Wet and Dry Periods and it's Effects on Water Resources Changes in Buin Plain Watershed

Water Resources have close relationship with precipitation and runoff in the watershed, and rainfall that coming on watershed, support water consuming by plants. Drinking water, industry and agriculturing from ways including infiltration in soil, surface and subsurface flow. On this basis, studies about rainfall and ground water has been aimed in Buin watershed with area 290.95 Km2 Located in Isfahan province. This watershed has a good situation from rainfall and surface and ground water aspects in Isfahan province. But in some recent years because of annual and rainfall reduction over exploration of water resources, Resulting in water shortage in agriculture thus it is necessary that to investigate rainfall changes, wet and dry period predication and their effects on water resources changes (surface and ground water). In this study, with investigation of rainfall trend changes, flood discharge determination by manning, fuller, SCS methods and flood hydrograph in different return period, determined flood situation in watershed, after that with investigation of ground water level changes, determined rainfall changes effects on ground water changes in study area using correlation coefficient in lag time 0,1,2,3,4,5, and 6 monthly for recent years (2000-2003) in 36 month duration.Result shoes that is a significant relationship between rainfall and ground water level changes in study area, and it can be described that a for majoring of station is a 3 monthly lag time from rainfall occurrence to ground water changes. Additional, common trend of ground water level changes has a Descending status.