Adopting “Difference-in-Differences” Method to Monitor Crop Response to Agrometeorological Hazards with Satellite Data: A Case Study of Dry-Hot Wind

Quantifying the coal mining impact on the ecological environment of Gobi open-pit mines

Xinjiang is a coal-rich region with many bare rocky and gravelly areas with a delicate and fragile ecology. What is the ecological impact of mining activities? In this study, the Salinity Index (SI-T), New Gravel Land Index (NGLI), and Land Deterioration Index (LD) were used to establish an improved remote sensing ecological index (IRSEI) for the HongShaQuan open-pit coal mine (HSQ). The spatial and temporal evolution of the ecological environment of the HSQ was revealed by IRSEI and unary linear regression analysis. Moreover, the influence of mining on the ecological environment of the Gobi mining area was quantitatively evaluated by the random forest model (RF) and difference-in-difference (DID) approach. The results indicated that the value of IRSEI in HSQ had typically decreased over the last 30a. The ecological environment in most areas of the study area was poor and fair levels. The ecological environment of the whole study area showed a decreasing pattern from southeast to northwest. The proportion of degraded area (52.33 %) was much higher than that of improved area (0.39 %). The average residual before and after mining in HSQ were -0.1011 and -0.2323, respectively, which were much higher than that of the whole study area (-0.0330 and -0.0658, respectively), indicating that the mining activities in HSQ harmed the ecological environment and aggravated the degradation of the ecological environment. The impact of mining activities on the ecological environment from 2000 to 2021 was -0.138 using DID. The results from the multiple regression model (MR), RF, and DID during the pre-mining period (2000-2011) were -0.0709, -0.1011, and -0.1345, respectively, while they became -0.1765, -0.2323, and -0.1963 during the post-mining period (2012-2020), respectively. The latter was worse than the former, all showing that the mining activities of HSQ had resulted in a negative effect on the ecological environment. It also demonstrated that the negative value of mining from the MR, RF, and DID have a very similar change trend and was near in value. This verified the feasibility of DID and RF in quantitative analysis of the ecological environment. The ecological environment quality of HSQ was mainly affected by climate change, and less influenced by mining, the contribution rates of both in the IRSEI improved area were 88.48 % and 11.52 %, respectively; and in the degraded area were 69.45 % and 30.55 %, respectively. Therefore, the Gobi mining area should pay attention to the protection of the ecosystem while developing coal. Planting vegetation can promote the governance and restoration of the ecological environment in the mining area.

Spatial Zoning of Dry-Hot Wind Disasters in Shandong Province

As a major agricultural province of China, Shandong province has long ranked first in agricultural growth value among all of the provinces; at the same time, it is also the province that is most affected by dry-hot wind. Therefore, it is of great significance to study the spatial zoning of the risks of dry-hot wind in this province. Based on meteorological, slope, and altitude data, and the principle of disaster risk assessment, this study uses a weighted comprehensive evaluation method, analytic hierarchy process, and ARC-GIS spatial analysis to study the spatial zoning of the risks of dry-hot wind in Shandong province. The results show that the high-risk regions of dry-hot wind are concentrated in the north-central portion of the province, the medium-risk regions are in the peripheral areas, and the low-risk regions are located mainly in the west, southwest, and east. Exposure of disaster-bearing bodies is high in the south and low in the north, while vulnerability to disaster-bearing bodies is high in the west and low in the east. The more developed areas in the east show high disaster prevention and mitigation capability, whereas this is weak in the west. In summary, dry-hot wind risk in Shandong province varies significantly by area. The medium- and high-risk areas are mainly in the west and central portions of the province.