under differential empowerment systems. Study finds that difference in water resources utilization efficiency is the precondition of water resources compensation policy implementation. With changes of water resources utilization efficiency, the compensation price changes in the same direction and the compensation amount changes in the opposite direction. Finally, water resources compensation policy will improve the welfare of both areas, which is highly consistent with Coase theorem.

Abstract: This article illustrates different methods of calculating average areal precipitation, especially Thieseen polygon method and its modified method: percentage weighted polygon method.it compares various conditions of application and gives some suggestions for further study about areal precipitation estimation.

Abstract: Magnetic susceptibility is the most commonly used soil magnetic parameters, reflecting the degree of magnetization substance. The investigation of two typical soil sections in Pingyi County, Shandong Province shows that there are some differences on magnetic susceptibility between the cinnamon soil profile and the brown soil profile. The results indicate that: (1) Significant difference of magnetic properties is existed among the cinnamon soil profile and the brown soil profile. The mean χ_lf value of the samples from the cinnamon soil profile is 82.80×10-8m3/kg, distinctly lower than those from the brown soil profile, which have a mean value of 616.72×10-8 m3/kg; (2) This indicates a low proportion of SP in samples from the brown soil profile and a high proportion of SP in samples from the cinnamon soil profile; (3) Magnetic susceptibility features is a new method which can be used for soil preliminary classification.

Abstract: Green roofs (GRs) may represent a solution for minimizing the impact of urbanization on the hydrological cycle and for sustainably managing water resources in urban environment. Several studies have shown that GRs effectively control the surface runoff conveyed into the combined sewer systems, by reducing overall volumes and peak flow rates. The hydrological/hydraulic performance of a GR is strongly dependent upon vegetation species used. In this study the influence of plants on the sub-surface runoff is investigated by monitoring two experimental GRs in wet weather conditions. It is hypothesized that although plants reduce sub-surface runoff, they may also boost the formation of preferential flow paths. The results showed that the sub-surface runoff is strongly influenced by vegetation. While for smaller storm events the GR highly retains stormwater due to the plant interception, for larger storm events the GR’s performance decreases due to the increase of sub-surface runoff. This may be due to the presence of the plant root which produces preferential macropores flow through the substrate.

Abstract: Bi ̊Char soil amendment has been accepted as a low-risk soil carbon sequestration method. Some other agricultural benefits also reported in previous researches. Two kinds of bi ̊Chars, produced from walnut shell and soft wood, with significantly different surface characteristics and a severe saline sandy loam soil was used in our research. Physical and chemical parameters of bi ̊Char and soil were analyzed. The results pressure plate analysis indicated that high surface area bi ̊Char can increase water retention and plant available water in severe saline agriculture soil, however, such effect wasn’t observed in all the low surface area bi ̊Char treatments. Based on these results, a simulated soil water loss experiment was conducted under 3 different temperatures (from 25 ^̊C to 40 ^̊C), with 4 bi ̊Char doses for 120 h. Our results shown that high dose of high surface area bi ̊Char can reduce the rate of soil water loss under high temperature. Such effect indicated that high surface area bi ̊Cahr can help soil hold more water under lab condition and simulated field condition. In bi ̊Char soil application, the interaction between bi ̊Char, soil and climate condition needs to be considered carefully to acheive optimum solution for both environmental and agricultural purposes.

Abstract: Sediment issues, especially the channel siltation issues in silty-sand Coast are becoming more and more prominent as the development of harbor construction in silty-sand coasts. In order to learn the incipient motion characteristics under influence of wave, current and wave-current combination of sediment in silty-sand coasts, provide necessary parameters for engineering analysis of fluvial process and mathematical model analysis, and then provide science and technology fundamentals for harbor construction, experiments are carried out with samples from the under construction Haiyanghong port area in Dandong. Under the same condition, when the initial sediment density, which is of great influence on incipient motion, is larger, the incipient motion is harder to occur; and wave is the main hydrodynamic force to devote to sediment incipient motion. Generally, sediment in silty-sand coasts shows the characteristic of silt. However, fine sediment rises obviously in the experiment and the water gets muddy very easily as the existence of a certain amount of clay.

Abstract: To investigate the impacts of land-use patterns on the sediment yield characteristics in the upper Huaihe River, Xixian hydrological controlling station was selected as the case study site. Soil and Water Assessment Tool (SWAT) model was used to simulate land-use change effects on sediment yield by the use of three-phase (1980s, 1990s and 2000s) land-use maps, soil type map (1:200000) and 1987 to 2008 daily time series of rainfall from the upper Huaihe River basin. On the basis of the simulated time series of daily sediment concentration, land-use change effects on spatio-temporal change patterns of soil erosion modulus. The results revealed that under the same condition of soil texture and terrain slope the advantage for sediment yield was descended by woodland, paddy field and farmland. The outputs of the paper could provide references for soil and water conservation and river health protection in the upper stream of Huaihe River.

Abstract: The red loam had abundant rainfall, rich in light and heat resource of Yunnan Province. But the uneven distribution of rainfall temporal during the year, it restricts the development of agriculture in this region. Thus how to use soil water resources reasonably and efficiency become the key to ensure crop and vegetation growth of needed water and improve the ecological environment. In this study, the key factor is district’s slope. Setting the runoff district’s rainfall intensity was 28.7mm/24h under rainfall simulation, selected four Yunnan Province read loam’ slop: 7.5°、10°、12.5°、15°.The results showed that at the same soil prophase water content and rainfall intensity, the higher runoff district’s slope will make it less time to product flow; At the beginning of product flow, flow of underground runoff was little, product flow was reached stable increase.

Abstract: According to Luoyang rainfall data from 1951 to 2011, this paper discussed the distribution characteristics of rainfall in the whole year. It analyzed summer maize growth period with the coupling of water consumption. It set up the estimation model of summer maize water consumption, the mathematical model of yield and water relationship, and then analyzed its mutual relations. The experimental results showed that the water requirement and rainfall distribution would fit well during summer maize growth. But summer maize growth stage should be irrigated suitably in the dry and median water year.