堤防工程在流域生态综合治理项目中的应用——以甘肃省岷县藏河流域生态综合治理项目为例

在流域生态综合治理项目中,堤防工程的应用,能有效控制流域内水土流失。通过区域水土流失野外调查、室内调绘、资料分析等方法,探讨了藏河流域生态综合治理项目中堤防工程布设位置及配置模式,建立了岷县藏河流域堤防工程与生态措施相结合的综合防治技术体系,对促进流域治理与保护环境的协调发展具重要的指导价值,对保护河堤两岸耕地及保障河堤两岸居民安全具有重要的现实意义。

Extensive genetic divergence among Diptychus maculatus populations in northwest China

D. maculates is a kind of specialized Schizothoracinae fish has been locally listed as a protected animal in Xinjiang Province, China. Ill River located in north of Tianshan Mountain and Tarim River located in north of Qinghai-Tibetan Plateau were two main distribution areas of this fish. To investigate the genetic diversity and genetic structure ofD. maculates, four populations from Tarim River system and two populations from Ili River system were collected in this study. A 570-bp sequence of the control region was obtained for 105 specimens. Twenty-four haplotypes were detected from six populations, only Kunes River population and Kashi River population shared haplotypes with each other. For all the populations examined, the haplotype diversity （h） was 0.904 8±0.012 6, nucleotide diversity （n） was 0.027 9±0.013 9, and the average number of pairwise nucleotide differences （k） was 15.878 3±7.139 1. The analysis of molecular variance （AMOVA） showed that 86.31% of the total genetic variation was apportioned among populations, and the variation within sampled populations was 13.69%. Genetic differences among sampled populations were highly significant. Fst statistical test indicated that all populations were significantly divergent from each other （P〈0.01）. The largest Fst value was between Yurungkash River population and Muzat River population, while the smallest fst value was between Kunes River population and Kashi River population. NJ phylogenetic tree of D-loop haplotypes revealed two main clades. The neutrality test and mismatch distribution analysis suggested that the fish had went through a recent population expansion. The uplift of Tianshan Mountain and movement of Qinghai-Tibetan Plateau might contribute to the wide genetic divergence of D. maculates in northwest China.

Livelihood Strategy Change and Land Use Change——Case of Danzam Village in Upper Dadu River Watershed,Tibetan Plateau of China

Land use change in rural China since the 1980s, induced by institution reforms, urbanization, industrialization and population increase, has received more attention. However, case studies on how institution reforms affect farmers＇ livelihood strategies and drive land use change are scarce. By means of cropland plots investigations and interviews with farmers, this study examines livelihood strategy change and land use change in Danzam Village of Jinchuan County in the upper Dadu River watershed, eastern Tibetan Plateau, China. The results show that, during the collective system period, as surplus labor forces could not be transferred to the secondary and tertiary industries, they had to choose agricultural involution as their livelihood strategy, then the farmers had to produce more grains by land reclamation, increasing multiple cropping index, improving input of labor, fertilizer, pesticide and adopting advanced agricultural techniques. During the household responsibility system period, as labors being transferred to the secondary and tertiary industries, farmers chose livelihood diversification strategy. Therefore, labor input to grain planting was greatly reduced, which drove the transformation of grain to horticulture, vegetable or wasteland and decrease of multiple cropping index. This study provides a new insight into understanding linkages among institution reforms, livelihood strategy of smallholders and land use change in rural China.

Analysis of Longitudinal Profiles along the Eastern Margin of the Qinghai-Tibetan Plateau

Resulting from the collision of the Eurasian and Indian plates, the Qinghai-Tibetan Plateau is commonly known as the ＇roof of the world＇. Collectively the Yarlung Tsangpo, Nu, Laneang, Yangtze, Yalong, and Yellow River basins drain the eastern margin of the plateau. In this paper, we utilize Shuttle Radar Topography Mission elevation data to examine morphometric and relief attributes of these basins to reveal insights rates of incision. A robust into tectonic activity and technique using Maflab is proposed to alleviate errors associated with SRTM data in the derivation of river longitudinal profiles. Convex longitudinal profiles are interpreted to be a product of uplift rates that exceed rates of channel incision along the entire margin of the Qinghai- Tibetan Plateau. Highest relief towards the south reflects extensive fluvial incision. High relief is also prominent along major active faults. Erosion patterns are related to distance from knickpoints. Highest rates of erosion and incision are evident towards the south, with decreasing values towards the north, suggesting a link between tectonic activity and erosion.

Thermokarst lake changes between 1969 and 2010 in the Beilu River Basin, Qinghai–Tibet Plateau, China

This work presents changes of thermokarst lakes from Beilu River Basin on the Qinghai-Tibet Plateau over the past four decades （1969-2010） using aerial and satellite image interpretation. The results indicated that thermokarst lake activity had generally increased rapidly between 1969 and 2010. The number of thermokarst lakes had increased by approximately 534, and their coverage expanded by about 410 ha. The two main changes observed were an increase in the number of small lakes and the expansion of larger lakes. These changes are likely the result of persistent climate warming and a gradually increasing imbalance between precipitation and evapotranspiration （PET）. However, some non-climatic factors, such as the lake-bottom substrate and local engineering activities, have also influenced the lake changes. If air temperature and P-ET continue to rise, the number of thermokarst lakes and the area they cover may continue to increase in the future.