Challenges and Countermeasures in Soil and Water Conservation under Climate Change in the Loess Plateau of China Dr. Jianen Gao, Huijuan L,Yuanxing Z et al. Northwest A&F University Institute of Soil and Water Conservation, CAS&MWR Aug.22nd.2016 Good afternoon, Professor Zheng, ladies and gentlemen, First, I’d like to thank Professor Zheng and the Conference committee for offering me this opportunity to speak you on a subject of Challenges and Countermeasures in Soil and Water Conservation under Climate Change in the Loess Plateau of China.
Outline Backgrounds Rainfall Changes Erosion Changes Challenges Countermeasures My report have five part.
1. Backgrounds Area studied in China Beijing Xi’an Shanghai the Yellow Rive Area studied in China Beijing Loess Plateau Xi’an Shanghai This is the China map. These are the Yangtz River and The Yelow River. This is the Loess Plateau. The area is 0.62 million km2,The people is about 60 million,and the average Rainfall is 429 mm (250-600 mm) Area: 0.62 million km2 people: 60 million Average Rainfall: 429 mm (250-600 mm)
Soil erosion intensity map of the Loess Plateau The Loess Plateau are made of many hills and gullies. The gullies were very deep and hills were rare vegetation. The ecological environment was very bad. Average erosion intensity:E=3700t/(km2a);Emax=30000-50000t/(km2a). The soil and water erosion is very serious and controlled difficultly. The Loess Plateau are made of many hills and gullies. The gullies are very deep and hills are rare vegetation. The ecological environment was very bad. The average erosion intensity was E=3700t/(km2.a);Emax=30000-50000t/(km2a). The soil and water erosion was very serious and controlled difficultly.
The variation of sediment quantity of the Yellow River The Yellow river is the fifth longest river, but the highest river in sediment concentration in the world. 1919~1959 Annual sediment yield (Ws=)1.6 billion ton，around the earth 30 laps by 1 square volume. Maximum sediment yield Ws max=37 billion ton. The silt comes from the Loess Plateau mainly. The erosion and sediment delivery ratio is almost 1 The Yellow river is the fifth longest river, but the highest river in sediment concentration in the world. 1919~1959 Annual sediment yield (Ws=)1.6 billion ton，around the earth 30 laps by 1 square volume. Maximum sediment yield Ws max=37 billion ton. The silt comes from the Loess Plateau mainly.
1. Rainstorm characteristics The an important cause of severe erosion is the heavy rainfall. The maximum rain intensity can reach 18.3mm/min. ＞100mm ＞50mm The an important cause of severe erosion was the heavy rainfall. The maximum rain intensity can reach 18.3mm/min.
Annual mean temperature anomaly 2. Temperature Changes(Climate change) warm period 1960~2001 (42 years) Temperature increased by about 1.5 o C cold period 1987 Annual mean temperature anomaly The temperature is a mainly characteristic parameter reflecting climate change. This graph is the change of temperature and runoff and precipitation. This graph is the change of annual mean temperature anomaly. From 1960~2001 (42 years),the temperature increased by about 1.5 o C.
2. Precipitation Changes Comparison of the precipitation in different ages at the upper and middle yellow river 1960-1997 Compared with 50s and 60s, the annual precipitation in 90s decreased by 4.2% and 15.2% before Lanzhou section and in the middle Yellow River respectively. Reach Ages 1956~ 1969 1970~ 1979 1980~ 1989 1990~ 2000 1990 Before Lanzhou section value（mm） 486 484.4 496.3 465.8 486.9 483.0 anomaly（%） 0.6 0.3 2.8 -3.6 0.8 Lanzhou-Hekouzhen 277.1 265.9 239.4 258.7 264.1 261.7 5.9 1.6 -8.5 -1.1 0.9 Hekouzhen-Longmen 476.7 429.4 414.8 399.3 445.9 433.5 10.0 -0.9 -4.3 -7.9 2.9 Longmen~Sanmenxia 578.8 530.8 551.6 490.4 557.9 540.5 7.1 -1.8 2.1 -9.3 3.2 Sanmenxia-Huayuankou 702.7 641.9 667 608.5 673.6 658.2 6.8 -2.5 1.3 -7.6 2.3 Hekouzhen 560.8 511.5 521.3 475.2 535.7 520.2 7.8 -1.7 0.2 -8.7 3.0 Decreased 3 times This chart is comparison of the precipitation in different ages at the upper and middle yellow river. This graph is the Annual mean Precipitation anomaly. compared with 50s and 60s, the annual precipitation in 90s decreased by 4.2% and 15.2% before Lanzhou section and in the middle Yellow River respectively. Annual mean Precipitation anomaly
2. Precipitation Change (1997-2015) But since 1997, the precipitation had a obvious rise. This graph was precipitation, runoff and sediment transportation of Ganguyi Station in Yanhe river. From This Graph, There were two precipaions in 2013 and 2014. The rainfall has an increasing trend since 1997.
2. Precipitation Changes Yanan Precipitation Station 1997-2014,Precipitation is increasing; annual: 505.3mm: 2013: 959mm; 2014: 706mm. Sediment discharge is decreasing; Runoff is increasing and there was no zero flow for the Yellow River since 1999. Yanan Precipitation Station 1997-2014,Precipitation is increasing; annual: 505.3mm: 2013: 959mm; 2014: 706mm. Sediment discharge is decreasing;Runoff is increasing and there was no zero flow for the Yellow River since 1999. Tongguan Hydrometric Station
2. Precipitation Changes (2013) Precipitation Characteristics of 2013 Yan’an The total precipitation and flood season precipitation of 2013comparison with multi-year average value:1.9,2.1; The total precipitation and flood season precipitation of 2013comparison with multi-year average value Monthly rainfall (2013) comparison with annual mean monthly rainfall (1951-2012)
2. Precipitation Changes (2013) The rainfall frequency analysis of Yan’an station in 2013 A significant change in the form of precipitation: Large amount, Moderate intensity, Long duration
3. Erosion Changes 1、Gravity erosion increasing: Landslide, Collapidation, Mudflow Landslide, Collapidation, Mudflow
3. Erosion Changes 2、Reduction of sediment and runoff in Yellow River The Yellow River natural drying began in 1972, mainly occurred in the lower reaches of the Shandong River. After 1987, stop was almost every year. In 1995, there were drying up of 122 days, 683km. Reduction of sediment and runoff in Yellow River. The Yellow River natural drying began in 1972, mainly occurred in the lower reaches of the Shandong River. After 1987, stop was almost every year. In 1995, there were drying up of 122 days, 683km.
3. Erosion Changes Erosion transport in Yanhe River 3、Change in the ratio of erosion transport The change in the ratio of erosion transport from 1 to 0.3-0.5. Erosion transport in Yanhe River
4.Challenges 1、Gravity Erosion increasing (1) The amount of precipitation was bigger (2) Rainfall Intensity becoming smaller (3) Soil moisture content was increasing (4) Increased vegetation cover
4.Challenges Who’s faults？ 2、River runoff reduction, ecological base flow shortage (1) The Yellow River breaking (2) The water resource shortage (3) The ecological flow shortage Who’s faults？
4.Challenges 3、The shocking soil erosion in construction projects (1) Point project: Large slag field (2) Line project (3) Surface project
4.Challenges 4、Non-point source pollution (1) Pesticides (2) Chemical fertilizer (3) Heavy metal of industrial commodity
5. Countermeasures Rainfall runoff regulation and control technology. Development of soil and water conservation and high efficiency agriculture. Research on strengthening soil and water conservation monitoring technology. Strengthening the slope protection on important projects to prevent the occurrence of gravity erosion. Explore the law of soil and water loss in construction projects.
Thanks for your attention！