Journal of Irrigation and Drainage Engineering

The longevity of drainage pipes is dependent on the material properties of the pipe, the surrounding load, the abrasive characteristics of the effluent, and the frequency, velocity, and quantity of the effluent that flows through the pipe. Each of these parameters has impacts on the age-related abrasive decrease in the wall thickness of the drainage pipe. Traditionally, the rotating pipe test is used to assess the vulnerability of drainage pipes to abrasion. To simulate more realistically the natural environment of drainage pipes, we designed an abrasion test that keeps the drainage pipe at variable slope with respect to the horizontal and continuously pumps abrasive slurry through the pipe for $30\text{days}$ . The time dependent change in wall thickness of a cellulose fiber reinforced cement pipe was simultaneously compared to the change in wall thickness of a steel-reinforced concrete pipe. The wall thickness of the fiber reinforced cement pipe decreased approximately 5 times faster than the thickness of the steel-reinforced cement pipe.

A computer model for the analysis and design of grass swale perforated pipe systems is presented. The model, which was calibrated and validated using experimental as well as field data, performs detailed computations for flow through the system on a lot by lot basis (i.e., from one catchbasin to another). Several parameters affecting the system performance are considered in the modeling approach. These especially included lot size and imperviousness, grass swale dimensions and its infiltration capacity, pipe length, number of orifices and their configuration, trench dimensions, and native soil infiltration capacity. The model was used to simulate the minimum trench depth required to capture runoff from a $25\mathrm{mm}$ storm for different native soils and different lot imperviousness ratios. Trench depths varied from 0.3 to $1.4\mathrm{mm}$ depending on native soil infiltration capacity and lot imperviousness.

A model is developed using data from an on-demand pressurized water distribution network located in sector VIII of the Genil-Cabra irrigation district of Santaella, Córdoba (southern Spain), to simulate an irrigation season and calculate the flows that circulate in the system at any given time during the irrigation day. Using the results obtained by the model, water demand frequencies can be estimated. These results are compared to those attained by Clément’s and Mavropoulos’s formulas. This procedure enables us to determine to what extent it is possible to adjust statistical distributions to the demand obtained by both models and to verify if the hypotheses upon which these models are based are, in fact, fulfilled. Moreover, we are able to study which periods are the most appropriate for determining peak demand. Our results show that the statistical methods slightly underestimate demand because demand tends to be concentrated at two peak times during the day: one at mid-morning and another in the late afternoon. Nonetheless, the design flow obtained by the models is valid for designing the system. After studying the demand frequencies, we concluded that a better fit is achieved when a more flexible distribution such as the gamma distribution is used.

Elevated selenium concentrations have been observed in several rivers in the western United States and are a concern for healthy aquatic systems. Water quality modeling is a valuable tool for quantifying the importance of sources and assessing management alternatives for stream standards compliance in basins with impaired water quality. This modeling study uses a relatively simple approach to describe a water distribution system and processes that drive loading of dissolved selenium and salts from the naturally occurring Cretaceous shale soils in the extensively irrigated Uncompahgre and Gunnison River Basins in Western Colorado. Calibrated model output characterizes processes that load an average total of $\mathrm{4,130}\mathrm{kg}$ $\left(\mathrm{9,100}\mathrm{lb}\right)$ of selenium and $2.9\times {10}^8\mathrm{kg}$ $\left(\mathrm{316,000}\text{t}\right)$ of salts per year from agricultural subbasins to the Uncompahgre River. Simulations of best management practices predict that extensive implementation of methods to minimize seepage and constituent loading would be required to reduce selenium concentrations to comply with the current water quality standards.

Minimum cost irrigation network design has been conventionally based on crisp pressure requirements at the hydrants of the network. In order to incorporate obscure knowledge on these pressure requirements at the design stage, an interactive fuzzy integer programming methodology is proposed. In the integer linear programming, formulation membership functions are adopted for expressing pressure constraints. Also, the interactive character of the proposed methodology enables the designer to select a less demanding range of pressures at some “critical” hydrants. By using the proposed methodology significant economic gains may be achieved reducing the cost of the network, since the energy line is adapted more satisfactorily to the ranging pressure requirements. Finally, an application of the methodology to an irrigation network is presented.

The surface infiltration rates of 40 permeable pavement sites were tested in North Carolina, Maryland, Virginia, and Delaware. Two surface infiltration tests (pre- and postmaintenance) were performed on 15 concrete grid paver lots filled with sand. Maintenance was simulated by removing the top layer of residual material $(13–19\mathrm{mm})$ . Simulated maintenance significantly $(p<0.007)$ improved the surface infiltration rate. The median site surface infiltration rate increased from $4.9\mathrm{cm}∕\mathrm{h}$ for existing conditions to $8.6\mathrm{cm}∕\mathrm{h}$ after simulated maintenance. Fourteen permeable interlocking concrete pavers (PICP) and eleven porous concrete (PC) sites were also tested. PICP and PC sites built in close proximity to disturbed soil areas had surface infiltration rates significantly ( $p<0.0014$ and $p<0.0074$ , respectively) less than stable landscape sites. Median PICP surface infiltration rates of each condition were $80\mathrm{cm}∕\mathrm{h}$ and $\mathrm{2,000}\mathrm{cm}∕\mathrm{h}$ , respectively. Median PC surface infiltration rates with and without fines were $13\mathrm{cm}∕\mathrm{h}$ and $\mathrm{4,000}\mathrm{cm}∕\mathrm{h}$ , respectively. This study showed that: (1) the location of permeable pavements; and (2) maintenance of permeable pavements were critical to maintaining high surface infiltration rates.

A new technique for testing the erodibility of cohesive stream banks using an in situ flume is presented. The erosion rate is estimated from direct measurements of bed surface elevations by acoustic sensors. The sediment resuspension rate is obtained using data on sediment concentrations measured by optical backscatter sensors and from water samples. The bed-load contribution to the total erosion rate is evaluated from the conservation equation for sediments. Temporal patterns of erosion and resuspension rates are studied employing stepwise increments of bed-shear stress. The data show that bed load plays a significant role in cohesive bank erosion. The data analysis suggests that erosion and resuspension thresholds observed in experiments were very low or equal to zero. The data support the power type equation for the erosion and resuspension rates with bed-shear stress as the key factor. The data also highlights the potential importance of mud content and water content on erosion.

Net radiation $\left(R_n\right)$ estimated using the California Irrigation Management Information System (CIMIS) Penman and the Penman–Monteith (PM) methods are compared using hourly data from July 17, 2004 to October 24, 2004. Results showed that differences between the two estimates get larger towards higher values of $R_n$ because of the inability of the two methods to accurately estimate net outgoing longwave radiation $\left(R_{\mathrm{nl}}\right)$ . This was determined by comparing the two $R_n$ estimates against values measured using the Kipp and Zonen CNR1 net radiometer. On average, the CIMIS Penman $R_n$ was 4% lower and the PM $R_n$ was 8% higher when compared to the measured values. An attempt to modify the PM method for estimating $R_{\mathrm{nl}}$ resulted in significant improvements. $R_n$ values measured by four Kipp and Zonen NR-Lite radiometers are also compared with the corresponding values measured by the CNR1. The NR-Lites performed well under the given sets of surface and environmental conditions. Average values of slope, coefficient of determination $\left(r^2\right)$ , and standard error of estimates from the linear regressions of the four NR-Lites against CNR1 were 0.97, 0.99, and $18.79\mathrm{W}∕{\mathrm{m}}^2$ , respectively.

An objective method and a diagnostic curve method are developed for estimating the aquifer parameters (storage coefficient and transmissivity) from slug test data on a fully penetrating well. In the objective method, explicit equations are developed for estimating the aquifer parameters. In the diagnostic curve method, a set of unimodal diagnostic curves is developed along with a guiding straight line. The rise or fall in water level of the well is plotted diagnostically on a double logarithmic graph and matched to one of the diagnostic curves plotted on the same scale with a parallel shift of axes, to estimate the aquifer parameters from the dual coordinates of a selected point on the matched portion of the graphs. The unimodal shape of the diagnostic curves and the guiding straight line facilitate the matching and limit the subjectivity. The proposed methods can easily identify a nonideal condition. The estimates of the aquifer parameters obtained using the proposed methods are more accurate than those obtained using the prior curve matching methods. The proposed methods are also able to identify nonideal conditions. It is hoped that the new methods will be of help to field and practicing engineers.

The Programa para el Manejo del Agua y del Suelo (PROMAS) assists the local farming community in introducing new types of locally available irrigation equipment that are both inexpensive and water efficient. Field experiments enabled determining the maximum application rates that cause zero runoff for slopes above 16% for low-cost sprinkler systems.

Simple equations are proposed for estimating storage coefficient and transmissivity of an aquifer from drawdowns in large- diameter wells. The proposed method requires determination of the peak and time to peak of a unimodal curve. Using these values and utilizing the provided set of equations, the aquifer parameters are estimated through an iterative procedure. The proposed method is void of subjectivity involved in the previously proposed curve matching methods. Also, the new method can be used when the conventional curve matching methods cannot be applied to estimate the aquifer parameters. The new method can be used to estimate the aquifer parameters from the drawdown data observed only up to a time so that the peak could be determined.

A simple approximation of the well function for a constant drawdown is developed. This approximation is used to estimate the storage coefficient and transmissivity of the aquifer from observed unsteady discharge under a constant drawdown condition, using an optimization method. Another simple approximation for calculating the total production volume during a time span is also developed. The developed approximations for the well function and production function are accurate within a maximum error of 0.7% for the practical range of the argument.