黄河中游流瑾特性对产沙量与降雨关系影响   总被引：7，自引：0，他引：7  

卢金发 《地理学报》2000,55(6):737-743

在黄河中游河龙区间选择了１６个不同自然地理类型流域,通过流域产沙量与降雨指标之间关系分析表明,不同类型流域产沙量－降雨之间相关曲线的斜率不同;在相同的降雨指标条件下,越往北部产沙量变幅越大。流域产沙量与降雨指标之间关系的上述分异,主要受流域下垫面环境特性和暴雨分布特征控制。  相似文献   

The Origin and Evolution of Safe-Yield Policies in the Kansas Groundwater Management Districts   总被引：1，自引：0，他引：1  

Sophocleous  Marios 《Natural Resources Research》2000,9(2):99-110

The management of groundwater resources in Kansas continues to evolve. Declines in theHigh Plains aquifer led to the establishment of groundwater management districts in themid-1970s and reduced streamflows prompted the enactment of minimum desirable streamflowstandards in the mid-1980s. Nonetheless, groundwater levels and streamflows continued todecline, although at reduced rates compared to premid-1980s rates. As a result, safe-yieldpolicies were revised to take into account natural groundwater discharge in the form of streambaseflow. These policies, although a step in the right direction, are deficient in several ways.In addition to the need for more accurate recharge data, pumping-induced streamflow depletion,natural stream losses, and groundwater evapotranspiration need to be accounted for in therevised safe-yield policies. Furthermore, the choice of the 90% flow-duration statistic as ameasure of baseflow needs to be reevaluated, as it significantly underestimates mean baseflowestimated from baseflow separation computer programs; moreover, baseflow estimation needsto be refined and validated.  相似文献   

The sustained yield forest management act and the roots of environmental conflict in Northern New Mexico     

David Correia 《Geoforum》2007,38(5):1040-1051

Recent research on environmental conflict in New Mexico has focused on racial and ethnic conflict between environmentalists and Hispanic loggers as a means to explain the trajectory of environmental struggle and the failure of Hispano/environmentalist coalitions opposing Forest Service management policies. This paper seeks to extend this explanation by considering the constraining role of federal legislation, institutional management and commercial resource exploitation that limited opportunities for Hispano/environmental collaborative challenges to federal resource management arrangements. I analyze the foundations of sustained yield forestry on the Carson National Forest in northern New Mexico though a focus on the legal construction of sustained yield policies and the practices of implementing sustained yield on the Vallecitos Federal Sustained Yield Unit, a special timber production sub-unit of the Carson. The paper illustrates how the deployment of sustained yield forestry in New Mexico produced not only conditions of production favorable to commercial timber operators, but also established a complex and contradictory regulatory environment that effectively constrained collaborative efforts between environmentalists and small-scale loggers in their efforts to construct alternative futures for resource management in the region.  相似文献   

漳河流域气象水文预报模型研究     

童哲堂  陈国刚  潘传殿  鲁礼炳  刘火胜 《湖北气象》2007,26(4):344-347

通过对漳河产流、汇流、河道汇流和水库调洪演算,建立了漳河流域气象水文预报模型。本模型可根据实测降水量预报未来一定时期内入库洪水总量、洪峰、峰现时间、入库洪水过程,考虑水库出流及串联水库水量交换,经调洪演算得出水库水位变化过程。同时,也可输入气象预报的降水量或人工估算的未来可能降水量,进行水库未来洪水的可能发展趋势预测。  相似文献   

On the gap in the spectra of surface-layer atmospheric turbulence     

V. Voronovich  G. Kiely 《Boundary-Layer Meteorology》2007,122(1):67-83

A large set of tower data was used to identify the gap that separates small-scale turbulence and mesoscale structures in the cospectra of surface fluxes. The cospectra were obtained using a multi-resolution decomposition algorithm. The gap time scale τ _g was found by fitting a fifth-order polynomial to the cospectra and identifying special points occurring after the peak at small scales. In unstable conditions (day) τ _g was found to fall as the mean wind speed increased, while no such dependence was observed in stable conditions (night). The gap scale was found to change very weakly with stability both in moderately stable and moderately unstable conditions, with a sharp drop from about 1100 to 250 s occurring in near-neutral conditions. The vertical fluxes computed at different averaging intervals were found to correlate exceptionally well with each other, the scatter being somewhat larger during the night. Although considerable discrepancy may occur for individual records, when averaged over 10 months, the difference in the flux estimated at 7 to 109 min intervals never exceeded 4%, which is comparable or less than the instrumental error.  相似文献   

安阳夏玉米生长期气候要素与产量的灰色关联分析     

刘燕  卜晓娜  赵武  李琳 《河南气象》2007,(Z1)

采用灰色关联度分析了安阳夏玉米生育期间主要气象要素与夏玉米产量的关系,明确了当地夏玉米产量在年度间的差异主要以积温为主导因素,不同生育期中的气候因素以拔节-乳熟期的光照和降水量对产量影响最大,而乳熟-成熟的降水量对产量的影响程度最弱。  相似文献   

Accounting for phenology in maize yield prediction using remotely sensed dry dekads     

Farai Kuri  Amon Murwira  Karin S. Murwira  Mhosisi Masocha 《国际地球制图》2018,33(7):723-736

Rain-fed agriculture is threatened by an increased frequency of droughts worldwide thereby putting millions of livelihoods at risk especially in sub-Saharan Africa. This makes drought preparedness critical. In this study, we sought to establish whether maize yield can be predicted using the number of dry dekads that occur at specific maize growth stages for purposes of yield early warning. The dry dekads were derived from remotely sensed Vegetation Condition Index calculated from the SPOT NDVI time series ranging from 1998 to 2013. Regression between dry dekads and maize yield show a negative linear relationship for four growing seasons (2010–2013) and indicates that dry dekads at both the vegetative and reproductive stages are important for predicting maize yield. Results suggest that early warning alert could be given using dry dekads that occur at the vegetative stage, while those at the reproductive stage can be used to give better yield estimate later on.  相似文献   

民族煤矿水文地质特征的分析与研究     

刘怡君  彭彪 《化工矿产地质》2015,(2):106-110

通过对民族煤矿水文地质条件分析,认为煤矿主要的充水水源来自于龙潭组含煤地层基岩裂隙水、长兴组岩溶裂隙水以及小煤矿及老窑积水,同时计算了矿区内的最大涌水量,从而为建立矿区的防治水保障体系提供了有效的依据。  相似文献   

注浆堵水后试验排水期间矿井残留水量估算     

李朋  刘忠礼  沈超 《中国煤炭地质》2021,(2)

注浆堵水后期,矿井试验排水是对注浆效果进行综合评定,同时也是检查矿井是否具备复矿条件的重要指标。但由于各个矿井地质条件的差异性,致使试验排水得到的一些数据存在一定的歧义,从而误导正常的判断,进而影响矿井生产。以新疆兴陶大北矿业公司大北煤矿试验排水为例,阐述影响矿井试验排水的主要因素,并提出简单估算矿井残留水量的方法,为类似矿井提供了借鉴。  相似文献   

昭通太阳背斜山地浅层页岩气"三维封存体系"富集成藏模式   总被引：3，自引：0，他引：3  

梁兴  单长安  张朝  徐政语  徐进宾  王维旭  张介辉  徐云俊 《地质学报》2021,95(11):3380-3399

本文系统分析了太阳地区构造断裂系统、顶底板条件、沉积岩相、优质页岩展布、源储条件及富集高产规律,提出了"多场协同多元耦合"共同作用下太阳背斜区山地浅层页岩气"三维封存体系"富集成藏赋存模式,具有5个特征:①页岩储层上覆龙马溪组一段二亚段—石牛栏组厚层致密页岩和泥灰岩,下伏临湘组—宝塔组厚层致密瘤状灰岩,具有良好的封隔层条件,形成了封存体系的顶板和底板;②压扭应力背景下形成的断裂系统属于挤压性逆冲断层、压扭性走滑断层,断层的纵向封闭性好,有效地保护了优质页岩气藏;③断层两盘页岩气层对接岩性均为致密泥灰岩和灰岩,侧向封堵性防止了页岩气泄漏点出现,使得山地浅层页岩气仍具有连续型气藏特征;④前陆盆地"水体滞留+火山灰沉降"造就了"海洋漂浮生物繁盛+缺氧强还原"深水陆棚沉积环境,形成了"富碳、高硅、低黏、高脆"的优质烃源岩储集体,构建了"规模生烃、高效吸附富集"的页岩微纳米级储集孔隙空间;⑤页岩储层具有相对小的地应力和两向水平应力差,既利于在中低泵压下的储层压裂施工作业,又具备体积压裂打碎页岩形成复杂缝网和气井获得高产的关键要素.提出了复杂构造区山地浅层页岩气"多元富集高产"的规律性认识,即:前陆盆地深水缺氧强还原环境促使了"富碳、高硅、低黏"页岩储层发育(沉积成岩控制源储特征)、持续良好的三维封闭保存体系有效保护了富有机质页岩生烃留烃富烃和超压保孔(保存条件控制天然气藏)、页岩脆性与地应力以及水平应力差决定了体积压裂改造的难易程度并影响了人造页岩气藏的构建效果(应力可压性控制人造气藏)、Ⅰ类优质页岩气储层连续厚度和地层压力系数决定了页岩气禀赋的资源储量丰度与气井高产(烃储禀赋控制单井产量).研究成果对中国南方复杂构造区海相浅层页岩气的高效勘探开发具有重要的借鉴引领和指导意义.  相似文献