A sheet erodibility parameter for water erosion modeling in regions with low intensity rain

2013 ◽  
Vol 44 (6) ◽  
pp. 1013-1021 ◽  
Author(s):  
Mohammad H. Hussein
Keyword(s):  
Probability Distribution ◽  
Agricultural Land ◽  
Silty Clay ◽  
Storm Events ◽  
Sheet Flow ◽  
Northern Iraq ◽  
Flow Power ◽  
Normal Rainfall ◽  
Lognormal Probability ◽  
Sheet Erosion

Soil erodibility reflects the soil effect on the detachment process by rainfall and runoff; an evaluation of this parameter for single storm events was carried out using natural runoff plot data collected for two rainfall seasons in northern Iraq. The region is characterized by a semiarid Mediterranean-type climate with normal rainfall intensity below 20 mm/h and dominant sheet erosion on agricultural land. The plots were three 30 × 3 m and three 10 × 3 m, in fallow, situated on a 6% uniform slope; the soil at the site has a silty clay loam texture and belongs to the Calciorthid suborder. Sheet erosion rate was assumed linearly proportional to the storm power and the sheet flow power; a steady-state turbulent and kinematic sheet flow was also assumed. The results indicated a dominant detachment by rainfall with a substantial variability in storm by storm calculated sheet erodibility. The two-parameter lognormal probability distribution fitted the obtained sheet erodibility values reasonably well. Using this probability distribution, a representative sheet erodibility value of 0.056 × 10−3kg/J was obtained for use at the experimental site.

Length distribution of strike-slip faults and the process of breakage in continental crust

1976 ◽  
Vol 13 (5) ◽  
pp. 704-707 ◽  
Author(s):  
G. Ranalli
Keyword(s):  
Probability Distribution ◽  
Random Process ◽  
Continental Crust ◽  
Length Distribution ◽  
Strike Slip ◽  
Kolmogorov Type ◽  
The Law ◽  
Lognormal Probability

The distribution of lengths of regional strike-slip faults in continental crust is adequately described by the lognormal probability distribution. It is therefore suggested that the faulting process can be modelled as a random process obeying the law of proportionate effect (Kolmogorov type).

Modelling the temporal variation in the seed production of North American trees

2004 ◽  
Vol 34 (1) ◽  
pp. 65-75 ◽  
Author(s):  
D F Greene ◽  
E A Johnson
Keyword(s):  
Probability Distribution ◽  
Temporal Variation ◽  
Seed Production ◽  
Large Fraction ◽  
Basal Area ◽  
Tree Regeneration ◽  
Narrow Strip ◽  
Area Source ◽  
Endogenous Cycles ◽  
Lognormal Probability

Many aspects of temporal variation in tree seed production (e.g., the proability distribution, periodicity, uni modality) are poorly understood. In this paper, we used 32 annual seed production records from 22 species to show that there are no discernible endogenous cycles, and there is a modest (but seldom significant) tendency for a high seed production year to be followed by an unusually low production year. Finally, we found that all of the records conformed to a single lognormal probability distribution, although our ability to discriminate among species, given short and extremely variable records, is admittedly very limited. We used the lognormal to develop the distribution of the sums of local seed production events (summed across 4 years) as an aid in predicting postharvest or postfire tree regeneration success. Our conclusion is that reliable (defined as 90% of the time) adequate stocking at the edge of an area source requires that the species of interest must comprise a very large fraction of the total basal area per area. Indeed, if the species constitutes less than about 50% of the source, neither burns nor even very narrow strip cuts will be reliably stocked.

scholarly journals Evaluating MODIS Dust-Detection Indices over the Arabian Peninsula

2018 ◽  
Vol 10 (12) ◽  
pp. 1993 ◽  
Author(s):  
Sarah Albugami ◽  
Steven Palmer ◽  
Jeroen Meersmans ◽  
Toby Waine
Keyword(s):  
Land Cover ◽  
Agricultural Land ◽  
Arabian Peninsula ◽  
Source Region ◽  
Temporal Trends ◽  
Dust Storms ◽  
Storm Events ◽  
Near Surface ◽  
Airborne Dust ◽  
Land Cover Types

Sand and dust storm events (SDEs), which result from strong surface winds in arid and semi-arid areas, exhibiting loose dry soil surfaces are detrimental to human health, agricultural land, infrastructure, and transport. The accurate detection of near-surface dust is crucial for quantifying the spatial and temporal occurrence of SDEs globally. The Arabian Peninsula is an important source region for global dust due to the presence of extensive deserts. This paper evaluates the suitability of five different MODIS-based methods for detecting airborne dust over the Arabian Peninsula: (a) Normalized Difference Dust Index (NDDI); (b) Brightness Temperature Difference (BTD) (31–32); (c) BTD (20–31); (d) Middle East Dust Index (MEDI) and (e) Reflective Solar Band (RSB). We derive detection thresholds for each index by comparing observed values for ‘dust-present’ versus ‘dust-free’ conditions, taking into account various land cover settings and analyzing associated temporal trends. Our results suggest that the BTD (31–32) method and the RSB index are the most suitable indices for detecting dust storms over different land-cover types across the Arabian Peninsula. The NDDI and BTD (20–31) methods have limitations in identifying dust over multiple land-cover types. Furthermore, the MEDI has been found to be unsuitable for detecting dust in the study area across all land-cover types.

Soil erosion of agricultural land in Western Australia estimated by cesium-137

Soil Research ◽  
1992 ◽  
Vol 30 (4) ◽  
pp. 533 ◽  
Author(s):  
DJ Mcfarlane ◽  
RJ Loughran ◽  
BL Campbell
Keyword(s):  
Western Australia ◽  
Agricultural Land ◽  
Soil Surface ◽  
137Cs Activity ◽  
Rock Outcrops ◽  
Severe Erosion ◽  
Cesium 137 ◽  
Water Repellence ◽  
Soil Losses ◽  
Sheet Erosion

The caesium-137 technique was used to estimate net soil loss from 10 hillslopes in the agricultural area of Western Australia. The gravel fraction of the soil was found to have approximately 56% of the total 137Cs activity found on the <2 mm fraction of the soil on three slopes where it was measured. In the lower rainfall zones, 137Cs appeared not to have uniformly labelled the soils in uncleared areas, possibly due to the redistribution of rainfall in the canopy and above the soil surface, and the water repellence of some soils. A previously established calibration curve was used to calculate net soil losses from the 10 hillslopes. Potato-growing land and slopes below rock outcrops in the Wheatbelt appear to have experienced the most severe erosion since the soils were first labelled with 137Cs in the mid 1950s (19-27 t ha-1 yr-1). Hillslopes below rock outcrops had appreciably less 137Cs than those below lateritic breakaways, indicating the presence of sheet erosion.

scholarly journals Investigating the Effect of the “Land between the Lakes” on Storm Patterns

2014 ◽  
Vol 53 (6) ◽  
pp. 1506-1524 ◽  
Author(s):  
Josh Durkee ◽  
Ahmed M. Degu ◽  
Faisal Hossain ◽  
Rezaul Mahmood ◽  
Jesse Winchester ◽  
...  
Keyword(s):  
Forest Cover ◽  
Agricultural Land ◽  
Open Water ◽  
Mississippi Valley ◽  
Storm Events ◽  
Hysplit Model ◽  
Near Surface ◽  
Synoptic Classification ◽  
Synoptic Conditions ◽  
Convective Cells

AbstractThe artificially created region around the “Land between the Lakes” (LBL) in Kentucky represents unique land use and land cover (LULC) heterogeneities. Over a distance of 100 km, the LULC comprises artificially created open water bodies (i.e., two parallel large run-on-river dams separated by the LBL), mountainous terrain, forest cover, and extensive agricultural land. Such heterogeneities increase (decrease) moisture supply and sensible heat, resulting in a differential air mass boundary that helps to initiate (inhibit) convection. Hence, the LBL can potentially modify precipitation formation. Historical anecdotes reveal a tendency for storms to dissipate or reintensify near the LBL. The specific scientific question pursued in this study is therefore the following: Has the unique development of two parallel run-on-river reservoirs and the surrounding LULC heterogeneity modified storm patterns in the region? Ten storm events during the growing season were selected. Two additional events, observed by the newly established high-resolution Kentucky Mesonet network, were also considered. Radar reflectivity images were visually inspected to understand the evolution of convective cells that originated or were modified near the LBL. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) Model was used to determine near-surface trajectories that led to the selected events. The spatial synoptic classification and merged Geostationary Operational Environmental Satellite (GOES) IR images were analyzed to determine the prevailing synoptic conditions on the event dates. Six storm events showed a pattern wherein the convective cells lost strength as it passed over the LBL in a northeasterly direction. In two events, Next Generation Weather Radar (NEXRAD) reflectivity imagery revealed enhancement of convection as the storm passed over the LBL toward the Mississippi valley. Further dissection of the storm morphology suggested that the thermodynamic environment may have played an important role for the eight events where modification of precipitation near LBL has been clearly observed.

scholarly journals Characteristics of chloride loading from urban and agricultural watersheds during storm and non-storm period

2020 ◽  
Author(s):  
Jina Beom ◽  
Minhyuk Jeung ◽  
Woojung Choi ◽  
Younggu Her ◽  
Kwangsik Yoon
Keyword(s):  
Agricultural Land ◽  
Chloride Ion ◽  
Transport Processes ◽  
Agricultural Watersheds ◽  
First Flush ◽  
Land Uses ◽  
Storm Events ◽  
Northern Regions ◽  
Management Plans ◽  
Water Management Plans

Abstract The chloride ion (Cl−) can adversely affect an aquatic ecosystem, but it is not clear how Cl− moves with runoff and how its transport processes are related to land uses and covers. This study investigated how the loading characteristics of Cl− vary depending on storm events and land covers in temperate region. We monitored Cl− concentrations in three study watersheds that have the different compositions of urban and agricultural land uses. In addition, a Mass First Flush ratio (MFFn) was determined to quantify the effect of first flush on Cl− loading. Overall, the observed concentrations and loadings in this study were found less than those reported in the cold northern regions. The monitoring data showed that Cl− concentrations and loads observed in an urban watershed were significantly larger than that of a rural watershed. The results suggest water management plans to focus on urbanized areas and their storm water to efficiently reduce chloride loading to downstream waterbodies. However, a further study is recommended to identify the sources and pathways of Cl− loaded to waterbodies.

Exploring the potential for using hierarchical sediment fingerprinting as an urban management tool in monitoring changing sediment sources

2020 ◽  
Author(s):  
Rory Walsh ◽  
Carla Ferreira ◽  
William Blake ◽  
Sam Higton ◽  
Antonio Ferreira
Keyword(s):  
Land Use ◽  
Suspended Sediment ◽  
Agricultural Land ◽  
Management Tool ◽  
Sediment Fingerprinting ◽  
Storm Events ◽  
Sediment Sources ◽  
Wet Season ◽  
Stream Network ◽  
Urban Catchments

&lt;p&gt;An ability to identify and quantify changes in sediment sources and erosion within catchments would be of great use for landscape managers and planners. This is particularly the case in peri-urban catchments, which are characterized by complex and dynamically changing land-use mosaics &amp;#8211; and where today&amp;#8217;s planning decisions may be crucial as regards avoiding or exacerbating erosional, water quality and flooding problems. This study explores the potential for a sediment fingerprinting approach to provide a cost-effective way of assessing changes in sediment sources within a small peri-urban catchment. The study focuses on the Ribeira dos Cov&amp;#245;es catchment (6.2 km&lt;sup&gt;2&lt;/sup&gt;), on the outskirts of Coimbra in central Portugal. The climate is humid Mediterranean and the geology is 56% sandstone, 41% marly limestone and 3% alluvium. Current land-use is 56% woodland, 4% agricultural and 40% urban (mainly residential, but also a recently constructed enterprise park (5%) and major highway (1%)). Recent urbanization has largely occupied former agricultural land. The study adopts a multi-proxy sediment fingerprinting approach, based on geochemical (elemental) characterization of fluvial fine bed-sediment and soil samples, using a Niton x-ray fluorescence elemental analyser. Sampling of fluvial sediment was carried out at 33 sites within the stream network (including all significant tributaries, downstream sites and the catchment outlet). Samples were collected in July 2018 and November 2018 following contrasting &amp;#8216;late wet season&amp;#8217; and &amp;#8216;end of dry season&amp;#8217; events. In addition, in July 2018 composite samples of potential sediment sources were collected, including (i) soil surface (0-2cm) samples at 64 representative locations, (ii) 17 samples from eroding channel margin sites, and (iii) 15 samples of road sediment. All samples were sieved to obtain &lt;63&amp;#181;m, 63-125&amp;#181;m, 125-250 &amp;#181;m and 250-2000&amp;#181;m fractions, where the &lt;63&amp;#181;m fraction was taken to represent suspended sediment. The elemental geochemistry of each sample fraction was derived using the XRF analyser. Differences (and similarities) in geochemical signatures between the various tributaries and the various potential sources were assessed using a range of statistical techniques. Bayesian unmixing models were used in a hierarchical (confluence-based) fashion to assess the contributions of different sub-catchments to downstream sites including the catchment outlet. Modelling results were then compared with relative contributions for three previously analysed storm events of 2012-2015, at which time construction activities had been more active. Modelling results for the two 2018 events were also validated by comparing them with independent suspended sediment records collected at five locations on the principal tributaries and at the catchment outlet. Overall, the modelling was successful in indicating and quantifying significant changes in sediment sources through time within the catchment. Reasons as to why sediment fingerprinting was successful in this case are then examined and discussed, in part drawing comparisons with the findings from a parallel sediment fingerprinting study of changing sources in the dynamically changing partly logged rainforest, partly oil palm Brantian catchment in Sabah, Malaysian Borneo. The potential for a simple sediment fingerprinting methodology to be developed for more widespread use by urban/environmental managers and planners is then explored. &amp;#160;&lt;/p&gt;

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