陕西咸阳人工林地土壤干层研究

根据咸阳庞西村苹果林地、梧桐林地和草地土壤含水量测定,研究了0~6m土壤含水量的变化和土壤干层特点与分布。结果显示, 咸阳人工林地从表层向下含水量呈现由高到低再到低的变化;10龄苹果林地2~4m深处土壤含水量平均为8.3%,12龄梧桐林2~4m深处土壤含水量平均为8.6%,均发育了明显的土壤干层;4龄苹果林下土层有干化显示,但无干层发育;草地土层含水量明显较苹果林地高,无土壤干化的显示。研究表明,土壤干层形成的具体原因一是降水量少决定的薄膜水带埋藏深度小,二是薄膜水的运移速度缓慢和含水量低。为保持人工林基本正常的生长和土壤水的正常运移,应避免严重的土壤干层出现。咸阳附近土壤干层的出现表明土壤干层在黄土高原广泛分布,该区的植被恢复首先应以疏林或森林草原为主,待土壤水分改善后再考虑恢复森林植被。     

西安城市扩张及其驱动力分析

随着人口的增长与经济的发展,尤其我国西部城市在西部大开发的背景下,大中城市的扩张十分明显,深刻地影响城市周边的生态环境。如何快速准确地获取城市扩张信息,并分析其驱动力机制,对于指导城市规划,优化西部生态环境与可持续发展都具有十分重要的意义。作者分别采用了监督分类法和归一化裸露指数 (NDBI) 法提取了西安市的城市边界信息,并对二者进行对比分析,认为监督分类法提取的城市边界信息较为准确。在此基础上通过对相关统计资料的分析,认为西安市城区快速扩张与西部大开发以来西安市固定资产投资额的大幅增加以及经济的快速发展有密切的关系,此外人口的增加、交通等基础设施的发展也是重要的驱动因素。     

北京市不同土地利用类型的土壤镉含量特征

通过对北京市菜地、稻田、果园、绿化地、麦地以及自然土壤6种土地利用类型共595个土壤样品的调查分析,探讨了不同土地利用方式对土壤镉含量的影响。结果表明,绿化地、麦地以及自然土壤与背景值没有显著差别;菜地、稻田、果园的镉含量显著高于背景值。6种土地利用类型中,菜地土壤的镉含量最高,其次为稻田和果园,绿化地以及麦地土壤镉的含量最低。与土壤基线值相比,果园样品有9.5%的样品超出,绿化地与菜地分别有7.7%和4.6%超出。在全部土壤样品中,共有19个样品超标,超标率为3.2%。石景山、门头沟、丰台、海淀等地区的样品超标较多,应该合理规划这些地区的农业土地利用。     

A study on the early-warning technique concerning debris flow disasters

According to the principle of the eruption of debris flows, the new torrent classification techniques are brought forward. The torrent there can be divided into 4 types such as the debris flow torrent with high destructive strength, the debris flow torrent, high sand-carrying capacity flush flood torrent and common flush flood by the techniques. In this paper, the classification indices system and the quantitative rating methods are presented. Based on torrent classification, debris flow torrent hazard zone mapping techniques by which the debris flow disaster early-warning object can be ascertained accurately are identified. The key techniques of building the debris flow disaster neural network (NN)real time forecasting model are given detailed explanations in this paper, including the determination of neural node at the input layer, the output layer and the implicit layer, the construction of knowledge source and the initial weight value and so on. With this technique, the debris flow disaster real-time forecasting neural network model is built according to the rainfall features of the historical debris flow disasters, which includes multiple rain factors such as rainfall of the disaster day, the rainfall of 15 days before the disaster day, the maximal rate of rainfall in one hour and ten minutes. It can forecast the probability, critical rainfall of eruption of the debris flows, through the real-time rainfall monitoring or weather forecasting. Based on the torrent classification and hazard zone mapping, combined with rainfall monitoring in the rainy season and real-time forecasting models, the debris flow disaster early-warning system is built. In this system, the GIS technique, the advanced international software and hardware are applied, which makes the system′s performance steady with good expansibility. The system is a visual information system that serves management and decision-making, which can facilitate timely inspect of the variation of the torrent type and hazardous zone, the torrent management, the early-warning of disasters and the disaster reduction and prevention.     

Quaternary geomorphological evolution of the Kunlun Pass area and uplift of the Qinghai-Xizang (Tibet) Plateau

There is a set of Late Cenozoic sediments in the Kunlun Pass area, Tibetan Plateau, China. Paleomagnetic, ESR and TL dating suggest that they date from the Late Pliocene to the Early Pleistocene. Analyses of stratigraphy, sedimentary characteristic, and evolution of the fauna and flora indicate that, from the Pliocene to the early Quaternary (about 5–1.1 Ma BP), there was a relatively warm and humid environment, and a paleolake occurred around the Kunlun Pass. The elevation of the Kunlun Pass area was no more than 1500 m, and only one low topographic divide existed between the Qaidam Basin and the Kunlun Pass Basin. The geomorphic pattern in the Kunlun Pass area was influenced by the Kunlun–Yellow River Tectonic Movement 1.1–0.6 Ma BP. The Wangkun Glaciation (0.7–0.5 Ma) is the maximum Quaternary glaciation in the Pass and in other areas of the Plateau. During the glaciation, the area of the glaciers was 3–5 times larger than that of the present glacier in the Pass area. There was no Xidatan Valley that time. The extreme geomorphic changes in the Kunlun Pass area reflect an abrupt uplift of the Tibet Plateau during the Early and Middle Pleistocene. This uplift of the Plateau has significance on both the Plateau itself and the surrounding area.     

关于黄土碳酸盐与气候环境关系探讨

黄土中碳酸盐与气候环境密切相关。从碳酸盐的成因看，干冷的气候利于原生碳酸盐的保存，而温湿的气候使大量的次生碳酸盐产生。碳酸盐的存在形式与降水量多少有关，降水量大可形成结核层和钙板等，而降水量小则形成各种胶膜。胶膜中各种不同形态的方解石胶膜又可反映不同的气候条件。黄土一古土壤中形成的碳酸盐实际上在古土壤期形成的碳酸盐要高于黄土期形成的，只是由于古土壤期强烈的风化淋溶作用，大量的碳酸盐从古土壤中淀积到下伏的黄土层中。黄土中CaCO3的淀积可分为连续淀积和不连续淀积两类。依据淀积深度和降水量的关系，可建立二者定量的关系。从黄土碳酸盐的不同方面，得到其与气候环境关系较为全面的认识。     

塔里木沙漠南缘安迪尔河水文特征分析

安迪尔河位于塔里木沙漠南缘,发源于昆仑山,上游河水沿河床大量入渗,中游为干河床,下游为泉水溢出补给型河流。安迪尔河缺乏水文资料,以临时水文站1998年实测水文资料为依据,对安迪尔河的水文特征进行分析,以便说明泉水型河流水文特征。分析了安迪尔河水位年内变化、冰期水位、畅流期水位、洪水期水位的变化特征;对安迪尔河水位流量关系进行了分析,建立了相应的水位流量关系方程式,并对冰期、畅流期的、洪水期逐日平均流量和流量特征进行了推求和分析,安迪尔河1998年泉水溢出量为0.5528亿m3。     

人类活动对塔里木河年径流影响量的估算

塔里木河流域与环境的研究，一直是近年来新疆环境演化和可持续发展研究的热点问题。大规模的区域开发活动对该流域生态环境产生了根本性的影响，区域整体生态环境趋于恶化。本文通过对年径流量累积曲线和年径流量的相关分析，估算出人类活动对塔里木河各河段的年径流量变化及其对生态环境造成的影响。     

珠江三角洲地区一体化交通运输网络发展构想

从区域经济一体化角度分析了珠江三角洲经济区交通运输的现状、问题和发展趋势，提出了建设一体化交通运输网络的基本思路和总体构想。认为珠三角交通运输设施虽然种类齐全且发展迅速，但还存在数量、质量、结构、布局等方面与区域经济一体化和未来发展趋势不相适应的问题；为了促进区域经济一体化，交通运输应从被动适应变为主动发展并引导城镇体系和生产力布局，从注重设施数量变为强调设施质量并向高速高效型发展；应该分4个层次建设3个枢纽和3大组团并与大运量快速干线相连接，构建区域一体化的交通运输网络。     

我国低山丘陵区水土流失生态环境背景分析

我国是一个以山地为主的国家，山地多为大江大河的源头，而低山丘陵为这些大江大河支流的发源地，这些区域的水土流失必然会带来环境问题。本文以TM影象为数据源，以GIS为技术支撑，从DEM中获取低山丘陵层，以此为MASK层，提取水土流失及相应的生态环境背景各层，包括土地利用、坡度、年降水、积温、植被等生态背景层，这些背景层是多年数据的平均，然后把水土流失层与环境背景各层分别叠加，分析不同环境背景下水土流失状况，从而为治理水土流失提出科学依据。