Applied Mechanics and Materials Vols. 212-213

Abstract: Although there are frequent floods, the need of utilizing the flood-water resource in Yangtze River is becoming increasingly intense. Following the concept of ensuring health Yangtze River and promoting harmony between people and water, the Three Gorges Reservoir is practiced as an example for utilization of floodwater resource based on accurate hydrological forecast and moderately taking the flood control risks.

Abstract: In order to play a part in evaluation and manage of water resource for weather radar, the quantitative rainfall measurement of dual polarization doppler weather radar is developed. And based on the observed values of ombrometer, the differences of the measured values derived from different methods are analysed. The results show: The rainfall using K_DP to calculate, i.e. R(K_DP) method, is proximal to the data of ombrometer; R(Z_H) and R(Z_H, Z_DR) method is underestimate rainfall obviously; R(Z_DR, K_DP) method is overestimate rainfall. With further analysis, rainfall measured by dual-polarization radar, especially from R(K_DP) method, has higher precision, and provide the spatial distribution of the rainfall and the position of strong center well.

Abstract: With the combination of real coded accelerating genetic algorithm and projection pursuit technology (RAGA-PPT), RAGA-PPT model for water environment carrying capacity (WECC) evaluation was proposed. Eleven comprehensive indexes were selected to form WECC evaluation index system, and the predicted value of each index in different development processes was acquired by system dynamics simulating. Based on the data, RAGA-PPT model was used to evaluate WECC of Guanzhong area at the year 1997, 2015 and 2020. The results show that waste water emission per person and available water supply per person are the key factors influencing WECC of Guanzhong area, and the situation of WECC would be improved gradually, by taking measures of increasing the quantity of wastewater reuse and diversion water to improve water conservation and supply level.

Abstract: The numerical simulation of the effects of regulation projects is presented through the discussion of: (a) the influenceingf actors of fairway conditions; (b) the plan of channel alignment works; (c) the establishment of a 2D numerical model; (d) the numerical simulation of the effects of regulation works. Base on measured data in recently years, Periodically erosion and deposition of Tianxingzhou head bench (THB) was determined as the key factor of navigation conditions. The navigation width would increase if THB maintain high and large morphology. Reflecting on the erosion trends of THB, pavement works with the main patterns of fishbone- bench protection belt to prevent the sand bar from erosion are proposed. The type of projects is fishbone- bench protection belt. The effects of regulation projects is predicted by using a 2D low-sediment mathematical model, which is verified by measured water and sediment data.With the mathematical model, the channel fluvial process and navigation development trend after the implementation of regulation projects in the next decade are simulated. THB maintain high level and integral morphology, which also guarantee good waterway conditions.

Abstract: Sediment diverted from the Lower Yellow River is crucial for irrigation district sustainable development. As a complex problem, spatial distribution of sediment in district is related with natural geographical environment, incoming water amount and sediment concentration, methods of treatment, engineering facilities. Analysis of sediment distribution is the precondition for sediment utilization, transportation and treatment. As Bojili irrigation district for example, the paper analyzed sediment siltation characteristics in desilting branch, main canal, branch canal and field ditch with long term observed data from 1985 to 2009. Proportions of sediment siltation in different parts of irrigation system were calculated and difference of seasonal siltation in desilting branch was discussed. Besides, the paper proposed effective suggestions about reducing sediment siltation and improving transportation with long distance.

Abstract: Using Haoshuichuan watershed as an example, the infiltration deep of rainfall was analyzed, the comparison analysis of the water reduction between terrace and slope land were worked out through the results of penetration test and soil moisture. The result shows that the ratios of store water in soil to rainfall are 0.81 in terrace and 0.72 in slope land.

Abstract: Tailan river basin is a typical drought river basin in northwest China where construction of underground reservoirs is approved as an effective way to solve the problem of water resource shortage in the river basin. In order to ensure water supply efficiency of the underground reservoirs of the basin, it is necessary to research their recharge and supply patterns and to optimally operate them. This paper has, therefore, investigated different recharge locations and recharge ways through numerical simulation of underground flow in an underground reservoir area of the basin to explore a typical scheduling plan for optimal operation of the reservoir. The results show that it is better to recharge the reservoir using the flood season recharge approach at the centre of the reservoir area to ensure its continuous operation. Following from this recharge process, the use of a three-well pumping scheme is regarded as the best choice for optimal water supply from the reservoir. Also, the study indicates that for the same recharge amount, if the recharge time is closer to the pumping peak, then there is the more obvious effect of underground level recovery; the recovery is much better if the recharge time is more concentrated.

Abstract: First, the software ANUSPLIN4.3 was used to process 40-year observed precipitation data from 680 meteorological stations of China to generate grid precipitation data sets at resolution of 1km by 1km. Second, one-dimensional linear regression method and ArcGIS software were applied to analyze trend of precipitation change and its regional difference in China over the past 40 years. The results showed that general trend of precipitation change in nation-wide was not obvious but its regional difference clear. Precipitation in southeast coast areas rose obviously with a maximum of 5 millimeters per year, dropped in central areas including Circum-Bohai-Sea region, Shanxi, Shaanxi and south of Gansu. There was no obvious change trend of precipitation in the rest areas of China.

Abstract: Based on the theory of shallow-water wave, the theoretical model was established for calculating wash wave caused by ship moving at subcritical and supercritical speed. Wave elevation and pressure variation were obtained by numerical simulation, and their features were analyzed. A measuring system of wash wave and pressure variation was developed, and wave elevation and pressure variation induced by a towed ship model were measured. A good agreement existed between the calculated with experimental results.

Abstract: Aim to the high sandy river “ripping up the riverbed” phenomenon, by experiment, analyzing the relationship between clay dry density, water content, plasticity index and its shear strength, and its mechanical properties. Create the conditions for studying clay mechanical strength and the critical condition of “bottom tearing scour”.