جستجوی مقالات مرتبط با کلیدواژه « حجم کمبود » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

Hydrological drought usually have a considerable impact on the quantity and quality of water resources, causing water shortages in consumption sector and its study is important in terms of intensity, frequency and spatial extent. The aim of this study is to determine the periods of hydrological droughts, drought characteristics and amount of flow deficit in a 38-year recorded data over hydrometric stations of the Golestan Province. The weighting factor of drought importance for each month was calculated based on the flow distribution in different months. The subtracted mean discharge of particular month from the long-term average was multiplied by the weighting factor to determine the effective discharge. The difference of mean monthly discharge and effective discharge considered as monthly flow deficit. The onset and end of hydrological drought periods were defined and the cumulated flow deficits were calculated. The results showed that the highest flow deficit amounts were recognized for in Taghiabad, Basirabad, and Hajighoshan stations with 1.28, 1.27, and 1.07 respectively. In general, the flow deficit were observed in June, July and August in almost all river gauge stations of the study area. Moreover, the deficit volume was lower at stations located in upland areas.

The assessment of wet and dry hydrological periods is the primary and necessary basis of water resources management and planning. The aim of this study was to determine the hydrological drought spells, and its severity and duration variations at monthly time scale. For this purpose, 38-year recorded data (1975-2013) were used over 20 hydrometric stations in Golestan Province. The weighting factor of drought importance for each month was calculated based on the flow distribution in different months. The subtracted mean discharge of particular month from the long-term average was multiplied by the weighting factor to determine the effective discharge. The difference of mean monthly discharge and effective discharge was considered as monthly flow deficit. The onset and end of hydrological drought periods were defined and the cumulated flow deficits were calculated. According to the results, the NodeKhandoz and Sarmoo stations had no deficit amount in all months of the year which located at upland portions of the study area; while, the flow deficit durations were observed in July and August in almost all stations. The variations of flow deficit volume showed that the frequency of 4-5 month durations were higher than other duration spells. According to the clustering results, the similar stations (Taghiabad and Basirabad) had the highest flow deficit severity; while, the lowest flow deficit severity was observed in NodeKhandoz and Sarmoo stations.

Drought is known as an environmental phenomenon which leads to socio- economic and environmental issues. Therefore its analysis is crucial for proper management and planning of water resources. The Karkheh River basin is one of the important water resources in Iran and that is located in western Iran. Current paper tries to take one step ahead toward scientific and practical drought management in this basin through analyzing hydrological droughts. In this research, daily discharge time series from 13 hydrometric stations were used. The constant threshold level method was applied. Then dry periods were extracted and results were analyzed. The results showed that the largest volume and longest duration of drought in threshold level of 70% mostly happened after 1998. Finally, the suitable probability distribution for the annual maximum series of duration drought and deficit volume at each station was determined. The results revealed that the Johnson distribution is suitable for maximum deficit volume series at 38.5% of stations and the Johnson and Double exponential distributions are suitable for maximum duration series at 23% of stations. Based on the suitable probability distribution, return period of droughts were also computed and the possibility of drought predictions in future was determined.