Nadergholi Ebrahimi; Alireza Eslami; Fourod Sharifi
Abstract
Climatic conditions in arid and semi-arid regions, poor vegetation cover and mountainous conditions of watersheds concentrates surface water as floodwater and cause vital and financial damages in industrial, urban and rural areas. Runoff threshold is one of most important factors in accurately estimation ...
Read More
Climatic conditions in arid and semi-arid regions, poor vegetation cover and mountainous conditions of watersheds concentrates surface water as floodwater and cause vital and financial damages in industrial, urban and rural areas. Runoff threshold is one of most important factors in accurately estimation of flood volume and intensity for designing and securing constructive projects which saves expenses and leads to optimum dimensions of structures. In this research, rainfall simulator was used to investigate the effective factors on runoff threshold. Rainfall intensities of eight to 40 mm/h in periods of 15, 30, 60 and 120 minutes were simulated and runoff thresholds were measured. Acceptable methods for estimation of runoff threshold were introduced based on rainfall characteristics and pedology and geology parameters using measured data and multivariable linear and nonlinear regression methods. Results demonstrated that the rainfall volume and intensity as climatic factors, vegetation cover and slope as terrain factors and soil texture as pedologic factors are the most effective ones in runoff threshold. The relation of independent factors and their partnership in runoff threshold is statistically acceptable for the research area. The results showed a significant correlation (R2=0.98) between estimated and viewed runoff threshold.
Hossein Saadati; Foroud Sharifi; Mohammad Mahdavi; Hassan Ahmadi; Mohsen Mohseni Saravi
Volume 2, Issue 1 , May 2010, , Pages 56-64
Abstract
In this study, rainfall, runoff, groundwater and unsaturated water tracers sample were measured and analyzed. The average historical recharge through rainfall was calculated by interpreting of unsaturated water tracer in Hasthgerd plain. Four index profiles in Nazarabad, Jafarabad, Ghalechendar and Savojbolaq ...
Read More
In this study, rainfall, runoff, groundwater and unsaturated water tracers sample were measured and analyzed. The average historical recharge through rainfall was calculated by interpreting of unsaturated water tracer in Hasthgerd plain. Four index profiles in Nazarabad, Jafarabad, Ghalechendar and Savojbolaq were dug for measuring of unsaturated water tracer concentration. Chloride concentrations in profiles soil samples were measured and interpreted to provide temporal estimates of recharge. Applying the chloride mass balance technique to the profiles soil water improved the boundary conditions associated with wet and dry climate in last times and the long-term mean recharge rate. Recharge rate means were estimated in profiles equal to 3.42, 3.53 6.42 and 7.44 (mm/yr) with rainfall chloride concentration average that was measured equal to 1.653 mm in Hashtgerd Plain. It was concluded that concentrated recharge (CR) supplies groundwater rapidly and significant more than diffused recharge (DR) by rainfall. Concentrated recharge is fulfilled by watershed grand works such as flood spreading structural measures.
