Patterns, controls and predictions of water and land resources nexus in a typical inland river basina: A green-blue water perspective

The underlying surface structure is being reshaped by climate change and human activities, which in turn affects the hydrological processes in inland river basins, with significant consequences for coupling patterns of water and land resources in inland river basins of arid and semi-arid regions. However, current studies of coupling pattern of water and land resources analysis focus on available water and visible land resources in the districts, so that there is an urgent need for research on the simulation and prediction for water and land resources coupling of the micro-scale. Therefore, this study firstly evaluated and predicted the land resources by MCE-CA-Markov model and soil quality index function with environment factors and socio-economic factors, then generalized and simulated the water resources by SWAT, and construct the Water-Land Nexus Model for water conservation and water consumption zones to clear the impact mechanisms of water and land resources nexus in inland river basins. The results show that the nexus index of water and land resources present a decreasing distribution from water conservation area to water consumption area of the Shiyang River Basin, with that being lower than 0.1 (mainly in the water consumption area). The coupling index of water and land resources of Shiyang River Basin decreases from 0.1105 in 1980 to 0.1071 in 2000. In 2020-2050, the water conservation area exhibit an increasing trend, but that of the water consumption area is decreasing. The Geo-detector results show that soil quality index, blue water resource and DEM are the main factors influencing the coupling of water and land resources in Shiyang River Basin, follow by precipitation, temperature and green water resource, and the effects of POP and GDP could be negligible. Furthermore, the interactions between natural and socio-economic factors are stronger than the ones within each other, indicating that natural factors are the main influences on water-land nexus and it is important to consider the interactions of nature along with the human activities.