A model parameter identification technique based on the Bayesian inference is presented and applied to a long-term application of a distributed rainfall-runoff model. Initial model parameters are given from a probability distribution of values, which is called as "prior" distribution. This prior distribution is then updated by incorporating available observed data, producing a "posterior" probability distribution of model parameter values and the technique of update is repeated. Seven model parameters of the distributed runoff model, which are directly or indirectly related to generate surface and subsurface runoffs, are identified using this technique when the model is applied to the Daido River watershed of Shiga prefecture, Japan. The identified model parameters are capable to represent the watershed characteristics for application of distributed model. Most of the model parameters, population variances are found to be low to medium, which supports the stability of identified model parameters. However, model parameters in some cells show relatively high variance which expresses considerable uncertainty. The estimated hydrograph using the sequentially updated model parameters are well suited with the observed hydrograph. The identified model parameters can produce a good model efficiency criterion R^2 of 84.82%. The proposed model parameter identification technique could be a tool for understanding the spatial properties of the model parameters of a distributed rainfall-runoff model.
This paper presents the variation in key flow properties due to the standard deviation of obstruction shape variation in nature-like fishways, using a Godunov type numerical method of two dimensional shallow water equations. Elliptic obstructions having different aspect ratios are embedded in the model fishway. The variation of shape is evaluated from the standard deviation of diameter length. The change in flow parameters because of the increment in the standard deviation of shape variation was compared from four different test cases. The increment in the standard deviation showed a distinct effect on the flow parameters. Increase in standard deviation showed the decrease in the area occupied by higher velocities, as well as increase in variation of flow velocities. Likewise, the increase in standard deviation raised the average water depth in the fishways.
Irrigation has played a contributing role in enhancing agricultural production and productivity in Nepal. Farmer-Managed Irrigation Systems (FMIS) have been operating for more than 25years using local capacities. A survey was accomplished during April-May, 2005 to evaluate the changes that have been brought about by the introduction of FMIS at Kumroj in Chitwan district. The changes in crop species, cropping area, irrigated area, crop production, productivity and cropping intensity after the introduction of FMIS were explored. Comparisons were made in between farmers participating and not participating in FMIS. There was a total increase of about 47% in irrigated land since the introduction of FMIS. This has helped increase crop production as crops can be grown more than once a year and as a result cropping intensity has been tremendously improved to more than 256 percent. Further, the cropping areas as well as the crop productivity have been greatly influence with the inception of FMIS. The change in the cropping pattern from cash crop oriented to food crop production to combat food insufficiency in Nepal. Considering the successes of FMIS, development of small-scale farmers managed irrigation system to improve agricultural production in Nepal should be emphasized.
This paper presents secular variation in the pattern of rainfall in Miyazaki. The data used for examination are daily rainfall data observed for 103 years in Miyazaki local meteorological observatory. The total rainfall for every year or every season, the index of a heavy rain, and the index of a storm rainfall were computed using these data. And these indices were examined statistically whether the trend would be shown. Consequently, the followings became clear: the total rainfall is decreasing, the tendency which a heavy rain increases is not clearly seen, the pattern of rainfall is bipolarizing. Finally, the number of rainy days decreases and period of the non-rainy days are extended. Since the non-rain tendency of spring and autumn has been increasing especially sharply, it is worried about that this non-rain tendency may influence on our agricultural production activities.
Over the past few decades, some of the Sabo dam studies have been focused on the entrapment function of debris flow and structural of dam. Few attempts have been made to investigate the hydrologic data of Sabo dam. Therefore, we have been observed hydrological measurements in small drainage basin which include a Sabo dam. An observation was conducted to determine the effects of concentration time and runoff peak response time at downstream of a Sabo dam in discharge. The concentration times were 50-490 minutes and almost were longer than value of Kadoya expression. The runoff peak response times were 20-190 minutes. Moreover, we have been analyzed this hydrological measurements data by Sugawara tank model. As a result, we have concluded that we identified Sugawara tank model parameter using 30 minute runoff peak response time.
Suspended soil and nutrients have caused sea water pollution in coral reef seas in Okinawa. The purpose of this study was to research on runoff of suspended soil and particulated nutrients from a small upland watershed in Okinawa island. For the purpose of this study, we observed the runoff at several rainfall events occured during 2006. At the outlet of the watershed, discharge and rainfall data were collected through the year. Water samples were collected at the outlet during each event. Concentrations of suspended soil, nitrogen and phosphorus were analyzed. From the observed results, the runoff concentrations of suspended soil and nutrients were higher than that during non-rainfall periods. Time series of concentrations of participated nitrogen and phosphorus showed the similar trend to that of suspended soil. The participated nutrients were the main component of the total nutrients flowed out of the watershed. High correlation coefficients between suspended soil load and nutrient load were estimated. In conclusion, the results indicate that runoff of suspended soil and particulated nutrients from an upland watershed are closely linked, and further suggest that the runoff management contributes to conservation of sea water quality environment.
The Internet is recognized as an important communication method because Internet has been very popular for the last decade and can be used everywhere. Huge amount of information is accumulated on the Internet, but it is not easy to search for and access to what is really necessary. Although some searching engines are offered to assist to get correct information, it often takes much time to access them. Many local governments have subsidies for installation of rainwater use facilities and some of them open information about their subsidies on web sites to further promote rainwater use. They are very important to be known widely. In this paper, a tentative database system was designed and created, which can assist anybody who wants to know information about subsidies for rainwater use to search for and access to them easily. It can offer information about available facilities, total and upper limit of subsidies, enquiry etc. that are decided based on the result of analyzing information collected from the Internet. It has some choices in each item which user have to select for searching but it has a simple interface that enable user to easily select adequate ones by using a mouse.