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You are here : eLibrary : IAHR World Congress Proceedings : 32nd Congress - Venice (2007) : THEME A: Engineering and Management of Fresh-water Systems : Application of monte carlo method in recharge calculation of underground water resources
Application of monte carlo method in recharge calculation of underground water resources
Author : Zhou Zhenmin
Agricultural, urban and living water resources requirement are calculated based on different water requirement and water source features. Different water requirement is related to special frequencies. For instance, the required water resources probability for large and middle scale thermo-power plant is 90%, and living water requirement probability for residents is 95%, etc. The probabilities mentioned above generally refer to relative water resources volume, which implicate the probability of 5% or mean value. In underground water resources evaluation, calculation of underground water recharge is the most important and preliminary work. Therefore, usually, underground water resources evaluation begins with probability analysis of underground water recharge. If underground water recharge within an area comes from exclusive item, then it is easy to calculate any water volume related to each probability based on the empirical frequency curve. In most cases, underground water recharge is not a single item, but four or five items or even more items. Therefore, in underground water resources evaluation, it is necessary to carry out frequency analysis for multi-items of underground water recharge. There are a lot of methods to deal with frequency analysis on comprehensive recharges of underground water resources, each with certain theory or empirical reasons. But up to now, there is not a satisfactory and ideal method. The general method at the present is as follows; for example, to calculate the total water recharge relative to frequency of 97%, every single recharge volume relative to frequency 97% will be added together to get the total volume of underground water recharge. This method is not perfectly reasonable. It is because that, based on probability theory, the co-realized probability for several independent events equals to the multiplication of each realized probability. Therefore, if the frequency for all recharge items is 97%, then the co-realized frequency will be(3/100)n. For 6 recharge items, the co-realized frequency will be (3/100)6,the return period will be 1.3109, obviously, here, the serious error has happened. When dealing with total water recharge relative to different frequencies in an area, the ideal condition is that every recharge item has long term measured data series. Then the sum of every independent sample within one year can be considered as a new sample. The empirical frequency curve can be plotted based on new sample series. Then the total recharge volume can be calculated based on the empirical frequency curve. But the problem is that it is difficult to find such ideal data series. The real data series are far from requirement. Therefore, it is very important to solve frequency calculation problems in underground water evaluation. The paper tries to solve above problems by using Monte Carlo method.
File Size : 76,082 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 32nd Congress - Venice (2007)
Article : THEME A: Engineering and Management of Fresh-water Systems
Date Published : 01/07/2007
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