Fog collection in the western Mediterranean basin (Valencia region, Spain)

Four different mountainous locations were selected in the Valencia region, East coast of the Iberian Peninsula, for fog water collection studies. Data for 2004 were obtained by means of an instrument ensemble consisting essentially of a passive cylindrical fog water collector, a raingauge, a wind direction and velocity sensor and a temperature and humidity probe. An approximate data reduction technique was also found for this specific ensemble to eliminate the simultaneous rain water component from the fog water measurements. Main results indicate that fog water collection holds significant potential in this region, and especially for southern locations. Annual rates of fog water yield can be as high as 7.0 l/m²/day in the southern locations, in contrast to 2.0 l/m²/day collected at one site in a northern location. The highest summer fog water yield was 4.6 l/m²/day, a relatively large value. Except for the summer period, fog episodes delivering sizeable water volumes are inherently coupled to rainfall. Hourly frequencies of fog collection were also examined to show a distinct daily cycle in summer, denoting orographic fog formation during this period. Lastly, winds were analysed to resolve the most suitable directions for fog collector alignment.     

祁连山空中云水资源开发潜力研究新进展

祁连山及河西走廊地区是我国气候变化敏感区和生态脆弱区。本文通过对2005a以来祁连山云水资源相关最新研究成果的总结,旨在揭示气候变暖对祁连山云水资源影响包括气候变化、水汽时空变化、地形云特征的基础上,分析评估了祁连山云水资源开发潜力及效益。实验研究表明,在祁连山区开展人工增雨(雪)作业,每年可增加降水量3.7×10_⁸～７.4×10_⁸m_³。近10年来,甘肃春季飞机人工增雨作业年均增加降水量为13.5×10_⁸m_³,平均投入产出比为1:30。     

DEVELOPMENT OF A DECISION SUPPORT SYSTEM FOR MANAGING PESTICIDE LOSSES IN AGRICULTURAL WATERSHEDS

1 INTRODUCTION Agricultural use of pesticides has been recognized as one of the important non-point pollution sources in the world, and the pesticide application to agricultural lands has led to large amounts of residues discharged into surface water through runoff (Leonard, 1990). There have been growing concerns about the fate and transport of pesticides in agricultural lands, due to the associated adverse impacts on water environment and human health (Agassi et al., 1995; Ng and Clegg…     

Cloud tracking using satellite data for predicting the probability of heavy rainfall events in the Mediterranean area

The use of cloud tracking techniques and storm identification procedures is proposed in this paper with the aim of predicting the evolution of cloud entities associated with the highest rainfall probability within a given meteorological scenario. Suitable algorithms for this kind of analysis are based on the processing of digital images in the thermal infrared (IR) band from geostationary satellites: a selection of such algorithms is described in some detail together with a few real case applications. Three heavy rainfall events have been selected for this purpose with reference to the extreme meteorological situation observed during Fall 1992 and 1993 over the Mediterranean area. A window from 30 to 60 °N and from 20 °W to 30 °E has been identified for the analysis of data from the radiometer on board the ESA Meteosat platform. In conclusion, the suitability of cloud tracking techniques for predicting the probability of heavy rainfall events is discussed provided that the former are associated with proper modeling of small scale rainfall distribution.     

大灰厂跨断层形变资料的地震信息识别

利用具有明显物理意义的断层蠕动模型在充分考虑可能存在的干扰因素影响的基础上，对大灰石台跨断层地形变资料在１９８９年大同地震前后出现的较大幅度变化进行了异常属性分析。结果表明，这个时期的异常变化尽管叠加有一定的降雨影响，但蠕动模型计算得出的地表变化理论值与实际变化有一定程度的符合，显示出在区域应力场作用下，八宝山断层局部地段在大同地震前后可能存在着与区域应力场应力增强及应力调理有关的构造活动。     

中国东部夏季持续性降水日变化在淮河南北的差异分析

本文利用1961—2006年我国285站观测的逐时降水数据,分析了中国东部不同地区夏季平均降水日变化随降水持续时间的变化特征. 虽然整个东部地区都表现为短时降水峰值较一致地出现在下午17时左右,持续较长时间降水在清晨前后发生峰值降水,但持续性降水日变化的平均峰值时间以淮河为界存在显著南北差异. 北部地区的持续性降水峰值主要出现在02—06时前后;南部地区的持续性降水峰值时间出现在06—10时. 无论是降水强度或频次的日变化峰值的南北差异均较明显,但降水强度差异更为突出,且主要表现在持续性强降水中. 进一步分析发现：一方面北部地区持续性强降水开始时间较南部地区更早;另一方面,北部地区降水从开始到峰值经历的时间更短. 最后,对持续性强降水峰值时间南北差异的可能原因进行了初步讨论.     

Empirically-based modeling of spatial sampling uncertainties associated with rainfall measurements by rain gauges

In the quantitative evaluation of radar-rainfall products (maps), rain gauge data are generally used as a good approximation of the true ground rainfall. However, rain gauges provide accurate measurements for a specific location, while radar estimates represent areal averages. Because these sampling discrepancies could introduce noise into the comparisons between these two sensors, they need to be accounted for. In this study, the spatial sampling error is defined as the ratio between the measurements by a single rain gauge and the true areal rainfall, defined as the value obtained by averaging the measurements by an adequate number of gauges within a pixel. Using a non-parametric scheme, the authors characterize its full statistical distribution for several spatial (4, 16 and 36 km²) and temporal (15 min and hourly) scales.     

Movement of Heavy Metals in Soil through Preferential Flow Paths under Different Rainfall Intensities

Preferential flow in soils deserves attention due to its potential role in accelerating the movement of contaminants to groundwater. This study investigates the movement of Cd, Cu, and Pb through preferential flow paths under different applied rainfall intensities. Artificial acid rain (pH of 4.1) containing CdCl₂, CuCl₂, and Pb(NO₃)₂ was applied to undisturbed soil and repacked sand columns at low and high intensities, and leachate metals and chloride concentrations were measured. Cd was found in the leachate at both low and high rates in all columns, while the increase in Cu concentrations in the leachate was detected only at the high rate of the undisturbed columns. Pb was retained in both columns. For undisturbed columns, the breakthrough curves of Cd and Cu were similar to those of Cl, showing early initial breakthrough by preferential flow and dependency on rainfall intensities. The Cd concentrations were detected in the leachate from repacked columns for high rate rainfall, implying that even homogeneous soil may not be perfectly able to retain metals and the initially wet condition is more harmful for subsurface contaminant transport. In conclusion, the study demonstrated that, despite its highly sorptive nature, the transport of some metals may be as fast as that of a tracer under preferential flow conditions, and the rainfall intensity is a significant factor for the degree of transport.     

Is rainfall intensity significant in the rainfall–runoff process within tropical rainforests of northeast Queensland? The Hewlett regression analyses revisited

Following the statistical analyses of long‐term rainfall‐runoff records from research basins in humid temperate latitudes, Hewlett and co‐workers extended the global challenge to disprove their findings that rainfall intensity was non‐significant. This paper responds to Hewlett's challenge as no preceding analyses have involved forested basins in a tropical cyclone‐prone area. Based on a 7 year rainfall‐runoff record, quickflow (QF), peak flow (QP) and quickflow response ratios (QRR) were regressed as dependent variables against rainfall parameters (intensity, P_i, amount, P), storm duration, D and antecedent flow, I. These data sets were categorised into total streamflow (Q) classes and stratified into three seasons, (monsoon, post‐monsoon and dry) for forested and cleared catchments. Where rainfall variable collinearity met acceptable levels, the addition of P_i to regression models including P, D, I contributed up to 9% and 66% of the respective variations in quickflow and peak flow. For the highest Q storm classes (monsoon), P_i alone accounted for up to 67% and 91% of the variation in Q_F and Q_P respectively and was the dominant influence on Q_P for all seasons. The very high rainfall intensities experienced in the monsoon season is a causal factor why these results differ from those of other research drainage basins. Surprisingly, P_i continued to have a significant influence on Q_F for dry season classes when less‐intense rainfall occurs. Further the results were similar for both catchments across all seasons. P was the dominant independent variable affecting Q_F above a threshold Q of 50 mm (monsoon), as rainfall contributes directly to saturation overland flow and return flow under saturated conditions. Further although QRR increased with increasing Q for each season, the regression results for that parameter were poor possibly due to the non‐linearity of the rainfall‐runoff relationship. Copyright © 2010 John Wiley & Sons, Ltd.     

降雨条件下边坡体积含水率变化规律研究

持续降雨是边坡发生失稳破坏的主要诱因之一,基于饱和—非饱和渗流理论,对梅州市大埔县某边坡的渗流场进行模拟,研究在不同降雨工况下该边坡土体体积含水率的时空变化规律。研究结果表明:相同条件下,降雨强度越大(降雨历时越长),边坡表层土体体积含水率变化越大;降雨强度60 mm/d历时1 d的暴雨对边坡表层土体体积含水率的增幅作用存在着一定的滞后性,其余工况未表现出滞后现象;降雨强度为120mm/d和300 mm/d的两种工况各研究点任意时段体积含水率较为接近;当降雨强度达到60 mm/d以上时,边坡内部体积含水率空间变化主要受降雨历时影响,降雨历时越长,降雨入渗深度和体积含水率变化越大。