Science for Policy: Resource Nexus in Land-Use and Watershed Management

  • 2021/08/15     Dresden, Germany

    Image: Lulu Zhang/UNU-FLORES

    At the 54th instalment of the Nexus Seminar Series, Dr Lulu Zhang, Associate Programme Officer, addressed the role of science in supporting coherent policy by integrating the Resource Nexus, particularly in land-use and watershed management.

    By Atiqah Fairuz Salleh, Communications & Advocacy

    In her lecture entitled “The Role of Science in Supporting Coherent Policy: Integrating Resource Nexus in Land-Use and Watershed Management” on 19 July 2021, Dr Lulu Zhang illustrated how environmental resources are not isolated from one another and a holistic understanding and evaluation of their interactions are necessary to derive coherent policies.

    Dr Lulu Zhang began by giving a background on the water and soil crises we are faced with today. With 2.2 billion people lacking access to safely managed drinking water services (WHO/UNICEF 2019) and 3.2 billion people living in agricultural areas with high to very high water shortages (FAO 2020), the world faces major water-related challenges. Meanwhile, the global soil crisis can be illustrated by the annual loss of one football pitch of soil every five seconds (FAO and ITPS 2015). By elaborating on the multiple functions and ecosystem services of soil, Dr Zhang established the nexus between soil and water.

    Illustrating with the case of China, where 6.3 per cent of the country’s soil is highly eroded (Wuepper et al. 2020), Dr Zhang presented an example of the Loess Plateau. An area about the size of France, the Loess Plateau is a hotspot for soil erosion worldwide. The Yellow River – named after the colour of the water flowing through it – flows through the Plateau and has one of the highest sediment loads in the world. In response, the Chinese government launched a long-term national forestation strategy to restore China’s soils and environment. Within 15 years from 2001, the forest cover of the Loess Plateau doubled from 8 to 16 per cent (Cao et al. 2019; Wang et al. 2018).

    While the forest cover has increased and soil erosion minimised, there was a significant trend in decreasing discharge and annual streamflow in the Yellow River, raising concerns on water scarcity.

    Dr Zhang presented a study in the area of the Upper Jinghe watershed. Combining both bottom-up (field scale) and top-down (watershed scale) approaches, the research aimed to formulate strategies for adapting to climate change and balancing ecosystem services through management based on the Resource Nexus.

    Based on the studies, Dr Zhang and colleagues found that changes in the land cover chiefly contributed to the reduced water supply in the region while climate change has played a minor role. Any further expansion of forest cover would aggravate the water scarcity, especially under the latter scenarios.

    Furthermore, a multi-layer forest structure heavily consumes water and did not help with water provision on the Loess Plateau. While restorative policies have helped alleviate the soil dilemma, they have unintentionally caused a trade-off in water resources management in the region. Forest management and structure transformation are a critical linkage to consider to attain an integrated and balanced approach and multifunctionality.

    Going forward, Dr Zhang recommended integrating economic incentives for participants to manage forestland in the most optimal way (Zhang and Schwärzel 2017). Maintaining a rational tree density and undergrowth would, for example, would help control soil erosion while producing more water. A payment scheme that is participatorily designed would be more effective than a “one-size-fits-all” solution. Capacity building and training would support a more sustainable forest management.


    Cao, Q., Wu, J., Yu, D. and Wang, W. 2019. “The Biophysical Effects of the Vegetation Restoration Program on Regional Climate Metrics in the Loess Plateau, China.” Agricultural and Forest Meteorology 268:169-180.

    FAO. 2020. “The State of Food and Agriculture 2020. Overcoming Water Challenges in Agriculture.” Rome. DOI:10.4060/cb1447en

    FAO and ITPS. 2015. “Status of the World’s Soil Resources (SWSR) Main Report.” Food and Agriculture Organization of the United Nations and Intergovernmental Technical Panel on Soils, Rome, Italy.

    UNICEF and WHO. 2019. “Progress on Household Drinking Water, Sanitation and Hygiene 2000-2017. Special Focus on Inequalities.” New York: United Nations Children’s Fund (UNICEF) and World Health Organization.

    Wang, Y., Brandt, M., Zhao, M., Tong, X., Xing, K., Xue, F., Kang, M., Wang, L., Jiang, Y. and Fensholt , R. 2018. “Major Forest Increase on the Loess Plateau, China (2001 2016).” Land Degradation & Development 29(11):4080-4091.

    Wuepper , D., Borrelli, P. and Finger, R. 2020. “Countries and the Global Rate of Soil Erosion.” Nature Sustainability 3(1):51-55.

    Zhang, L. and Schwärzel, K. 2017. “China’s Land Resources Dilemma: Problems, Outcomes, and Options for Sustainable Land Restoration.” Sustainability 9(12):2362.

    Further Reading

    Zhang, L., Podlasly , C., Ren, Y., Feger, K.H., Wang, Y. and Schwärzel, K. 2014. “Separating the Effects of Changes in Land Management and Climatic Conditions on Long Term Streamflow Trends Analyzed for a Small Catchment in the Loess Plateau Region, NW China.” Hydrological Processes 28(3):1284-1293.

    Zhang, L., Podlasly , C., Feger, K.H., Wang, Y. and Schwärzel, K. 2015. “Different Land Management Measures and Climate Change Impacts on the Run Off – A Simple Empirical Method Derived in a Mesoscale Catchment on the Loess Plateau.” Journal of Arid Environments 120:42-50.

    Zhang, L. and Schwärzel, K. eds. 2017. Multifunctional Land Use Systems for Managing the Nexus of Environmental Resources. Springer International Publishing.