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Hydrological models play an important role in water resource management, but they always suffer from various sources of uncertainties. Therefore, it is necessary to implement uncertainty analysis to gain more confidence in numerical modeling. The study employed three methods (i.e., Parameter Solution (ParaSol), Sequential Uncertainty Fitting (SUFI2), and Generalized Likelihood Uncertainty Estimation (GLUE)) to quantify the parameter sensitivity and uncertainty of the SWAT (Soil and Water Assessment Tool) model in a mountain-loess transitional watershed-Jingchuan River Basin (JCRB) on the Loess Plateau, China. The model was calibrated and validated using monthly observed streamflow at the Jingchuan gaging station and the modeling results showed that SWAT performed well in the study period in the JCRB. The parameter sensitivity results demonstrated that any of the three methods were capable for the parameter sensitivity analysis in this area. Among the parameters, CN2, SOL_K, and ALPHA_BF were more sensitive to the simulation of peak flow, average flow, and low flow, respectively, compared to others (e.g., ESCO, CH_K2, and SOL_AWC) in this basin. Although the ParaSol method was more efficient in capturing the most optimal parameter set, it showed limited ability in uncertainty analysis due to the narrower 95CI and poor P-factor and R-factor in this area. In contrast, the 95CIs in SUFI2 and GLUE were wider than ParaSol, indicating that these two methods can be promising in analyzing the model parameter uncertainty. However, for the model prediction uncertainty within the same parameter range, SUFI2 was proven to be slightly more superior to GLUE. Overall, through the comparisons of the proposed evaluation criteria for uncertainty analysis (e.g., P-factor, R-factor, NSE, and R 2) and the computational efficiencies, SUFI2 can be a potentially efficient tool for the parameter optimization and uncertainty analysis. This study provides an insight into selecting uncertainty analysis method in the modeling field, especially for the hydrological modeling community.

[1] A long-term transient simulation is conducted using the Community Climate System Model version 3 and the orbital acceleration technique to analyze the impact of insolation change caused by the Earth's orbital forcing on precipitation in the monsoonal East Asia (EA) and arid central Asia (CA) over the past 150 ka. Our results show that annual precipitation in both EA and CA has strong signals of the 20 ka precessional cycles and varies in phase with the Northern Hemisphere (NH) summer insolation. Similar characteristics can also be observed from previously published oxygen isotope records of stalagmites near EA and CA. Composite analyses based on seven precessional cycles suggest that the increase (decrease) in the NH summer (winter) insolation enhances EA (CA) summer (winter) precipitation by modulation of the Asian monsoon (westerly) circulation in summer (winter). When the precession-induced NH summer insolation increases, the Asian summer monsoon circulation is enhanced and EA precipitation increases significantly. Meanwhile, the increase in the summer insolation at the precessional scale is accompanied by a decrease in the winter insolation, which causes dramatic cooling of the troposphere in the lower latitudes. Consequently, the CA winter precipitation increases due to the changes in the temperature gradient and the westerly circulation. Therefore, the responses of the Asian monsoon and westerly circulation to summer and winter insolation variations induced by the precessional cycles determine precipitation in the respective rainy seasons and are the primary cause leading to the synchronous variation patterns of annual precipitation in EA and CA at the orbital scale.

A low aspect ratio tokamak energy system has been proposed, which aims at the near time application of the fusion energy. This system include a low aspect ratio tokamak as fusion neutron driver, a Radioactivity Clean Nuclear power System as blanket and a novel concept of liquid metal conductor as center conductor post. On the conceptual design 100MW driver under 1MW/m 2 neutron wall loading can transmute High Level Waste(include minor nuclides and fission products) produced by 10 GW PWR, self-sustain tritium and output a great mount of energy. After the operation of 30 years, the BHP level of whole system will decreased 2 orders of magnitude.

Compared with the conventional fossil fuel, bioenergy has obvious advantages due to its renewability and large quantity, and thus plays a crucial role in helping defend the energy security. However, the bioenergy development may potentially cause serious environmental alterations, which remain unclear. The study summarizes the environmental impacts of bioenergy production based on the compilation and published data. Our analysis shows that more and more attention is being paid to the environmental protection as the development of bioenergy, and among the influencing terms of bioenergy production, water issues (i.e., water quantity and quality) gain the greatest concern, whereas the least attention has been given to soil erosion. Although we recognize that the bioenergy production can indeed exert negative effects on the environment in terms of water quantity and quality, greenhouse gas emissions, biodiversity and soil organic carbon, and soil erosion, the adverse impacts varied greatly depending on biomass types, land locations, and management practices. Identifying the reasonable cultivation locations, appropriate bioenergy crop types, and optimal management practices can be beneficial to environment and sustainable development of bioenergy. In this field, Chinese bioenergy production has lagged behind and does not match its rising energy consumption, but it has a great potential of and demand for biomass-based energy especially under its urbanization, in spite of the negative environmental impacts. Therefore, this article is expected to serve as a reference and guideline on what has been done in the bioenergy-oriented countries that might stimulate development of more effective and environmentally sound guidelines for promoting bioenergy production in China and other developing countries as well.

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Abstract. The hydrological effects of the "Grain for Green" project (GFGP) on the Loess Plateau have been extensively debated due to the complexity of the water system and its multiple driving factors. The aim of this study was to investigate the response of the hydrological cycle to the GFGP measures based in a case study of the Yanhe Basin, a typical hilly-gully area on the Loess Plateau of China. First, we analyzed the land use and land cover (LULC) changes from 1990 to 2010. Then, we evaluated the effects of LULC changes and sloping land conversion on the main hydrological components in the basin using the Soil and Water Assessment Tool (SWAT). The results indicated that cropland exhibited a decreasing trend, declining from 40.2 % of the basin area in 1990 to 17.6 % in 2010, and that the woodland and grassland areas correspondingly increased. With the land use changes from 1990 to 2010, the water yield showed a decreasing trend which was mainly due to decrease in surface runoff. In contrast, evapotranspiration (ET) showed an increasing trend over the same period, resulting in a persistent decrease in soil water. The conversion of sloping cropland to grassland or woodland exerted negative effects on water yield and soil water. Compared with the land use condition in 2010, the negative effects were most evident where cropland with a slope ≥ 15 • was converted to woodland, with decreases in surface runoff and soil water of 17.1 and 6.4 %, respectively. These results suggest that the expansive reforestation on sloping land in the loess hilly-gully region decreased water yield and increased ET, resulting in reduced soil water. The results of this study can be used to support sustainable land use planning and water resource management on the Loess Plateau in China.

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