حسین خلیلی شایان

Data and information play a special role in the transparency of water governance. On the other hand, witnessing contradictions in water resources data and information, inconsistent readings and narratives about water assets, outdated hardware equipment, and to some extent software enhancement in the preparation and presentation of water resources information compared to global advances, necessitates a serious review of water resources data collection and processing systems. In this regard, artificial intelligence methods, sensors, and remote sensing technologies are considered in accurate water resources accounting. This article is a systematic review of about 100 international articles that present the latest findings related to software and hardware equipment for monitoring hydrological cycle meta-indicators. These meta-indicators include precipitation, water depth/water level/flow velocity and discharge of rivers, and groundwater level. In each case, while providing a list of the most important technologies, the application level of these technologies in monitoring surface and groundwater resources in Iran was evaluated. The conducted studies prove the unfavorable application technologies in monitoring hydrological cycle in Iran. For example, out of a total of twenty-six known technologies related to surface flow measurements, only two technologies have been widely used Iran; four technologies have reached the knowledge frontier and widespread production by domestic knowledge-based companies, and eleven technologies have not yet reached the knowledge frontier Iran. In this paper, suggestions were presented to outline the path for developing new technologies for water cycle data collection and transformation in the modernization of Iran's water resources data collection and data processing infrastructure.

Due to the measurement problems related to direct methods for estimating discharge, indirect methods based on the concept of surface velocity have been recently developed. In the present research according to the limited number of studies and the lack of appropriate relations between river geometric and hydraulic parameters with velocity index, the effect of dimensionless parameters including dimensionless Manning roughness coefficient, relative depth, Froud number and bed slope on the velocity index has been experimentally investigated. The results showed that by increasing the parameters of relative depth, dimensionless Manning roughness coefficient and Froude number the velocity index decreases. Meanwhile the influence of the bed slope is not clear. The mean value of the velocity index in rectangular channels was 0.92 and the its average error was estimated to be about 4.9%. Also, the analysis of the analytical models of the vertical velocity distribution showed that in the case of a smooth bed, the power law model with 4.5% average error and in the case of the bed with metal mesh, the logarithmic law with 10% average error have the best estimate of the velocity index.

Determining the discharge in rivers using the cross-sectional area-velocity method, especially under flood conditions, is associated with serious challenges. Due to advances in measurement techniques, many researchers have strongly suggested the use of non-contact methods. The non-contact method that use surface velocity radar to determine the discharge are becoming more and more popular especially in flood conditions. This method is to use the concept of index velocity based on the generalization of surface velocity to mean velocity and discharge. Also index-velocity method was used for discharge monitoring or recording at streamflow- gaging stations with flow reversals, backwater effects, hysteresis effects and channel-roughness changes that the use of conventional "stage-discharge rating" method impractical or impossible. During floods, natural rivers appear in the form of a compound cross-section in their middle and end sections. Due to momentum exchange between main channel and flood plains, the flow hydraulic in compound channels is complicate. Most studies in index-velocity method are focused on prediction of the discharge in simple channels. Due to the hydraulic difference between the flow of simple and compound cross-sections, the velocity index (ratio of surface velocity to average velocity) for compound channels is still unknown.

The purpose of this study is how to apply the index velocity method in flood conditions (compound sections) and actually determine the optimal velocity index in compound sections and the highest percentage of its location in the width of the compound section. Also, by performing dimensional analysis, the influence of relative roughness parameters, Froude number, relative depth and relative width on the velocity index in compound channels was investigated. In order to build a laboratory compound channel, a channel with a rectangular cross-section with a width and height of 60 cm with a metal frame and glass walls was used. The height of the flood plain in all tests is constant and equal to 7 cm and three different widths of the flood plain 40, 45 and 50 cm in the smooth state and also one state of the flood plain with a width of 40 cm with metal mesh in compound form was made. Velocity distribution measurements were made in the compound channel, in the main channel and floodplain at 7 or 8 transverse points. In the present study, the velocity index in compound channels at a fixed bed slope of 0.1% and for the relative depth of the main section is 4.2-6.12 relative roughness 0.0003-0.0031 and Froude number 0.14-0.79 has been studied.

By examining the velocity index values across the compound cross-section it was found that the range of average of the velocity index in the width of the compound channels is 0.76-0.98 and with 63% relative frequency is in the range of 0.87-0.93. By fitting between all surface velocity and average velocity data in the entire compound cross-section, it was determined that the optimal value of the velocity index (with R2=0.95) for compound channels is 0.88 with value of absolute relative error of about 0.01-10.06% and an average relative error of 3.3%. The results showed that the increase in the relative roughness and Froude number of the approaching flow and the decrease in the relative depth in the floodplain cause a decrease in the velocity index. The relative error values of discharge estimation showed that in flood conditions (overbank), the velocity index value is different from the normal conditions (inbank) of the river and considering the same velocity index value for both normal and flood conditions will cause more error in the discharge estimation. By examining the location of the optimal value of the velocity index of 0.88 in the entire width of the compound section, it was determined that 71% of the density of points is located on the border of the compound channel and in the last quarter of the flood plain and the first half of the main section. Also, the velocity index is 0.92 in the main channel and 0.86 in flood plain, and if use them, a better estimate of the discharge in the compound channel is obtained. Analytical models of velocity distribution also showed that the velocity power law provides the best estimation of the velocity index than other models if the power index is chosen correctly.

The results showed that the use of the velocity index value of 0.88 for compound channels has an average relative error of about 3.3% in flow estimation. Therefore, by adjusting the default value, it is possible to improve the accuracy of flow estimation in flood conditions. In situations where the possibility of direct measurement in open channels (flood conditions) is not available, it is possible to use the cross section, the surface velocity at the border of flood plain and the main channel and the optimal velocity index of 0.88 can be accurately estimated.

In practical applications, for instance, at the downstream of hydraulic structures, in some cases the width of the basin may be larger than the upstream supercritical flow (sudden expansion in flow section). In such cases, an expanding hydraulic jump with symmetrical or asymmetrical shape will be developed at the downstream. Under the design of three parallel gates, the operation of the side or middle gate can be lead to the asymmetrical or symmetrical hydraulic jump, respectively. According to the position of jump toe, expanding hydraulic jump can be classified into four types. The present study focuses on a T-shaped hydraulic jump which the toe is established at the beginning of the divergence section.Most of the previous studies are related to the symmetrical expanding hydraulic jump. In this case, the downstream diverging channel is symmetric on the central axis of the channel. However, a systematic study investigating the effect of symmetry and asymmetry on the expanding hydraulic jump was not found in the literature. In this study, using the momentum principle, some theoretical equations were derived to determine the sequent depths ratio of symmetrical and asymmetrical expanding hydraulic jump. Also, some regression relations were proposed to estimate the length of expanding hydraulic jump. The new proposed equations were also extended for the presence of a sill. The equations were calibrated using available experimental data from this study and the literature. This research also considered the characteristics of expanding hydraulic jump under the symmetrical and asymmetrical operation of parallel gates.

To calibrate the new proposed relations and investigate the effects of different parameters on the expanding hydraulic jump characteristics, two experimental data sets were used. In addition to the data set from Bremen (1990), the experimental data from the present study were used. The data were collected from a hydraulic model of three parallel radial gates for operating the side or middle gate which corresponds with the asymmetrical or symmetrical expanding hydraulic jump, respectively. The experiments provided a wide range of different parameters as the approaching Froude number, hydraulic jump length, sequent depths ratio, divergence ratio, sill height and relative length of gate separator wall.

Equation (4) was developed to determine the ratio of the sequent depths of expanding hydraulic jump based on the Momentum equation. For the presence of a sill, a combination of Equations (4), (7) and (8) can be used to calculate the ratio of sequent depths under the asymmetric and symmetric developments, respectively.Determining the ratio of the sequent depths requires the calculation of the adjacent water depths of the closed gates. For this purpose, in addition to developing the regression equation (Equation 13), Equation (12) was proposed which based on the calculation of the hydraulic jump profile. It was observed that under the calibration range, the regression equation is more accurate. However, Equation (12) is recommended for the range outside of the experimental observations. The results showed that:As the divergence ratio increases, the ratio of sequent depths approaches to the classic hydraulic jump.By decreasing the relative length of the gate separator wall and decreasing the width of the gate on the downstream channel width, the relative depth at the side gate and consequently the ratio of the sequent depths will decrease.For the lower length of separator wall and under operation of the middle gate, more lengths are needed to develop the jump than the side gate. However, as the length of the separator wall increases, the length and sequent depth of hydraulic jump due to the side gate increases on the middle gate.In the presence of a sill, the relative length of hydraulic jump decreases and the ratio of secondary depths increases.It was observed that the hydraulic jump due to the operation of the middle gate leans toward the left or right side of the channel due to oscillatory behavior.Under operating the middle gate and in the absence of a sill, an asymmetric hydraulic jump is formed in the channel face when the length of the separator wall is less than 38% of the classical hydraulic jump length. For the presence of a sill, the minimum length of the separator wall decreases to about 26%.By decreasing the initial depth of the hydraulic jump on the width of the gate and converting the output jet into a linear jet, the relative development length will increase.
As the sill height increases, the difference in the depths attached to the side gates will decrease and the hydraulic jump will develop more symmetrically.As the relative height of the sill decreases, the minimum length of the separator wall to form a symmetrical hydraulic jump in the flanks, increases.

This research developed a set of theoretical and regression relationships for estimating the length and sequent depth ratio of expanding hydraulic jump. Moreover, the effects of sill height, divergence ratio and the length of the gate separator wall, were investigated. This study compares the effects of side and middle gate operations based on the variation of jump length and sequent depth ratio. The results can be used as a guide for the hydraulic structures operators to reduce the asymmetric severity of the expanding hydraulic jump and achieve the complete development under the minimum length.

Most of the previous studies related to radial gates are focused on the estimation of discharge from the gates as a flow measurement structure. However, determination of the gate opening for passing a certain value of the discharge is rarely considered in previous studies as a regulator structure. The present work presents some theoretical equations for explicit estimation of the outflow from the gate (first problem), and gate opening (second problem) for free and submerged flow conditions by combination of Energy and Momentum principles. For any problems, it was developed some criteria to identify flow conditions These equations were calibrated and validated by means of 2657 experimental records retrieved from research conducted on three types of radial gates. The paper would present an analytical approach to illustrate the reliability of proposed equations for estimation of discharge and the opening of the gate by taking benefits from the mean absolute relative errors which observed to be 1.94% and 2.67, respectively. It was noted that the used criteria conform with 99.6% and 98.8% of all observations at first and second problems, respectively. The results show that the tailwater depth under distinguishing limiting decreases by increasing in the gate lip angle and the ratio of turnnion pin height to the gate arm radius. Also, the hard rubber bar gate tends to operate under free flow condition in a wider range in comparison with two other gates.

Discharge measurement by sluice gates is one of the classical issues in hydraulic engineering. Based on the energy conservation relation, this study presents a novel method for estimating the discharge coefficient of sluice gates under free and submerged flow conditions. This method gives the discharge coefficient of sluice gates only as a function of upstream depth and bottom pressure measured by manometers located under the gate lip and is independent of flow conditions (free and submerged), gate opening and tailwater depth. For evaluating the applicability of the proposed equation in this research for estimating the flow discharge, the experimental results (418 runs) of two sluice gates with 25 and 40 cm widths are used in the conditions of presence and absence of end baffle blocks for both free and submerged flows. Independency of discharge coefficient from the tailwater depth has important advantages such as: continuous estimation of discharge coefficient under free and submerged flow conditions using a unified equation and higher accuracy at the lower submergence. Also being independent of tailwater depth makes easy flow estimation even at the presence of baffle blocks on the stilling basins. The results show that, applying the energy loss coefficient in the proposed equation decreases the mean absolute relative errors to 0.4% and 2.6% for free and submerged flow conditions respectively. Also the proposed equation has a relative error less than 5% under submerged flow conditions. The proposed method is very sensitive to bottom pressure head especially under higher submergence levels.

The paper describes the evolution of local scour hole downstream of an adverse stilling basin. The research was conducted using a wide range of Froude number, sediment size, tailwater depth, length and slope of stilling basin. The maximum depth of scour and its distance from the stilling basin attained 87.5% in the first 24 hours and 86.3% when the experiment was continued for 54 hours. A power equation was adopted describe the characteristic dimensions of scour hole, time scale as well as geometry of stilling basin and sluice gate. The results showed a certain similarity among the scour profiles developed at different times. However, the shape of the holes was influenced with the change in length and slope of stilling basin. As the slope of stilling basin increased by 15%, the volume of sediment removed from the unit width of the hole, was increased by 30%.

The development of an enhanced approach for the use of radial gates as flow measurement structures is important in irrigation networks. In this study, new theoretical relationships were developed to estimate the discharge coefficient (Cd) for a single radial gate with three different sills, at free and submerged flow conditions. These equations were calibrated and verified by using about 2600 laboratory data from the world-wide literature. Results indicated that the flow rate under the radial gates can be estimated by an error in the order of ±5%. The reliability of the proposed relationships and in particular the scale effects, were tested using 530 field data of radial gates operating on different canal networks. The predictions of the flow rates from the proposed method are shown to be superior compare with the other predictive methods. In the presence of multi radial gates in a given cross section, the total discharge is estimated by an error up to ±30% when using single radial gate relationships. This discrepancy is considered to be mainly due to the influence of different gate openingsand the difference between gate and canal widths. A self-developed correction factor, k, was introduced to account for the dimensionless effective parameters such as the ratio of gate-to-canal width, the geometry of the gates, and the ratios of upstream and downstream depths to the average gates openings. The results are promising the predictive errors of the total flow rates are reduced by ±5% and ±10% for 74% and 94% of the flow data, respectively.

This research is focused on local scour downstream of adverse stilling basins where the flow jet was issuing from a submerged sluice gate. Totally, 233 tests were performed and 3262 scour profiles were recorded in a wide range of Froude numbers, sediment grain sizes, tail-water depths, stilling basin lengths and bed slopes. The results showed that the scour holes are self-similar at any slopes. A polynomial equation was derived to define the non-dimensional scour profiles at different slopes. In a certain condition of sediment grain Froude number, tail-water depth and length of basin, a change in the slope of basin from 0 to 15.6%, caused a decrease of 15% in maximum depth of scour hole. A theoretical approach was also derived to evaluate the bed shear stress, weight shear stress and shear stress at threshold state along the scour hole. It was found that the weight and bed shear stresses along the scour hole follow a time-dependent similar trend of variation. Finally, the geometry of basin was investigated to examine its effects on the weight and bed shear stresses.