In snowy regions, snowmelt is a significant water resource. Changes in snow water equivalent and snowmelt season caused by global warming may have a great impact on the volume and use of agricultural water supply. Such changes are expected to manifest differently according to the elevation of the basin. In this study, we conducted runoff analyses at three spots of different elevation in the Northern Sorachi Region to investigate how future warming will affect the changes in snow water equivalent and snowmelt runoff. Predicted values of temperature and precipitation provided by nine climate models were used. It was forecast that decreases in snow water equivalent would bring decreases in snowmelt runoff during the snowmelt and irrigation seasons, and that the basins with lower average elevation would experience earlier peaks in snowmelt runoff.
In recent years, various surface protection methods have been developed and applied toward restoring the performance of frost-damaged concrete open channels in cold regions. Such methods work by repelling moisture and thus, inhibiting freeze-thaw in concrete. For these methods to demonstrate long-term performance, they must demonstrate sufficient adhesion to concrete. In this study, new kinds of freezing and thawing tests were used to evaluate various surface protection methods for concrete open channels in terms of their durability of adhesion. The evaluation proved that the adhesive deterioration is caused by freeze-thaw action when inorganic and organic surface protection coatings are conducted and it was also proved that the adhesive deterioration differs according to the characteristic of protection material.
Soil cement underground continuous wall construction method is largely affected by the quality of soil in-situ, because the method utilizes soil in-situ as a part of wall materials. Since soil cement on a sandy earth ground has possibility to subject to execution defect caused by segregation and settling of gravel and sand, it needs to minimize segregation as possible with ensuring flowability for both execution and core material insertion. In this study, for the purpose of improvement of fresh soil cement property on sandy earth ground, we investigated the utility of using paper sludge generated from paper factory as additive to sandy soil cement, and verified its workability at a field of soil cement construction work. The results demonstrated that, when soil cement were mixed with about 10kg paper sludge per sandy soil of 1m3, its characteristics of both flowability and segregation improved because paper sludge produced tiny closed cells and fibers into the soil cement. Moreover, we verified workability of soil cement using paper sludge in an actual construction, and confirmed that it was free from execution defect and strength dispersion was small.
To estimate reliable actual evapotranspiration from a paddy field with flooding water using a simple measurement system, first, the relationship between actual and potential evapotranspiration (LFw,efand LFPM) was examined. LFw,efwas estimated with the energy balance flux ratio method, and LFPMwas calculated by the FAO Penman-Monteith equation. LFw,efwas sufficiently proportional to LFPMin each month of June, July, Aug. and Sept.. Next, actual evapotranspiration (LFw,eb or LFw,ef) was estimated by the energy balance Bowen ratio method or the energy balance flux ratio method, after unreliable values obtained by those methods were corrected from the relationship between reliable values by those methods and LFPM. Potential evapotranspiration (LFpe) was calculated by the equation simplified from the FAO Penman-Monteith equation. The sum of LFw,eb or LFw,ef for a day was sufficiently proportional to that of LFpe, although the value of proportional coefficient in the early growth stage was different from that in the late growth stage. The former value was 0.885, the latter was 0.996. In conclusion, reliable daily actual evapotranspiration could be estimated from daily potential evapotranspiration calculated by the FAO Penman-Monteith simple equation.
Bending tests of RC beams which the cover concrete was omitted were carried out in order to clarify the relationship between the flexural strength with progress of abrasion RC open channel side wall. As a result, in the case of RC beams without cover concrete on tension side, significant difference did not occur in the flexural strength of the undamaged (i.e control) beam and three beams without the cover concrete. In the case of RC beams without cover concrete on compression side, it was found that 1) flexural strength of RC Beams without cover concrete is reduced in proportion to the depth cross-section loss, 2) if the amount of reinforcing steel equal, doubly reinforced beams shows slightly larger flexural strength and deformation as compared to single reinforced beams. The calculating method is shown to predict the yield load of RC beams without cover concrete on compression side; flexural analysis of a singly reinforced beam using the new effective height value obtained by subtracting the depth of cover concrete loss from the effective height of the undamaged beams. Proposed method is in good agreement with the experimental results.
This research examined the infrared thermography method as the technique of evaluating a degradation part by repetition of freezing and thawing in concrete structure of cold climates. First, the test condition of the infrared thermography method by the active method for extracted core was examined. And micro cracks evaluated being detected by this test condition. Next, the technique for evaluating a frost damage degradation part quantitatively was examined. The relation between the degradation part rate evaluated by this technique and ultrasonic propagation velocity was considered, and applied condition of the proposal technique was clarified.
To analyze genetic diversity of endangered medaka (Oryzias latipes), primers for PCR (polymerase chain reaction) were constructed that could amplify ten microsatellite loci of medaka genome based on the contig/scaffold sequences published. DNA was extracted from the caudal fin of medaka collected at six different sampling points in Wanouchi Town, Gifu Prefecture. Genetic diversity within each sampling point was relatively high, whereas genetic differentiation between sampling points was small (pairwise FST= 0.023-0.086) but significant for all except three pairs of the sampling points. The genetic difference between the populations of the sampling points could be explained not only by the geographical distances but by the waterway connectivity between the points. These results indicated the importance of planning agricultural channel corrections considering migration of medaka between populations, to conserve genetic features of medaka in this study site where within-population genetic diversity is not much deteriorated yet.
Numerical simulations were executed to clarify the occurrence condition of water surface fluctuation, that occurs at the drop in the irrigation canal and makes division of irrigation water difficult, for the case the downstream side of the drop was regarded as uniform flow state. As a result, the three type of flow regime, supercritical flow, plunging flow and streaming flow, occurred by the difference of shape of stilling pool in drop, at the condition of the same drop length and discharge. Furthermore, big fluctuation of water surface was observed in spite of the condition of plunging flow that is said to be most stable. The occurrence condition of water surface fluctuation was clarified by using two indices, one was the ratio of the specific energy of upstreamside of the drop to the drop length, the other was the aspect ratio of the drop part including the stilling pool.
As a result of global warming, the snow water equivalent is forecast to decrease and the snow melt season is forecast to start earlier. If the current typical water storage start dates at irrigation reservoirs in cold, snowy regions remain unchanged, the water stored in reservoirs may be insufficient in some years. Therefore, if the snow water equivalent can be estimated before the water storage start dates in spring, the estimated value will be useful for reservoir operation in the succeeding irrigation period. This study was carried out to develop a method for predicting snow water equivalent in irrigation reservoir basins using precipitation and temperature data from the Automated Meteorological Data Acquisition System (AMeDAS), which are easy to acquire. The following were discovered for the Sorachi and Kamikawa regions in Hokkaido. 1) Estimation of snow water equivalent is possible, and the estimation has satisfactory accuracy for actual use. 2) Estimation precision is stable when inflow data of about 5 years in the basins are used.
At present, in facilities management project, the hydraulic function is not diagnosed for patchy concrete open channels that have been repaired sporadically by several repair methods over a short distance. Therefore, it is necessary to clarify the influences of sporadic repairs of a channel on its flow transmissibility. This study aimed to evaluate flow transmissibility in the hydraulic function of patchy concrete open channels based on field surveys and nonequivalent flow analysis. The field surveys resulted in small changes in water level and flow velocity at the center of each repair section in the channel. The nonequivalent flow analysis showed that patchy repairs led to longitudinal fluctuations of water surface by changes in the longitudinal slope of channel bottom, but hardly by changes in the wall roughness and width of the channel. Accordingly, we suggested a new procedure for the diagnosis of the hydraulic function, i.e. flow transmissibility, in patchy concrete open channels. In this procedure, we proposed three factors—roughness, bottom slope, and width of the channel—as diagnosis indicators, and moreover did the way of field investigations to examine the three factors.
This study clarified the conditions for continuation or abolishment of Irrigation Water Wheels (IWWs) over the past 30 years in JAPAN. The research approach involved interviews and measurements of the IWW components. Results of interviews revealed the reasons for abolishment were ‘upgrade to a pump’, ‘abolition of paddy use’ and ‘absence of a millwright’, whereas reasons for continuation were ‘reduction in expense and labor load are good’, and ‘good water sharing method without backwater’. Results of measurements of the IWW components showed most cases of continuation used IWWs with a diameter between 1.5 m and 2.5 m and average beneficial paddy field area of large, whereas most cases of abolishment used IWWs with a diameter more than 2.0 m and beneficial paddy field area of small. In fact, the continuation or abolishment of IWWs differs depending on their diameter and beneficial paddy field area. User of IWW judge expense of IWW on diameter of IWW and beneficial paddy field area. If diameter is more than 2.0 m, IWWs introduced from outside funds are continuously used for irrigation. In this way, over the past 30 years, the components of IWWs that are utilized have converged with expense advantage. Other conditions (i.e., absence of millwright and use for sightseeing) for continuation or abolishment were clarified as not related to expense.