1 | INTRODUCTION
China has long been suffering from serious soil erosion. The environmental problems caused by soil erosion, i.e. land degradation and the loss of land resources, have become more serious, which have seriously threatened food security, biodiversity, water resources safety, and human living environment in China (Li & Fang, 2016). Soil erosion caused by natural factors is widely distributed on all the earth surfaces, so numerous studies focus on the soil erosion problems caused by natural factors, e.g. rainfall (Xu et al., 2020), topography slope (Li et al., 2020), wind (Wang & shao, 2013), vegetation cover (Zhou, 2008), freeze-thaw (Wu et al., 2018).
However, as everyone knows, soil erosion is strongly influenced by not only natural factors but also unreasonable human activities. It is estimated that nearly 60% of present soil erosions are induced by human activity (Yang et al., 2003). Currently, China faces economic development, numerous productive and constructive engineerings as one kind of severe human activity are being conducted. Jiang (2007) found that the total number of productive and constructive engineering was 7.68 × 104, the total area was 552.8 × 104hm2 in China from 2001 to 2005. However, productive and constructive engineering involves extensive land disturbance, which results in the removal of vegetation, mass wasting along the cut slopes, runoff over bare areas formed by excavation, unconsolidated deposition, and reshaping of the topography (Li et al., 2014). Such activities directly cause soil erosion and land degradation. For example, Jiang (2007) pointed out that the total amount of abandoned soil and slag was about 92.1× 108 t, and the total amount of soil erosion was 9.5× 108 t in China from 2001 to 2005. Also, Zhang et al. (2006) estimated that the area of land degradation caused by productive and constructive engineering accounted for 66% of the total area of land degradation and about 60% of land occupied by productive and constructive engineering was farmland. The loss of land resources caused by that farmland is converted into construction land in China indirectly results in that a large amount of ecological land is reclaimed as farmland. So, productive and constructive engineering has brought serious land degradation, loss of land resources and loss of ecological land along with soil erosion. However, these environmental issues caused by productive and constructive engineering in China have not gained enough attention. Only a few studies of soil erosion caused by mining (Sinha et al., 2017) and road (Dong et al., 2012) projects are available. Therefore, this article focuses on the problem of soil erosion and related environmental issues caused by productive and constructive engineering, and specifically selects clean energy projects, such as photovoltaics and wind energy, across China as case studies. Because clean energy emits fewer greenhouse gases and is more environmentally friendly than traditional energy projects such as petroleum, natural gas, and coal, clean energy will be the trend of future energy supply. At the same time, it also causes many man-made environmental problems like other construction projects, which can provide a reference for the construction projects of other industries.
Here, the authors have conducted field investigations and statistical analysis of clean energy projects in China for years, which have been used to understand the reasons causing these environmental issues. In turn, some comprehensive policy suggestions are proposed to enhance the awareness of protecting environments in the process of constructive engineering and to control these issues. And, the conclusions and policy recommendations of this article will provide reference and guidance for clean energy projects construction in the future and even other large-scale productive and constructive projects in China or other countries.