Chuancheng Zhao

Understanding the impact of mountain landscapes on water balance in the upper Heihe River watershed in northwestern China

Estimating the impact of mountain landscape on hydrology or water balance is essential for the sustainable development strategies of water resources. Specifically, understanding how the change of each landscape influences hydrological components will greatly improve the predictability of hydrological responses to mountain landscape changes and thus can help the government make sounder decisions. In the paper, we used the VIC (Variable Infiltration Capacity) model to conduct hydrological modeling in the upper Heihe River watershed, along with a frozen-soil module and a glacier melting module to improve the simulation. The improved model performed satisfactorily. We concluded that there are differences in the runoff generation of mountain landscape both in space and time. About 50% of the total runoff at the catchment outlet were generated in mid-mountain zone (2,900–4,000 m asl), and water was mainly consumed in low mountain region (1,700–2,900 m asl) because of the higher requirements of trees and grasses. The runoff coefficient was 0.37 in the upper Heihe River watershed. Barren landscape produced the largest runoff yields (52.46% of the total runoff) in the upper Heihe River watershed, followed by grassland (34.15%), shrub (9.02%), glacier (3.57%), and forest (0.49%). In order to simulate the impact of landscape change on hydrological components, three landscape change scenarios were designed in the study. Scenario 1, 2 and 3 were to convert all shady slope landscapes at 2,000–3,300 m, 2,000–3,700 m, and 2,000–4,000 m asl respectively to forest lands, with forest coverage rate increased to 12.4%, 28.5% and 42.0%, respectively. The runoff at the catchment outlet correspondingly declined by 3.5%, 13.1% and 24.2% under the three scenarios. The forest landscape is very important in water conservation as it reduced the flood peak and increased the base flow. The mountains as “water towers” play important roles in water resources generation and the impact of mountain landscapes on hydrology is significant.

Modeling Hydrologic Response to Climate Change and Shrinking Glaciers in the Highly Glacierized Kunma Like River Catchment, Central Tian Shan

AbstractArid and semiarid lowland areas of central Asia are largely dependent on fluvial water originating from the Tian Shan. Mountain glaciers contribute significantly to runoff, particularly in summer. With global warming, the total glacier area in the Kunma Like River catchment declined by 13.2% during 1990–2007. For future water resources, it is essential to quantify the responses of hydrologic processes to both climate change and shrinking glaciers in glacierized catchments, such as the headwaters of the Tarim River. Thus, a degree-day glacier melt algorithm was integrated into the macroscale hydrologic Variable Infiltration Capacity model (VIC). Good results were obtained for monthly runoff simulations in the Kunma Like River catchment, which suggest that the extended VIC has acceptable performance. Because of increased precipitation and air temperature, annual runoff in the catchment has increased by about 4.07 × 108 m3 decade−1 during 1984/85–2006/07. Under the assumption of the same climatic con...

Effects of environmental factors on the distribution of plant communities in a semi-arid region of the Qinghai-Tibet Plateau

Against the background of global climate warming, the relationship between plant communities in high-cold ecosystems and environmental gradients has attracted much attention. We investigated the relationship between the distribution of plant communities and environmental factors in a semi-arid region of the Qinghai-Tibet Plateau. We analyzed the effects of environmental factors on the distribution of plant communities using two-way indicator species analysis and canonical correspondence analysis. The most important factor explaining the distribution of plant communities was the depth of the active layer of permafrost (denoted as PF), followed by soil water content at 40-cm soil depth. There was a strong correlation between these two factors. With changes in the PF, the dominant species in plant communities showed an obvious transition. The indices of species richness and species diversity decreased markedly with increasing PF, whereas biomass and vegetation coverage showed weaker responses to changes in the PF. The distribution structure for plant communities in this area mainly results from changes in the PF. Furthermore, the PF has remarkable and important effects on the characteristics of the plant community.

Detection of precipitation variability based on entropy over nearly 50 years in Xinjiang, northwestern China

Based on precipitation data of 53 meteorological stations from 1960 to 2008, the entropy method was used to analyze spatial variability of precipitation in Xinjiang, China, over monthly, seasonal, and annual timescales. The spatial distribution of precipitation variability was significantly affected by topography and was zonal on all timescales. The nonparametric Mann-Kendall test was used to analyze changes in the distributions. A precipitation concentration index was developed to categorize the variability of annual precipitation. Summer variability contributed less to annual variability than that of other seasons. Various months contributed to annual mean variability differently across the years. Overall, the variability of precipitation was shown to increase north of Xinjiang, especially in mountainous regions, where the increase was statistically significant (P = 0.05). South of Xinjiang, the variability increased only slightly, consistent with the distribution of precipitation.

Validation of the Accuracy of Different Precipitation Datasets over Tianshan Mountainous Area

Precipitation is one of the important water supplies in the arid and semiarid regions of northwestern China, playing a vital role in maintaining the fragile ecosystem. In remote mountainous area, it is difficult to obtain an accurate and reliable spatialization of the precipitation amount at the regional scale due to the inaccessibility, the sparsity of observation stations, and the complexity of relationships between precipitation and topography. Furthermore, accurate precipitation is important driven data for hydrological models to assess the water balance and water resource for hydrologists. Therefore, the use of satellite remote sensing becomes an important means over mountainous area. Precipitation datasets based on station data or pure satellite data have been increasingly available in spite of several weaknesses. This paper evaluates the usefulness of three precipitation datasets including TRMM 3B43_V6, 3B43_V7, and Asian Precipitation Highly Resolved Observational Data Integration Towards Evaluation with rain gauge data over Tianshan mountainous area where precipitation data is scarce. The results suggest that precipitation measurements only provided accurate information on a small scale, while the satellite remote sensing of precipitation had obvious advantages in basin scale or large scale especially over remote mountainous area.

The Temporal Precipitation in the Rainy Season of Koxkar Glacier Based on Observation Over Tianshan Mountain in Northwest of China

Precipitation, as one of important input variable for land surface hydrologic and ecological models, shows a high spatial and temporal variation. The daily precipitation by manual measurement is collected in Koxkar glacier catchment in rainy season during the period of 2009–2016, and hourly precipitation by standard tipping rain gauge is collected from May 19 to August 22 in 2016. Comparing the manual and standard tipping rain gauge, the performance of standard tipping rain gauge is suited in Koxkar glacier catchment in rainy season. The distribution of hourly precipitation is analyzed. The results have shown that precipitation is occurred more in daytime than in night, and frequency is concentrated at 15:00 to 17:00. The trend of precipitation and precipitation days are consistent at night, but obvious inconsistency in the daytime. These characteristics of precipitation have important role for further understanding of glacier changes with climate change.

The Application of Greedy Algorithm in Real Life

Greedy algorithm, also known as voracity algorithm, and is simple and easy to adapt to the local area of the optimization strategy. In other words, every time it makes the choice is the best choice in the current. It is not considered from the point of view of the overall optimization to consider, but every time the choice is only in a sense of the local optimal choice. So, for a problem, we should consider whether it can use the greedy algorithm strategy, and whether the solution we find is the optimal solution. It is not an overall optimal solution to any problem, but most of the problems with a wide range of problems can be solved by the global optimal solution or the similar solution of the global optimal solution. With the arrival of the era of big data, a large number of data information needs to be processed in a timely manner, In order to meet the needs of people to deal with a large number of data information, and to solve various practical problems in a timely manner, computer algorithm got the rapid development, A large number of operations research models have been applied to the computer algorithm, which has produced many effective algorithms to solve practical problems. Greedy algorithm in solving the problem, it is from the initial stage, in each stage is to make a local optimal greedy choice. Each time the greedy choice transforms the original problem into a sub problem of the same form as the original problem. Greedy algorithm has no fixed algorithm framework, the key of the design algorithm is the choice and determination of greedy strategy.

On the Vertex-Distinguishing Edge Chromatic Number of ∨

A proper edge coloring of graph G is called equitable adjacent strong edge coloring if colored sets from every two adjacent vertices incident edge are different, and the number of edges in any two color classes differ by at most one, which the required minimum number of colors is called the adjacent strong equitable edge chromatic number. In this paper, we present the edge coloring of join-graphs about path and cycle, and gain the vertex-distinguishing edge chromatic number of 𝑃𝑚 ∨ 𝐶𝑛.

The Spatial-temporal Distribution of Precipitation in Northwest China (1960-2008)

Northwest China, covering the provinces of Shaanxi, Gansu, Qinghai, Ningxia, Xinjiang, and a portion of Inner Mongolia, has an extremely complex climate due to the varied terrain where environment is sensitive to climate change. We employed the Mann-Kendal test to investigate trends of precipitation distributions using annual, seasonal and monthly data records from 1960 to 2008. On the whole, the trends of precipitation are more complex than those for temperature. The trends of annual, seasonal and monthly precipitation have shown remarkable difference between the east and west. In the west, such as in northern Xinjiang and western Qinghai, the trend has shown a significant increase, consistent with the temperature change. Whereas in the east such as in eastern Gansu, southern Shaanxi, the trend has shown a remarkable decline, opposite to the change observed in temperatures.