Extent Of Encroachment Research Articles

Impact of Slope Orientation on Inlet Spacing: Gutter Flow Analyses

A roadway’s capacity to drain itself is of utmost importance for the safety and comfort of its users. Standing water and any amount of channelized flow on roadways create nuisances to the users, and the extent of encroachment into the lanes and the water-film thickness over the lanes are crucial for motorists with relatively high speed. Guidelines cover a wide range of subjects from size and type of inlets, which capture the channelized flow for conveyance into enclosed drains, to the decision for slope orientation, but the guidelines seem to lack in checking the depth of channelized flow. HEC-22 (the urban drainage design manual of US Department of Transportation) endorses limiting the flow depths to curb height (as if the concern is no longer the roadway users) and fixes the criterion for the inlet spacing (restricted to 90 to 150 m) to maximum allowable flow spreads. This study analyzed the maximum allowable inlet spacing via setting three criteria: fixed maximums to flow depth, spread for the channel flow, and to over-lane water-film thickness. The impact of slope orientation on inlet spacing is tested along with some other factors for roadways of two types (local and highway). The results were graphed for various uniform slope orientations under a wide range of rainfall intensities for the determined inlet spacing values. This was performed by combining a kinematic wave equation solution to dismiss the conditions that lead to hydroplaning depths when using the Rational Method and Manning’s equation to obtain water depths and inlet spacings for an inlet of full capture capacity. It is found that the allowable spacing values do not constitute any major restrictions in highway setting (3 m shoulder) in terms of recommended spacing. In the local setting, however, with a maximum spread of 1.8 m, maximum allowable inlet spacing becomes a limitation in many orientations, and slope optimization under such conditions becomes crucial at times when providing the same spacing for two orientations.

Biohydrologic effects of eastern redcedar encroachment into grassland, Oklahoma, USA

Woody encroachment affects the biohydrology of rangelands worldwide and can increase evapotranspiration by increasing plant rooting depth, increasing the duration of the growing season, or by initiating a process of hydrologic recovery in formerly overgrazed landscapes. Eastern redcedar (Juniperus virginiana) is encroaching rapidly into rangelands in the Southern Great Plains of the USA, and beyond, including Oklahoma. However, the degree to which increasing growing season duration causes higher evapotranspiration after encroachment is not known. Here we show that increasing the duration of the growing season in north-central Oklahoma’s water-limited climate from seven months (April–October) to 12 months increases modeled evapotranspiration only marginally, from 95% to 97% of precipitation. However, this increase in evapotranspiration with woody encroachment into grassland corresponded to a two-thirds reduction in deep drainage. This study’s estimate of the hydrologic effects of eastern redcedar encroachment is likely to be highly conservative because it does not take into account the runoff-inducing effects of livestock grazing. Comparing simulated hydrologic fluxes in the present study to past work measuring runoff from grazinglands suggests that eastern redcedar encroachment into overgrazed rangelands is likely to increase evapotranspiration significantly. Whether or not eastern redcedar encroachment effects on evapotranspiration are discernable at the watershed scale will depend on the extent of encroachment throughout the watershed. Further research is necessary to quantify how the hydrologic effects of eastern redcedar encroachment vary due to climatic gradient.

Evaluating Pterygium Severity

Accurate and reliable evaluation techniques are essential for clinical and epidemiologic studies. This survey of corneal specialists was designed to lay a foundation for the further development of methods for evaluating and staging pterygium. In a self-administered, mailed questionnaire, 213 corneal specialists rated the importance of nine symptoms, nine signs, and nine clinical tests for the severity of primary pterygium. Severity was defined as the present need for surgical intervention. The most important factors for determining primary pterygium severity were the extent of encroachment onto the cornea, decreased visual acuity, restricted ocular motility, and increased rate of growth. Many patient symptoms were rated as moderately to highly important. The questionnaire was shown to have good response reliability by test-retest comparisons. Cronbach's alpha was 0.89, which indicates very good internal consistency reliability. The survey identifies the priorities of experts in determining the severity of pterygium. More precise and clearly defined evaluation methods will enhance future clinical and epidemiologic studies of pterygium. The ranked list of pterygium signs, symptoms, and tests can serve as a guide for developing pterygium evaluation methods in the future. There is a need for a method that accurately and precisely quantifies the distance of pterygium encroachment onto the cornea and the pterygium progression rate. Furthermore, there is a need for an assessment of patient symptoms.