Hydrological Ecological Effects and Climate Response in the Middle reaches of the Heihe River

HYDROLOGICAL ECOLOGICAL EFFECTS AND CLIMATE RESPONSE IN THE MIDDLE REACHES OF THE HEIHE RIVER

Sun Yan

Master's Degree Student, Moscow State University,

Russia, Moscow

Lo Shubin

Master's degree student, Chengdu University of Technology,

China, Chengdu

Li GuLin

Master's Degree student, Chengdu University of Technology,

China, Chengdu

Gou Xiaojuan

Master's Degree student, Chengdu University of Technology,

China, Chengdu

Xu yuan

Master's Degree student, Chengdu University of Technology,

China, Chengdu

By establishing a soil-vegetation-atmosphere model, the qualitative analysis of soil temperature change, the influence of soil water content and plant transpiration in Zhangye area in the middle reaches of the Heihe River under a typical moon, and the quantitative analysis of the relationship between groundwater level and atmospheric precipitation evaporation in the research area on soil water content by using the gray system correlation, and the comparison of groundwater hydrogen and oxygen stable isotopes with atmospheric precipitation isotopes in the research area to determine the main sources of groundwater in the research area.Through the envi-met model, the soil temperature showed uniformity in the dry desert Gobi environment, and there was a downward trend in the soil area near the Heihe Region, but the decline was not large.In forests, crop areas, soil temperature increased significantly, in urban areas, roads and airports and other areas, soil temperature showed a correlation with the thermal radiation of buildings, roads and other building materials in the city; through the gray correlation analysis of groundwater and soil moisture atmospheric evapotranspiration can be seen, shallow groundwater for atmospheric precipitation evaporation dependence is high, surface water and groundwater is the main factor of climate change.When the increase in precipitation leads to a rise in the groundwater diving level, the soil moisture content increases, and the surface evaporation decreases.Compared with the atmospheric precipitation equation, the stable isotope value of groundwater in shallow groundwater and groundwater exposed areas is close to the atmospheric precipitation line, indicating that atmospheric precipitation is its main source of recharge, while deep groundwater is mainly replenished laterally by the aquifer.

1 Overview of the research Area

1.1 Geographical Conditions

Heihe flows to Yingluo Gorge into the Hexi Corridor, flows through the northwest of Zhangye City near 10km, Nashandan River,flood River, flows northwest, through Linze, Gaotai Hui Liyuan River,Dinglang River through the justice Gap, flows into the Alashan Plain, the length of the river 204km, an area of 25,600 km2, the research area was selected in the middle reaches of the Heihe River basin Zhangye City, geographical coordinates 40°92'-38°50'n, 99°8'-99°51'e.In the middle reaches of the Heihe River, the terrain is flat,the altitude is between 1200~1700m,the sunshine time is long and the light resources are sufficient,the climate is arid, the annual precipitation is only about 140mm, the average annual temperature is 7.2℃, the annual sunshine hours are up to 3000 ~ 4000 hours, the annual evaporation capacity is 1410mm.

1.2 Hydrological atmospheric conditions

The research area is located in the middle reaches of the Heihe River Basin, located in the center of Eurasia, the climate type is continental monsoon climate, the climate of the region is dry, belongs to the northwest inland temperate continental arid climate, the annual precipitation is small evaporation intensity, the temperature difference between day and night is obvious, the sunshine is sufficient, the climate is clear.The main sources of groundwater in the research area are the groundwater of Qilian Mountain in the upper reaches of the Heihe and the lateral recharge of the Heihe.

The main rivers of Zhangye Basin are Heihe,Liyuan River, Shandan River, Da Porcelain Kiln River, Dayokou River, Ghee Kou River, Dazu Ma River, Xiaojiu Ma River, Haichao Dam River, Flood River, Yudai River, Tongzi Dam River, the black River as the main river accounted for 70.1% of the region's rivers, the average annual runoff of 15.94.

Figure 1． Runoff of Yingluo Gorge

Figure 2． Runoff at Hongshuihe Station

From April to May, the upper reaches of the snow melt,the flow of the Black River increases,June to August, the temperature rise leads to the melting of glaciers and the precipitation period increases, the flow of the Black River reaches its peak, forming a flood period,after October to March the following year with the reduction of precipitation temperature decreases, the Black River enters the freezing period.After the Heihe flows through the Zhangye Basin, due to the increase in population and the large demand for water, the surface runoff has been significantly reduced and changed, coupled with the scarcity of precipitation in the study area, groundwater resources have become one of the main sources of water supply.

1.3 Geological structure

The fourth formation of the research area is completely developed, mainly river phase debris deposition,the main exposed lithology is holocene (Q4) gravel stone, upper renewal system (Q3) sand, sub-sand soil, sub-clay and gravel, lower renewal system (Q1) sandstone, gravel rock sandwich sand stone.The thickness of the fourth series of loose sediments is 300-500m, the thickness of the fourth series of sediments at the bottom of the Black River is not more than 50m, the main aquifer is the fourth series of pore water, lithology is mainly gravel and gravel stone.

The research area is located between Qilian Mountain Front and Hexi Corridor with a north-west fault zone with an inclination of 60°-85°and a pressure-torsion inverse fault.The fault zone was formed in the Caledonian period,and the fault plays a controlling role in the transformation process of bedrock fracture water and pore water of the fourth system.

1.4 Social water conditions

The water resources of the Heihe Basin are mainly concentrated in the middle reaches, of which the water consumption is 86.5% of the total basin, and about 70% of them are concentrated in the Zhangye basin.Social water use is mainly concentrated in the use of surface water and spring water, surface water use accounted for 64.7%, groundwater mining and use is concentrated in April to June.

It is mainly used for residential water, agricultural irrigation and industrial water.

2 Ecological effects of the middle reaches of the Heihe River

2.1 Data Sources

The data are mainly used by the national Qinghai-Tibet Plateau Scientific Data Center for multi-month average humidity in Heihe Basin (1961-2010) 1. Heihe Comprehensive remote sensing joint test: Zhangye Regional weather Station observation data set (2008-2009) 2. Heihe Basin satellite cell-scale surface evapotranspiration relative truth data set (2012-2015) 2. Heihe Basin satellite cell-scale surface evapotranspiration relative truth data set (2012-2015) 2. Heihe Basin satellite cell-scale surface evapotranspiration relative truth data set (2015-2015) 2. Heihe Basin satellite cell-scale）

Version 1.03, National Glacial Permafrost Desert Scientific Data Center 2009-2010 Physical characteristics of typical soil profile in the middle reaches of the Heihe River Basin 4, physical characteristics of typical soil profile in the middle reaches of the Heihe River Basin 2009-2010 5, 2001 Heihe River Basin 1: 1 million vegetation types (Figure 6).

2.2 Envi-met model establishment

envi-met 3D urban climate simulation software developed by Bruse and Fleer in 19987, this model simulation modeling using envi-met version 4.0.The software is based on hydrodynamics and thermodynamics to simulate the interaction between the ground, vegetation, buildings and atmosphere in urban space.

(1) Atmospheric electron model

The model site is solved using three-dimensional non-static incompressible mode, taking into account the influence of earth bias force, buoyancy and plant drag force, using the standard k-ε model, bringing into the wind tangential change, buoyancy and turbulence and dissipation that plants can produce.

(2) Soil submodel

The source of the model soil data is the National Glacial Permafrost Desert Scientific Data Center (2009-2010). 8. Physical properties of typical soil profiles in the middle reaches of the Heihe River Basin (2009-2010).Consider the process of heat and water transfer of soil in the natural environment, heat transfer and radiation absorption of artificially hardened ground.The effect of water flow on the heat transfer process in soil is also referenced.

Figure 4. Grid division of soil model

Table 1.

Soil components and bulk density

(3) Plant submodel

The above-ground part of the plant and the underground part are divided into 10 layers, the leaf area density LAD and vegetation root area density RAD is defined as 35 ㎡/m3 and 57 ㎡/m3.Consider plant root water absorption,heat exchange between leaves and the atmosphere, foliar evaporation transpiration, photosynthesis, heat exchange between leaves and the atmosphere, the effect of plants on the air, plant shading effect.

The model vegetation data is used by the National Qinghai-Tibet Plateau Scientific Data Center The main vegetation is one year

One-cooked grain crops and cold-tolerant economic fields,deciduous fruit orchards, semi-shrubs, dwarf semi-shrubs, shrubs; the rest of the vegetation-free Gobi and desert.

(4) Building sub-model

The building model uses a three-node expansion multi-node model, which takes into account the physical parameters of building components, including the density, reflectivity, transmittance, thermal conductivity, specific heat and thickness of building materials.

Figure 6． Building vegetation modeling and reference

2.3 Soil component temperature comparison

Through the 1961-2010 data reference analysis, May as a typical month, May frequent precipitation, large range of temperature changes, the average number of hours of sunshine and other characteristics.By envi-met modeling, it is obtained that the soil temperature and soil component distribution in a typical month is relative.In the desert Gobi environment with dry soil, the soil temperature showed uniformity,with an average soil temperature of 14.5 ° C.In the soil area adjacent to the Heihe region there is a downward trend, but the decline is not large.In forests, crop areas soil temperature increased significantly,in urban areas, roads and airports and other areas, soil temperature showed a relatively high average of 22℃, which is related to the thermal radiation of buildings in the city, roads and other building materials.The radiation temperature of the more arid soil-forest-covered soil-urban areas showed trapezoidal space, while correlating with the distribution of shallow groundwater and soil moisture content and vegetation transpiration range, indirectly affecting the heat exchange between the surface and the atmosphere.

Figure 7. Typical changes in soil temperature in the middle reaches of the Heihe River

Taking into account the direct exposed dry soil, wind speed and other meteorological elements are the influence factors of the main soil temperature changes in the Gobi Desert area, so the wind speed of the middle reaches of the Hei River is simulated for a typical month.Through wind speed simulation, it can be seen that atmospheric wind speed and surface water, vegetation cover, human activities have a certain correlation.Wind speed changes and soil temperature changes show the opposite trend, the wind speed of the plains desert areas, surface water areas of the soil temperature is relatively low, while vegetation cover areas and residential areas of the wind speed is relatively low and the soil temperature is relatively high.

Figure 8. Wind speed changes in the middle reaches of the Heihe River in a typical month

In summary, the soil in the case of plant cover or building cover, the reflectivity of the soil, aerodynamics and vegetation foliar evaporation has significant changes.

2.4 Vegetation transpiration effects

By comparing the simulation of soil moisture content change under a typical moon in the middle reaches of the Black River with the simulation of vegetation foliar evaporation change in the middle reaches of the Black River, foliar evaporation with the change of soil moisture content, surface evaporation content with the carbon cycle, energy cycle and water cycle receive the influence of vegetation transpiration, soil humidity and atmospheric water pressure difference on behalf of soil moisture condition and atmospheric moisture condition, when excluding human interference factors, in arid areas, during high temperature vegetation pores closed, then the shallow water in the soil by vegetation transpiration is small, mainly affected by surface temperature and wind speed, When the temperature is appropriate, the vegetation pores open, vegetation transpiration is the main flow power of shallow groundwater.

Figure 9. Changes in soil moisture content in the middle reaches of the typical Yuehei River

Figure 10. Typical monthly vegetation page evaporation changes in the middle reaches of the Heihe River

Conclusion

(1) Through the typical monthly soil-vegetation-atmospheric envi-met modeling analysis of the study area, the soil temperature showed uniformity in the dry desert Gobi environment, the average soil temperature was 14.5℃.In the soil area adjacent to the Heihe region there is a downward trend, but the decline is not large.In forests, crop areas soil temperature increased significantly,in urban areas, roads and airports and other areas, soil temperature showed a relatively high average of 22℃, which is related to the thermal radiation of buildings in the city, roads and other building materials.The radiation temperature of the more arid soil-forest-covered soil-urban areas showed trapezoidal space, while correlating with the distribution of shallow groundwater and soil moisture content and vegetation transpiration range, indirectly affecting the heat exchange between the surface and the atmosphere.Through wind speed simulation, it can be seen that atmospheric wind speed and surface water, vegetation cover, human activities have a certain correlation.Wind speed changes and soil temperature changes show the opposite trend, the wind speed of the plains desert areas, surface water areas of the soil temperature is relatively low, while vegetation cover areas and residential areas of the wind speed is relatively low and the soil temperature is relatively high.

(2) Through the simulation of the change in soil moisture content under a typical moon in the middle reaches of the Black River and the simulation of the change in foliar evaporation of vegetation in the middle reaches of the Black River, the influence of foliar evaporation with the change of soil moisture content, the content of surface evaporation with the carbon cycle, energy cycle and water cycle receive the influence of vegetation transpiration, soil humidity and atmospheric water pressure difference represents the moisture condition in the soil and the moisture condition in the atmosphere, When the light is sufficient and the temperature is appropriate, the vegetation pores are opened, and vegetation transpiration is the main flow power of shallow groundwater.

References:

1. Yue Tianxiang, Zhao Na. Multi-year average humidity in the Heihe River Basin(1961-2010). National Qinghai-Tibet Plateau Scientific Data Center, 2017. DOI: 10.11888/Geogra.tpdc.270566. CSTR: 18046.11.Geogra.tpdc.270566.
2. Gansu Province Meteorological Bureau, Heihe Middle Reaches Meteorological Bureau. Heihe Integrated Remote Sensing Joint Test:Observation Data set of Zhangye Regional Weather Station (2008-2009). National Qinghai-Tibet Plateau Scientific Data Center, 2010. DOI: 10.3972/water973.0154.db. CSTR: 18046.11.water973.0154.db.
3. LIU Shaomin, XU Ziwei, XU Tongren. Relative Truth Data set for surface Evapotranspiration at satellite cell Scale in Heihe Basin (2012-2015) Version 1.0. National Qinghai-Tibet Plateau Scientific Data Center, 2019. DOI: 10.11888/Meteoro.tpdc.270142. CSTR: 18046.11.Meteoro.tpdc.270142.
4. Han Xujun.Physical properties data of typical soil profiles in the middle reaches of the Heihe River Basin (2009-2010). National Glacial Permafrost Desert Science Data Center(www.ncdc.ac.cn (), 2020. doi:10.12072/ncdc.973Desert.db0045.2020
5. Han Xujun.Physical properties data of typical soil profiles in the middle reaches of the Heihe River Basin (2009-2010). National Glacial Permafrost Desert Science Data Center(www.ncdc.ac.cn (), 2020. doi:10.12072/ncdc.973Desert.db0045.2020
6. Hou Xueyu.Chinese Vegetation Atlas(1: 1 million), Science Press, 2001.
7. Bruse M,Fleer H. Simulating surface-plant-air interactions inside urban envionments with a three dimensional numerical mode [J]. Environmetal Modelling & Software,1998,13:373-384
8. Han Xujun.Physical properties data of typical soil profiles in the middle reaches of the Heihe River Basin (2009-2010). National Glacial Permafrost Desert Science Data Center(www.ncdc.ac.cn (), 2020. doi:10.12072/ncdc.973Desert.db0045.2020
9. Hou Xueyu.Chinese Vegetation Atlas(1: 1 million), Science Press, 2001.