The Applicability of Remote Sensing Models of Soil Salinization Based on Feature Space

Soil salinization is a major challenge for the sustainable use of land resources. An optimal remote sensing inversion model could monitor regional soil salinity across diverse geographical areas. In this study, the feature space method was used to study the applicability of the inversion model for typical salt-affected soils in China (Yanqi Basin (arid area) and Kenli County (coastal area)), and to obtain soil salinity grade distribution maps. The salinity index (SI) surface albedo (Albedo)model was the most accurate in both arid and coastal regions with overall accuracy reaching 93.3% and 88.8%, respectively. The sensitivity factors for the inversion of salinity in both regions were the same, indicating that the SI-Albedo model is applicable for monitoring salinity in arid and coastal areas of China. We combined Landsat 8 Operational Land Imager image data and field data to obtain the distribution pattern of soil salinity using the SI-Albedo model and proposed corresponding countermeasures for soil salinity in the Yanqi Basin and Kenli County according to the degree of salinity. This study on soil salinity in arid and coastal areas of China will provide a useful reference for future research on soil salinity both in China and globally.

Water Use Conflict and Coordination between Agricultural and Wetlands—A Case Study of Yanqi Basin

Increased groundwater extraction leads to the decrease of the extent of wetlands due to the implementation of a water-saving transformation project in an arid irrigation area. The application of integrated mitigation tools and strategies in China have increasing significance. In this study, an integrated approach (SWAT-MODFLOW) was followed; it is based on a soil and water assessment tool (SWAT) coupled with a modular three-dimensional finite difference groundwater model (MODFLOW). Recharge and evaporation values were estimated by SWAT and were then used to simulate groundwater in a MODFLOW model. Calibration (over the years 2000–2010) and validation (over the years 2010–2016) were performed, based on observed groundwater-level data; results showed that the combined SWAT-MODFLOW provides more accurate simulation and prediction of the dynamic changes of surface water and groundwater in irrigation areas than results from individual MODFLOW models. This method was applied to the Yanqi Basin, which is one of the most appropriate arid agricultural basins for modeling lake wetland and groundwater in China. The correlation coefficients (R2) between the simulated and real groundwater level are 0.96 and 0.91 in SWAT-MODFLOW and MODFLOW, respectively. With the gradual increase in the extraction to 248%, 0.62 × 108 m3 of groundwater discharged into the lake became −2.25 × 108 m3. The lake level drops 1.3 m compared with the current year, when the groundwater exploitation increases by 10 × 108 m3/year. Overall, the results of the coupling model offer scientific evidence for agricultural water management and lake recovery, so as to enhance the water use coordination.

Simulation evaluation of groundwater resources in southeastern Bosten Lake based on GMS

Bosten Lake is located in Yanqi Basin of Xinjiang. A working area in the southeast of China is influenced by the regulation of Bosten Lake, and the transitional zone of climate in the north and south of Xinjiang, forming a climate of large evaporation, dry and little rain, and groundwater is a very important fresh water resource. In order to find out the composition of groundwater resources in the working area, the groundwater steady flow model is established by using the data of borehole, well, pumping test and so on, and the groundwater resources in this area are evaluated. The groundwater exploitation mode in the simulated area is evaluated. The results show that: the exploitable groundwater resources in the simulated area is about 22.045 million m3/a. Changing the mode of agricultural water use under the existing groundwater equilibrium condition can effectively reduce the waste of groundwater resources.

Suitable oasis scales under a government plan in the Kaidu-Konqi River Basin of northwest arid region, China

The Yanqi Basin and the Konqi River Basin of the Kaidu-Konqi River Basin were chosen as the study sites in this paper in order to investigate suitable scales of natural and artificial oases with a specified water resource and water quantity planned by the local government. Combined with remote-sensing images from 2013, water resources in 2013, 2025 and 2035, and weather and socioeconomic data, suitable scales of oases were analyzed. The results showed that: (1) The total available water quantities in the Yanqi Basin and the Konqi River Basin without river base flow, and the input of water into Bosten Lake and Tarim River, over high-, normal and low-flow periods, in 2025 and 2035, were 19.04 × 108 m3, 10.52 × 108 m3, 4.95 × 108 m3, 9.95 × 108 m3 and 9.95 × 108 m3, as well as 21.77 × 108 m3, 13.95 × 108 m3, 10.11 × 108 m3, 12.50 × 108 m3, and 9.74 × 108 m3. (2) The water demand of the natural oasis in the Yanqi Basin and the Konqi River Basin was 2.59 × 108 m3, and 4.59 × 108 m3, respectively. (3) The total water consumption of the artificial oasis in 2013, 2025, and 2035 were 10.51 × 108 m3, 10.99 × 108 m3 and 10.74 × 108 m3 in the Yanqi Basin, respectively, and 18.59 × 108 m3, 14.07 × 108 m3 and 13.30 × 108m3 in the Kongqi River Basin, respectively. (4) Under government planning, the optimal area in 2025 and 2035 should be 5,100.06 km2 and 5,096.15 km2 in the Yanqi Basin oases, and 6,008.53 km2 and 4,691.36 km2 in the Konqi River Basin oases, respectively, under the different inflow variations, and 4,972.71 km2 and 4,969.22 km2 in the Yanqi Basin oases, and 5,975.17 km2 and 4,665.67 km2 in the Kongqi River Basin oases, respectively, under the appropriate proportion. (5) The artificial oases in these basins should be greatly decreased in the future due to limited water resources.