Suggestions for Revegetation over the Next 30 Years Based on Precipitation in the Three North Region of China

Afforestation in the Three North Region (TNR) of China has received wide concern due to the low survival rate and threats to water security associated with the lack of available precipitation for vegetation. It is crucial to provide a spatial layout for revegetation according to the available precipitation to achieve the vegetation cover target. This study investigated the spatial pattern of precipitation, determined the suitable vegetation distribution based on the ecological water requirements and precipitation, and proposed an optimized revegetation scheme by comparing the actual and suitable vegetation patterns. The results indicated that the actual vegetation that matched the pixel-level precipitation accounted for 67.24% of the total vegetation area in the TNR. However, 18.50% of the actual forest, 21.82% of the actual shrublands, and 19.95% of the actual grasslands were overloaded with respect to precipitation. The total suitable vegetation area was reduced slightly compared to the actual vegetation area. There is still some potential for the revegetation of forest and shrublands, mainly those in the eastern and south-eastern parts of the TNR. The optimized revegetation area in the TNR was 3.04 × 106 km2, including a maintenance management type of 2.19 × 106 km2, an upgrade type of 0.49 × 106 km2, and a degradation type of 0.37 × 106 km2. Maintenance management (natural restoration) and transformation to vegetation types with lower ecological water requirements were recognized as important revegetation practices in the TNR. This study provides guidelines to adjust the Three North Shelterbelt Project policies based on precipitation data to reduce the negative impact of revegetation on the hydrological cycle.

Remote Sensing and Geospatial Models to Simulate Land Use and Land Cover and Estimate Water Supply and Demand for Water Balancing in Phuket Island, Thailand

Currently, Phuket Island is facing water scarcity because water demand for consumption was approximately 51 million m3/year, whereas water supply was only about 46 million m3/year. Thus, the study of water supply, demand and balancing are important for effective water resources management. This study aims to simulate the LULC data using the CLUE-S model, estimate water supply using the SWAT model, and calculate water demand using a water footprint basis for water balancing on the Island. In addition, tourist water demand was separately estimated under normal and new normal conditions (COVID-19 pandemic) to fit with the actual situation at national and international levels. Water balance results with the consideration of ecological water requirements suggest that a water deficit occurs every year under the dry year scenario in normal and new normal conditions. In addition, the monthly water balance indicates that a water deficit occurs in the summer season every year, both without and with the consideration of ecological water requirements. Consequently, it can be concluded that remote sensing data with advanced geospatial models can provide essential information about water supply, demand, and balance for water resources management, particularly water scarcity, in Phuket Island in the future. Additionally, this study’s conceptual framework and research workflows can assist government agencies in examining water deficits in other areas.

Ecological water requirements of wetlands in the middle and lower reaches of the Naoli River

In the last few decades, the wetland area of the Sanjiang Plain in northeast China has shrunk severely. To provide a scientific basis for the protection and restoration of wetlands in the Sanjiang Plain, Landsat TM images of 13 typical years of four well-preserved and contiguous wetlands are interpreted by remote sensing technology in the Sanjiang Plain of the Naoli River Drainage Basin. According to the results of the interpretation, the calculation of the minimum and the optimal ecological water requirements of the four wetlands was carried out by combining ecology with remote sensing technology. At the same time, considering the rainfall and surface runoff at different guarantee rates, the artificial recharge of four wetlands was calculated according to the principle of water balance. The results indicate that the wetland area decreased significantly from 1984 to 2013, and natural inflow of water cannot meet the actual water requirements of wetlands. The calculated artificial recharge of the four reserves provides technical support for replenishment of wetlands in the Sanjiang Plain, and lays a good foundation for the restoration of wetland ecosystems in the Sanjiang Plain. At the same time, it also provides a good habitat for rare waterfowl.