valiollah karimi

Importance of rice as a staple crop for feeding of human being is obvious. Besides, water is major input for rice production. Water crisis is one the serious interest for present and future conditions of IRAN. Then, this research conducted for investigation of mid-summer drainage effects on yield, Water consumption and water productivity of Hashemi and Fajr rice cultivars. For obtaining this purpose, a field experiment was carried out as a factorial in basis of randomized complete block design in 3 replications with 5 mid- summer drainage treatments i.e. 0, 3, 5, 7 and 9 in Babolsar. Results showed that the effects of mid- summer drainage and variety on water consumption, Grain yield and water productivity were significant (p<0.01), and mid-summer drainage with 5 days’ duration on both cultivars had the highest water productivity, 0.91 and 1.29 Kg/m3 respectively. Also maximum yield and minimum water consumption resulted for 5 days’ mid-summer drainage treatment. Thus, 5 days’ duration for mid-summer drainage of Paddyfield was recommended for this region.

Industrialization of communities and increased greenhouse gasses in the previous decades have resulted in increased global temperature and changes in climate parameters which are generally called climate change in scientific texts. Climate change has resulted in changes of temporal and local precipitation patterns all around the world. Consequently, hydrological cycle has changed affecting intensity, duration and frequency of rainfall events. Intensity- duration- frequency curves are used to provide an economic and safe design for drainage facilities, check dams, urban water management structures such as culverts, surface water and sewage systems. They are also used in landslides studies. The present study seeks to compare rainfall intensities in Babolsar Synoptic Station before and after 1993 to understand the effect of climate changes on rainfall intensities during the mentioned 52-year statistical period.

The first synoptic station of Mazandaran province was set up in Babolsar city in 1952. With an elevation of -21 m from sea level and 7 m from the Caspian Sea level, it is located at the east longitude of 52o, 39̍, 30̎ and the north latitude of 36o, 43. The station has a mean annual rainfall of 928 mm and an average of 99 rainy days.To understand the effect of climate changes on rainfall intensities in different durations and return periods in Babolsar Synoptic Station, statistical period was divided into two 26-year subperiods (before: from 1968 to 1993 and after: from 1994 to 2019). Rainfall intensities were calculated separately for each of the 14 duration series (10, 20, 30, 40, 50, 60, 90 minutes and 2, 4, 6, 9, 12, 18 and 24 hours) with return periods of 2, 5, 10, 25, 50 and 100 years and compared together. Then, a paired t-test was conducted to prove the difference between two series of rainfall intensity to be significant. Moreover, 5 annual air temperature parameters including minimum absolute temperature, maximum absolute temperature, average minimum temperature, average maximum temperature and average temperature were investigated in both subperiods and analyzed using a paired t-test in SPSS software. Results were used to investigate temperature and precipitation changes during the statistical period and prove the difference between before and after time series data to be significant.  Mann-Kendall test was also carried out on 5 air temperature parameters collected during the 52-year time series data to find ascending or descending trends.

Compared to the first subperiod, the average rainfall intensities have increased in 10, 20, 30 minute and 12, 18 and 24-hour durations of the second statistical subperiod, while the opposite has occurred in 40, 50, 60, 90-minute, and 2, 4, 6 and 9-hour durations. However, statistical analysis has proved increased rainfall intensities in 10 and 20-minute, and 18 and 24-hour durations and decreased rainfall intensities in 50, 60, 90-minute, and 2, 4, 6 and 9-hour durations of the second statistical period to be significant. A paired t-test was conducted to compare rainfall intensity in the statistical subperiods and find out its effects on climate change. Results indicated that except for data collected in 30 and 40-minute and 12-hour durations, the difference between other paired series was significant at a less than 5% level.Moreover, except for maximum absolute air temperature, other air temperature parameters showed a significant difference at less than 0.5% level. Furthermore, all 5 parameters showed an increase in the second study period indicating a warmer climate in Babolsar.However, paired t-test results indicated that despite the reduction of mean annual rainfall in the second statistical period, difference between the two series was not significant at any acceptable level of significance. Moreover, results of the Mann-Kendall test indicated that average air temperature, average maximum air temperature, average minimum air temperature and minimum absolute air temperature have shown an ascending trend at a 1% significant level, while maximum absolute temperature lacked a specific trend and showed leap changes. Annual rainfall also showed random changes and lacked a specific trend during the 52 year statistical period.

Results of the Man-Kendall and paired t-test have shown that a significant increase have occurred in air temperature during the 52-year statistical period (1968-2019) resulting in climate changes.
It can be concluded that climate change has increased the intensity of short-term (shorter than 40 minutes) and long-term (longer than 12 hours) precipitations and reduced the intensity of medium-term precipitations in Babolsar Synoptic Station. Moreover, climate change has increased the intensity of precipitations with short and long return periods while reducing the intensity of precipitations with medium-term return periods in the aforementioned Synoptic Station.

Due to the low spatial resolution and simplification of atmosphere general circulation models compared to regional and short-term models, the outputs of these models cannot represent an accurate approximation of climatic conditions of the study area. Due to time-consuming and lack of economic efficiency in the use of dynamic models, there has been increased public attention to the use of statistical downscaling methods. One of the most useful and common methods in statistical downscaling is SDSM. For this purpose, the first, the atmospheric parameters in the region over the past 32 years (1984-2015) was investigated by the Mann-Kendall test. The results showed that changes in temperature and rainfall data have a significant trend. Then, by down-scaling, the data using SDSM software, the daily parameters of maximum, minimum, average temperature and rainfall of Haraz river basin in Mazandaran province were simulated according to RCP2.6 (optimistic) and RCP8.5 (pessimistic) scenarios and CanESM2 Climatic Model from the new CMIP5 series in three periods of twenty years from 2020 to 2079. Finally, under the RCP8.5 critical scenario, until the end of the prediction period, the maximum, minimum and average temperature of the basin will be increased 0.91, 1.13 and 0.96o C, respectively and precipitation decreased 15.1% (7.4 mm) compared to the base period.

Drought caused by abnormal dry period which its continuation makes unbalance hydrologic system in a region, if some prevention countermeasures are taken against drought, its damages will be declined. In order to Drought monitoring and management by use of some indices, 33 meteorological stations which belongs to ministry of Energy in Mazandaran province were selected. Thus required data were collected and statistically analyzed. To reconstruct and statistical prolongation of incomplete station, differential and ratios method are applied. Run test was used for homogeneity assessment of data. Finally, based on available data analysis, 35 year data series from 1976 to 2000 as a research statistical period was used. Then, drought indices includes Standardized Precipitation Index (SPI), Normal Percentage(PN), Chinese Z(CZI), Modified Chinese Z(MCZI), Z- Score Index(ZSI), Deciles Index(DI) on 1 year time scale in all stations was calculated and related curves were drawn. Based on Correlation test, pair significance of these indices was satisfied at 5% level in all stations. PN, ZSI and SPI with maximum average correlations and least standard errors respect to others, had better results, but MCZI with minimum correlation had the worst results. Maximum correlation between annual precipitation and each one of indices belongs to PN, ZSI, SPI, CZI, DI, MCZI with determination coefficient of 0.998, 0.99, 0.986, 0.942, 0.908 and 0.057 respectively. Results show that for study and investigation of meteorological drought in Mazandaran province, PN, ZSI and SPI indices has the same status and prior to other indices.

Urban watershed shows quite different hydrological and hydraulic behavior from natural watershed. Cities, that located along the Caspian coastline, have been flooded annually several times by relatively extreme storms and it creates a negative outlook in the cities. Comprehensive planning, design and management of surface water drainage systems are essential for creating a safe environment for the citizens. Computer models control urban run-off. Studying area is 39.64 (ha) that it was divided into 51 sub-basins. The simulation of flooding in urban catchment basins for this study was required information such as climatic, topographic, hydrologic regime, current status of surface water collecting network and hydraulic properties. In this study, urban flooding is simulated by MIKE SWMM model. By applying this model, in term of hydrologic and hydraulic data of the drainage systems, capability of surface water collecting system were evaluated for safe passage wandering water with design storm for 2, 4 and 6 hours and return periods of 2, 5, 10 and 25. The critical nodes and channels were identified after simulation. In result, simulation also showed that some existing water channels in this region, have not capability of passing design floods and this inability causes extra load and creates flooding condition in ending nodes over critical routs. Thereby, this long-time condition creates serious difficulties in transportation system and make inundation in the roads.

Abstract: (91 Views)
Quantitation and evaluation of infiltration models are used in soil conservation, irrigation systems, hydrology investigations, watershed and watershed management systems. The purpose of this study was to estimate the infiltration by using statistical and experimental various models in two soils of plowed and without plowed in Haraz Technology and Development center paddy fields of Mazandaran province. The infiltration value was measured by the double rings in plowed and without plowed soils and then was compared with Kostiakov, Kostiakov-Lewis, Philippe, Horton and Soil Conservation Service (SCS) models. The results showed that the final infiltration rate in plowed and not plowed soils were 0.12 and 0.21 cm/min, respectively. The comparison of the estimated infiltration from each of the models with real amounts was done by the average normal root mean square error (NRMSE). The results showed that NRMSE values in plowed and not plowed soils were 21.53 and 6.45 %, respectively. With optimization of models in Solver Excel, amount of NRMSE reduced to 2.48 and 1.9%, respectively. Also according to comparison of infiltration models in both plowed and not plowed soils, the SCS and Kostiakov-Lewis models showed better fits than other models. So that, SCS model for not plowed soil was I=0.8459t1.0417 .6985 and for plowed soil was I=0.891t1.026 .6985. In general, could be said that fitting of physical and empirical models had good accuracy on Mazandaran paddy fields. Another finding of this study was the better results in the plowed soil based on NRMSE. Therefore, this method can use in paddy fields.

Flooding due to the failure of drainage systems is a serious problem for many urban watershed of Iran. This paper shows how flooding in urban drainage systems can be simulated by one- dimensional hydrodynamic modeling incorporating the interaction between (I) the buried pipe systems (II) the streets with open channel flow. The values of the NS, RMSE, and %BIAS statistics were also calculated to assess the validity of the model structure. The NS results for calibration and validation of the case study demonstrate that the calibrated model simulated acceptably the shape of the actual hydrograph. The lower RMSE values also support the accuracy of the calibrated model in simulating the shape of the hydrograph. The absolute value of %BIAS is never more than 20%, which demonstrates that the calibrated model simulated acceptably the total flow volume. The results of this study emphasize the use of one-dimensional hydrodynamic model to Simulation of flooding in urban drainage systems.

To increase productivity of paddy fields, a suitable management of midseason drainage can be considered. This study was conducted to investigate the effect of surface midseason drainage duration in paddy fields of Mazandaran province on surface cracks of soil. The planted rice cultivar was Tarom-Hashemi. A field experiment was done with the six surface drainage duration treatments of 0, 5, 7, 9, 11, 13 days and three replications at Haraz Extension and Technology Development Center. Base on the results, the effects of surface midseason drainage duration on length, width and depth of the soil cracks were significant. Maximum width and length of the soil cracks were 7 mm and 10 cm, respectively, which were gained by 13-day drainage duration treatment. Application of the 11 and 13 days drainage duration treatments significantly increased the depth of soil cracks. With considering the maximum of soil crack depth be less than hardpan depth, applying 17-day midseason drainage duration in study area is recommended.

Because of urban rapid growth of Iran, some problems such as propagation of environmental pollutions, urban inundation and flood hazards due to lack of appropriate drainage systems and irregularity of conduits & streams are the major difficulties in urban watersheds. Because of hydrological & hydraulic processes complexities in urban area, using of computer models would be effective. In this study, EPA-SWMM model applied for quantitative simulation of flash flood in some parts of Babolsar urban watershed.12 hour's simulation was done for 2 hours design storm with 2, 5 and 10 years return periods. Quantities simulation results shows that among the 259 junctions in the drainage network of study area, 32, 57 and 60 junctions for 2, 5 and 10 years return periods were inundated respectively. Peak discharges for 10 junctions of study area drainage network, estimated by rational method compared with simulated ones shows good linear correlation. Field investigations, Elevation maps of conduits and conducted simulation implies that the main reasons of inundation are small cross section area of conduits and also low bed slope & invert slope in some places. Conformity of flooded junction's simulation results due to rainfall with historical events in study area verifies the model simulations.

Proper water management in the paddy fields has an important role in the efficacy of other production inputs in rice cultivation. One of the important parts of paddy water management is midseason drainage. To investigate the influence of surface mid-season drainage on growth and yield of rice cultivar Tarom-Hashemi، a field experiment was carried out in randomized complete block design with six treatments and three replications in Haraz Promotion and Technology Development Center in 2013 growing season. The experimental treatments were continuous drainage of zero (control)، 5، 7، 9، 11 and 13 days and their effect was evaluated on plant height، number of tillers، panicle length، grain filling percentage، harvest index، dry weight، leaf area index، crop growth rate، net assimilation rate and grain yield. Statistical analysis showed that the effect of midseason surface drainage on dry matter was significant and there were no significant difference for other studied characteristics in compared with control treatment. Application of midseason drainage increased the crop growth rate and net assimilation rate than control treatment. Increasing midseason drainage duration to 13 day caused in decreasing grain yield as 13% with compared to control treatment. Therefore، in drought condition and due to midseason drainage benefits، duration of midseason drainage could be increased to 13-day without not-significant decreasing in grain yield.