Agenda - 07-05-1983 - Laserfiche WebLink

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Page 8 HYDROLOGY Hydrology deals with the occurance and distribution of water. More spe- cifically, analysis of the hydrology of an area includes consideration of the factors precilpitation, stream drainage systems, surface and subsurface water resources andl potential for flooding. Orange County receives about 43 inches of precipitation a year. Although the precipitation is fairly evenly distributed throughout the year, the driest season is thel fall. July and August are the wettest months with the precipi- tation total 'augmented by thundershowers. Major Features. The Eno River is the largest flowing body of water in the Harmon Young Area Study. it is located along the northern boundary of the area study and is one of the main streams in the Neuse drainage basin. The Eno drains into the Flat River in Durham County. Cates Creek is the second largest stream in the area study. This creek flows in a noitherly direction into the Eno River and is located between Old and New 86. 1 Stoney Creek, the next largest stream in the area study, originates in the southeastern corner and flows in a southerly direction, where it inter- sect with a second branch of the Creek. Stoney Creek eventually flows back to the Eno Rh1er. There are a number of small impoundment areas located throughout the study area. Most of these were, or are, being used as farm ponds. Drainage Patterns. With the numerous ridge lines running in a north- south direction throughout the area, the majority of surface drainage flows in an east-west direction. The surface drainage in the north-west section of the study area flows into a number of small unnamed streams and creeks that empty into the Eno River. Runoff from the central portion of the study area flows into Cates Creek which also empties into the Eno. Stoney Creek, in the southeastern corner of the study area, collects the majority of drainage in that area. Floodplains. Floodplains are those areas which will be inundated by water in a specific storm event, normally defined as that storm whose probability for occuring is once every one hundred years. (SEE Hydrology-Vegetation Map). There are two streams in the Harmon Young Area Study which are associated with a 100 year floodplains as designated on the U.S. Army Corps of Engineer Flood Maps. The Eno River i;s characterized by a large area within the northernmost edge of the study arealthat would be considered 100 year floodplain, while Cates Creek has a more defilned, narrower floodplain that runs the entire north-south length of the area study. Development limitations along streams with floodplains and potential for flooding must be observed. In addition, if a stream is within a water supply watershed, its limportance is compounded as pollution or sedimentation of the streams could result in eventual damage to the water supply source.