Study on the Status and Topographic Heterogeneity of the Headwater Region of the Three Rivers

Dan WU

Shaanxi Land Engineering and Technology Research Institute Co., Ltd., Xi’an 710075, China; Shaanxi Land Engineering Construction Group Co., Ltd., Xi’an 710075, China; Key Laboratory of Degraded and Unused Land Consolidation Engineering, Ministry of Natural Resources, Xi’an 710075, China; Shaanxi Land Consolidation Engineering Technology Research Center, Xi’an 710075, China

Abstract The ecological environment of the Three-River Headwater Region is primitive and unique, and sensitive and complex to external influences. The Three-River Headwater Region is the largest nature reserve in China, and is also a nature reserve with the highest concentration of biodiversity in the world’s high-altitude areas, so the protection of ecological diversity in this region is particularly important. Ecological diversity is the material basis on which the entire humanity depends to survive and develop. It not only provides humans with basic needs such as food, energy and materials, and is also extremely important for maintaining ecological balance, regulating the climate and promoting the sustainable development of the region. Studying the topographical heterogeneity of the region is first of all a true grasp of the topography of the region, which has certain guiding significance for people’s production and life. In addition, studying the impact of topographical heterogeneity on the climate of the region will help to study the formation and variation of regional climate.

Key words Three-River Headwater Region, Ecological environment, Humanistic environment, Topographic heterogeneity

1 Introduction

The Three-Water Headwater Region is the birthplace of the Yangtze River, Yellow River and Lancang-Mekong River, an international river, and it is a treasure trove of biodiversity resources. The study on the topographic heterogeneity of this region is helpful to understand the natural, ecological and human resources in this region.

For geographic research, topographic analysis is the most important basic research. Topographic analysis is widely used in geography, ecology, humanities, civil engineering related research. As the initial research object, it provides a basis for further impact research and analysis. The concept of heterogeneity comes from biology. The heterogeneity in topography can be simply understood as the degree of change in terrain per unit area. In nature, it refers to the different nature and performance of terrain. Since the 18th century, hypsographic map has been introduced to topography. It is currently treated as an important method to study the terrain.

2 Current status of the region

2.1 Ecological statusThe overall environment of the Headwater Region of the Three Rivers has deteriorated. The main culprits are global warming and increased human activity. The original ecological environment of this region is more vulnerable than other regions in China, and its response to changes is also more rapid. The impact of climate change alone has produced a relatively large change in the environment of the region, and coupled with the impact of human activities, the region has undergone tremendous changes. In recent years, the population of the Three-River Headwater Region has increased significantly, and due to excessive exploitation and utilization of natural resources, coupled with the global warming, the natural ecological environment has been gradually deteriorating, the original grazing pastures have been severely degrading, and the natural environment of the entire region has been slowly deteriorating. The alpine meadows in the Three-River Headwater Region are the main body of the alpine grassland ecosystem. Since the 1990s, grassland degradation has accelerated, and it has become the region with the most severe, the largest, and the fastest grassland degradation, and the most prominent ecological problems in the entire Qinghai Province. According to the statistics, there are currently moderate to above-grade degraded grasslands accounting for 63.3% of the total grassland area in the region, the output of natural grassland decreased by an average of 53.2% compared with the 1980s, and large areas of alpine meadows have degraded into secondary barren "black mudflat"[1]. According to survey figures provided by the Qinghai Forestry Bureau, in recent years, the area of "black mudflat" in the Headwater Region of the Three Rivers has reached 1.19 million ha; the desertification area has reached 253 ha, and it is expanding at an annual rate of 5 200 ha; and the rate of desertification has increased from 3.9% in the 1970s to 1980s to 20% in the 1980s and 1990s[2].

2.2 Humanistic statusAmong the 16 counties in the entire Three-River Headwater Region, 14 counties are key counties for national poverty alleviation work. More than 70% of the population in the region is poor. The production and lifestyle of people in this region are mainly based on animal husbandry. In the region, the Tibetan population accounts for nearly 90% of the total population. In addition, there are Han, Hui, Sahara, Mongol and other nationalities. Due to large area and small population, the average population density in the region is only 0.5 people/km2, which is relatively small. In the region, Tibetan nationality has a large population, and almost all the Tibetan population believes in Lamaism (a type of Buddhism), so Tibetan Buddhism is the main religion in this region[3]. Due to the convenience of transportation in recent years, the tourism resources in the Three-River Headwater Region, the so-called "inaccessible virgin land", are gradually being developed. In particular, the tourism centered on Yushu has a distinct advantage for its unique charm. The original natural landscapes such as mountains, rivers, vast grasslands, wetland resources, and animal paradise in this region are also generally accepted by tourists. Among them, the Tibetan Buddhism scenery and the unique animal resources such as Tibetan antelope, Tibetan wild ass and Tibetan yak unique to the Three-River Headwater Region have attracted tourists from other places. As a rich area for tourism in Qinghai, the Three-River Headwater Region is also a scarce resource zone for China’s tourism and the world’s tourism industry. There are many aspects that can be developed and utilized. The so-called true green and pollution-free tourism resources are irreplaceable. To this end, this region has been planned as a key region for tourism development by Qinghai Province, with quite rich humanities landscapes.

2.3 Protection measuresFor the protection of the Headwater Region of the Three Rivers, national policy orientation has become an important factor. In general, the management of the region mainly includes control of rodent damage, reclamation of black mudflat (bare land), returning farmland to grassland, ecological migration, controlled grazing and policy protection. (i) In terms of policy, a no-pastoral area should be established, and economic compensation (e.g. forage compensation) should be provided to herders to let herders reduce the amount of livestock and frequency of grazing, and try to change from free grazing to captivity. (ii) Returning farmland to grassland and forestry to enable natural restoration of grasslands and woodlands, when necessary, artificial planting of saplings and grass seeds and artificial protection can be carried out to allow natural restoration. (iii) Water consumption should be reduced. Ecological migration can be conducted to the population, and the water supply and resource compensation can be unified to reduce the consumption of natural resources. (iv) Mining areas with small mineral resource production in the region and self-developed private mines such as gold mines and coal mines should be shut down to reduce damage to the ground. (v) Rodent damage must be controlled comprehensively. Cats or natural enemies can be introduced for elimination. Species that affect local ecology are not allowed to be introduced. (vi) When weather permits, artificial rainfall should be increased to supplement surface runoff. The phenomenon of unauthorized drilling and unauthorized trenching should be reduced. GDP should not be used to estimate the economy in the region, that is, GDP should not be taken as the primary task. Instead, the main direction should be put on comprehensive governance. (vii) When conditions are ripe, the policy of downstream supporting upstream should be formulated. That is, a portion of money is added to the financial expenses of downstream provinces and cities and used to provide certain compensation to the people’s production and life and the protection of the region. Among these measures, in particular, national and government policies should be used as a guide to carry out relevant deployments. Groups or individuals in civil forces must also actively respond to national policies. A leadership responsibility system should be implemented to government officials. Zoning should be carried out in relevant areas. If the comprehensive management of the region is achieved, the people of the region will be given with a good ecology, Qinghai Province will be given with a pollution-free tourist resort, and people throughout China and even the world will be given with a good place to relax and vacation.

3 Research methods of topographic heterogeneity

The topographic heterogeneity of the DEM grid cell can be understood as the complexity of the terrain inside the grid unit. In digital terrain analysis, its existence may result in an analysis result that is inconsistent with reality. However, at present, there is no comprehensive measurement index that can measure the degree of the topographic heterogeneity of DEM grid cells. The analysis of the topographic heterogeneity of DEM grid cells mainly uses the four indicators of elevation standard deviation, topographic relief amplitude, surface roughness and average slope. Digital elevation model (DEM) is one of the basic data for digital terrain analysis. It divides the terrain surface into a series of grid cells. In flat terrain or terrain with consistent changes, DEM data has a very high horizontal resolution[4]. DEM data can be used as the first choice for studying topographic heterogeneity. Its data acquisition is relatively simple, processing process is easy to achieve, and results obtained are credible. By processing the four indicators of topographic relief, elevation standard deviation, average slope and surface roughness in a certain area, topographic heterogeneity can be analyzed from four directions. Processing of DEM data includes the relevant acquisition of the results about elevation analysis, slope analysis, aspect analysis, flow direction analysis, and flow direction analysis of no depressions. Based on the processing results obtained, further conclusions are drawn.

3.1 Topographic relief amplitudeTopographic relief refers to the difference between the maximum altitude and the minimum altitude. This value can reflect the variation of terrain in a certain area to a certain extent, and show the ground undulation in the area. But the problem with the study of the difference between the maximum elevation and the minimum elevation is that it cannot objectively reflect the overall vertical topographic changes in a certain area, and as a single data, it can only be regarded as a reference value, because the map statistics of different scales are very different.

3.2 Elevation standard deviationStandard deviation, a frequently used parameter in mathematics, can be used to reflect the dispersion of certain data and standard data when it is used in the description of terrain changes. Elevation standard deviation refers to the change of elevation in the area. It can be used as an indicator to measure the variation of terrain in grid cells. Standard deviation of elevation reflects the degree of dispersion of the elevation of each point and the average of elevation. When using the elevation standard deviation to describe the terrain, it reflects the elevation variation of the terrain within the grid cell when the grid cell size is close to or consistent with the slope length or gives the roughness of the geomorphologic landscape unit when the grid cell size is inconsistent with the slope length.

3.3 Average slopeAverage slope in a general sense refers to a relatively average performance value of the slope of a certain area. Strictly speaking, the slope of a point on the ground refers to the angle between the tangent plane and the horizontal plane of the changed point, which indicates the inclination of the terrain surface at that point. Objectively, the topography at this point is a relatively full reflection of the region, and is an important data of the vertical change of the terrain.

3.4 Surface roughnessWhen roughness is applied to the description of terrain, it can reflect the deformation characteristics of terrain in the horizontal direction. Its general definition is the ratio of the surface area of the surface unit to its projected area on the horizontal plane. The terrain change in the vertical direction is expressed by the height of the undulation. Roughness indicates the change in the topography in the horizontal direction.

4 Conclusions

The Headwater Region of the Three Rivers is rich in natural resources. It is rich in minerals, plants, and animal resources, and also has some precious animals and plants that only this place has in the world. The contribution of these animals and plants to the richness of the world’s gene pool is incalculable. The support of human production and life culture for intangible cultural heritage also exists only in this area, and the intangible culture is shining. However, due to the impact of global warming on the region and the uncontrolled human activities in the region after the founding of the People’s Republic of China, the original landforms and original biological activities in this region have been greatly affected. With the response of national policies and the increasing awareness of environmental protection among the people in the new century, the previous pollution, waste and indiscriminate killing in the region have clearly improved. It is believed that under the comprehensive consciousness and synchronized action of China and people, the Three-River Headwater Region will be ushered to a bright tomorrow. According to some relevant studies in recent years, it is found that the evolution of the ecological environment in the region has been controlled and influenced by the warming and drying trend of the general environment. At the same time, it is also influenced by the occurrence of regional ecological and environmental problems caused and promoted by human unreasonable activities. Analysis on the evolution of the regional large-scale environment has shown that the development trend of the warm and dry climate of the Qinghai-Tibet Plateau, including the Three-River Headwater Region is becoming increasingly obvious. Aiming at the ecological changes in the region, it is not only necessary but also urgent to carry out relevant topographic heterogeneity analysis. Through the analysis of topographic heterogeneity in this region, we can grasp the unique natural and humanistic status in this region, in order to provide practical method for further protection and guidance measures.