An evaluation of the pesera soil erosion model and its application to a case study in Zakynthos, Greece

Abstract. The Pan‐European Soil Erosion Risk Assessment (pesera ) model was evaluated using existing soil erosion data collected under various types of climate, vegetation, landscape and soil conditions. The data used represent a variety of typical Mediterranean land uses such as winter wheat, vines, olives and bare, stony land prevailing in hilly areas. Using this data, the model was calibrated for sediment transport by overland flow and results compared to measured soil erosion values from runoff plots and a watershed on a monthly basis. The performance of the model was assessed statistically, showing that it can be satisfactorily used for predicting soil erosion rates under the conditions included in the study. The overall model estimate including all the available experimental data was 0.69 t ha^?1 yr^?1 with a maximum error of 1.49 t ha^?1 yr^?1. After validation, the model was applied to a small watershed (60 ha) of great ecological importance for the sea turtle Caretta caretta. For this purpose, soil and vegetation maps were compiled from all the necessary data for applying the model. The model was run for three years using daily data from an existing nearby meteorological station. The predicted and measured soil erosion rates for a 7‐month period were 0.31 t and 0.18 t, respectively. Application of the model to each mapping unit showed the over‐riding importance of land use for sediment generation under the given climatic conditions. Bare land, occupying 5.5% of the watershed area, generated up to 69% of the total sediments estimated for the watershed. It is concluded that the pesera model can be used as a regional diagnostic tool under a range of soil, topographic and climatic conditions for identifying the best land use type and vegetation cover to protect hilly areas from soil erosion. The calculated overall root mean square error for the model is 0.06 t ha^?1 yr^?1, compared to a soil erosion rate of 0.04 t ha^?1 yr^?1, which can be tolerated for protecting the area for the sea turtle.     

研究森林变化对河川水沙影响的一种便捷方法──以四川省都江堰市白沙河为例

依据航片判读、森林资源调查资料和水文数据，利用流域自身对比法，得出森林变化对河川径流泥沙的定量关系。文中还阐明本方法的技术关键——消除降雨量不同对水沙的影响．该方法具有适合我国国情、费小效宏、精度较高、简捷易行等优点，值得推广提倡。     

Does sand content in spawning substrate result in early larval emergence? Evidence from a lithophilic cyprinid fish

The spawning success of lithophilic salmonids is strongly influenced by the fine sediment content (“fines”) of spawning substrates, yet knowledge on the impacts of fines on the spawning of non‐salmonid lithophiles remains limited, despite their ecological and socio‐economic importance in European rivers. Consequently, the aim here was to use an ex‐situ experiment to investigate the impact of sand content on egg survival and timing of larval emergence of the surface‐spawning cyprinid European barbel Barbus barbus. Thirty incubator boxes within a recirculating system were filled with one of five experimental sediment mixtures (0%–40% sand by mass) that each contained 300 fertilised eggs at a depth of 50 mm. Emerged, free‐swimming larvae were captured and counted daily to assess grain‐size effects on larval survival and emergence. Specifically, total proportion of emerged larvae, cumulative daily proportion of emerged larvae and time required to reach 50% emergence were measured during the study. Whilst the proportion of sand in the sediments did not have a significant impact on egg‐to‐emergence survival (mean survival per treatment 75%–79%), it significantly affected the timing of larval emergence to the water column; early emergence was detected in treatments with elevated sand content (on average, 50% emergence after 12–13 days versus 19 days in the control). Similar to findings from salmonid studies, these results suggest high sand content in spawning gravels can influence timing of larval emergence and potentially cyprinid lithophilic fish survival.     

Estimation of Runoff,Peak Discharge and Sediment Load at the Event Scale in a Medium‐Size Mediterranean Watershed Using the Annagnps Model

In this paper, the Annualized Agricultural Non‐Point Source (AnnAGNPS) model has been used to estimate runoff, peak discharge and sediment load at the event scale in a Mediterranean watershed. The study area is the Carapelle torrent, Southern Italy (area = 506 km²), where continuous rainfall, streamflow and sediment load data are available. Nineteen flood events have been registered in the period 2007–2009 and were used for the application of the model. The aim of the paper is to evaluate the predictive accuracy of the model at the event scale, in a medium‐size watershed, given the specific conditions of the semi‐arid environments. A sensitivity analysis has been carried out to assign the correct parameterization: the mean normalized output variation of the most meaningful input parameters pointed out the influence of the curve number on runoff, peak discharge and sediment load predictions (values greater than 1); the MN Manning's roughness coefficient and K, C and P factors of the universal soil loss equation showed a moderate influence on sediment load simulations (values between 0·5 and 1). The selection of the Soil Conservation Service synthetic storm types has been based on the observed storm events analysis to improve the peak discharge simulations. The model prediction has proved to be good for runoff (R² = 0·74, NSE = 0·75, W = 0·92) and peak discharge (R² = 0·85, NSE = 0·70, W = 0·94), and satisfactory for sediment yield (R² = 0·70, NSE = 0·63, W = 0·91). The relative error is lower for high events; this result is quite interesting in semi‐arid environments, where most of the annual sediment yield is concentrated in a few, severe events. Copyright © 2013 John Wiley & Sons, Ltd.     

香葱连作障碍的成因及其修复试验

选取不同连作年限(0、2、4、6、10、15 a)的葱田土壤,测定土壤的养分、微量元素和重金属含量,发现不同连作年限土壤中的铁、硼、镁等微量元素含量丰富,但是连作葱田土壤的容重、有机质含量和铵态氮含量有不同程度降低,硝态氮含量显著提高。用5种土壤改良剂对连作年限为15 a的葱田进行土壤淋施处理,试验结果表明,奥普尔冲施肥使土壤中的硝态氮含量降低11.57%,铵态氮含量提高50.27%,香葱产量提高2.66%,是最佳的土壤改良剂。     

除草剂莠去津降解菌SFAD3的分离鉴定及其土壤修复潜力

为获得能够修复除草剂莠去津污染土壤的高效降解菌,采用摇瓶富集法、平板分离法从莠去津过量使用的土壤中分离得到降解菌SFAD3,通过形态学、生理生化特征观察以及16S rDNA和ITS序列分析进行种类鉴定,测定获得菌株的最适降解条件,并通过土壤接种和盆栽试验验证菌株对莠去津污染土壤的修复作用。结果表明,菌株SFAD3最终被鉴定为门多萨假单胞菌Pseudomonas mendocina,该菌株培养30 d时对污染土壤中50 mg/kg莠去津的降解率可达72.6%;菌株SFAD3在MM液体培养基中最适降解条件为温度37℃、pH 7、莠去津初始浓度6.25 mg/L、接种量2%,对莠去津降的降解率为50.0%～72.2%;与仅有莠去津的处理相比,添加有SFAD3发酵液的处理20 d后芝麻的株高、根长、湿重和干重能够显著恢复,并且该菌对芝麻还具有一定的促生作用。表明降解菌SFAD3在修复莠去津污染土壤方面具有潜在的应用价值。     

Analysis of the Sediment Development and Trend In Jinshajiang River Drainage Area

Jinshajiang River, which has a drainage area of 485,100 Km 2, average flux of 142.9 billion m 3, and soil conveyance of 247 million t/a, is the largest branch of Changjiang river. It is also the largest soil resource of the Three Gorges reservoir and upper reach of Changjiang River. To research the development and trend of Jinshajiang sediment not only has a relation to Jinshajiang water resource strategy, but also has important meaning to control the silt in Three Gorges reservoir and the Changjiang water resource development. The paper statistically analyses the flux and sediment conveyance of the Pingshan station, which is the primary hydrological station in the Jinshajiang River Drainage Area. Through several non-parameter statistical methods such as Spearman order correlativity check, Kendell order correlativity check, and linear regression check, the paper concludes that the sediment evolvement trend of Pingshan station is not distinct.     

硝酸钙在底泥修复中的作用机理及

受污染底泥的修复已经成为水环境修复中的重要组成部分，在底泥中注入硝酸钙则是近十多年来发展起来的一种污染底泥原位处理技术。全面分析了硝酸钙在底泥修复中去除有机物、抑制磷的释放以及消除水体黑臭现象的机理，并介绍了这一技术在国内外的研究和应用状况。研究成果表明：在底泥中注入硝酸钙的技术已从实验室和中试研究阶段发展到了实际的工程动作阶段，并且在有机物PAHS的降解和硫化物的去除方面已经得到了很好的效果。     

Main experiences on design and management of the Dujiangyan irrigation system

The largescale Dujiangyan Irrigation System has had a long history. Built some 2200 years ago, it still operates smoothly today. Two major causes for the obvious profits it has provided are:Firstly, Yuzui (a bifurcation pier), Feishayan (a sand outlet and spillway) and Baopingkou (a diversion intake for the general trunk canal), the three main head-works were built in accordance with the terrain and topography of the river and appropriately arranged, thus successfully solving the problem of sand discharge and flood control. Consequently the task of gravity diversion could be fulfilled over a long period.Secondly, there is a special management and maintenance system, which is made up of a technical and an administrative department. The former is in charge of the maintenance and drawing-up of flood control and water consuming plans. The latter is responsible to mobilize and organize farmers which benefit from the system to carry out related plans and tasks. The most apparent characteristics of management is that many farmers are organized to participate in the management of this irrigation system. At present, techniques like remote control and telemetery have been adopted. Also experiments on management automation and optimization of water allocation are being conducted.