Identification of Sediment Sources in Forested Watersheds With Surface Coal Mining Disturbance Using Carbon and Nitrogen Isotopes1

Abstract: Sediments and soils were analyzed using stable carbon and nitrogen isotope ratio mass spectrometry and carbon and nitrogen elemental analyses to evaluate the their ability to indicate land‐use and land management disturbance and pinpoint loading from sediment transport sources in forested watersheds disturbed by surface coal mining. Samples of transported sediment particulate organic matter were collected from four watersheds in the Southern Appalachian forest region of southeastern Kentucky. The four watersheds had different surface coal mining history that were classified as undisturbed, active mining, and reclaimed conditions. Soil samples were analyzed including reclaimed grassland soils, undisturbed forest soils, geogenic organic matter associated with coal fragments in mining spoil, and soil organic matter from un‐mined grassland soils. Statistically significant differences were found for all biogeochemical signatures when comparing transported sediments from undisturbed watersheds and surface coal mining disturbed watersheds, and the results were attributed to differences in erosion sources and the presence of geogenic organic matter. Sediment transport sources in the surface coal mining watersheds were analyzed using Monte Carlo mass balance un‐mixing and it was found that: δ¹⁵N showed the ability to differentiate streambank erosion and surface soil erosion; and δ¹³C showed the ability to differentiate soil organic matter and geogenic organic matter. Results from the analyses suggest that streambank erosion downstream of surface coal mining sites is an especially significant source of sediment in coal mining disturbed watersheds. Further, the results suggest that the sediment transport processes governing streambank erosion loads are taking longer to reach geomorphologic equilibrium in the watershed as compared with the surface erosion processes. The dual‐isotope technique provides a useful method for further investigation of the impact of surface coal mining in the uplands of the watershed upon the geomorphologic state of the channel and the source of organic matter in aquatic systems impacted by surface coal mining.     

Design and Testing of a Turbulence Probe for Harsh Flows

The force of wind on the ground created by turbulent eddies is commonly used to describe the horizontal flux of material during wind erosion. Here we present the Murdoch Turbulence Probe, an instrument for use in both clean and eroding flows which uses pressure differences to measure the three components of wind velocity. Correlation techniques calculate the forces near the ground and turbulence statistics in nearly real time, including turbulent velocity fluctuations from less than 0.1 Hz to 200 Hz, mean flow velocities, Reynolds stresses as well as the integral length and time scales. In the portable wind-tunnel used by Agriculture Western Australia, turbulence statistics were recorded over stable surfaces and in blowing sand from the initiation of erosion up to the time the sand supply was exhausted. Estimates of the friction velocity derived from the turbulence probe were compared with estimates obtained from the wind speed profile measured with a rake of pitot and static tubes. The Murdoch Turbulence Probe appears to work well in sandblasting conditions. Relative turbulence intensities ranged from 0.11 to 0.2 and are in close agreement with values in the literature. The ratio of the turbulence to the friction velocity (3 to 3.2) is at the high end of the reported range. The Reynolds stress measurements agree closely with predictions of the threshold friction velocities of the sand and estimates from the wind speed profile with a von Kármán constant of about 0.3, lower than the commonly accepted value of 0.4. We suggest that the wind-tunnel profile represents the `outer layer' of the boundary-layer that may best be described by a `Wake Law' or `Defect Law'. At about 54 mm above the surface, the friction velocity decreases from 0.64 m/s to 0.39 m/s and the mean velocity increases from 9.6 m/s to 11.6 m/s as the supply of sand is depleted. In addition to the friction velocity, other scales may be necessary to characterise the overriding effect of the wind and in extending wind-tunnel results to the field.     

A coastal conservation programme for the chennai sea shore, India —A case study

The Chennai coast, an integral part of the east coast of India, extends over ca. 35 km. Over the past 120 yr the coastline has witnessed both man-made and natural disturbances which led to the destruction of the beach front. The construction of Madras harbour in 1876, was the prime cause of the degradation of this very sensitive coastal region. Continued growth of Madras harbour has helped in the natural formation of the wide ‘Marina Beach’, south of the harbour. But the shoreline north of the harbour suffered the consequences of harbour development activities. The north shore receded by ca. 500 m over the past 120 yr and received attention from the authorities in the past few decades because of the growing awareness of the conservation value of the coast. This paper highlights the effects of Madras harbour development on the adjoining coast and on the shortterm mitigation measures planned and executed by the Government agencies to protect the fragile coastline. In spite of sincere efforts to protect the coastline, the destruction continues unabated due to various reasons. This paper analyses the facts and suggests a long-term solution to protect the coastline and to regain the past glory. Feasible and cost effective permanent measures are identified, construction methods suggested and the advantages that the community can derive from the longterm solutions are discussed.     

珠江三角洲地区人类活动造成的水土流失及其危害──以广州市为例

以广州市为例,重点分析人类活动造成的水土流失现状与危害。广州市的水土流失类型可分为自然侵蚀和人为侵蚀,其中自然侵蚀主要有面蚀、沟蚀两种形式,在广州市范围面积分布相对较广,但侵蚀强度内并不严重;而人为侵蚀突出,侵蚀类型和强度也更为复杂多样。人为侵蚀的成因主要有：采石取土、交通道路建设、开发区建设以及坡耕地。人为侵蚀已经成为广州市水土流失灾害的主要表现形式。     

珠江三角洲地区人类活动造成的水土流失及其危害

以广州市为例,重点分析人类活动造成的水土流失现状与危害。广州市的水土流失类型可分为自然侵蚀和人为侵蚀,其中自然侵蚀主要有面蚀、沟蚀两种形式,在广州市范围面积分布相对较广,但侵蚀强度内并不严重;而人为侵蚀突出,侵蚀类型和强度也更为复杂多样。人为侵蚀的成因主要有采石取土、交通道路建设、开发区建设以及坡耕地。人为侵蚀已经成为广州市水土流失灾害的主要表现形式。     

长江流域生态环境对洪涝影响的评价

长江流域的生态环境问题近年来变得越来越严重,其集中表现为：人口急剧增长的情况下,土地资源过度利用和不合理的开发,使生态环境的脆弱性增强,造成生态环境的恶化,结果导致洪水威胁加剧。本文通过对长江流域生态环境问题的分析,提出目前存在的问题是上游森林的过度开发、毁林开荒、陡坡开荒造成水土流失,增加了中下游河湖的泥沙淤积;中下游地区盲目围湖造田,占用行洪洲滩,湿地生态环境遭到破坏,造成水调蓄面积减少。最后就生态环境问题对洪涝的影响进行了评价。     

GIS and multiple-criteria evaluation for the optimisation of tsetse fly eradication programmes

Tsetse flies are the vectors of trypanosomes, the causal agent of trypanosomiasis, a widespread disease of livestock and people in Africa. Control of tsetse may open vast areas of land to livestock-keeping, with the associated benefits of developing mixed crop-livestock production systems. However, as well as possible positive impacts there are also risks: bush clearing would accelerate and cattle numbers would rise, leading to a reduction of vegetation cover, and an increase in runoff and erosion; there may also be increased pressure on conserved areas and reductions in biodiversity. The objective of this study is to show how remotely sensed and other environmental data can be combined in a decision support system to help inform tsetse control programmes in a manner that could be used to limit possible detrimental effects of tsetse control. For Zambia, a methodology is developed that combines a tree-based decision-support approach with the use of Multiple-Criteria Evaluation (MCE), within a Geographical Information System (GIS), in order to target areas for tsetse control. The results show clear differentiation of priority areas under a series of hypothetical scenarios, and some areas (e.g. northwest of Petauke in the Eastern Province of Zambia) are consistently flagged as high priority for control. It is also demonstrated that priority areas do not comprise isolated tsetse populations, meaning that disease control using an integrated approach is likely to be more economically viable than local eradication.     

桉树人工林地力衰退防治研究──改全垦为带垦

主要讨论了桉树造林整地方式──全垦与带垦对桉树生长的影响,以及对土壤侵蚀、土壤养分和土壤物理性质的影响．研究结果表明,改全垦为带垦对防止桉树人工林地力衰退有积极作用．     

葫芦岛市水土流失防控体系建设研究

分析了葫芦岛市水土流失现状及水土保持方面存在的问题,提出水土流失防控体系建设策略。建议采取水土流失分区治理、工程措施、林业措施、管理措施等建设葫芦岛市水土流失防控体系。     

三江源区高寒草甸退化草地土壤侵蚀模型与模拟研究

探讨三江源区高寒草甸退化草地土壤侵蚀模型的建立方法并利用模型对土壤侵蚀进行模拟。通过构建NetLogo模型,模拟了研究区3年时限土壤侵蚀面积的变化,表现为随时间的延续侵蚀面积增大,模拟结果与实测结果间未达极显著差异（P〉0.01）。以研究区当前土壤侵蚀现状为初始状态,模拟单位草地面积上侵蚀比例达100%时经历的年限,则坡地中度退化、坡地重度退化、滩地中度退化、滩地重度退化样地经历的年限分别为27.10±0.23 a、13.83±0.40 a、32.03±0.29 a、25.70±0.30 a。