Journal of Irrigation and Drainage Engineering

The inverse problem of determining soil hydraulic parameters (saturated hydraulic conductivity and water retention parameters) of border-strip irrigation from irrigation event data is analyzed. The inverse problem is solved using sequential unconstrained minimization technique. The forward problem involves the solution of coupled Saint-Venant’s equation governing overland flow and Richard’s equation governing subsurface flow. Saint-Venant’s equations are solved using the MacCormack scheme–based finite-difference method while Richard’s equation is solved using a mass conservative fully implicit finite-difference method. Field experiments are conducted on two border strips to obtain surface and subsurface irrigation data such as irrigation advance, recession, flow depth, and soil moisture content. The soil hydraulic parameters, i.e., saturated hydraulic conductivity and soil retention parameters, are estimated by minimizing the deviations between the model-predicted and field-observed irrigation data. The results indicate that defining the objective function in terms of flow depths results in the optimization algorithm converging to the true values as compared to the use of irrigation advance data. Further, it is observed that underestimating the initial guess results in the least number of iterations for the optimization algorithm to converge to the true values. It is also observed that simultaneous estimation of all three soil hydraulic parameters is not possible even with the inclusion of subsurface moisture content data in the objective function.

Over the last 10 years, telecontrol systems have been incorporated into the majority of modern collective pressurized irrigation networks in Spain. This type of infrastructure provides many opportunities for irrigation management but actually, in Spain, is only used for standardized network operations. The Candasnos irrigation district (CID), located in northeastern Spain, is equipped with this system, and contains a variety of different pressurized systems. Telecontrol data and crop water requirements were used to analyze the evolution of irrigation performance (SIPI) of maize, alfalfa, and stone fruits. Irrigation guidelines for stone fruit were analyzed and compared with those of standard and regulated deficit irrigation (RDI) irrigation strategies. Ten solid-set irrigation systems were monitored to determine on-farm irrigation patterns. The average SIPI of maize, alfalfa, and peach was 83, 107, and 123%, respectively. The average SIPI showed a high irrigation performance, but the spatial and temporal variability of SIPI showed possibilities for improvement. Deficit irrigation practices were conducted on peach trees but not adjusted to the recommended RDI strategy. The results of plot monitoring showed crop differences on irrigation time per event (1–1.5 h in maize and 2–3 h in alfalfa) and on time interval between irrigation (larger in alfalfa than in maize). The short and frequent irrigation timing for the corn crop could be a disadvantageous practice because it yielded high evaporation losses from crop-intercepted water. Two irrigation patterns were established at the CID: the first was characterized by structured irrigation schedules and the second was characterized by weekly changes in the irrigation schedule. The second pattern was more commonly employed in solid-set systems than in those with pivots. The analysis of telecontrol data following this methodology could be easily implemented in the daily routines of the district office to improve irrigation management at the plot level. Further, telecontrol data can be an important tool for promoting and facilitating regulated deficit irrigation strategies in stone fruits.

The agricultural sector is the main victim of drought and efficient water planning, and management is the best strategy to reduce drought pressures on this sector. One operational approach is the application of real-time models to help water managers decide on mitigation measures, such as deficient irrigation or reducing cropped areas using the new incoming information (for example, recorded inflows and precipitation). The present paper introduces a real-time modeling approach for optimal water allocation during a drought. The model includes two main components: forecasting and optimization modules. The forecasting module uses a recurrent neural network technique to forecast annual inflows that is updated as monthly climate and hydrological data are introduced to the model. The optimization module allocates water among the irrigation units and their crops by considering growing stage, sensitivity to water stress at different stages, available/forecasted water, and previous decisions about water release. The model was tested for the 1999 drought of the Zayandeh Rud irrigation system. Traditional operating procedures were shown to produce 42% loss whereas the proposed method would have reduced loss to 12%.

The current methods used to calculate urban landscape water budgets are limited because they lack site specificity. The objective of this study was to create a landscape water budget web interface based on ground-proofed information, such as plant coefficients ($K_s$), vegetation components, and reference evapotranspiration ($\mathrm{E}{\mathrm{T}}_{\mathrm{o}}$). Using Albuquerque, New Mexico as the base city, mixed landscape and monthly turf grass coefficients for each zip code in Albuquerque were developed. The spatial variability of zip code $\mathrm{E}{\mathrm{T}}_{\mathrm{o}}$ and $\mathrm{E}{\mathrm{T}}_{\mathrm{o}}$ weather anomalies was assessed because of their potential effect on water budgets. Evapotranspiration varied among zip codes, months, and El Niño Southern Oscillation (ENSO) phases. To improve the water budget estimate, the interface accounts for spatial and temporal variability of the monthly, historical (monthly and yearly), and the ENSO phases $\mathrm{E}{\mathrm{T}}_{\mathrm{o}}$. Because nonturf landscape plant $K_s$s were unavailable for Albuquerque, the authors developed a Region Match Analysis to transfer nonturf plant $K_s$s from the most similar California climate region to Albuquerque. The interface allows users to input an address and view its image. Users can digitize a site image and calculate the water budget based on either total vegetated areas, areas of trees, shrubs, and grass, or areas of specific plant species. The water budget calculation based on the developed approaches showed a reduction in the estimated water budget compared with the common water budget approach. The web interface can be utilized as a planning tool to estimate water budgets for new developments, irrigation scheduling, and planning for ordinances and policies. The web interface uses improved methods to calculate water budgets and possesses an enhanced potential to provide accurate water budgets.

This paper outlines a life-cycle cost analysis comparing a green (rain gardens) and gray (tunnels) infrastructure combination to a gray-only option to control combined sewer overflow in the Turkey Creek Combined Sewer Overflow Basin in Kansas City, MO. The area of this basin is 2,248 ha (5,554 acres). A set of spreadsheets was developed upon which this life-cycle cost analysis is based. The spreadsheets allow the user to vary the length and/or the diameter of the tunnels. The spreadsheets calculate the additional number of rain gardens needed to handle a given amount of stormwater when the tunnel sizes are reduced. The difference in life-cycle costs between the green/gray and gray-only alternatives is calculated. For a range of options for the number of rain gardens, the green/gray combined alternative is more cost-effective than the gray-only option. The potential present worth of the cost savings for the 50-year expected lifespan of both the gray and green infrastructure could reach as much as $35 million for the Turkey Creek Basin.

In this study, water flow over rectangular sharp-crested side weirs of various heights and widths was investigated. The distribution of the three-dimensional velocity over the crest and in the vicinity of the side weir was obtained using an acoustic Doppler velocity (ADV) meter. The structure of each component of velocity was examined separately. The velocity distributions showed that longitudinal velocity peaked near the beginning of the side weir, whereas velocity in the direction of spill flow was highest at the end of the weir. The observed values of vertical velocity showed that the direction of flow near the crest was upward, but at the highest depths, the flow direction was reversed and a downward flow was generated near the water surface. Analysis of the velocity profiles indicated that the local discharge increased along the crest of the weir; local discharge also increased as the relative width of the weir decreased. Since the angle of the spilling jet ($\phi$) plays a large role in shaping the hydraulic characteristics of a side structure, variation in this angle was investigated, and an expression for estimating $\phi$ was developed.

Labyrinth spillway is the effective and economical solution to increase the discharge by increasing the spillway crest length without an associated increase in structure width. Use of labyrinth spillway is particularly suited to sites where the spillway width and upstream water surface are limited and larger discharging capacities are required. Weir and spillways designed on the basis of the labyrinth concept may be adopted with facility at sites in which certain constraints render other types unsuitable. Recently, their use is found to be attractive solution for upgrading existing development to satisfy more demanding design flood criteria in the limited waterway. The existing spillway is overcoming its earlier limitations of unusual shape and other complicated flow patterns. Continued efforts are being focused towards development of design curves with different shapes and configurations. The present research primarily aims at evaluating various characteristics of a flow-over labyrinth weir by conducting experimentations at wider range of values for important parameters. This paper deals with experimental study of flow-over labyrinth weir for variation of side wall angles ($\alpha$) from 8 to 30°.

This paper presents the design and validation of a relatively cost-effective test rig to simulate high rainfall events; such a rig offers a great opportunity for conducting studies (e.g., high infiltration studies) that require high intensity of rainfall on pervious pavements and other permeable systems. The calibration of the test rig, which produced more than $600\mathrm{mm}/\mathrm{h}$ rainfall intensity, was successful. A simple method of using digital photography to capture raindrops and determine raindrop diameter was developed and used successfully to determine the drop size of simulated rainfall by the test rig. Results obtained by this method indicated that the raindrop diameter varied from 0.69–8.97 mm, which was consistent with the high rainfall intensity generated by test rig. Categorization of raindrop size according to Wilson Bentley’s classification showed 1.84, 6.42, 33.95, 26.61, and 31.19% for very small, small, medium, large, and very large drops, respectively, which was considered consistent with the relatively high rainfall intensity generated by the test rig.

A flow-measuring system was developed to measure the flow rate of a river called Assi, a tributary to River Ganges in the city of Varanasi, India. The Assi River carries a huge quantity of sewage water, and thus serves as large sewerage drain for the city. A sewage treatment plant that was under consideration to treat the wastewater discharge into the Ganges needed empirical flow data to establish its design capacity. This gave rise to the installation of a flow-measuring system. The distinctive features of the measuring system, which has potential for application to other areas around the world, are discussed.

Published labyrinth weir design methods, which have primarily been developed on the basis of labyrinth weir test data from laboratory flumes, are specific to in-channel labyrinth weir applications in which the approach flow is oriented normal to the weir axis. Consequently, some uncertainty exists regarding the hydraulic performance of labyrinth weir configurations that are specific to reservoir applications (i.e., projecting, flush, rounded inlet, and arced labyrinth weirs). The discharge efficiency, as characterized by the weir discharge coefficient, of laboratory-scale projecting, flush, rounded inlet, and arced labyrinth weirs with 12 degree sidewall angles, were evaluated as a function of $H_T/P$ and compared with in-channel labyrinth weir discharge efficiencies. The arced labyrinth weir configuration had a higher discharge efficiency ($\sim 5–11\%$ higher than an in-channel labyrinth weir orientation). In general, the projecting, flush, and rounded inlet orientations were less efficient than the in-channel labyrinth weir configuration.

Manhole drops in drainage systems are often designed for providing energy dissipation, for controlling high velocities and for minimizing sewers structural damage. The flow is characterized by excessive air-entrainment and high turbulence. The manhole geometry, the upstream and downstream flow characteristics and possible transitions between the manhole and the sewers control the flow inside the manhole. This experimental research aims to investigate the effects of a free jet in a square drop manhole with a downstream control gate by analyzing the flow conditions, discharge coefficients, turbulence downstream, and energy dissipation for three different flow regimes, R1, R2, and R3. This research propose to (1) adjust the limits of the existing regimes classification by including a new impact number based on downstream gate opening, and (2) obtain empirical equations for predicting the discharge coefficients with the flow regime. Non dimensional discharges were better predicted for R1 by using critical velocity. The energy dissipation and turbulence was found to respectively decrease and increase by raising the water discharge from the inlet and by opening the gate.

Sprinkler irrigation is one of the advanced water-saving irrigation technologies, which has a significant effect for the development of agriculture. Sprinklers are designed to rotate in a circle. In practice, sprinklers can also be used to generate electric power by attaching a generator (dynamo) to its rotating head. Thus, the sprinklers can be converted into a turbine. Hydropower generation from a sprinkler system is theoretically discussed in textbooks on fluid mechanics. Therefore, the aim of this paper is to evaluate theoretical considerations and experimental results of hydropower generation from a sprinkler system. In this study, hydropower generation from a sprinkler system is simply tested with a practical application. The results indicate that a sprinkler irrigation device is capable for hydropower generation, i.e., electrical energy can be produced using sprinkler devices. Hence, the generated energy can be used for energy requirements (e.g., remote-controlled electric sprinkler, lighting, and other uses). If sprinkler devices are technological redesigned for both irrigation and power generation, they will generate low-cost electricity for energy requirements. Also, hydropower can be produced from sprinkler head series in center pivot sprinkler irrigation type.