چکیده:
Soil hydrau-physical data are important for many hydrological modelings. They are the main variables controlling the key processes such as water and chemicals movement and transport in the soil profiles. This study was conducted in order to analyze the spatial distribution of selected soil hydrau-physcial characteristics including infiltration rate (IR), saturated hydraulic conductivity (Ks), bulk density (BD), clay, silt, and sand content. The study area was sampled on a pseudo-regular sampling scheme with initial grid spacing of 1 km during June and July 2007. Maximum coefficient of variation (CV) was found for IR (72%) and Ks (67%). While, BD showed a minimum CV of
9%. Statistical analyses illustrated that there is a significant difference (P<0.05) in the mean values of IR in two different landforms, i.e., plateaus and alluvial plains. However, different land uses including rangelands and dry farming revealed no significant differences in the mean values of measured IR. The contrasting results were obtained for Ks. Geostatistical analyses revealed that the spatially dependent stochastic component (structure) was predominant over the nugget variance (noise). The developed and modeled variograms of each variable were used in
generating kriged maps. As expected, these maps exploited spatial similarities among soil properties.
خلاصه ماشینی:
Catchment-scale spatial variability analysis of soil hydro-physical properties in a semi-arid region of Iran Abstract Soil hydrau-physical data are important for many hydrological modelings.
This study was conducted in order to analyze the spatial distribution of selected soil hydrau-physcial characteristics including infiltration rate (IR), saturated hydraulic conductivity (Ks), bulk density (BD), clay, silt, and sand content.
Spatial variability of soil physical and chemical properties at a large-scale, like catchment-scale, is mainly due to geological, geomorophological and pedological soil forming factors that could be altered and induced by other factors such as different land use managements.
Variability of hydrau-physical properties can be investigated with respect to various environmental processes at different spatial and temporal scales (McBratney, 1998; Rasse et al.
Infiltration rate and saturated hydraulic conductivity on a large-scale region may vary from very low to very high because of variability in the related soil physical and chemical properties.
Some studies used variograms, kriging and cokriging techniques to characterize the spatial patterns of soil hydrau-physical properties, and examples include Wilson et al.
In summary, soil properties like infiltration rate, bulk density, textural fractions, and saturated hydraulic conductivity are spatially variables which in turn are scale-dependent.
The main objectives of this study were (i) to explore probable close relationships among IR, Ks, and easily measured soil physical and chemical variables and (ii) to determine and assess the spatial variability in various soil hydraulic and physical properties at a catchment -scale in a semi-arid region.
Some authors conducted the multi-scale study on the spatial structure of different soil variables and exampled include Sobieraj et al.