Influencing factors and improvement paths of green water use efficiency in the Yellow River Basin: a new perspective based on ecogeographical divisions.

Exploring the influencing factors and improvement paths of green water use efficiency (GWUE) based on different regions is very important for the protection and utilization of water resources in the Yellow River Basin (YRB). However, previous studies focused only on the external impact of water use efficiency and did not take into account both internal and external factors. For the zoning of the YRB, the traditional upper, middle, and lower zoning methods were mostly used, and they could not show the impact of climatic and geological conditions. Therefore, based on ecogeographical divisions, the dynamic evolutionary characteristics, regional differences, and internal inefficiencies of green water use efficiency for 48 cities in the YRB from 2008 to 2018 are analyzed using a data envelopment analysis-slack-based measure (DEA-SBM) model, global Malmquist‒Luenberger (GML) index decomposition, and kernel density estimation. We further use a panel Tobit model to analyze the external influencing factors of green water use efficiency and propose ways to improve the utilization of water resources in different regions from both the internal and external perspectives. The results are as follows: (1) During the study period, the GWUE fluctuated between 0.58 and 0.67 and showed a trend of improving in the arid areas and deteriorating in the humid area. (2) Exploring the sources of inefficiency from the internal perspective reveals that the labor redundancy, capital redundancy, and wastewater redundancy in the semihumid area are higher; the energy redundancy in the semiarid area is higher; and the economic output in the arid area is insufficient. (3) From the GML perspective, the absolute difference in the green water use efficiency of the cities in the YRB is expanding. Regarding the technical efficiency (EC) index, the technical efficiency of the semiarid area has a convergence effect. Regarding the technological progress (TC) index, the gap in the arid area has been widening, and the technology in the semihumid and semiarid areas is converging backward. (4) There are significant differences in the external factors affecting GWUE in different ecogeographical regions. This study can help the government consider ecogeographical factors when formulating water resource-related policies, and it provides a scientific reference for how to better utilize water resources in different regions of the YRB from both the internal and external perspectives. [ABSTRACT FROM AUTHOR]