ارزيابي مشخصات خشكسالي به وسيله شاخص هاي هيدرولوژيكي و هواشناسي با داده‌هاي ماهواره‌اي مطالعه موردي: زير حوضه چلگرد

چكيده انگليسي :

16 Drought Characteristics Assessment by Hydrological and Meteorological Indices using Satellite Data Case Study Chelgerd Watershed Ahmad Barezaei a barezaei@cv iut ac ir Civil Engineering Department Isfahan University of Technology 84156 83111 Isfahan Iran Degree M Sc Language Farsi Supervisor Dr Keyvan Asghari kasghari@cc iut ac ir Abstract Drought is a natural threat to human societies that is not restricted to specific areas and affectsmany people around the world Drought is a gradual threat that roots from a shortage of rainfall thatis expected and when the water shortage lasts more than a season meeting the human andenvironmental demands become a challenging issue Given the importance of drought as well as itsspatial and temporal range drought characteristics start end duration and intensity can beevaluated In this study the Precipitation Estimation from Remotely Sensed Information usingArtificial Neural Networks Climate Data Record PERSIANN CDR is used and compared withmeasured data to derive drought indices Two single variable indicators including standardizedprecipitation index SPI standard runoff index SRI and a combined multivariate index NMSDI were developed in order to propose the most effective indices according to their performance PERSIANN CDR precipitation satellite data were used to develop the SPI index The SRI Index wasalso developed from the runoff resulted from the rainfall runoff model input for the PERSIANN CDR precipitation data model To study and consider the various hydrological characteristics rainfall and generated runoff variables were integrated to generate a combined multivariate droughtindex NMSDI In this research the standardization procedure is recommended with the help ofnon parametric functions to introduce a new compatible index The semi distributed model of SWAT in this study was used to simulate the outflow runoff fromCheljord sub basin in Zayanderoud basin Iran The studied area has a high altitude difference at lowdistances This difference caused a variety of simultaneous precipitation quantity in different partsof the basin In this situation due to scatter and unevenly distributed rain gauge stations satellitedata was used for runoff production The coefficient of NS 0 78 obtained from comparison ofsimulated and measured runoff which represents the well behaved performance of the model The performance of the single variable and multivariate indices was studied and evaluated Theresults showed that the SPI index developed using PERSIANN CDR data accurately detectedmeteorological droughts with an average probability of 75 at the threshold of 0 5 The NMSDI smultivariate index also showed a threshold of 0 5 drought with an average probability of 84 The comparison of probabilities of SPI standardized rainfall indices SRI standardized runoff andNMSDI combined index indicated that for the diagnosis of the drought by using satellite dataPERSIANN CDR the combination of the precipitation and runoff modeling had a significant impacton drought detection in comparison to the single variable index for drought analysis alone SPI andNMSDI in the early detection of drought compared to the SRI index which is an index ofhydrological drought is assessed and the results showed that the SPI and NMSDI indices coulddetermine the beginning of the drought with a probability of 27 27 and 42 85 ahead of the SRIindex respectively Keywords Rainfall runoff simulation SWAT Hydrological Model Evaluation of droughtcharacteristics Early Drought Analysis Multivariate Index NMSDI SPI SRI PERSIANN CDR

برضائي، احمد

ارزيابي مشخصات خشكسالي به وسيله شاخص هاي هيدرولوژيكي و هواشناسي با داده‌هاي ماهواره‌اي مطالعه موردي: زير حوضه چلگرد

شبيه‌سازي بارش-رواناب , مدل هيدرولوژيكي SWAT , ارزيابي مشخصات خشكسالي , تحليل زودهنگام خشكسالي , شاخص چند متغيره NMSDI , شاخص SPI , شاخص SRI , بارش PERSIANN-CDR