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Generic Method for Merging Satellite and Historical Ground Station Data to Design Rainfall Intensity Duration Frequency (IDF) Curves in Recordless Sub-Saharian Countries  [PDF]
Jorge E. Matos
Open Journal of Modern Hydrology (OJMH) , 2018, DOI: 10.4236/ojmh.2018.84008
Abstract: The availability of long-term rainfall records is essential to conduct a serious frequency analysis in order to estimate the effective precipitation depth. The development of the process of elaboration of IDF (Intensity-Duration-Frequency) curves for a given location requires very precise data, at least with daily frequency, obtained through the use of rainfall records. The present study presents a method used to merge historical precipitation data with the latest data collected by satellite in order to perform graphs with IDF curves in places where rainfall records are scarce. The homogeneity of the data used is analyzed in order to guarantee its statistical utility and the frequency analysis was performed with the statistical distributions of Extreme Values Type I (Gumbel), Gamma, Pearson Type III and finally with Log-Pearson Type III, in order to verify which one of them applies better to the sites chosen for this analysis: the cities of Benguela and Lobito in the south of Angola. Daily rainfall data from the TRMM mission and historical daily data were used to derive the relationships between the maximum daily precipitation and the sub-daily precipitation values. From the observed daily data, techniques of disaggregation of the collected data were used, in order to generate a synthetic precipitation sequence with the extreme values in periods of time inferior to the daily one, with statistical properties similar to the registered data. Then IDF equations are established, with which the occasional storm depth is calculated for various return periods and various durations and, after them, the IDF curves are drawn for these two geographic stations.
Development of Rainfall Intensity Duration Frequency Curves for Mumbai City, India  [PDF]
P. E. Zope, Eldho T. I., V. Jothiprakash
Journal of Water Resource and Protection (JWARP) , 2016, DOI: 10.4236/jwarp.2016.87061
Abstract: The change in rainfall pattern and intensity is becoming a great concern for hydrologic engineers and planners. Many parts of the world are experiencing extreme rainfall events such as experienced on 26th July 2005 in Mumbai, India. For the appropriate design and planning of urban drainage system in an area, Intensity Duration Frequency (IDF) curves for given rainfall conditions are required. The aim of the present study is to derive the IDF curves for the rainfall in the Mumbai city, Maharashtra, India. Observed rainfall data from 1901 pertaining to Colaba and from 1951 of the Santacruz rain gauge stations in Mumbai are used in the present study to derive the IDF curves. Initially, the proposed IDF curves are derived using an empirical equation (Kothyari and Garde), by using probability distribution for annual maximum rainfall and then IDF curves are derived by modifying the equation. IDF curves developed by the modified equation gives good results in the changing hydrologic conditions and are compatible even with the extreme rainfall of 26th July 2005 in Mumbai.
Impact of Global Warming on Intensity-Duration-Frequency (IDF) Relationship of Precipitation: A Case Study of Toronto, Canada  [PDF]
Erick Carlier, Jamal El Khattabi
Open Journal of Modern Hydrology (OJMH) , 2016, DOI: 10.4236/ojmh.2016.61001
Abstract: Annual maximum rainfall intensity for several duration and return periods has been analyzed according to the Gumbel distribution. The Intensity-Duration-Frequency (IDF) curves before and after 1980 have been computed and compared. For the city of Toronto, it is shown that the rainfall intensities after 1980 are lower than those from before this date. This is especially clear for those of short duration. Comparing our results with those of other authors, it appears that, for the moment, no general law on the impact of global warming on the curves intensity duration frequency cannot be made. It appears that the impact of global warming on rainfall varies with geographic location and that it is not possible to draw some general conclusions across the planet.
Rainfall and agricultural production in Botswana
P. Vossen
Afrika Focus , 1990,
Abstract: The interannual variability of traditional, rainfed agricultural production of Botswana, a country with a typical semi-arid climate, is almost completely accounted for by the quality of the rainy season. It appears that the variability of the national cattle death ratio, total plantedarea and crop yield are, for more than 95% accounted for by rainy season conditions. As a result, also the nutritional state of the population highly correlates with rainfall. Despite the severe droughts of1978179 and 1985/86, farmers were not discouraged to practice agriculture: in fact, crop production shows a significant positive time trend which becomes apparent, when the trend and the rainy season conditions are analysed in combination with each other. As part of this study, models were developed and validated for a precise and areawise agricultural rainy season quality monitoring and for national agricultural production forecasting in Botswana. One of these models could possibly also be used for the areawise assessment of risks for malnutrition of children under five years old.
Improvement in Intensity-Duration-Frequency Relationships of Rainfall in Iran  [cached]
B. Ghahraman,H. Abkhezr
Journal of Science and Technology of Agriculture and Natural Resources , 2004,
Abstract: Rainfall intensity with different frequencies is needed for many hydrologic models. Rainfall intensity–duration–frequency relationships (IDF) have been investigated for different regions using previously recorded data. Iran Meteorological Organization has prepared IDF curves for 66 stations in Iran since which are the most updated data. Comprehensive IDF relationships were developed for these data. The results showed remarkable changes when compared with previous studies of Iran. This may be due to a change in parameters of probability distribution function as a result of increased record length of stations. Some relationships were also developed for ten year-hourly ( P6010) rainfall estimation from some parameters such as average annual rainfall and average maximum daily rainfall. Such a relationship was made for all stations and also for different classifications of regions (based on average annual rainfall and apparent climatically divisions). The validity of all relations was analyzed for eight independent stations with suitable spatial distribution. It was shown that all relationships are nearly valid as far as a suitable region is choosen. The previous relationship for Iran is not useful at present.
Martins Okey Isikwue,Sam Baba Onoja,Kefas J. Laudan
International Journal of Advances in Engineering and Technology , 2012,
Abstract: Rainfall records for 30 years (1979-2009) were used to establish an emperical model that correlates rainfall-intensity-duration-frequency for Makurdiarea. They were analyzed by sorting out the maximum monthly rainfall depths with their corresponding durations and ranked in descending order of magnitude and their return periods were computed. All ranked rainfall depths for each return period were converted to rainfall intensities. The Sherman’s mathematical method was first employed to develop station constants and IDF curves for Makurdi. The station constants for Makurdi area were found to be c = 21.429, m = 0.6905, b = 0.2129. Values of durations of rainfall were substituted in each regression equation to compute corresponding rainfall intensity for each return period. Graphs of rainfall intensities and corresponding durations for each return period were plotted with the subsequent derivation of IDF empirical equations for Makurdi. They were used to develop the IDF curves for 2yrs, 5yrs, 10yrs, 25yrs, 50yrs and 100yrs return periods. It was observed that for a given return period, the IDF curves decreased with increasing time interval.Rainfall Intensity -Durations -Frequency (IDF) data was produced andamodel expressing the relationship between the rainfall intensity, the duration and frequency was developed for Makurdiarea.These will be useful for construction of hydrologic structures such as dams and other drainage systems in Makurdi metropolis.
Analysis of Rainfall Intensity-Duration-Frequency Relationship for Rwanda  [PDF]
Negash Wagesho, Marie Claire
Journal of Water Resource and Protection (JWARP) , 2016, DOI: 10.4236/jwarp.2016.87058
Abstract: Global atmospheric and oceanic perturbations and local weather variability induced factors highly alter the rainfall pattern of a region. Such factors result in extreme events of devastating nature to mankind. Rainfall Intensity Duration Frequency (IDF) is one of the most commonly used tools in water resources engineering particularly to identify design storm event of various magnitude, duration and return period simultaneously. In light of this, the present study is aimed at developing rainfall IDF relationship for entire Rwanda based on selected twenty six (26) rainfall gauging stations. The gauging stations have been selected based on reliable rainfall records representing the different geographical locations varying from 14 to 83 years of record length. Daily annual maximum rainfall data has been disaggregated into sub-daily values such as 0.5 hr, 1 hr, 3 hr, 6 hr and 12 hr and fitted to the probability distributions. Quantile estimation has been made for different return periods and best fit distribution is identified based on least square standard error of estimate. At-site and regional IDF parameters were computed and subsequent curves were established for different return period. The moment ratio diagram (MRD) and L-moment ratio diagram (LMRD) methods have been used to fit frequency distributions and identify homogeneous regions for observed 24-hr maximum annual rainfall. The rainfall stations have been divided into five homogeneous rainfall regions for all 26 stations. The results of present analysis can be used as useful information for future water resources development planning purposes.
Rainfall Intensity-Duration-Frequency Relationship in the Mujib Basin in Jordan  [PDF]
Nidal A. Hadadin
Journal of Applied Sciences , 2005,
Abstract: Variables needed for hydrologic design of hydraulic structures include the rainfall intensities, critical storm duration (concentration times for determination of peak discharges) for the catchments area, and the selected frequencies (return period). These variables together constitute the design storm. In this study, the relationship between the rainfall amount, duration and frequency are studied for Mujib basin in Jordan. Intensities-Duration-Frequency (IDF) equations were developed for each of the 8 rainfall recording station in the basin. The 8 IDF equations obtained were compared with the curves obtained by Gumbel method and Water Authority of Jordan (WAJ); the results predicted by the writer are closer to the measured values. There are some differences in the results between this study and the studies of other investigators; these differences are due to: differences in the record length used by this study and WAJ study; extrapolation of WAJ curves to include the 5 min duration and some of the relative error was due to small values of reading. Peak discharges were calculating for different location in the basin; it was found that the peak discharge which gotten from Manning`s equation is closed to the peak discharge that gotten from rational method at recurrence interval equal to 25 years.
A Novel Approach for the Joint Use of Rainfall Monthly and Daily Ground Station Data with TRMM Data to Generate IDF Estimates in a Poorly Gauged Arid Region  [PDF]
Ayman G. Awadallah, Nabil A. Awadallah
Open Journal of Modern Hydrology (OJMH) , 2013, DOI: 10.4236/ojmh.2013.31001
Abstract: In poorly gauged regions, rainfall data are often short or even absent, hindering the possibility of estimating Intensity-Duration-Frequency (IDF) relations with operationally acceptable accuracy. In this research, a novel idea is presented for the use of three separate rainfall datasets: maximum annual daily data, monthly data and Tropical Rainfall Measuring Mission (TRMM) satellite data to develop robust IDF in Namibe, south ofAngola. TRMM data is used to derive relations between maximum monthly and maximum daily rainfall and between sub-daily and daily rainfall depths. Frequency analysis is undertaken on the mixed daily record using several distributions and the best fitting is selected based on discriminant plots of the distribution tails and the moment ratio diagram as well as Bayesian criteria. The IDF curves are derived based on the estimates of daily rainfall at various return periods, with the derived sub-daily rainfall duration ratios. Robust IDFs are thus developed for a scarce data region inAfrica.
Rainfall reliability, drought and flood vulnerability in Botswana
Rejoice Tsheko
Water SA , 2003,
Abstract: Rainfall data from 14 stations (cities, towns and major villages) spanning 26 years (1970 to 1995) were used to calculate reliability and vulnerability of rainfall in Botswana. Time series data for 72 years were generated from the long-term rainfall gauging stations and the number of wet and dry years determined. Apart from Mahalapye, most places have rainfall reliability greater than 0.5 but less than 0.7. Palapye and Serowe are the most vulnerable to flooding. During the 1995 floods, 87% of casualties were from these areas. Other factors such as rivers, topography, land use etc. can influence flooding vulnerability, but these have not been dealt with in the study, and hence vulnerability is purely based on rainfall amounts. Using two methods, the correlation coefficient is 0.9 (p<0.005) for reliability and risk values. The first method was originally developed for water resource system performance evaluation and the second method is based on dry/wet year sequences. Water SA Vol.29(4): 389-392
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