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101.
AbstractSoil water content (θ) and saturated hydraulic conductivity (Ks) vary in space. The objective of this study was to examine the effects of initial soil water content (θi) and Ks variability on runoff simulations using the LImburg Soil Erosion Model (LISEM) in a small watershed in the Chinese Loess Plateau, based on model parameters derived from intensive measurements. The results showed that the total discharge (TD) and peak discharge (PD) were underestimated when the variability of θi and Ks was partially considered or completely ignored compared with those when the variability was fully considered. Time to peak (TP) was less affected by the spatial variability compared to TD and PD. Except for TP in some cases, significant differences were found in all hydrological variables (TD, PD and TP) between the cases in which spatial variability of θi or Ks was fully considered and those in which spatial variability was partially considered or completely ignored. Furthermore, runoff simulations were affected more strongly by Ks variability than by θi variability. The degree of spatial variability influences on runoff simulations was related to the rainfall pattern and θi. Greater rainfall depth and instantaneous rainfall intensity corresponded to a smaller influence of the spatial variability. Stronger effects of the θi variability on runoff simulation were found in wetter soils, while stronger effects of the Ks variability were found in drier soils. For accurate runoff simulation, the θi variability can be completely ignored in cases of a 1-h duration storm with a return period greater than 10 years, while Ks variability should be fully considered even in the case of a 1-h duration storm with a return period of 20 years.
Editor D. Koutsoyiannis; Associate editor A. Fiori 相似文献
102.
Hai Wang Zheng‐Xin Chen Xiao‐Yu Zhang Si‐Xi Zhu Ying Ge Scott‐X. Chang Chong‐Bang Zhang Cheng‐Cai Huang Jie Chang 《洁净——土壤、空气、水》2013,41(7):657-664
The effects of plant species richness on both above‐ and belowground plant biomass, plant nitrogen (N) pool size, and substrate N concentrations were studied in a full‐scale subsurface vertical‐flow constructed wetland (CW). Results showed that (i) plant species richness increased belowground plant biomass and its N pool size but had no effect on aboveground plant biomass and its N pool size; (ii) plant species richness increased substrate N removal, especially ammonium N removal; and (iii) plant species richness had no effect on plant N use efficiency, suggesting that the N pool size increased with increasing plant species richness. More N accumulation could be removed through harvesting plant biomass. We concluded that the N removal performance of the CW improved by plant species richness through increasing belowground biomass and relevant N pool size. 相似文献
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The Dynamical-Statistical-Analog Ensemble Forecast model for landfalling tropical cyclones (TCs) precipitation (DSAEF_LTP) utilises an operational numerical weather prediction (NWP) model for the forecast track, while the precipitation forecast is obtained by finding analog cyclones, and making a precipitation forecast from an ensemble of the analogs. This study addresses TCs that occurred from 2004 to 2019 in Southeast China with 47 TCs as training samples and 18 TCs for independent forecast experiments. Experiments use four model versions. The control experiment DSAEF_LTP_1 includes three factors including TC track, landfall season, and TC intensity to determine analogs. Versions DSAEF_LTP_2, DSAEF_LTP_3, and DSAEF_LTP_4 respectively integrate improved similarity region, improved ensemble method, and improvements in both parameters. Results show that the DSAEF_LTP model with new values of similarity region and ensemble method (DSAEF_LTP_4) performs best in the simulation experiment, while the DSAEF_LTP model with new values only of ensemble method (DSAEF_LTP_3) performs best in the forecast experiment. The reason for the difference between simulation (training sample) and forecast (independent sample) may be that the proportion of TC with typical tracks (southeast to northwest movement or landfall over Southeast China) has changed significantly between samples. Forecast performance is compared with that of three global dynamical models (ECMWF, GRAPES, and GFS) and a regional dynamical model (SMS-WARMS). The DSAEF_LTP model performs better than the dynamical models and tends to produce more false alarms in accumulated forecast precipitation above 250 mm and 100 mm. Compared with TCs without heavy precipitation or typical tracks, TCs with these characteristics are better forecasted by the DSAEF_LTP model. 相似文献
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以三峡库区消落区表层沉积物为研究对象,通过对干湿交替沉积物中磷的赋存形式、吸附等温曲线的分析,揭示了干湿交替过程中沉积物磷的分布规律、吸附特征以及磷的源汇变化。结果表明:上覆水总磷变化呈现11月总磷<5月总磷<8月总磷。消落区覆水到出露沉积物最大磷吸附量、土壤最大缓冲能力在增加,磷零吸持平衡浓度、易解吸磷在降低,表明沉积物在夏季出露落干的过程中,固磷能力增强,释磷能力减弱;消落区土壤首次覆水过程中土壤磷呈现出由源到汇的转变。成库初期,覆水时沉积物主要表现为磷的积累,次年水库开闸放水排沙时,消落区表层富磷沉积物被冲刷排出。 相似文献
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The changes of vegetation cover in Ejina Oasis based on water resources redistribution in Heihe River 总被引：1，自引：0，他引：1
Wang Yaobin Feng Qi Si Jianhua Su Yonghong Chang Zongqiang Xi Haiyang 《Environmental Earth Sciences》2011,64(7):1965-1973
The Ejina Oasis (EO), located in arid northwest China, is a typical arid area in the world. The ecosystem in the oasis has
become worse since the 1990s. However, it began to improve after the Chinese government took the mandatory measure to redistribute
the water in Heihe in 2000. To understand this change, the remote sensing images in 1990, 2000 and 2006 were selected, and
exertion related Land Use/Cover Change (LUCC) model was employed. Results showed that: (1) non-vegetation cover was the main
body of the vegetation cover in oasis, showing a trend of increase at the beginning and diminution later, while low, medium
and high vegetation cover was the other way around; (2) the area of low, medium and high vegetation cover in 2006 was less
than that in 1990; the status and trend index P
t of oasis vegetation cover was 0.62 in 1990–2000, which means that the oasis ecosystem of Ejina was getting worse and was
under an unbalanced status; P
t was 0.27 in 2000–2006 indicating that the oasis ecosystem was restored obviously and the whole system tended to be balanced;
(3) all of these changes should be attributed to the water resources redistribution in Heihe River, which played a leading
role, as well as the measures and relevant policies taken by the local government, which promoted the rapid recovery of the
medium and high vegetation. 相似文献