Landuse/landcover changes in Zhangye oasis of Hexi Corridor

Taking two f alse color composite Landsat 5 TM (Thematic Mapper) images of band 4,3,2 taken in 1995 and 2000 as data resources, this paper carried out study on LUCC of Zhan gye oasis in recent five years by interpretation according to land reso urces classification system of 1:100,000 Resources and Environmental Data base of the Chinese Academy of Sciences. The results show that great changes have taken place in landuse/landcover in Zhangye oasis since 1 995: (1) Changes of landuse structure show that cropland and land for urban c onstruction and built-up area increased, on the contrary, water area an d grassland decreased. These changes reflect the deterioration of eco-e nvironment and the acceleration of urbanization, and also indicate the problems existing in the arrangement of water and land resources betw een the upper and lower reaches of the Heihe River. (2) Regional diff erences of landuse/landcover are evident, characterized by following asp ects: in Sunan County located in Qilian Mountain area, unused land an d grassland decreased, but cropland and land for urban construction an d built-up area increased. In Minle and Shandan counties located in f oothills, unused land, water area and cropland decreased, but grassland and land for urban construction and built-up area increased. In Zhan gye City, Linze County and Gaotai County located in plain area of th e middle reaches of the Heihe River, unused land, water area and gra ssland decreased, while woodland, cropland and land for urban construction and built-up area increased.

Analysis of Anomalous Characteristics of Regional Crustal Deformation before the September 16^th,2019 Zhangye MS5.0 Earthquake,Gansu,China

To study the crustal movement in the vicinity of the epicenter before the Zhangye MS5.0 earthquake in 2019, the characteristics of crustal deformation before the earthquake are discussed through the GPS velocity field analysis based on the CMONOC data observed from GPS. The baseline time series between two continuous GPS stations and the strain time series of an area among several stations are analyzed in the epicenter area. The resulting time series of baseline azimuth around the epicenter reflects that the energy of the fault in the northern margin of Qilian Mountain is accumulated continuously before 2017. Besides,the movement trend of azimuth slows down after 2017,indicating the stress accumulation on both sides of the seismogenic fault zone has reached a certain degree. The first shear strain and EWdirection linear strain in the epicentral area of the Zhangye MS5.0 earthquake remain steady after 2017,and the surface strain rate decreases gradually after 2016. It is illustrated that there is an obvious deformation loss at the epicentral region three years before the earthquake,indicating that a certain degree of strain energy is accumulated in this area before the earthquake.

Dynamic evaluation of groundwater resources in Zhangye Basin

Groundwater resource is vital to the sustainable development of socio-economics in arid and semi-arid regions of Northwest China. An estimation of the groundwater resources variation in Zhangye Basin was made during 1985-2013 based on long-term groundwater observation data and geostatistical method. The results show that from 1985 to 2013, groundwater storage exhibited tremendous dissimilarity on temporal and spatial scale for the whole Zhangye Basin, especially before and after implementation of the water diversion policy. Trend of groundwater storage varied from quick to slow decline or increase. The accumulative groundwater storage decreased nearly 47.52~ 108 m3, and annual average depletion rate reached 1.64x 108 m3/a. Among which, the accumulative groundwater storage of the river and well water mixed irrigation district decreased by 37.48x 108 m3, accounting for about 78.87% of the total groundwater depletion of the Zhangye Basin. Accumulative depletion of groundwater storage varied in respective irrigation districts. Though groundwater resources depletion rate slowed down from 2005, the overall storage in the whole basin and re- spective districts during 1985-2013 was still in a severe deficit such that, the groundwater resource was in a rather negative balance, which could threaten the local aquifer. This is the joint effect of climate change and human activities, however human activities, such as water diversion policy and groundwater exploitation, became increasingly intense. Our research results could provide a reasonable estimation for the groundwater balance in Zhangye Basin, providing a scientific basis for water resources unified planning and, this method can provide a relatively reliable way of estimation for large scale groundwater resources.

Development of Agricultural Recycle Economy in Arid Areas of Hexi Corridor——A Case Study of Zhangye City, China

Taking Zhangye City as an example, the thesis analyzes the restricted factors of resources and environment confronted by the agriculture in arid area of Hexi Corridor: the first is the agricultural natural resources. The area of cultivated land decreases year by year, and there are sharp decrease of biological diversity as well as the shortage and waste of water resources; the second is the ecological environment. There are critical soil erosion, frequent natural disaster and outstanding agricultural area source pollution; the third is the rural economy. The agricultural structure still can not meet the need of agricultural development in recent years, and the proportion of agricultural product processing is low. It points out that implementation of agricultural recycle economy is the necessary choice of the agricultural development in Zhangye City. Developing recycle economy is conducive to improving ecological environment and realizing agricultural sustainable development; developing recycle economy can solve the agricultural area source pollution to much extent and protect rural environment; developing recycle economy is conducive to adjusting rural industrial structure, increasing job opportunities and increasing farmers' income; developing recycle economy is conducive to elevating the international competitiveness of agricultural products. The thesis also has put forward the countermeasures of developing agricultural recycle economy in Zhangye City as follows: firstly, fostering the ambience of the development of agricultural recycle economy; secondly, forming the incentive mechanism of development of agricultural recycle economy; thirdly, broadening the investment channel of development of agricultural recycle economy; fourthly, perfecting socialized service system of agricultural recycle economy.

The role of social resource of indigenous people in local ecological resource management in China: A preliminary case in Zhangye, Northwestern China

Social resources of indigenous people are valuable wealth, including the social norms, the relational network, belief, attitude as well as the social system which is accumulated from generation to generation. Those social resources are very important for local ecological resource management, which can help diffuseness and communion of skills and traditional conservation techniques for conserving and restoring the ecological sites. Social capital is one indicator of social resources, which is accepted widely. In order to investigate the role of social resources of indigenous people in local ecological resource management, the authors studied the relation between social capital of indigenous people and local ecological resource management, taking Zhangye City as an exam-ple. In this paper, social capital of indigenous people is quantified by constructing social capital index, composed of structural so-cial capital and cognitive social capital; local ecological resource management is quantified by constructing 'Grain for Green Pro-ject' performance index. Based on correlation analysis approach and logistic regression analysis approach, the authors analyzed the relation between social capital and 'Grain for Green Project' performance index, as well as the relations between 'Grain for Green Project' performance index and other factors such as per capita net income, medical treatment and so on. Results showed that the correlation between social capital and 'Grain for Green Project' performance index was positive, the coefficient was 0.761, with P<0.01. An increase of 1 unit in social capital is associated with an increase of 1.550 units in 'Grain for Green Project' per-formance. With factor, such as faction, per capita net income, medical treatment, increasing 1 unit, the 'Grain for Green Project' performance index will increase 3.912, 1.039 and 1.005 units, respectively.

Effect of Long-Term Fertilization on Soil Productivity and Nitrate Accumulation in Gansu Oasis

A long-term （1982-2001） field experiment was conducted in a calcareous soil under wheat （Triticum aestivum L.）-wheat （Triticum aestivum L.）-maize （Zea mays L.） rotation system at Zhangye, Gansu Province, China to determine the effects of long-term fertilization on crop yield, nutrients interactions, content and accumulation of nitrate-N in soil profiles. Twenty- four plots in a split-plot factorial with a combination of eight treatments （from nitrogen （N）, phosphorus （P）, potassium （K） and farmyard manure （M） applications） and 3 replications were selected. Main treatments were M and without M, and the sub-treatments were no-fertilizer （CK）, N, NP and NPK. When P and K fertilizers were part of treatments, their ratio to N was 1N：0.22P：0.42K. All M, P and K fertilizers were applied as the basal dressing. The grain yield was harvested each experimental period and straw yield for the period from 1988 to 1997. After crop harvest in 2000, the soil was sampled from the 0-20, 20-60, 60-100, 100-140 and 140-180 cm depths to determine NO3^--N content. Maize yield of CK in 2000 was only 28.2% of that in 1984, and wheat in 2001 was 25.7% of that observed in 1982. Average impact of fertilizers on grain yield decreased in the order of N 〉 M 〉 P 〉 K. Yield response to N and P fertilizers increased with progress of the experiment. The impact of K fertilizer showed no increase in grain yield during the initial 6 years （1982-1987）, moderate increase in the next 5 years （1988-1992）, and considerable increase in the last 9 years （1993-2001）. The straw yield trend was similar to grain yield. Accumulation and distribution of NO3^--N in soil was significantly affected by annual fertilizations. Mineral fertilizers （NP and NPK） led to NO3^- -N accumulation in most subsoil layers, with major impact in the 20-140 cm depth. The combination of mineral fertilizers and farmyard manure （MNP and MNPK） reduced soil NO3^--N accumulation in comparison to mineral fertilizers, It can be argued that long-term fertilization significantly enhanced grain and straw yield in this rotation scheme. The findings of this research suggest that it is important to balance application of mineral fertilizers and farmyard manure in order to protect soil and underground water from potential NO3^--N pollution while sustaining high productivity in the oasis agro-ecosystem.

Characterization of Nitrate Contamination in an Arid Region of China

There are two pathways for nitrate to enter into human body: drinking water and food. Therefore, nitrate contamination of drinking water and agricultural crops is of particular interest to governments and the general public owing to the possible implications for health. This work investigated nitrate contents in various crops and in different parts of each crop and in drinking water as well in the Zhangye Basin, Northwest China. It provided evidence of severe nitrate contamination of drinking water, especially, in vegetable-growing villages. As to the nitrate contamination of crops, the present study revealed that all sampled crops adjust their nitrate distributions in a way that the edible parts contain much less nitrate than non-edible parts except lettuce. The nitrate content in the edible root of lettuce reached up to 5900 mg/kg exceeding the limit set by the European Commission.