Assessment of Spatial Heterogeneity of Soil Moisture in the Critical Zone of Gully Consolidation and Highland Protection

The Gully Consolidation and Highland Protection (GCHP) project (such as for gully head landfills), a consideration of soil and water conservation measures, has been explored and developed continuously in recent decades in the Chinese Loess Plateau. Using high-precision images taken by drones to extract the topography of the basin, the changes in vegetation and land use were also analyzed. The observation of soil moisture in the critical gully head area of the GCHP was carried out. The results indicated that the critical zones of the GCHP project implementation include the gully head landfill, the gully, and the highland farming area. The soil moisture of the landfill area was 6.91% and 23.61% higher than that of the gully and farming area, respectively, with obvious spatial heterogeneity. The soil sand content in the gully head landfill area was higher than that in the gully area and the agricultural area of the plateau. The main reason for the high soil moisture in the gully head landfill area is that the terrain at the outlet is low, and it is at the lowest point of the whole basin. Analyzing the spatial distribution of soil moisture can point out the direction for the monitoring, prevention, and treatment of geological disasters, such as landslides and debris flow, induced by water erosion. This study will help to understand in detail the spatial heterogeneity and influencing factors of soil moisture under the implementation of the GCHP and improve the GCHP project management system

Winter Potato Water Footprint Response to Climate Change in Egypt

The limited amount of freshwater is the most important challenge facing Egypt due to increasing population and climate change. The objective of this study was to investigate how climatic change affects the winter potato water footprint at the Nile Delta covering 10 governorates from 1990 to 2016. Winter potato evapotranspiration (ETC) was calculated based on daily climate variables of minimum temperature, maximum temperature, wind speed and relative humidity during the growing season (October–February). The Mann–Kendall test was applied to determine the trend of climatic variables, crop evapotranspiration and water footprint. The results showed that the highest precipitation values were registered in the northwest governorates (Alexandria followed by Kafr El-Sheikh). The potato water footprint decreased from 170 m3 ton−1 in 1990 to 120 m3 ton−1 in 2016. The blue-water footprint contributed more than 75% of the total; the remainder came from the green-water footprint. The findings from this research can help government and policy makers better understand the impact of climate change on potato crop yield and to enhance sustainable water management in Egypt’s major crop-producing regions to alleviate water scarcity.Validerad;2022;Nivå 2;2022-07-01 (joosat);</p

Assessment of the Implementation Effect of a Gully Consolidation and Highland Protection (GCHP) Project Based on the GeoWEPP Model

The Gully Consolidation and Highland Protection (GCHP) project is an important governance measure for controlling source erosion and reducing soil erosion in the Loess Plateau, which has been explored and developed continuously in recent decades. However, there is no international precedent for research on the implementation effect of the GCHP project, and it is still relatively weak. In order to quantify the erosion of a small watershed under the construction of a gully head landfill, this study selected Yangjiagou (YJG) as the research area. The spatial analysis function of ArcGIS was used to process DEM and soil type data, the GeoWEPP model was used to simulate soil erosion, and the changes of runoff and sediment yield before and after gully head landfill were analyzed. The results showed that compared with the simulated original soil erosion amount, the annual runoff decreased by 13.13%, and the sediment yield decreased by 37.61% after gully head landfill, indicating that the GCHP project positively influenced soil erosion control. After the gully head landfill measures are taken, the flow path becomes shorter, so the flow scour capacity is weakened. Soil and water control is very effective in the short term, but if long-term maintenance is not carried out, the intensity of soil and water loss is likely to be aggravated. This study provides an effective verification method for the feasibility of a soil loss control scheme on the Loess Plateau and provides a reference for promoting ecological priority and efficient management in the Loess gully area. Ultimately, it will serve the ecological protection and high-quality development of the Yellow River Basin

A novel integrated approach for monitoring drought stress in an aeolian desertification area using Vegetation Drought Status Index

Drought is a costly natural disaster. The accuracy and applicability of different drought indexes in drought monitoring at different research areas are also different. Based on remote sensing (RS) and geographic information system technology, we propose a new RS-based drought index, Vegetation Drought Status Index (VDSI), for agricultural drought monitoring in both arid and humid regions using multi-sensor data. This index combines the Normalized Difference Vegetation Index (NDVI) data from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor and data from 81 verification points regarding the in situ soil drought status. The model was applied to drought monitoring in Xinjiang Uygur Autonomous Region of China. Based on the comprehensive influence of water absorption on the reflectance spectrum of vegetation and soil, the reflectance of soil in MODIS bands B6 and B7 is generally higher than that of vegetation, so the model can directly obtain the surface soil moisture index. The correlation analysis (R2 > 0.79) was valid; the change trends were the same; i.e., VDSI is a reliable referential index for agricultural drought monitoring. HIGHLIGHTS A new drought index based on remote sensing – Vegetation Drought State Index (VDSI) was proposed.; The model can directly obtain the surface soil moisture index.; The results are applicable to agricultural drought monitoring in arid and humid regions.

Identification of Potential Landslide Hazards Using Time-Series InSAR in Xiji County, Ningxia

Potential landslide identification and monitoring are essential to prevent geological disasters. However, in mountainous areas where the surface gradient changes significantly, the leveling effect is not completely removed, affecting the deformation results. In this paper, the SBAS-InSAR and PS-InSAR time-series processing methods were combined to interfere with the SAR image data of the ascending orbit in the southern mountainous area of Ningxia and its surrounding regions. Based on the obtained surface deformation monitoring results and optical images, landslide hazard identification was successfully carried out within the coverage area of 3130 km2 in Xiji County. The results show that the whole study area presented a relatively stable state, most of the deformation rates were concentrated in the range of 0 mm/a to −10 mm/a, and the deformation in the southwest area was larger. A total of 11 large potential landslides (which were already registered potential danger points of geological disasters) were identified in the study area, including three historical collapses. The landslide identification results were highly consistent with the field survey results after verification. The timing analysis of the typical landslide point of the Jiaowan landslide was further carried out, which showed that the Jiaowan landslide produced new deformation during the monitoring time, but it was still in a basically stable state. It can do a good job in disaster prevention and reduction while strengthening monitoring. The results of this study have a guiding effect on landslide prevention and mitigation in the mountainous areas of southern Ningxia