The rapid expansion of construction land has been a common phenomenon worldwide, which resulted in the loss of high-quality arable land and severe land degradation. Here, a statistical analysis, together with a field investigation, was carried out in China to address the challenges. This study has gathered data on the reduction of land amount and quality caused by construction activities and has collected the relevant policies to control land deterioration caused by those activities. The increasing amount of farmland and open space are occupied by construction use. The annual growth of construction land from 2001 to 2017 was 43.64 × 10⁴ hm², with an annual average of about 38 × 10⁴ hm² of cultivated land being converted to construction land in China. Construction activities usually cause a deterioration of the physico-chemical properties in and around construction site soils. The organic matter of post-construction soil was lower than the pre-construction by 257.4~879.8%. A lack of strong economic incentives for developers, limited effectiveness of measures to control land degradation, and weak requirements and enforcement of relevant laws and regulations allow land degradation from construction activities to remain at a significant level. For more efficiency and success, the study proposes effective measures to control the hazards that occur so widely in China.

Periodic shock waves of roll waves may cause the flow to jump over the canal bank, increase soil erosion, and enhance the destructive power of debris flow. This paper focuses on the spatiotemporal changes in waveform, velocity, discharge, shear stress, and Froude number during the development process of roll waves, taking the non-uniform flow as the initial condition. This work studied numerically the influence mechanism of different variables on the development process of roll waves based on steep slope shallow water equations. The roll wave is unstable when the disturbance amplitude is too large. By reducing the inlet velocity, increasing the disturbance wavelength, and reducing the roughness coefficient, it can make the roll wave stable. Reducing the inlet velocity not only reduces the frequency of the shock wave but also keeps the wave crest from rising. Under different boundary conditions of disturbance amplitude, the crest growth rate (crest water depth difference/crest distance difference) of the roll wave development segment at a certain time is almost consistent. For different initial water depths, there is overlap in the roll wave development segment at a certain time. Under the initial condition of non-uniform flow, the congestion at the inlet means that the initial water depth is less than the normal water depth, and the decline of the water depth at the inlet means that the initial water depth is greater than the uniform water depth.