Modeling Carbon and Water Budgets in the Lushi Basin with Biome-BGC

Abstract

In this article, annual evapotranspiration (ET) and net primary productivity (NPP) of four types of vegetation were estimated for the Lushi basin, a subbasin of the Yellow River in China. These four vegetation types include: deciduous broadleaf forest, evergreen needle leaf forest, dwarf shrub and grass. Biome-BGC—a biogeochemical process model was used to calculate annual ET and NPP for each vegetation type in the study area from 1954 to 2000. Daily microclimate data of 47 years monitored by Lushi meteorological station was extrapolated to cover the basin using MT-CLIM, a mountain microclimate simulator. The output files of MT-CLIM were used to feed Biome-BGC. We used average ecophysiological values of each type of vegetation supplied by Numerical Terradynamic Simulation Group (NTSG) in the University of Montana as input ecophysiological constants file. The estimates of daily NPP in early July and annual ET on these four biome groups were compared respectively with field measurements and other studies. Daily gross primary production (GPP) of evergreen needle leaf forest measurements were very close to the output of Biome-BGC, but measurements of broadleaf forest and dwarf shrub were much smaller than the simulation result. Simulated annual ET and NPP had a significant correlation with precipitation, indicating precipitation is the major environmental factor affecting ET and NPP in the study area. Precipitation also is the key climatic factor for the interannual ET and NPP variations.     

131105综采面地面钻孔抽采煤层卸压瓦斯技术研究

为了合理布置地面抽采瓦斯钻孔,基于矿山压力与顶板控制理、保护层开采理论等,研究了地面钻孔平面布置和结构,地面钻孔抽采瓦斯量和抽采瓦斯浓度随工作面距钻孔距离的变化规律,同时利用双示踪技术对地面钻孔抽采范围进行了测试,综合考察了地面钻孔抽采煤层卸压瓦斯的有效范围。结果表明：地面钻孔抽采瓦斯有效范围不小于200m。     

Automated Calibration of the METRIC‐Landsat Evapotranspiration Process

A remaining challenge to applying satellite‐based energy‐balance algorithms for operational estimation of evapotranspiration (ET) is the calibration of the energy‐balance model. Customized calibration for each image date is generally required to overcome biases associated with radiometric accuracy of the image, uncertainties in aerodynamic features of the landscape, background thermal conditions, and model assumptions. The CIMEC process (calibration using inverse modeling at extreme conditions) is an endpoint calibration procedure where near extreme conditions in the image are identified where the ET can be estimated and assigned. In the Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC?) energy‐balance model, two endpoints represent the dry and wet ends of the ET spectrum. Generally, user‐intervention is required to select locations in the image to produce best accuracy. To bring the METRIC and similar processes into the domain of less experienced operators, a consistent, reproducible, and dependable statistics‐based procedure is introduced where relationships between vegetation amount and surface temperature are used to identify a subpopulation of locations (pixels) in an image that may best represent the calibration endpoints. This article describes the background and logic for the statistical approach, how the statistics were developed, area of interest requirements and assumptions, adjustment for dry conditions in desert climates, and implementation in a common image processing environment (ERDAS Imagine).     

沸石芦苇床除氮中试研究

对沸石芦苇床去除农田回归水和农村生活污水组成的混合污水中的氮进行了中试研究.结果表明,在0.6m/d的水力负荷下,系统对总氮、氨氮、硝酸盐氮、亚硝酸盐氮的平均去除率冬季和春季分别为38.9%和58.2%,93.11%和78.84%,10.01%和48.99%,38.81%和98.45%.春季运行效果明显好于冬季.在相同条件下,总氮、氨氮、硝酸盐氮去除率比砾石芦苇床分别高28%、67%、35%.沸石对氨氮的吸附、离子交换,微生物的哪硝化、反硝化作用是沸石芦苇床系统去除氮的主要途径.     

Research and application of drainage parameters for gas accumulation zone in overlying strata of goaf area

While coal seam is being mined, an annular fissure circle with gas accumulation will be formed in the fissure zone as a result of desorption, dissipation and permeation of gas in the goaf area and overlying strata due to fissures from rock caving and mitigation in the roof. The methods for computation of spatial locations of the fissure circle are researched in this paper. Based on these methods, gas drainage technique for the fissure zone is optimized. By applying drill hole returning water method of variables, the height of caving zone that most affects the drainage effects of inclined high dip drill hole was measured on the site. Due to the consistency of the expected height with the computed height of caving lines at different positions, the correctness of the theoretical computation method is further validated. Meanwhile, the parameters of the inclined high dip drill hole at #3311 working face of Hexi Coal Mine are determined by a case study.     

走向高抽巷抽放采空区瓦斯数值模拟与试验分析

为获取走向高抽巷抽放瓦斯的合理参数,依据采空区瓦斯运移基本方程,采用FLUENT数值模拟的方法确定走向高抽巷的最佳抽放位置,即竖直方向高度为综采工作面底板上方20m,倾斜方向距上风巷水平距离为14 m,并在张集矿1111工作面进行现场试验;从试验效果来看:采用FLUENT数值模拟方法确定走向高抽巷位置是可靠的,布置合理的走向高抽巷具有抽放瓦斯浓度高、瓦斯抽放量大和稳定性好的优越性,能有效地解决综采工作面和上隅角瓦斯超限问题,以确保矿井安全生产;抽放参数可在类似矿区加以推广应用,安全效益、经济效益和社会效益明显.     

低透气性薄煤层煤与瓦斯共采技术研究

煤与瓦斯共采技术是煤矿绿色开采技术的重要组成部分之一.针对矿井煤层薄、煤层透气性低、煤层瓦斯含量低等特点,应用岩层移动理论和采空区瓦斯流动规律,研究了采场内卸压瓦斯的运移路径和富集区域,建立了矿井煤与瓦斯共采系统,采用了高位顶板穿层钻孔瓦斯抽采方法和老采空区瓦斯抽采方法等综合瓦斯抽采方法,降低了矿井瓦斯涌出量,消除了工作面瓦斯积聚现象,提高了矿井瓦斯抽采率和抽采浓度.在保障煤炭资源安全开采的前提下实现了瓦斯资源的安全、高效抽采.     

排水管道内不同粒径沉积颗粒物冲刷率的分析与计算

为探究和量化在水流冲刷下,排水管道中不同粒径颗粒物冲刷沉积的过程,本文模拟排水管道内沉积颗粒的冲刷过程.冲刷过程中,粒径较小的悬移质颗粒(小于0.1 mm),在管道沿线取样测得水流中悬浮固体质量浓度(SS);粒径较大的推移质颗粒(0.1—2 mm),测得管道沿线不同位置沉积的颗粒质量.并建立两个数学模型分别计算排水管道内两类颗粒物的冲刷率.研究发现,悬移质颗粒,以水流中SS为依据,可计算出输送通量和冲刷率;推移质颗粒,以管道不同位置沉积下来的颗粒质量为依据,拟合出了管道中的沉积分布函数,是以e为底数的指数函数,可计算出冲刷量和冲刷率.模型计算出的冲刷率呈现出规律性:悬移质颗粒被冲刷成悬浮状态,随水流迁移过程中部分会再次沉积,使得悬移质颗粒的冲刷率从管道前段至中后段逐步降低,如初始沉积质量为100 g的0.045 mm悬移质颗粒,在0.30 m·s^-1的冲刷流速下,计算出管道前段冲刷率为78.94%,最终在管道后段降至13.89%;对于两类颗粒而言,颗粒物粒径越小,冲刷流速越大,初始沉积质量越小,冲刷率越高.     

地面L型钻孔在大采高综放工作面瓦斯治理工作中的探索

通过对目前瓦斯治理方法的对比,结合煤层瓦斯赋存与流动理论、回采工作面矿山压力规律及采场覆岩移动规律、采空区“O”型圈等理论,提出利用地面L型钻孔抽采煤层顶板裂隙带瓦斯的方法,用于缓解低位采空区抽采巷抽采负担,消除安全隐患。实践表明:地面L型钻孔使低位采空区抽采巷平均浓度由4.43%降低到3.37%,降低了24%,治理效果明显,该方法能为大采高综放工作面瓦斯治理工作提供新的思路。     

穿层水力冲孔措施在低透煤层中有效影响半径效果考察

为研究水力冲孔措施下煤层瓦斯高效抽采钻孔合理布置参数,提高煤层瓦斯抽采效率,以平煤十三矿己15-17-13051工作面为例,对水力冲孔有效影响半径进行效果考察。通过布置多组试验钻孔,分别对水力冲孔措施前后钻孔瓦斯浓度、瓦斯流量数据进行综合考察,结果表明:水力冲孔措施增大了煤层透气性系数,高效提升了煤层瓦斯抽采率,执行冲孔措施后瓦斯浓度最低可提高至2.05倍、瓦斯纯流量增至2.56倍以上,采用瓦斯流量法确定了己15-17煤层水力冲孔措施实际有效影响半径为4.8~5.9 m,对于指导煤层瓦斯抽采钻孔合理布置具有指导性意义。