Reducing runoff by managing crop location at the catchment level,considering agronomic constraints at farm level

Runoff and erosion cause frequent damage through muddy floods in the loess belt of Northern Europe. One possibility for reducing damage is to lower runoff on agricultural land by spatially alternating different crops at the catchment level. But crop location results from decisions taken at the farm level. This study aimed to assess the existing leeway to modify crop location in the farms of a catchment, in order to reduce runoff at the catchment's outlet. The case study was the Bourville catchment (1086 ha), cultivated by 28 farmers and located in Pays de Caux, France. First, crop location rules in the 14 main farms of the catchment were analysed on the basis of surveys carried out with farmers, distinguishing spatial constraints from temporal ones. These rules made it possible to simulate crop location on each farm territory for the 2001–2002 crop year. Each field of the catchment was classified depending on whether one or several crops could be sown, taking into account both field history and farmer decision rules. Then two extreme scenarios of crop location in the Bourville catchment were built. Runoff simulation at the outlet with the STREAM model showed that runoff could be reduced while sticking to current farmer decision rules in terms of crop location. Depending on rainfall event characteristics, runoff reduction varied between 13·5 per cent and 4·5 per cent. Copyright © 2006 John Wiley & Sons, Ltd.     

Soil erosion assessment of Lake Alemaya catchment,Ethiopia

Land degradation due to soil erosion is the major problem facing Ethiopia today. In the Lake Alemaya catchment soil erosion is caused by the intense rainfall, steep topography, and poor vegetation cover coupled with cultivation of steep lands, and inadequate conservation practices. Sediment from the catchment has affected the storage capacity of Lake Alemaya. This study has integrated the Agricultural Non‐point Source Pollution Model (AGNPS) and the technique of the Gographic Information System (GIS) to quantify soil erosion in the Lake Alemaya catchment. After application of the AGNPS, it appears that 66 per cent of the catchment has a soil erosion rate of 10 to more than 80 t ha⁻¹ y⁻¹. The annual soil loss is estimated at 31 t ha⁻¹, which is more than the permissible value of 1–16 t ha⁻¹ for different agro‐ecological zones of Ethiopia. The sediment yield of the catchment is about 10 148 ton with a delivery ratio of 6·82 per cent. Therefore, an effective management plan is needed for the conservation and rehabilitation of the catchment and to maintain the storage capacity of Lake Alemaya. Copyright © 2006 John Wiley & Sons, Ltd.     

岷江下游11种杂草对重金属的富集特征

为了解岷江下游11种杂草不同部位(根、地上部)中5种重金属(As、Cd、Cu、Pb、Zn)的含量特征,选取五通桥段典型集水区,采用野外调查与室内分析相结合的方法,探讨该区杂草对重金属的富集和转运能力.结果表明,集水区土壤除Cd污染严重外,整体污染较轻.11种草本植物重金属含量为Zn> Pb> Cu> As> Cd,且根系都对As有明显的滞留效应.淡竹叶、巴天酸模、一点红、云南海金沙、铁芒箕、麦冬、绣球藤、酸浆草和蜈蚣草植株都存在地上部均有2种或者2种以上的重金属含量高于根部.11种杂草对重金属As富集能力都不强,富集系数和转运系数均小于1.铁芒箕和蜈蚣草对重金属Cd、Cu、Pb、Zn,淡竹叶、一点红、云南海金沙和酸浆草对Cd、Pb、Zn,麦冬对Cd和Cu,绣球藤对Cd和Zn的富集系数和转运系数都大于1,这些植物均具有超富集植物的一些重要特征,具有成为超富集植物的潜力.     

临沂地区浅层地下水环境质量评价与分析

[目的]对临沂地区浅层地下水进行质量评价,确定地下水的污染现状。[方法]按每16km2一个采样点的采样密度采集临沂地区的浅层地下水,共分析35项指标,选取其中影响水环境质量的17项指标进行评价。[结果]临沂地区浅层地下水较差和极差的比例达到了42．69％,影响浅层地下水质量的主要指标为Mn、Pb、Cl-、F-、NO2-、总硬度、溶解性总固体和高锰酸钾指数,多分布在居民聚居区、工矿企业及周边地区。[结论]该研究可为临沂地区地下水水质改良提供基本依据。     

Classifying flow regimes of the Amazon basin

1. The Amazon River basin contains a vast diversity of lotic habitats and accompanying hydrological regimes. Further understanding the spatial distribution of flow regimes across the Amazon can be useful for recognizing riverine ecohydrological processes and informing river management and conservation, especially in areas with limited or inconsistent streamflow monitoring.
2. This study compares four inductive approaches for classifying streamflow regimes across the Amazon using an unprecedented compilation of streamflow records from Bolivia, Brazil, Colombia, Ecuador, and Peru.
3. Inductive classification schemes use attributes of streamflow data to categorize river reaches into similar classes, which then may be generalized to understand streamflow behaviour at the basin scale. In this study, classification was accomplished through hierarchical clustering of 67 flow metrics calculated using indicators of hydrologic alteration (IHA) and daily streamflow data from median annual hydrographs (MAHs) for 404 stations (representing >7,000 station-years) across five Amazonian countries.
4. Classification was performed using both flow magnitude-inclusive and flow magnitude-independent datasets. For flow magnitude-independent methods, optimal solutions included six or seven primary hydrological classes for IHA and MAH datasets; for approaches that retained magnitude, variance was sufficiently large to prevent convergence to a specific number of classes.
5. Across methods, class membership was strongly associated with the timing, frequency, and rate of change of flow, and spatially coherent clusters were associated with seasonal, elevational, and stream-order gradients. These results highlight the diversity of flow regimes across the Amazon and provide a framework for studying relationships between hydrological regimes and ecological responses in the context of changing climate, land use, and human-induced hydrological alteration.
6. The methodology applied provides a data-driven approach for classifying flow regimes based on observed data. When coupled with ecological knowledge and expertise, these classifications can be used to develop ecohydrologically informed and management-relevant conservation practices.

     

Atlantic salmon in a rapidly changing environment—Facing the challenges of reduced marine survival and climate change

1. Atlantic salmon populations have declined in recent decades. Many of the threats to the species during its freshwater and coastal residency periods are known, and management approaches are available to mitigate them. The global scale of climate change and altered ocean ecosystems make these threats more difficult to address.
2. Managers need to be aware that promoting strong, healthy, and resilient wild populations migrating from rivers is the optimal approach currently to reduce the impacts of changing ecosystems and low marine survival. We argue that a fundamental strategy should be to ensure that the highest number of wild smolts in the best condition leave from rivers and coastal areas to the ocean. There is great scope for water quality, river regulation, migration barriers, and physical river habitat improvements.
3. Maintenance of genetic integrity and diversity of wild populations by eliminating interbreeding with escaped farmed salmon, eliminating poorly planned stocking, and reducing impacts that reduce population sizes to dangerously low levels will support the ability of Atlantic salmon to adapt to changing environments. Reducing the impacts from aquaculture and other human activities in coastal areas can greatly increase marine survival in affected areas.
4. As most of the threats to wild salmon are the result of human activities, a focus on human dimensions and improved communication, from scientific and management perspectives, needs to be increasingly emphasized. When political and social will are coupled with adequate resources, managers often have the tools to mitigate many of the threats to wild salmon.

     

Instream and catchment characteristics affecting the occurrence and population density of brown trout, Salmo trutta L., in forest brooks of a boreal river basin

The occurrence and density of ≥ 1+ brown trout, Salmo trutta L., and their relationship with prevailing instream and catchment characteristics were studied in 50 small forest streams, partially dredged for forest ditching. The occurrence of trout at a stream site was largely determined by the abundance of pools, size of upper catchment and water pH. Moreover, at sites where trout occurred, the abundance of pools was lower at dredged locations than at those in a natural state. In riffles in a natural state, there was a positive relationship between trout density and three instream variables: the abundance of stream pools, cascades and instream vegetation, while an inverse relationship was found with the abundance of substratum of 2–10 cm in diameter. Of the catchment variables, correspondingly, the proportion of forest in the upper catchment was positively related and the proportion of peatland negatively related to trout density. No significant regression model could be fitted for dredged riffles. The possibility of enhancing trout populations in dredged riffles is discussed.     

以环县为例的黄土高原半干旱区景观化集水造绿的水绿调配规划与增长机制

文章以黄土高原东部半干旱区环县的人居环境为研究对象,在景观化集水造绿空间网络构建的基础上,基于水绿双赢理论,提出了以GIS空间分析技术为支撑的不同汇水区之间的平衡援助策略;指出根据区域内可收集雨水资源量,应优先保证该区域内优势节点和路径中集水造绿的生态需水,提出了测定区域内水绿平衡人为干预度临界点的方法;划分了大、中、小尺度汇水区,指出应根据各汇水区在人为干预度临界点的盈余和亏缺情况进行水绿调配规划;提出了近期、中期、远期的发展进程,预测了集水造绿区域的变化趋势。研究证明,以28.35%的人为干预度收集雨水,可以优先保证集水造绿优势"节点+路径"区的植物生长;将盈余区域的雨水收集调配至亏缺的汇水区,优先满足区域内节点、路径的生长,可以实现平衡援助;随着循序渐进的平衡增长,景观化集水造绿的空间网络可逐渐实现,以此作为人居环境改善的核心区域。     

坚持生态与民生共举谱写现代林业改革发展新篇章——中共国家林业局党校第43期党员领导干部进修班赴山东省临沂市、淄博市原山林场考察调研报告

近年来,临沂市生态文明建设的新模式,为全国生态林业民生林业的发展积累了宝贵经验,对推动全国林业改革发展提供了启示.当然,临沂市在现代林业建设取得显著成效的同时,在生态环境建设和促进社会经济可持续发展方面仍面临诸多新的挑战,建议采取完善生态效益补偿机制,制定生态目标保护红线等措施积极应对.     

临沂市酸雨特征及其与气象条件的关系

根据临沂市气象观测站2003-2013年11年间617次酸雨观测资料,计算和分析了临沂降水pH值、酸雨频率的年际和季节变化特征,研究了酸雨与风向、风速等气象条件的关系。结果表明,临沂市11年间酸雨平均pH值为4.84,酸雨频率为47.0豫,2003-2013年间酸雨频率呈下降趋势。季节变化特征为秋季和冬季酸雨频率较大,春季和夏季酸雨频率较小,表明秋、冬季两季的酸雨污染比春、夏两季严重。当风速≤3.0 m/s时,酸雨发生频率达67.6豫,随着风速的增大,酸雨发生频率越来越小。当风向为偏东北风和偏东南风时,酸雨发生的机会偏大。