Groundwater resources in the Jabal Al Hass region,northwest Syria: an assessment of past use and future potential

In many cases, the development of groundwater resources to boost agricultural production in dry areas has led to a continuous decline in groundwater levels; this has called into question the sustainability of such exploitation. In developing countries, limited budgets and scarce hydrological data often do not allow groundwater resources to be assessed through groundwater modeling. A case study is presented of a low-cost water-balance approach to groundwater resource assessments in a 1,550 km² semi-arid region in northwestern Syria. The past development of irrigated agriculture and its effect on the groundwater system were studied by analysis of Landsat images and long-term groundwater level changes, respectively. All components of the groundwater balance were determined. Groundwater recharge was estimated using the chloride mass balance method. Over the past three decades, groundwater levels have declined, on average, 23 m, coinciding with a two-fold increase in the groundwater-irrigated area. Groundwater resources are currently depleted by a value that lies between 9.5×10⁶ and 118×10⁶ m³ year^?1, which is larger than can be compensated for by a future decrease in natural discharge or changes in boundary conditions. However, groundwater resources are likely to be sufficient to supply domestic and livestock needs in the area.     

Pumping decisions for sustainable development of groundwater resources in areas of grassland degradation: a case study in Lanqi Banner, Inner Mongolia, China

The best planting alternatives for satisfying high water use demands of forage and fodder crops in a region of Inner Mongolia, China, were determined by a multiobjective distributed-parameter groundwater management model. These alternatives took account of different cropping patterns and pumping decisions associated with both temporal and spatial aspects of water allocation. The model was developed for phreatic, homogenous, and isotropic aquifers using the response matrix technique of quadratic programming theory and, in this case, using the alternative direction implicit (ADI) scheme. Model solutions using effective rainfall with a probability of 50%, show that average water table drawdown in the planning period (2006–2017) is 0.22 m and the groundwater fluctuation in each pumping well is very low. In order to evaluate the pumping decisions under an effective rainfall with a probability of 75%, a sensitive analysis was also conducted. Analysis shows that it is useful to apply the results from the proposed model to control the landscape degradation due to overgrazing and overpumping activities.     

Mid-infrared imaging of ultracompact H II regions

We discuss preliminary results of an 11.7 m imaging survey of ultracompact H II regions from the Wood and Churchwell radio survey. We find that that the morphologies of ionized gas and warm dust are often significantly different, indicating that an H II region classification scheme should be based on more than radio data.     

Hydrochemical and isotopical tracers in the lacustrine aquifer of the Cerro Prieto area, Baja California, México

A series of patterns in the chemical and isotopic composition of the groundwater of the Cerro Prieto area have been recognized. These patterns were used to define four hydrochemical and isotopical zones in the area. One of these areas located at the east side was found to be the source of recharge, while another in the central part is where an older aquifer exist in lacustrine deposits. The low permeability of the area causes the aquifer to act as an aquitard, which at least is partly surrounded by an interface zone where mixing of waters occurs. Tritium and radiocarbon method revealed that the aquitard is an isolate system whose residence time is of 32 ka.     

东北漫岗黑土区春季冻融期浅沟侵蚀

浅沟侵蚀是东北漫岗黑土区农耕地上常见的水蚀类型,往往对坡耕地造成严重的破坏。2005年春季,通过对两个小流域浅沟侵蚀的调查测量,发现该区浅沟侵蚀相当严重,两流域分别形成浅沟14条、16条,浅沟总长度分别达3 269 m、2 146 m,浅沟密度分别为908 m/km2、766 m/km2,侵蚀深度分别为0.17 mm、0.16 mm,侵蚀模数分别达181.8 t/km2、173.6 t/km2。2005年春季两流域浅沟侵蚀期的径流深分别是6.8 mm、7.7 mm。分析表明,研究区在春季表层土壤解冻、地表裸露和存在季节性冻土层的条件下,春季融雪及强降水易造成强烈的浅沟侵蚀。在分布上,浅沟一般位于坡面的中下部,而且多发育在瓦背状坡面的集流水路上。另外,耕作措施对浅沟的形成和发展也有重要影响。     

海南岛农业地貌

本文在充分消化前人已有资料的基础上,论述了海南岛的主要地貌类型与地貌轮廓,阐明了海南岛地貌形成的条件与过程、地貌对农业生产的影响及农业地貌分区。     

The use of modern statistical theories in the assessment of earthquake hazard, with application to quiet regions of eastern North America

It is generally accepted that both deterministic and statistical approaches are useful for the characterization of earthquake hazard. Although the most reliable estimates of seismic hazard can only be based on an improved understanding of the earthquake mechanism, efficient utilization of the appropriate methods provided by recent statistical theories is also important in seismic risk analysis. This is especially true in regions where the connection between seismicity and geologic structure is tenuous at best. We are particularly interested in developing better statistical treatments of data for regions with little known seismic activity. To this end, we have applied three statistical methods to the historical record of seismicity in relatively quiet regions of eastern North America. These are: (1) the threshold method for tail inference, a new theory for modeling earthquakes with sizes above a given threshold, (2) the ‘bootstrap’ technique in which the characteristics of an unknown population are simulated by replacing the true population by an estimated one, and (3) a technique to estimate the number of earthquakes below a given size, in order to compensate for the under-reporting of small earthquakes in most catalogs. A combination of these techniques has been used to estimate the probabilities of future large earthquakes for the regions studied. Because of limitations imposed by existing catalogs, the size estimate used has been maximum intensity.     

Identification of geomorphic process units in Kärkevagge, northern Sweden, by remote sensing and digital terrain analysis

Sediment transport processes in the Kärkevagge are investigated concerning their spatial and temporal characteristics due to long–term monitoring. Within this study remote sensing techniques and GIS modelling in connection with geomorphic mapping are applied for identification and characterization of geomorphic process units. Relationships between geomorphometric parameters and slope processes like solifluction, talus creep and rockfall have been analysed. Multitemporal Landsat–TM5 scenes are used as source for landcover characteristics (Normalized Difference Vegetation Index) after preprocessing involving orthorectification and topographic normalization in order to remove possible terrain–induced effects. Additionally, a digital elevation model with a resolution of 20 m for the Kärkevagge catchment is developed and parameters like slope gradient, slope aspect and profile curvature are extracted as input for the analysis of the sediment transport system. The combination of landcover information, geomorphometrical and topological features allows the definition of areas for single process activities. They show specific sediment displacement characteristics depending on material conditions, topological and geometrical features. Geomorphic process units, which show a homogenous composition, are extracted from these available layers.     

川滇藏三江流域生态环境功能区建设目标及影响预测

三江流域具有特殊严酷的自然环境和相对落后的经济条件,本区域的生态环境极度脆弱,不但限制了本区域的经济发展,还严重威胁着中下游地区的安全。本文运用景观生态学原理,从流域生态环境功能区建设目标及影响预测两个方面分析,提出了三江流域生态功能区建设的措施,对生态功能建设的效果进行了预测。     

星载微波散射计技术及其在极地的应用

简要介绍了微波散射计的原理、星载微波散射计的发展状况及用于提高散射计图像空间分辨率的图像滤波重建算法。在此基础上结合几种星载微波散射计数据简要介绍了微波散射计在南北两极的应用情况 (海冰图测绘、海冰运动监测、海冰分类、极地冰盖研究等 )及其未来研究展望。