Background Information
According to the IPCC report, most of regions in Asia are affected by increasing temperature, and precipitation is relevantly changed due to temperature. Besides, the report expresses that fresh water resources are extremely important for most countries in Asia because increasing population relies on those resources (IPCC, 2014). Poyang Lake is the largest freshwater lake in China, with an area of about 16,2200 km2 (62 thousand miles2). It receives water from five rivers, including Gan River, Fu River, Xin River, Rao River, and Xiu River, as well as small tributaries around the lake (Yan, 2013). The topography of Poyang Lake Basin is complex, and the topographic pattern in the basin is diverse, with hills as the main part and hills as the supplement. The altitude gradually decreases from south to north, showing a stepped distribution (Li, 2019). The average annual precipitation in the basin is 1580.8 mm, and the main rainy season is April-June each year. The concentrated rainstorm is liable to form floods. Poyang Lake is one of the ten ecological function protection zones in China and one of the most important ecological zones in the world delimited by WWF (Yue, 2018). However, Poyang Lake is very vulnerable towards climate change.
Location of Poyang Lake
Resource: Interactions between land use change, regional development, and climate change in the Poyang Lake District from 1985 to 2035.
The Vulnerability of Poyang Lake Basin under Climate Change
-In response to climate change, the temperature in Poyang Lake increases 0.02 ℃/year (Wang, 2018).
-Increasing temperature is correlated with increasing precipitation and evapotranspiration (Sun, 2013).
-Large variation of altitude around Poyang Lake triggers the extreme of precipitation (Li, 2019).
Precipitation
Precipitation Variation in China
Resource: Library of Congress
-The most important factor to affect the Poyang Lake ecosystem is precipitation. Precipitation is fluctuating due to climate change.
-The simulation conducts that the precipitation increasing trend is about 2.54 mm/year (Wang, 2018). Although the number is not very large, it still brings negative impacts.
-There are dry and wet seasons through the year. Usually, the wet season goes from spring to autumn, and late autumn and winter are dry seasons. However, climate change will intensify the difference in precipitation level. The phenomenon happens that summer has 350 mm precipitation versus 41mm precipitation in winter (Li, 2016). This situation will cause the imbalance of water resources which are hard to manage.
-Through correlation analysis, the correlation coefficient between annual precipitation and inflow is 0.92 which exceeds the 0.01 significant level (Wang, 2018).
-The streamflow is very sensitive towards precipitation by looking at the coefficient. The changing of precipitation in dry and wet seasons will change the streamflow of Poyang Lake and related rivers which will conduct domino effects for both flooding and droughts.
Evapotranspiration
The Definition of Evapotranspiration
Resource: Wikimedia Common
-Climate change, increasing temperature also brings decreased evapotranspiration.
-According to data collection, the mean evapotranspiration is about 1260 mm, and the overall trend of evapotranspiration is decreased in the past 5 decades (Wang, 2017).
-Decreased evapotranspiration makes streamflow easier to runoff. Evapotranspiration is highly related to temperature because summer has the highest rate of evapotranspiration, and winter has the lowest (Yin, 2011).
-The seasonal difference confirms that temperature contributes to evapotranspiration a lot. In most of times of the year, precipitation level is higher than evapotranspiration, but evapotranspiration is higher in several months which will lead to droughts in those months (Ye, 2013).
-When heavy precipitation and decreased evapotranspiration happen at the same time, the streamflow will become vulnerable to exceed capacity and flood (Wang, 2017).
-The changing relationship between precipitation and evapotranspiration will make the occurrence of flooding and droughts seasonly which are negative towards Poyang Lake water resources balance.
Topography
-Although the overall trend of precipitation is increasing, precipitation may be influenced by the complexity of topography.
-The elevation of Poyang Lake varies from 2200 m to 30m which influence the precipitation (Li, 2019).
-By data collection, the highest precipitation is about 3036 mm in Wuyuan station, but the lowest precipitation is only about 776 mm (Li, 2019). The spatial variation contributes to uneven precipitation and precipitation extremes.
-Under many results from different methods, the correlation between elevation and precipitation is positive which indicates that as elevation increases, the possibility of heavy precipitation is increasing (Li, 2019). Under the influence of climate change, the precipitation extreme is intensified because different altitudes have different temperatures, and lower elevation will be most affected.
-Climate change is presented by El Niño-Southern Oscillation (ENSO), which has the result of higher sea surface temperature. Lower elevation areas become warmer, and the occurrence of convective forces make precipitation increase. However, some areas with higher latitude may not have enough precipitation. Combining topographic characteristics and climate change leads to higher temperature and ENSO which affect precipitation in different regions. In the long term, flooding and droughts will occur in Poyang Lake (Zhang, 2016).
-By observing, the topography of northeastern and eastern parts of Poyang Lake have an increased chance of extreme precipitation (Li, 2019).
Topography in Poyang Lake
Resource: Spatiotemporal variations of temperature and precipitation extremes in the Poyang Lake basin, China
Hazards of Poyang Lake Basin
Water Quality
Open Pit Mining
Resource: Plxabay
Case study of heavy metal: Soil and water loss caused by the increase of surface runoff in Poyang Lake basin seriously threatens the water quality of the basin. Gong finds that heavy metals in some areas of Poyang Lake Basin are caused by soil erosion (Gong, 2006). Dexing Copper Mine and Yongping Copper Mine are well-known large-scale copper industry bases in China which are located near to Poyang Lake. The discharge of heavy metal acidic wastewater during the mining process is the main source of heavy metal pollution in the lake area. The increased surface runoff enlarges the pollution scope of heavy metal pollution wastewater. Further study finds that the time distribution of heavy metals in the sediment of Poyang Lake Basin is also different, and the land accumulation index of each element in the dry season is generally higher than that in the wet season (Gong, 2006). The study suggests that this is related to the increase in surface runoff caused by climate change.
Eutrophication: With climate change, the nitrogen and phosphorus content in Poyang Lake area is seriously exceeding the standard and is facing the risk of eutrophication. Studies have shown that the warming effect of climate warming not only promotes the growth of harmful algae, such as cyanobacteria, which are more adapted to higher temperatures but also increases the primary productivity of phytoplankton and accelerates the formation of algal lakes (Moss, 2011 & Liao, 2017). Besides, because omnivorous fish prefer warm water, their rapid reproduction will replace zooplankton as a dominant population, thus reducing the lake ecosystem. Its ability to control algae indirectly promotes the excessive proliferation of algae (Lyu, 2017). Under the influence of climate change, the change of water flow in Poyang Lake affects the flow of nutrients into the lake, which eventually leads to the occurrence of water eutrophication.
Eutrophication in Poyang Lake
Resource: Allied attack: Climate change and eutrophication
Ecological Environment
Migratory Path of Siberian Crane
Resource: Wikimedia Common
The climate of Poyang Lake Basin is complex, and biodiversity and ecological types are numerous. There are great differences in material, energy, and heat flux exchange among different ecosystems. There are significant differences in water, heat flux exchange and energy balance among different surface vegetation ecological types in the land surface process and boundary layer coupling model. The monitoring results show that climate change causes the temperature rise and the drought in spring and summer in Poyang Lake area (Wang, 2018). This led to a long period of drying up in the basin, which aggravated the sharp reduction of wetland area and the lack of ecological function. According to the investigation results, besides the lake beach within 10 meters from the water body, the surface of the lake beach becomes harder rapidly, and the ecological function of the wetland is basically lost. Fifteen meters away from the water body, the surface is drying up, there are many cracks and cracks, generally, the width of the cracks is 2-3 cm, the surface turf, vegetation withered (Yue, 2018). According to simulation, forests will decrease by 6.7% in the next 25 years (Yan, 2013). The degradation of wetland function in Poyang Lake has seriously affected the habitat, foraging, reproduction, and other animal and plant populations and communities of migratory birds.
Adaptation for Enhancing Resilience
There is not much research about adaption for Poyang Lake because the effects are gradual, and people are not aware of them, but some papers published recently show that people have begun to pay attention to adaptation. Although Poyang Lake, as a full functional ecosystem, has the ability to be resilient, the effects from climate change on Poyang Lake have further affected people nearby, so the adaptation for people is necessary.
-Synergy between social, natural, and technological subsystems puts effort on adapting floods in Poyang Lakes. The specific implements are changing the growing season of surrounding crops, making more agricultural policies, and protecting good-quality levees (Tian, 2018).
-Researchers use the GIS approach to examine 298 towns around the Poyang Lake in order to know the sensitivity and vulnerability towards floods and seek the developmental paths. The forecast is important to these towns because people lived there are relatively poor, and they are more dependent on natural resources and agriculture (Tian, 2015).
- The government provides subsidy for people living in rural areas which can increase income and decrease the pressure of losing agricultural production (Tian, 2016).
Levees in Poyang Lake Basin
Resource: Interactions of social, natural, and technological subsystems and synergy between development and adaptation to floods around poyang lake
Cooperative System
Resource: Interactions of social, natural, and technological subsystems and synergy between development and adaptation to floods around poyang lake
Looking forward
Poyang Lake, as the largest freshwater lake in China, has the significant value to provide water resources, suitable environment for both human and non-human species. Because of climate change, Poyang Lake is experiencing intensified damages. Many factors happen spontaneously to make Poyang Lake increasingly vulnerable. However, because of the complexity of factors and their interaction, many causes and effects are indirect and hard to explain. Furthermore, the negative effects of Poyang Lake are not obvious as other environmental problems in China like air pollution, so people do not pay much attention to it. Therefore, many problems are not be solved timely and many reasons for damages need further research. The time lag will make problems intensify, and indigenous people and species are affected more. Taking Poyang Lake as an example, people should focus more on impacts of climate change on lake resources in order to protect water resources and prevent damages for lands.
About the Author
Jingni Zhang (St.Lawrence University class of 2017) was Environmental Studies and Psychology majors. She came from Beijing, China which had many problems related with the environment and megacity. She was interest in Environmental Problems and interactions with communities. This web page was designed for Dr. Jon Rosales’ Adaptation to Climate Change course in the spring of 2019.
Photo was taken in Wangjing, Beijing
References
Fan, H., Xu, L., Tao, H., Feng, W., Cheng, J., & You, H. (2017). Accessing the difference in the climate elasticity of runoff across the Poyang Lake Basin, China. Water, 9(2), 135.
Gong, X., Chen, C., Zhou, W., Jian, M., & Zhang, Z. (2006). Assessment on Heavy Metal Pollution in the Sediment of Poyang Lake (In Chinese). Environmental Science, 27(4).
Intergovernmental Panel on Climate Change Staff. (2014). Climate change 2014: Impacts, adaptation and vulnerability part B: Regional aspects. West Nyack: Cambridge University Press. Retrieved from https://ebookcentral.proquest.com/lib/[SITE_ID]/detail.action?docID=3563521
Liao, M., Yu, G., & Guo, Y. (2017). Eutrophication in Poyang Lake (eastern China) over the last 300 years in response to changes in climate and lake biomass. PloS one, 12(1), e0169319.
Li, X., & Hu, Q. (2019). Spatiotemporal Changes in Extreme Precipitation and Its Dependence on Topography over the Poyang Lake Basin, China. Advances in Meteorology.
Li, Y., Tao, H., Yao, J., & Zhang, Q. (2016). Application of a distributed catchment model to investigate hydrological impacts of climate change within Poyang Lake catchment (China). Hydrology Research, 47 (S1), 120-135.
Lyu, X., Lyu, Y., Song, S., &Wang, T. (2017). Eutrophication in cold-water lakes driven by combined effects of climate change and human activities (In Chinese). Acta Ecologica Sinica, 37 (22), 7375-7386.
Moss, B., Kosten, S., Meerhoff, M., Battarbee, R. W., Jeppesen, E., Mazzeo, N., . . . Scheffer, M. (2011). Allied attack: Climate change and eutrophication. Inland Waters : Journal of the International Society of Limnology, 1(2), 101-105. doi:10.5268/IW-1.2.359
Sun, S., Chen, H., Ju, W., Song, J., Zhang, H., Sun, J., & Fang, Y. (2013). Effects of climate change on annual streamflow using climate elasticity in Poyang Lake Basin, China.
Tian, Q., Brown, D. G., Bao, S., & Qi, S. (2015). Assessing and mapping human well-being for sustainable development amid flood hazards: Poyang Lake Region of China. Applied Geography, 63, 66-76.
Tian, Q., Holland, J. H., & Brown, D. G. (2016). Social and economic impacts of subsidy policies on rural development in the poyang lake region, china: Insights from an agent-based model. Agricultural Systems, 148, 12-27. doi:10.1016/j.agsy.2016.06.005
Tian, Q., Jiang, L., Lemos, M., & Qi, S. (2018). Interactions of social, natural, and technological subsystems and synergy between development and adaptation to floods around poyang lake. Annals of GIS, 24(3), 209-220. doi:10.1080/19475683.2018.1471520
Wang, L., Guo, S., Hong, X., Liu, D., & Xiong, L. (2017). Projected hydrologic regime changes in the Poyang Lake Basin due to climate change. Frontiers of Earth Science, 11(1), 95-113.
Wang, R. N., Peng, W. Q., Liu, X. B., Wu, W. Q., Chen, X. K., Zhang, S. J., & Jiang, C. L. (2018). Quantitative estimation of the impacts of climate change and anthropogenic activities on inflow variations in the Poyang Lake Basin during the last 55 years. In IOP Conference Series: Earth and Environmental Science (Vol. 191, No. 1, p. 012080). IOP Publishing.
Yan, D., Schneider, U., Schmid, E., Huang, H., Pan, L., & Billy, O. (2013). Interactions between land use change, regional development, and climate change in the Poyang Lake District from 1985 to 2035. Agricultural Systems, 119, 10-21.
Ye, X., Zhang, Q., Liu, J., Li, X., & Xu, C. (2013). Distinguishing the relative impacts of climate change and human activities on variation of streamflow in the poyang lake catchment, china. Journal of Hydrology, 494, 83-85.
Yin, J., Wang, H., Zhan, M., Kong, P., & Jiang, Z. (2011). Climate Change in Poyang Lake Basin in the Past 50 Years. Jiangxi Climate Center.
Yue, T., Nixdorf, E., Zhou, C., Xu, B., Fan, Z., Huang, X., . . . Kolditz, O. (2018). Chinese water systems : Volume 3: Poyang lake basin. Cham: Springer. Retrieved from https://ebookcentral.proquest.com/lib/[SITE_ID]/detail.action?docID=5548702
Zhang, Q., Xiao, M., Singh, V. P., & Wang, Y. (2016). Spatiotemporal variations of temperature and precipitation extremes in the Poyang Lake basin, China. Theoretical and applied climatology, 124(3-4), 855-864.
Zhao, G., Hörmann, G., Fohrer, N., Zhang, Z., & Zhai, J. (2010). Streamflow trends and climate variability impacts in Poyang lake basin, china. Water Resources Management, 24(4), 689-706. doi:http://dx.doi.org/10.1007/s11269-009-9465-7
Picture References
Banner Picture: https://timgsa.baidu.com/timg?image&quality=80&size=b10000_10000&sec=1555600943&di=c81c8b3970a5924b09fa6e1aca673476&src=http://img.pconline.com.cn/images/upload/upc/tx/photoblog/1312/22/c2/29885696_29885696_1387710320136_mthumb.jpg
https://www.loc.gov/item/2013591104/
https://upload.wikimedia.org/wikipedia/commons/thumb/8/80/Surface_water_cycle.svg/674px-Surface_water_cycle.svg.png
Zhang, Q., Xiao, M., Singh, V. P., & Wang, Y. (2016). Spatiotemporal variations of temperature and precipitation extremes in the Poyang Lake basin, China. Theoretical and applied climatology, 124(3-4), 855-864.
https://cdn.pixabay.com/photo/2018/07/21/19/20/open-pit-mining-3553195_960_720.jpg
https://upload.wikimedia.org/wikipedia/commons/thumb/d/d0/SiberianCrane.svg/2000px-SiberianCrane.svg.png
Tian, Q., Jiang, L., Lemos, M., & Qi, S. (2018). Interactions of social, natural, and technological subsystems and synergy between development and adaptation to floods around poyang lake. Annals of GIS, 24(3), 209-220. doi:10.1080/19475683.2018.1471520
Moss, B., Kosten, S., Meerhoff, M., Battarbee, R. W., Jeppesen, E., Mazzeo, N., . . . Scheffer, M. (2011). Allied attack: Climate change and eutrophication. Inland Waters : Journal of the International Society of Limnology, 1(2), 101-105. doi:10.5268/IW-1.2.359
Yan, D., Schneider, U., Schmid, E., Huang, H., Pan, L., & Billy, O. (2013). Interactions between land use change, regional development, and climate change in the Poyang Lake District from 1985 to 2035. Agricultural Systems, 119, 10-21.