The study reported and analyzed the current state of wastewater treatment plants (WWTPs) in urban China from the perspective of treatment technologies, pollutant removals, operating load and effluent discharge standards. By the end of 2013, 3508 WWTPs have been built in 31 provinces and cities in China with a total treatment capacity of 1.48×10(8)m(3)/d. The uneven population distribution between China's east and west regions has resulted in notably different economic development outcomes. The technologies mostly used in WWTPs are AAO and oxidation ditch, which account for over 50% of the existing WWTPs. According to statistics, the efficiencies of COD and NH3-N removal are good in 656 WWTPs in 70 cities. The overall average COD removal is over 88% with few regional differences. The average removal efficiency of NH3-N is up to 80%. Large differences exist between the operating loads applied in different WWTPs. The average operating loading rate is approximately 83%, and 52% of WWTPs operate at loadings of <80%, treating up to 40% of the wastewater generated. The implementation of discharge standards has been low. Approximately 28% of WWTPs that achieved the Grade I-A Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002) were constructed after 2010. The sludge treatment and recycling rates are only 25%, and approximately 15% of wastewater is inefficiently treated. Approximately 60% of WWTPs have capacities of 1×10(4)m(3)/d-5×10(4)m(3)/d. Relatively high energy consumption is required for small-scale processing, and the utilization rate of recycled wastewater is low. The challenges of WWTPs are discussed with the aim of developing rational criteria and appropriate technologies for water recycling. Suggestions regarding potential technical and administrative measures are provided.

One of the world's largest revegetation programs, the Grain for Green Project (GfGP), has been taking place on the Loess Plateau of China since 1999. Such massive revegetation causes changes in the region's hydrological cycle, water availability, and ecological sustainability through enhanced evapotranspiration (ET). Here we quantify effects of the GfGP's revegetation on ET over this water-stressed region. Our approach involves use of a modified Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model, incorporating vegetation dynamics as a new component. The original PT-JPL model has been expanded from site scale to regional scale, thereby allowing its application to the Loess Plateau. The modified PT-JPL model was calibrated and validated against flux tower-measured and water balance-based ET observations. The model performed well at a regional scale with the incorporation of vegetation dynamics. To quantify the net effect of revegetation on evaporative water consumption after the GfGP, we compared scenarios with and without revegetation. We find the revegetation has led to a significant increase in ET across the Loess Plateau, of 4.39 mm/yr averaged over the past 15 years (mean annual precipitation was 464 mm). Compared with the no revegetation scenario, the GfGP revegetation appreciably enhanced evaporative water consumption across the Loess Plateau, by approximately 31 × 10 8 m 3 /yr (or 4.90 mm/yr). Our findings suggest that to maintain ecologically sustainable restoration and rational use of water resources, factors including the strength of revegetation and the relationship between evaporative water consumption and revegetation type should be considered. Key Points:• The PT-JPL model has been upgraded to allow incorporation of vegetation dynamics at a regional scale • The extended PT-JPL model performs well at regional scale • Compared with a no-revegetation scenario, revegetation increases evaporative water consumption byapproximately 31 × 108 m3/yr (4.90 mm/yr) across theLoess Plateau, China Supporting Information:• Supporting Information S1

Estimating long-term average annual water balance at the catchment scale has been an important scientific problem in hydrology and a reliable method for long-term estimates of evapotranspiration (D. Wang, 2012). Water and vegetation in the catchments have reached equilibrium through long-term evolution, so that there is an inextricable relationship between water balance and vegetation change (Gerten et al., 2004). Changes in vegetation affect the elements of water balance, thus vegetation coverage plays an influential role in regulating regional water balance (Heimann & Reichstein, 2008; Seddon et al., 2016). Precipitation (P), evapotranspiration (ET), streamflow (Q), and water storage changes (ΔS) are important components of water balance estimates. Previous studies (e.g., Shao et al., 2019) have demonstrated that vegetation restoration could lead to increases in regional ET over the Loess Plateau, thus changing the water availability. This could potentially exacerbate tensions between water supply and demand in water-stressed regions. Thus, it can be further hypothesized that the vegetation changes may influence the catchment-scale water balance. In addition, the relationship between ΔS and vegetation may be scale dependent and remains unclear, thus studying the time scale of ΔS in vegetation recovery areas is particularly important. The Loess Plateau, a typical arid and semi-arid region, accounts for 6.6% of China's total land area and supports 8.5% of the population (Fu et al., 2011). It is one of the most water scarce regions with the most fragile ecosystems in the world (Y. Wang et al., 2011; B. Zhang et al., 2016). In the past, the Loess Plateau, with its sparse vegetation coverage, frequent summer rains and intensive agricultural practices, suffered unprecedented water scarcity, soil erosion and fragile ecosystems (C. Wang et al., 2016; Z. Yang et al., 2016). These ecological and environmental problems significantly affect ecological environment and socioeconomic

The agricultural pastoral ecotone (APE) in Northwest China is an ecological transition zone in the arid area with a very fragile ecosystem. In recent years, the ecosystem has deteriorated sharply, and increasing desertification has made the regional ecosystem more vulnerable and sensitive. In this study, we analyzed (using classical statistical methods) spatial and temporal variations in soil water content (SWC) from 14 September 2016 to 22 April 2019 for high and low vegetation in two grassland sites in Yanchi County, Ningxia. The results showed that the largest average seasonal SWC occurred in autumn. The SWC of the first three layers (0 ÷ 15 cm) of the soil profile responded strongly to precipitation, whereas the SWC in deeper soil (30 ÷ 50 cm) could only be recharged markedly after continuous precipitation. Additionally, the growing process of plants proved to be a cause of variability in soil moisture profiles. Vegetation degradation sped up the course of desertification and decreased soil organic carbon content. These changes left the soil increasingly desiccated and enhanced soil variability. Meanwhile, vegetation degradation also prompted changes in soil temperature and shortened the soil’s frozen time in winter. With the acceleration of global warming, if the process of vegetation degeneration continues and soil temperatures keep rising, the ecosystem is likely to undergo irreversible degradation.

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