Rapid Urbanization and Agricultural Intensification Increase Regional Evaporative Water Consumption of the Loess Plateau

Abstract

Changing evapotranspiration (ET) will impact freshwater availability, knowledge of which is a critical prerequisite for policy development related to water resources management in an evolving climate, especially for water-limited regions. However, the socioeconomic effects are not considered due to the lack of detailed information about this. Here we used a well-validated remote sensing model and multiple socioeconomic factors to investigate the driving factors of ET changes over the Loess Plateau during 1982-2012. Results showed that the modeled annual ET significantly increased by~2 mm yr −2 during this period (p < 0.001), caused by increased transpiration (2.16 mm yr −2) and interception (0.27 mm yr −2), which was partly offset by decreased soil evaporation (−0.47 mm yr −2). Meanwhile, although the average ET of the forest was larger (480.4 ± 14.8 mm yr −1), it was found that the change in total ET of the region was dominated by that in grassland and cropland (1.1 km 3 yr −2 , 90% altogether). Factorial simulations indicated that the intensifying ET over 79.4% and 9.1% of the study area can be explained by vegetation greening and climate change, respectively. Further analysis suggested that the vegetation greening and the increased ET were primarily associated with the rapid urbanization and agricultural intensification. Our findings highlight the potential unfavorable effects of socioeconomic activities on water resources management on this coupled natural-human system that is already facing water scarcity issues. 1. Introduction Water is especially valuable for food production and ecosystem functioning (Immerzeel et al., 2020; Oki & Kanae, 2006). Global trends of population growth, rising living standards, and rapidly increasing urbanization are increasing the demand for water resources (Florke et al., 2013; Steffen et al., 2015; Wada et al., 2014). Added to this is the growing threat of climate change which will have enormous effects on water availability, and thus challenge global sustainable development (Qin et al., 2020). It has been reported that water scarcity affects more than 40% of the global population and is projected to rise. Over 1.7 billion people are currently living in river basins where water use exceeds recharge (https://www.un.org/sustainabledevelopment/ water-and-sanitation/). The contradiction between the supply and demand of water resources is particularly strong in arid and semi-arid regions where these competing uses can be found upstream, downstream, and sometimes across borders (

Changes in Dry-Season Water Availability and Attributions in the Yellow River Basin, China

“…However, other factors, such as the precipitation, carbon dioxide concentration, and water use efficiency, may also have played an important role in driving E change during the study period. As reported by Liang et al (2020), the rapid urbanization and agricultural intensification have significantly promoted the E during the past several decades in the Loess Plateau region. Jiang et al (2020) also found that the precipitation and relative humidity played an important role in E changes in the YRB during the period of 1981-2010.…”

“…With the rapid intensification of climate change and human activities, water shortage has become one of the most serious threats to sustainable development in the YRB (McVicar et al, 2007;Feng et al, 2016). Many studies have investigated the nature and human-induced changes in P (Wang et al, 2021;Zhang et al, 2021) and E in the region (Shao et al, 2019;Jiang et al, 2020;Liang et al, 2020). However, few studies have investigated the water availability over the dry season.…”

Divergent Hydrological Responses to Forest Expansion in Dry and Wet Basins of China: Implications for Future Afforestation Planning

“…As such, an increase in forest area would not affect runoff because the basin was still limited by water supply for HRB (Budyko, 1974; H. Yang et al., 2008). On the other hand, the absolute forest area was relatively small for WRB and HRB (Table 1), and therefore other land use changes such as agricultural practices and urbanization may also contribute to the runoff changes (e.g., Feng et al., 2016; Liang et al., 2020). Thus, exploration of the individual influences by these factors in future research can benefit from better understanding of the hydrological response for these two basins.…”

DataSheet1.docx

“…One with real E estimation with all varied climate variables and dynamic LAI and five control modelling experiments, which fixed only one contributing variable (i.e., Ta, LAI, VPD, Rn, and Wn) as the mean values during the period of 1982-1985 in each modelling experiment (Liang et al, 2020). This time series represented the mean climate and vegetation conditions of the 1980s.…”

“…We chose a relatively short period (4 years) as the control period because we tried to keep original trends and variations of both climate and vegetation. The differences between the real and control experiments highlight the contributions of controlled variables to the total E changes (Liang et al, 2020;Zhang et al, 2020). For example, the main effects of Ta are calculated as:…”