A comparison of element outputs in solution,suspended sediments and bedload for a small upland catchment

The individual outputs of several elements in solution, suspended solids and bedload were estimated for a stream draining a small upland catchment in mid-Wales. The data indicate the overall importance of transport in solution, although the solid phase can make a significant contribution to the export of potassium, iron and silicon from the site.     

Gate road layout design for two-seam longwall mining

Summary Results of instrumentation, test mining and computer aided stability analyses were combined to design the most stable gate road layout for two-seam longwall mining at the Plateau Mining Company. Five layouts were evaluated; these layouts used a combination of yield and/or large pillars with either three-entry or two-entry development systems.A layout which used a yield pillar within a two-entry development system resulted in the most stable gate roads for two-seam mining. Another layout using a yield and large pillar was shown to be most stable for single-seam mining of the top seam, but it was unsuitable for two-seam mining because of seam interaction problems.The size of the yield pillar was determined by satisfying several design requirements, as well as by limited test mining; test results showed good, medium-term stability for the yield pillars, with a possible need for rib control. It was shown that the yield pillars might be effective in controlling the floor heave, and could minimize interaction problems in two-seam mining.     

The output of sediments and solutes from forested and cultivated clayey drainage basins in Luxembourg

The output of material from 11 small drainage basins in the Keuper region of central Luxembourg is considered. Attention is given to differences between forested and cultivated basins. Whilst the output of suspended solids from the cultivated Mosergriecht catchment may be as much as five times higher than from the forested Keiwelsbaach, the solute load is only 50 per cent and the runoff 20 per cent higher. Relationships between dispersed clay in suspension and the water chemistry observed for the forested drainage basins are not present in the cultivated catchments. Water having a milky appearance and containing dispersed clay is of more frequent occurrence in forested basins where subsurface runoff occurs in macropores and cracks in the undisturbed soil.     

气候变化对作物产量影响的动态统计评价模式

气候变化对作物产量影响的动态统计评价模式，主要是运用积分回归原理，探索作物生育期内以旬为时间单位的气候变化对作物产量形成的影响规律。由于该模式能及时连续地进行气候影响评价，使评价工作能直接的为农业生产进行跟踪服务。在建模过程中引用了三项式产量预报模型、特殊影响因子诊断分析和选取最佳积分因归方程等方法，并在试用中取得了较满意的结果。     

甘肃省玉米产量的主成分分析

应用自然正交函数方法将甘肃省玉米产量的趋势产量项(Yt)和气候产量项(Yw) 进行展开，展开后的Yt、Yw第一特征向量都表明了Yt、Yw总趋势的一致性，其大值中心表明产量变率较大。通过对各主成分主要时间系数与各站Yt、Yw进行相关分布分析，筛选出全省玉米产量的八个站点，这些站点基本上代表了本省不同类型的农业气候区域的玉米产量水平和生育状况。     

Occurrence of soil erosion after repeated experimental fires in a Mediterranean environment

In the Mediterranean area, forest fires have become a first-order environmental problem. Increased fire frequency progressively reduces ecosystem recovery periods. The fire season, usually followed by torrential rains in autumn, intensifies erosion processes and increases desertification risk. In this work, the effect of repeated experimental fires on soil response to water erosion is studied in the Permanent Field Station of La Concordia, Valencia, Spain. In nine 80 m² plots (20 m long × 4 m wide), all runoff and sediment produced were measured after each rainfall event. In 1995, two fire treatments with the addition of different biomass amounts were applied. Three plots were burned with high fire intensity, three with moderate intensity, and three were unburned to be used as control. In 2003, the plots with the fire treatments were burned again with low fire intensities. During the 8-year interval between fires, plots remained undisturbed, allowing regeneration of the vegetation–soil system. Results obtained during the first 5 months after both fire experiments show the high vulnerability of the soil to erosion after a repeated fire. For the burned plots, runoff rates increased three times more than those of 1995, and soil losses increased almost twice. The highest sediment yield (514 g m^− 2) was measured in 2003, in the plots of the moderate fire intensity treatment, which yielded only 231 g m^− 2 of sediment during the corresponding period in 1995. Runoff yield from the control plots did not show significant temporal changes, while soil losses decreased from 5 g m^− 2 in the first post-fire period to 0.7 g m^− 2 in the second one.     

蒋家沟泥石流输沙年际变化及其灾变预测

根据云南东川蒋家沟泥石流年输沙量的时序资料,分析了蒋家沟泥石流输沙的年际变化特征,发现历年输沙量变动幅度大,波动明显且年际变化频繁,用灰色系统理论的灾变预测方法,建立泥石流年输沙量的等维新息灾变预测模型,能够对未来可能出现的灾变年份进行较好的预测。在前期研究基础上,补充最新观测资料,建立了新的灾变时间序列和相应的等维新息灾变预测模型,使蒋家沟泥石流的年输沙量灾变预测得以连续进行,并对预测结果进行了检验,效果较为理想。     

Sustainable groundwater management in Kinmen Island

Kinmen county is located in the southwest of Fujen province, China. It comprises Kinmen, Leiyu and other small islands. Its total area is around 150 km². Kinmen is the largest island, and 95% of the population resides there. The average annual precipitation is 1072 mm. Rainfall is concentrated in a 5 month period from mid‐April to mid‐September. Water resources are limited relative to demand. Eastern Kinmen utilizes surface water, whereas western Kinmen uses groundwater. Moreover, the Kinmen sorghum liquor is brewed using the native groundwater in the west of the island. MODFLOW‐96 was used to simulate the groundwater distribution and determine the annual amount of infiltration, pumping, and boundary inflow and outflow. Additionally, a groundwater management index was adopted to evaluate the status of groundwater level change, thus allowing local government officials to adjust the pumping scheme dynamically. To achieve a sustainable groundwater supply in Kinmen, an integrated groundwater extraction plan was proposed. This plan includes enhancing the infiltration by using treated wastewater from the east of the island, monitoring the groundwater level change, adjusting the groundwater pumping scheme, and constructing seawater desalination plants. If the hostile confrontation between Taiwan and mainland China is resolved, then the water supply through an undersea pipeline from Sharmen, China, to Kinmen can be another potential source of water for Kinmen in the future. Copyright © 2006 John Wiley & Sons, Ltd.     

SIMULATIONS OF SEDIMENT YIELD AND PHOSPHORUS YIELD FROM A WATERSHED IN TAIWAN, CHINA

1 INTRODUCTION Sediment and nutrients from a watershed may adversely affect a downstream reservoir by reducing its capacity or degrading water quality. Among the output nutrients, phosphorus is often a growth-limiting element for aquatic organisms and pla…