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RMR法与Q法是国内外八、九十年代岩体质量和参数估算的常用方法,然而RMR法和Q法对质量较差的岩体不太实用,而RMi法是一种既适用于软岩又适用于硬岩的岩体质量评价和参数估算方法。本文在介绍RMi法基本原理的基础上,对贵州省鱼简河水库坝基岩体变形模量进行确定。 相似文献
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天然气水合物微观模式及其速度参数估算方法研究 总被引：9，自引：2，他引：9
天然气水合物沉积介质速度的估算是水合物人工地震探测理论方法和技术研究的组成部分。文中针对水合物在介质孔隙中悬浮、颗粒接触和胶结 3种微观模式 ,对前人估算其速度的多种方法进行了分析研究 ,结合试算模型 ,重点考查时间平均方程、伍德方程、李权重方程和等效介质等方法估算速度的适用性和使用条件。研究结果表明 ,每种方法都有其适用和不适用 (或不太适用 )的条件 ,水合物悬浮模式、颗粒接触模式和胶结模式 ,最为适宜使用的速度估算方法分别是伍德方程、权重方程和时间平均方程。权重方程在合理调整权重参数时有较宽的适用性。 相似文献
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无实测资料河流逐月水量估算是最严格水资源管理制度考核的重要支撑。基于流域水文相似性原理和水量平衡原理,选用径流模数法、径流系数法、区域水量平衡法,研究提出其逐月水量估算适用范围和估算成果合理性分析标准。以现有水文站为假设断面,采用参证水文站资料进行假设断面水量估算,对三种方法的适用范围和估算成果合理性分析标准进行验证。结果表明,径流模数法适用于集水面积相差不超过20%情形和考虑区间蓄泄水变量情况的集水面积相差在20%至1倍之间情形;径流系数法适用于集水面积相差在20%至1.5倍之间且估算时段有洪水过程情形;区间水量平衡法适用于上下游参证水文站面积比在3倍以内情形;“两种方法相对偏差小于18%”的估算成果合理性分析标准可行。 相似文献
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利用FAO56-PM法计算潜在蒸散发时气象资料往往不易满足。针对该问题,本文研究了辐射法、温度法和基于温度及辐射资料的RBF神经网络预测模型。以FAO56-PM法计算值为标准,比较分析了Priestley-Taylor法、Hargreaves法、Mc Cloud法以及Makkink法在河南省五个典型地区(安阳、新乡、郑州、驻马店、信阳)的适用效果。并以新乡地区为例评价了校正参数后各估算方法和基于温度及辐射资料的RBF神经网络预测模型的适用性。结果表明,Makkink法在五个典型地区估算的潜在蒸散发量误差较小,其余方法误差较大。校正参数后,各估算方法在新乡地区的估算结果均得到明显改进,具有较好的地区适用性。基于温度及辐射资料的RBF神经网络预测模型具有较高的预测精度,可应用于潜在蒸散发量的估算和预测。 相似文献
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海底块状硫化物矿床具有巨大的经济价值和良好的开发前景。但是由于勘探难度和技术手段的限制,在全球已经发现的600多个海底热液喷口和硫化物矿床中,不到5%的矿床进行了详细的勘探,进行资源量计算的矿床更是屈指可数。选择适当的方法估算储量对于深海资源开发意义重大。本文系统总结了前人估算海底硫化物储量的方法,并以勘探程度相对较高、数据资料相对丰富的Atlantis-II-Deep矿床和Solwara 1矿床为例,评析了前人采用不同储量计算方法得到的结果和各种方法计算的准确性;针对有一定钻孔数据的TAG硫化物堆丘,采用距离反比法重新计算了储量,并和块段法估算的结果进行对比。得到以下结论:(1)海底硫化物矿体形态是制约储量估算方法适用性的一个重要因素;(2)传统几何法可以在极低勘探条件下估算海底硫化物储量量级;(3)对于海底硫化物储量估算,地质统计学的精度高于传统几何法;(4)较高勘探条件下距离反比法可以与地质统计学相互对照、验证;(5)在一定钻孔数量的条件下,可以应用距离反比法进行海底硫化物储量估算。 相似文献
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齐波夫定律作为一种矿产资源预测方法,计算过程简单,采用少量的已知数据就可估算潜在资源,效果明显。该法一般多应用于成矿区(带)的预测,而在范围较小的矿区应用还不多。本文应用齐波夫定律在大坊矿区对金、银资源预测进行了尝试。其结果表明,大坊矿床可望成为大型银金矿床,齐波夫定律同样适用于矿区范围的资源预测。 相似文献
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详细介绍了在立井平面联系测量中连接三角形法一井定向的测量和解算方法,特别提出了不同连接三角形解算适用不同的计算公式。并结合实践经验,阐述了一井定向连接三角形法和瞄直法的使用范围和测量注意事项。 相似文献
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工程土方量计算比较分析 总被引：20，自引：0，他引：20
土方计算的基本方法有断面法、方格网法、等高线法及基于数字高程模型(DEM)法。在实际生产应用中，不同的方法计算的同一场地土方量数量相差较大，所以不同方法土方计算精度不同，适用范围也不一样。本文基于对工程土方量计算中的断面法、方格网法、等高线法及基于数字高程模型(DEM)法的基本原理、方法和优缺点比较分析。从理论上讨论它们的适用范围、条件及精度分析。结果表明，DEM法适用于所有场地，且精度较高，方格网法只适用于平坦场地；断面法适用于特别复杂的狭长带状地形场地。 相似文献
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结合物理栖息地模拟模型的水力学与栖息地模型,以黄河干流兰州-石嘴山河段为研究样区及该河段的关键鱼种黄河鲤鱼为对象物种,以流速及水深二水力学因子进行研究,推求该研究样区兰州、安宁渡、下河沿、青铜峡和石嘴山五断面对象物种的流量与权重可使用面积的关系。通过对上述各断面1975-1985年汛前共11年生态、水文及断面资料的分析计算,归纳出研究断面汛前适合的生态流量分别为195、220、220、220、175 m3/s,计算结果在Tennant法界定的生态流量范围之内。 相似文献
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Q. Liu H. Yu L. Liang F. Ping X. Xia X. Mou J. Liang 《International Journal of Environmental Science and Technology》2017,14(3):509-520
Climate change alters ecohydrological processes on different temporal and spatial scales. The aim of this study was to estimate ecological instream flow requirements (EIFR) under climate change impacts and to ascertain optimum flow magnitude to maintain the health of river ecosystems. We used the Mann–Kendall test, the River2D Hydrodynamic model, and the frequency-weighted usable area (FWUA) model on an annual scale in the Juma River to investigate changes in EIFRs caused by climate change. Findings indicated that: (1) between 1956 and 2005, annual instream flow in the Juma River exhibited an abrupt downward trend (in 1981); (2) variation in instream flow governed the area of available fish habitat, and degrees of change for low flow threshold values and low and high FWUA threshold almost exclusively occurred in descending sequential order from winter, spring, autumn, and summer; (3) changes in hydrological regimes influenced both the quantity and quality of physical habitat area, contributing greater to quality than to the distribution of area of physical habitat for Pseudorasbora parva. Climate change, reflected in the changes in EIFR and the area of optimum physical habitat, has dramatically influenced ecological structure and function, even in the small river system investigated for this study. Findings indicated that more rational measures should be put into practice to help address climate change. 相似文献
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Ernest D. Estevez 《Estuaries and Coasts》2002,25(6):1291-1303
Published and gray literature, and works in progress, were reviewed to identify biotic variables and analytical methods used in studying freshwater inflow needs of estuaries. Landings, CPUE, and other measures of single-species abundance are most often used, especially for shellfish and finfish. These efforts work best when biomass is used and lag times are allowed for recruitment, but neither method is always used, and most efforts have assumed that physical habitat availability is constant. Efforts employing habitat and community-level variables are used less often but more recent attempts are using dynamic as well as stationary definitions of habitat. Even stationary habitat methods have given less attention to tidal freshwater and brackish estuarine reaches, than to other reaches. Natural long-period climate cycles (El Ninõ Southern Oscillation; North Atlantic Multi-Decadal Oscillation) are not factored into most inflow studies. Three promising approaches are encouraged; a mixture of variables representing different levels of ecological organization should be used, the natural non-linear geometry of estuaries (especially tidal rivers) should be exploited to identify critical thresholds of inflow, and the validity of using instream flow methods to calculate estuarine requirements by proxy should be determined. 相似文献
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河流生态用水安全是维持河流系统健康的基本条件。本文首先从河流生态系统特性入手,提出生态水文季节,构建了多参数生态需水(最小生态需水、适宜生态需水、洪水期生态需水)体系并分析其内涵,组成了能反映河流生态系统健康的流量等级。生态需水按生态水文季节形成具有时间特征的生态标准河流。在此基础上,提出生态用水预警制度和危机管理机制,探讨保障生态用水安全的调度和管理模式。以黄河流域中下游为例,开展实践应用研究,为黄河中下游的生态用水安全调度和管理提供科学依据。 相似文献
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Introducing a new method to determine rivers’ ecological water requirement in comparison with hydrological and hydraulic methods 总被引：1，自引：1，他引：0
A. Shokoohi M. Amini 《International Journal of Environmental Science and Technology》2014,11(3):747-756
The absence of a rational, comprehensive, flexible and easy to use method with minimum data requirement to determine rivers’ environmental flow requirements is the main motivation for this research. Based on the microhabitat preferences of index species, hydrological (the Tennant and Q 95) and hydraulic methods for determining the environmental flow requirement (EFR) are compared. Using an ad hoc procedure, the important species of a river at the southern part of the Caspian Sea in Iran were distinguished, and the discharges to maintain the microhabitat (depth and velocity) in critical months were calculated. The observed differences between the index species’ required velocity and depth and those suggested by the Tennant method emphasize the importance of the rivers morphological properties for this method application. Allocating EFR by the Tennant and Q 95 methods would degrade the aquatic life. The EFR determined by the hydraulic method is equal to 95 % of the average annual discharge, which could maintain the ecological habitat in good situation, but may provoke a conflict in the region. The Tennant, Q 95 and hydraulic methods allocate EFR as 14, 36 and 79 % of the annual flow volume, respectively. Developing a new combined method based on using the hydraulic method’s discharge for critical months and the Tennant method suggestion for the excellent condition in other months allocates 50 % of the average annual discharge. This new method is a compromise between protecting environment and considering the water rights of rivers’ flow consumers and is suggested specially for dry regions of the world. 相似文献
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S. Shaeri Karimi M. Yasi S. Eslamian 《International Journal of Environmental Science and Technology》2012,9(3):549-558
Environmental flow assessment and maintenance are relatively new practices, especially in developing countries. This paper describes the desktop assessment of environmental flows in a river with insufficient data on ecological features and values. In this study, the potential environmental flows in a typical river reach of the Shahr Chai River in Iran were investigated using a newly developed hydrological method (flow duration curve (FDC) shifting) and Global Environmental Flow Calculator software. This approach uses monthly flow data to develop an environmental FDC and to generate flow requirements corresponding to different features of the river ecosystem. Results were compared with those from four alternative hydrological methods: the desktop reserve model (DRM), Tennant, low-flow index, and flow duration curve analysis (FDCA). Comparisons of these methods indicated that to maintain the basic function of the river ecosystem, the river flows should be managed within an acceptable environmental level. The predictions from the Tennant method and the low-flow index (7-day low flow with a 10-year return period), and from the FDCA (for flows exceeding 90?% of occurrence) are not as reliable as those from the FDC shifting technique and DRM. Comparative results indicate that a minimum flow rate of 1.2?m3/s (equivalent to 23?% of the natural mean annual runoff, or flow with 80?% occurrence depicted from the FDC) is required for the Shahr Chai River to run toward the internationally recognized Urmia Lake in Iran. 相似文献
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为量化水库下游河道生态修复所需水量,以滦河下游潘家口水库—滦河口为研究样区,采用逐月频率法和生态水力学法估算河道生态需水量,既具有水文学方法的简便,又考虑生物学特性,强调了水文-生态的联系。通过对研究区河道1956~2000年生态、水文及水力资料的分析计算,结果表明:①逐月频率法和生态水力学法在计算滦河下游河道生态需水中均合理;②最小、适宜、理想等级年生态需水量分别为4.29亿,8.93亿和16.29亿m3,分别占河道天然径流量的10.18%、21.21%和38.68%;③年内汛期8月份及生物繁殖期(4~6月)需水量分别达到年度总量的33.5%和11.5%。 相似文献