Evaluating rural sustainable land use from a system perspective based on the ecosystem service value

Rural sustainable land use(RSLU) is important to China’s implementation of the UN 2030 Agenda for Sustainable Development Goals and the goals of rural revitalization strategy in China. Research on RSLU is key to understanding the impact of human activities on rural sustainability. This paper explored the evaluation method of RSLU from a system perspective based on the ecosystem service value(ESV). Three systems were proposed for consideration when conducting this evaluation method. One was the sustainability of the land system, the other was the sustainability of the ecoeconomic system, and the rest was the sustainability of the land-eco-economy system. Indicators including(1) land use intensity and land system stability,(2) gross domestic production(GDP), ESV, and the eco-economic harmony degree(EEHD), and(3) coupling degree and coupling coordination degree were used to analyze the sustainability of the land, eco-economic, and landeco-economic systems, respectively. An empirical research on Yanhe ecovillage was conducted and the study period extended from 2008 to 2020. The results showed that forest land had always accounted for more than 81.20% of the total area in Yanhe eco-village from 2008 to 2020, which greatly influenced land system stability and restricted economic development. This feature contrasted with RSLU. The total ESV of Yanhe eco-village declined by 1.60×106CNY during 2008–2020 because of land use changes. The EEHD was –0.01, which presented that there was a very slight unharmonious between ecology and economy. The coupling degree and coupling coordination degree showed that the development between the land and ecoeconomic systems exhibited a coupling coordination relationship. The results indicated that ecology and economy in Yanhe eco-village will change significantly in response to land use changes in rural areas, which further revealed the dynamic linkage between human beings and nature. Moreover, opposite variation tendencies in land system stability and ESV revealed that the contradiction between the high stability of the land system and well development of the eco-economic system. The results of this study implied that it is necessary and useful to integrate ESV into land management to achieve RSLU.

Approach and landing guidance design for reusable launch vehicle using multiple sliding surfaces technique

An autonomous approach and landing（A＆L） guidance law is presented in this paper for landing an unpowered reusable launch vehicle（RLV） at the designated runway touchdown. Considering the full nonlinear point-mass dynamics, a guidance scheme is developed in threedimensional space. In order to guarantee a successful A＆L movement, the multiple sliding surfaces guidance（MSSG） technique is applied to derive the closed-loop guidance law, which stems from higher order sliding mode control theory and has advantage in the finite time reaching property.The global stability of the proposed guidance approach is proved by the Lyapunov-based method.The designed guidance law can generate new trajectories on-line without any specific requirement on off-line analysis except for the information on the boundary conditions of the A＆L phase and instantaneous states of the RLV. Therefore, the designed guidance law is flexible enough to target different touchdown points on the runway and is capable of dealing with large initial condition errors resulted from the previous flight phase. Finally, simulation results show the effectiveness of the proposed guidance law in different scenarios.

Assessing effectiveness of nature-based solution with big earth data:60 years mangrove plantation program in Bangladesh coast

Background In the climate change context,nature-based solution(NBS)is considered one of the effective tools to increase the resilience of socio-ecological system.The concept coincides with the government’s attempts of afforestation and reforestation programs that have been going on for 60 years in Bangladesh.This study,therefore,envisaged understanding how NBS(mangrove afforestation and reforestation)works to promote climate change resilience through the synthetization of remote sensing-based big earth data,statistical tools,and models.The study took the entire coast of Bangladesh except for Sundarbans Reserve Forest and rolled back to 1962 to work on 60 years’time series data.Declassified CORONA satellite imagery along with Landsat satellite imagery was used,which is the first-ever attempt in the remote sensing-based ecosystem work in Bangladesh.Results The study’s main innovation is to spatially establish the effectiveness of the NBS.The study critically assessed and estimated stable lands and their socio-economic benefits as part of the effectiveness of the NBS.As part of the NBS-derived benefits in the context of climate change,it estimated the sequestrated carbon in mangrove forests.A significant positive relationship was observed between the increase of mangroves and stable lands.Near about 448,011 ha of agricultural land was stabilized due to the NBS intervention whose economic value is 18,837 million USD.In addition,29,755.71 kt of carbon have been sequestrated due to NBS program.Conclusions The concept of NBS is still in the development stage and very little or no work has been done so far in measuring and labeling the effectiveness of the NBS.Therefore,our study can innovatively contribute to the scientific community to show the effectiveness of the NBS in three domains(social,economic and ecological)in the changing climatic scenario.