This intensity will be less than the actual peak intensity if the duration of the rainfall event was less than the fixed time interval for which measurements are reported. Convective precipitation events (thunderstorms) tend to produce shorter duration storm events than orographic precipitation. Duration, intensity, and frequency of rainfall events are important to flood prediction. Short duration precipitation is more significant to flooding within small drainage basins.The most important upslope factor in determining flood magnitude is the land area of the watershed upstream of the area of interest. Rainfall intensity is the second most important factor for watersheds of less than approximately 30 square miles or 80 square kilometres. The main channel slope is the second most important factor for larger watersheds. Channel slope and rainfall intensity become the third most important factors for small and large watersheds, respectively.Time of Concentration is the time required for runoff from the most distant point of the upstream drainage area to reach the point of the drainage channel controlling flooding of the area of interest. The time of concentration defines the critical duration of peak rainfall for the area of interest. The critical duration of intense rainfall might be only a few minutes for roof and parking lot drainage structures, while cumulative rainfall over several days would be critical for river basins. Downslope factors
Water flowing downhill ultimately encounters downstream conditions slowing movement. The final limitation in coastal flooding lands is often the ocean or some coastal flooding bars which form natural lakes.
Rubeosis iridis is a medical condition of the iris of the eye in which new abnormal blood vessels (formed by neovascularization) are found on the surface of the iris. Causes
This condition is often associated with diabetes in advanced proliferative diabetic retinopathy. Other conditions causing rubeosis iridis include central retinal vein occlusion, ocular ischemic syndrome, and chronic retinal detachment. Pathophysiology
It is usually associated with disease processes in the retina, which involve the retina becoming starved of oxygen (ischaemic). The ischemic retina releases a variety of factors, the most important of which is vascular endothelial growth factor (VEGF). These factors stimulate the formation of new blood vessels (angiogenesis). These new vessels do not have the same characteristics as the blood vessels originally formed in the eye. In addition, new blood vessels can form in areas that do not have them. Specifically, new blood vessels can be observed on the iris. In addition to the blood vessels in the iris, they can grow into the angle of the eye. These blood vessels eventually go through a process called fibrosis which closes the normal physiologic anatomy of the angle. The closing of the angle prevents fluid from leaving the eye resulting in an increase in intraocular pressure. This is called neovascular glaucoma. Treatment
If caught early, the neovascularization can be reversed with prompt panretinal photocoagulation (PRP), or injection of anti-VEGF medications with subsequent PRP. The injection blocks the direct effect of VEGF and acts more quickly but will wear off in about six weeks.