Spatial Dynamics of Soil Moisture in a Complex Terrain in the Semi‐Arid Loess Plateau Region,China1

Abstract: Soil moisture is an important hydrological variable in reforestation practices in a water‐limited region of the Loess Plateau of northwestern China. The objective of this study was to quantify the spatial dynamics of soil moisture on a complex terrain. During 2004‐2006, a total of 313 sample points in two kinds of grid (2 × 2 m and 20 × 20 m) were arranged for soil moisture measurements (two soil layers: 0‐30 and 30‐60 cm) with Time Domain Reflectometry. The geostatistical properties of soil moisture patterns, the variance and correlation structure of the soil moisture, and the effects of terrain factors on soil moisture were analyzed. The results suggested that our sampling grid captured the spatial variability of soil moisture distributions for this complex terrain. Principal Component Analysis and Cluster Analysis statistics showed that soil moisture decreased as slope gradient increased; that sunny aspects (112.5°‐292.5°) had relatively lower soil moisture than did shady aspects (292.5°‐112.5°); that soil moisture was lowest in the SWW direction and highest in the NWN direction; and that hillslope aspect was the main factor affecting soil moisture in the 0‐ to 30‐cm soil layer, whereas the main factor for the 30‐ to 60‐cm layer was slope gradient. It was found that the relative values of soil moisture for steep slopes (>36%) with shady aspect (292.5°‐112.5°), gentle slopes (<36%) with sunny aspect (112.5°‐292.5°), and steep slopes with sunny aspect were 99, 82, and 80, respectively – assuming a soil moisture value of 100 for gentle slopes with shady aspect. The results of this study are expected to be relevant to and useful for reforestation planning and design, parameterization of distributed hydrology models, and land productivity assessment in the study region.     

黄土高原地区生态旅游开发的优势及前景分析

黄土高原地区生态环境非常脆弱,该区进行旅游开发必须以生态旅游为指导。该区自然和人文旅游资源丰富而独特,开发生态旅游具有类型多样、功能齐全、有利于组合开发的资源优势;西部大开发、中部崛起战略为其提供了政策优势,同时该区劳动力资源丰富,因此开发生态旅游优势明显。分析了黄土高原地区生态旅游开发的国际、国内及区域市场前景,提出了在该区进行生态旅游开发应注意的问题。     

Evaluation of the MIKE SHE Model for Application in the Loess Plateau,China1

Abstract: Quantifying the hydrologic responses to land use/land cover change and climate variability is essential for integrated sustainable watershed management in water limited regions such as the Loess Plateau in Northwestern China where an adaptive watershed management approach is being implemented. Traditional empirical modeling approach to quantifying the accumulated hydrologic effects of watershed management is limited due to its complex nature of soil and water conservation practices (e.g., biological, structural, and agricultural measures) in the region. Therefore, the objective of this study was to evaluate the ability of the distributed hydrologic model, MIKE SHE to simulate basin runoff. Streamflow data measured from an overland flow‐dominant watershed (12 km²) in northwestern China were used for model evaluation. Model calibration and validation suggested that the model could capture the dominant runoff process of the small watershed. We found that the physically based model required calibration at appropriate scales and estimated model parameters were influenced by both temporal and spatial scales of input data. We concluded that the model was useful for understanding the rainfall‐runoff mechanisms. However, more measured data with higher temporal resolution are needed to further test the model for regional applications.     

关于黄土高原陇东地区环境变化的回顾与思考

在近七八十年里,生态环境脆弱的陇东地区由于人口增加引起乱砍滥伐、过度放牧、陡坡开垦造成的水土流失和引起大量开垦坡地,广种薄收,形成“越穷越垦、越垦越穷”的恶性循环等等,出现了一系列人地矛盾.随着植树造林,退耕还林,禁止放牧等一系列政策措施的实施和社会经济的快速发展,使得这一矛盾得到了一定程度的缓解,可今后怎样保持和继续深化以及怎样在环境可承载下发展经济和提高人民的生活水平是我们要思考的问题.从环境变化的几个方面进行讨论并得出一些存在的问题及建议.     

Quantifying the Effects of Conservation Practices on Soil,Water, and Nutrients in the Loess Mesa Ravine Region of the Loess Plateau,China

A large number of soil and water conservation programs have been implemented on the Loess Plateau of China since the 1950s. To comprehensively assess the merits and demerits of the conservation practices is of great importance in further supervising the conservation strategy for the Loess Plateau. This study calculates the impact factors of conservation practices on soil, water, and nutrients during the period 1954–2004 in the Nanxiaohegou Catchment, a representative catchment in the Loess Mesa Ravine Region of the Loess Plateau, China. Brief conclusions could be drawn as follows: (1) Soil erosion and nutrient loss had been greatly mitigated through various conservation practices. About half of the total transported water and 94.8 % of the total transported soil and nutrients, had been locally retained in the selected catchment. The soil retained from small watersheds do not only form large-scale fertile farmland but also safeguard the Yellow River against overflow. (2) Check dam was the most appropriate conservation practice on the Loess Plateau. In the selected catchment, more than 90 % of the retained soil and water were accomplished by the dam farmland, although the dam farmland occupied only 2.3 % of the total area of all conservation measures. Retention abilities of the characteristic conservation practices were in the following order: dam farmland > terrace farmland > forest land and grassland. (3) The conservation practices were more powerful in retaining sediment than in reducing runoff from the Loess Plateau, and the negative effects of the conservation practices on reducing water to the Yellow River were relatively slight.     

寒区芦笋复合高效种植技术

在寒区种植多年生蔬菜芦笋能安全越冬,一年种植,多年收获。由于种植芦笋前期植株小,易造成土地资源的浪费和水土流失,针对这一特点,本文着重探讨了如何有效利用芦笋与其它作物进行复合种植的技术     

东北地区粮食生产及其可持续性因子分析

通过对东北地区耕地面积、粮食单产及总产的时间序列分析,揭示了该地区粮食生产发展趋势,并结合粮食生产发展的影响因子分析,探该区粮食生产可持续发展的影响因子,指出今后提高粮食生产的途径。     

华北地区汽车拥有量与CO2排放量关系研究

研究了华北地区5省（市、自治区）汽车拥有量和人均CO2排放量现状.采用变异系数分析方法对汽车拥有量和入均CO2排放量各地区差异大小变化趋势进行了分析,采用一元线性回归模型对华北地区未来10年汽车拥有量和人均CO2排放趋势及其地区差异大小变化趋势进行了预测,提出了相关建议,以期为该地区乃至全国经济和环境的和谐发展提供参考.