نتایج جستجو برای: layer soil
تعداد نتایج: 456925 فیلتر نتایج به سال:
This paper aims to establish evidence for available phosphorous (AP) binding with total nitrogen (N) in subtropical forest soils. Soil organic carbon (SOC), total N, total phosphorous (P) and AP concentration were measured for three contrasting forest types in southern China: Masson pine forest (MPF), coniferous and broadleaved mixed forest (CBMF) and monsoon evergreen broadleaved forest (MEBF)...
Florida Everglades restoration plans are aimed at maintaining and restoring characteristic landscape features such as soil, vegetation, and hydrologic patterns. This study presents the results from an exhaustive spatial sampling of key soil properties in Water Conservation Area 1 (WCA 1), which is part of the northern Everglades. Three soil strata were sampled: floc, upper 0- to 10-cm soil laye...
BACKGROUND Wildfires are an increasingly important component of the forces that drive the global carbon (C) cycle and climate change as progressive warming is expected in boreal areas. This study estimated C emissions from the wildfires across the Alaskan Yukon River Basin in 2004. We spatially related the firescars to land cover types and defined the C fractions of aboveground biomass and the ...
The 50% variation in the estimates of carbon (C) content in the forest soils of Russia at present is caused by confusion of terms and ignorance of the soil geographical representativeness in forests. The GIS-based analysis closes the gap to the estimate published earlier by Alexeyev and Birdsey (1994, p. 170). The average soil carbon density (SCD) for the 0.3 meter (m) layer of the forest soils...
A piezometric head method is proposed to estimate the impermeable layer depth used in drain spacing formulae. The method was tested and compared with soil texture changes and the US Bureau of Reclamation (USBR, 1978) criterion of impermeable layer being one with hydraulic conductivity one tenth to one fifth that of the weighted hydraulic conductivity of the upper layers. The proposed method, wh...
[1] In this paper, we investigate floods and droughts in the Upper Mississippi basin over a 50-year period (1950–1999) using a hydrological model (Variable Infiltration Capacity Model – 3 Layer). Simulations have been carried out between January 1950 and December 1999 at daily timestep and 1/8 spatial resolution for the water budget and at hourly time-step and 1 spatial resolution for the energ...
Based on the laboratory study, the effects of sodium polyacrylate (SP) was investigated at 5 rates of 0, 0.08, 0.2, 0.5, and 1%, on water retention, saturated hydraulic conductivity(Ks), infiltration characteristic and water distribution profiles of a sandy soil. The results showed that water retention and available water capacity effectively increased with increasing SP rate. The Ks and the ra...
SHAKE2000 and DEEPSOIL are the two most important programs to calculate the response analysis of soil layer. In order to analyze the similarities and differences between them, and to guide the improvement of the method and program of seismic response analysis of soil layer, 25 KiK net seismic records from 9 stations were selected as the research objects in this paper, from the aspects of surfac...
Exfiltration of waste water in sewer networks represents a potential danger for the soil and the aquifer. Various modelling approaches have been proposed to quantify sewerage exfiltration and its spatial and temporal variation. Common models are based on the law of Darcy, extended by a more or less detailed consideration of the expansion of leaks, the characteristics of the soil and the colmati...
Using 19 years of Chinese soil moisture data from 1981-1999, we evaluate soil moisture in three reanalysis outputs: ERA40, NCEP/NCAR reanalysis (R-1), and NCEP/DOE reanalysis 2 (R-2) over China. R-2 shows better interannual variability and seasonal patterns of soil moisture than R-1 as the result of incorporation of observed precipitation. ERA40 produces a better mean value of soil moisture for...
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