Journal of Irrigation and Drainage Engineering

The objectives of this study are: (1) to evaluate the LANDSAT best band combinations to estimate soil salinity with different crop types; (2) to compare ordinary kriging, regression kriging, and cokriging techniques to generate accurate soil salinity maps when applied to LANDSAT images; and (3) to compare the performance of different crop types: alfalfa, cantaloupe, corn, and wheat as indicators of soil salinity. This study was conducted in an area in the southern part of the Arkansas River Basin in Colorado. Six LANDSAT images acquired during the years: 2000, 2001, 2003, 2004, 2005, and 2006 in conjunction with field data were used to estimate soil salinity in the study area. The optimal subsets of band combinations from the LANDSAT images that correlate best with the soil salinity data sets were selected. Ordinary kriging, regression kriging, and cokriging were applied to 2,914 soil salinity data points collected in alfalfa, cantaloupe, corn, and wheat fields in conjunction with the selected LANDSAT image band combination subsets. Ordinary least-squares (OLSs) were used to regress the correlated band combinations to generate a soil salinity surface. The residuals of the OLS multiple regression model were kriged and combined with the soil salinity surface generated using the OLS multiple regression model to produce the final soil salinity surface of the regression kriging model. The same LANDSAT band combinations used with the regression kriging technique were used as secondary data variables with the cokriging technique, while the soil salinity data was used as a primary variable. The results show that the best band combinations for estimating soil salinity with different crops are as follows: alfalfa [red, near infrared, and normalized difference vegetation index (NDVI)]; cantaloupe (blue and green); corn (near, thermal, and NDVI); and wheat (blue and thermal). The performance of the different geostatistical models used in this study is: (1) ordinary kriging; (2) regression kriging; and (3) cokriging. Estimation of soil salinity works best for corn, then wheat, cantaloupe, and alfalfa.

A cross-section-averaged advection-dispersion equation (ADE) model was developed to simulate the transport of fertilizer in furrow irrigation. The advection and dispersion processes were solved separately at each time step by implementing a method of characteristics with cubic-spline interpolation and a time-weighted finite-difference scheme, respectively. The upstream boundary condition was a prescribed concentration. Downstream, a zero-flux boundary condition during advance and a concentration gradient following completion of advance were prescribed. Local pseudosteady state was assumed in order to apply Fischer’s longitudinal dispersion equation under nonuniform and unsteady furrow flow conditions. Statistical parameters were used to evaluate the ADE model performance.

In this paper a knowledge-based model for supplementary irrigation assessment in rainfed agricultural watersheds is presented. The supplementary irrigation assessment problem is divided into different components and is modeled separately. Geographic Information System (GIS) is used to aggregate spatially varying attributes required for the modeling. A graphical user interface is developed in a GIS platform by using the ERDAS macro language tools. The model was applied to two case study areas in India: a subwatershed of Gandheshwari area (West Bengal), and Harsul watershed (Maharashtra). In the Gandheshwari subwatershed, the water availability was found to be inadequate to meet the irrigation requirement and hence the model identified the areas that can be irrigated with different outsource water supply. On the other hand, surface runoff generated in the Harsul watershed was found to be sufficient to meet the supplementary irrigation requirement, thereby showing the feasibility for supplementary irrigation in the area. Using the model, the effect of any rainfall condition can be simulated and hence appropriate measures can be taken in advance to reduce the risk of crop failure.

An approximated linear model of unsteady open-channel flow is necessary to design the water-level controller for irrigation open channels. Toward this end, this paper presents the matrix approach to derive the linear model of open-channel system in analytical form mainly according to the Saint Venant equations and the backwater profile at the steady state of open channel. The hydraulic model of the check structure at the downstream end of open channel is also incorporated into the linear model. A practical example indicates that the frequency response of the open-channel system can be accurately analyzed with the linear model. The simulation results in the time domain show that the dynamic behavior of the linear model approximates to that of the nonlinear model of the open-channel system. Finally, the limitations of the linear model are discussed.

The particular challenges of modeling controlled water systems are discussed. The high degree of freedom due to the control structures increases the risk of producing the right output for the wrong reasons. On the other hand, many controlled water systems are (partly) manually operated or at least supervised by an operational water manager. The decisions of these managers are not as rigid as a computer simulated control strategy. Therefore, getting a very close fit with a water-system control model is mostly not possible. A modeling framework is proposed that takes advantage of the vast availability of measurement data in controlled water systems. The water level and flow data at control structures allow for intensive validation and subsystem calibration to reduce the degree of modeling freedom and to model separately the natural rainfall-runoff and hydrodynamic processes. The framework is successfully applied to improve a simulation model of the controlled water system of Rijnland, The Netherlands. The yearly volume error was reduced from 11% to less than 1% and as a consequence, the short-term peak events were modeled more accurately as well. The resulting water-system control model is more reliable for both design studies and operational decision support. The framework will contribute to prepare more reliable simulation models of controlled water systems.

Controlling soil erosion during and after construction is a major concern due to the impacts of sediment on stream water quality, and many studies have focused on the effectiveness of erosion control best management practices (BMPs) to prevent erosion. However, their ability to reduce runoff volume and peak discharge is not commonly studied or integrated into storm water designs due to lack of data and design guidelines. This study investigated runoff characteristics (total runoff, peak flow rate, curve number, and rational method runoff coefficient) from bare compacted soil conditions with and without erosion control BMPs, with an emphasis on compost erosion control blankets (CECBs), at three different slope (2H:1V, 3H:1V, and 4H:1V). Experiments were performed in the San Diego State University, Soil Erosion Research Laboratory on a 3-m by 10-m indoor titling soil bed using simulated rainfall based on conditions specified in ASTM D-6459. Eleven erosion control BMPs were evaluated at a slope of 2H:1V, three at 3H:1V, and three at 4H:1V. The variations in slope were used to assess the effects of slope and CECB thickness on runoff. The results from this study provide new insight regarding the runoff characteristics from bare soil and erosion control BMPs that can be used to improve construction-site storm water design. The results show that 2.5- and 5.0-cm-thick CECBs on top of netting or an excelsior fiber blanket provided a significant reduction in runoff relative to the bare soil and the other BMPs (e.g., 1.3-cm CECBs, other blankets) due to water storage within the CECB, the mass of the CECB providing a strong bond between the soil surface and the bottom of the blanket reducing the potential for flowing water from coming in contact with the soil surface, and the netting/blanket under the CECB providing additional friction that helps keep the CECB from sliding down slope. The results show that slope impacts on runoff are minimal but that as CECB thickness increases runoff was reduced due to the added storage within the blanket. The results from this study can be used to aid in the selection of CECB thickness and to assess the effects of CECBs on runoff for more efficient cost effective storm water designs.

Nowadays, it is necessary to develop methodologies, tools, and actions that try to optimize the use of the energy resources. One of the main problems found was the improper dimensioning of the pumping for undergroundwater extractions that supply water to reservoirs. In this paper, a new methodology to obtain the minimum total cost ( $\text{investment}+\text{operation}$ costs) by optimizing the characteristic and efficiency curves, together with the pumping pipe diameter, was developed. This methodology was based on the theoretical relations between the characteristic and efficiency curves and it considered different variables such as: hydrologic, topographic, hydraulic, and economic variables. In addition, software implemented in MATLAB environment was developed to facilitate the transference of this methodology to engineers and managers of irrigable areas. The results show that the steepness of the characteristic curve is mainly associated with the water table level variation throughout the year, and the pumping pipe diameter is mainly associated with the water demand (volume). In addition, the operation point with the maximum efficiency should correspond with the month of highest demand.

The objective of this paper is to investigate and analyze the silting and subsequent aggradation of the irrigation canals in Žitný Ostrov (Rye Island). The irrigation canal network, located in Southern Slovakia, was built to provide for irrigation water and drainage in the region. The water level in the irrigation canals and groundwater level in Žitný Ostrov area affect each other. Because of this mutual interaction, it has been necessary to evaluate the impact of silting in the canal network due to the presence of the alluvials. Water surface elevations in Danube River affect groundwater infiltration from the Žitný Ostrov aquifer, in and out of the canals, and causes fluctuation of the flow in the canals. The amount of groundwater infiltration is a function of the silt hydraulic conductivity. Tests were done in 1993 and 2004 to measure the silt thickness and granularity at 166 measurement points along approximately 77 km of the canal network. This paper discusses the change in silt thicknesses and silt volume in the canals as they built up over an 11-year period. As a secondary goal of the paper, the silt granularity and hydraulic conductivity was determined. The results of our research are useful in establishing the canals’ maintenance program. The regional planning commission will use the study to forecast silting in the future.

Water application uniformity is an important performance criterion that must be considered during the design and evaluation of the microirrigation systems. This study was conducted to evaluate the water application uniformity considering field slopes. The uniformity parameters including coefficient of variation (CV), Christiansen’s uniformity coefficient (UCC), distribution uniformity (DU), emitter discharge variation $q_{v\left(q\text{max}\right)}$ expressed by the difference between the maximum emitter flow rate $q_{\text{max}}$ and the minimum emitter flow rate $q_{\text{min}}$ to $q_{\text{max}}$ , emitter discharge variation $q_{v\left(qd\right)}$ expressed by the difference between $q_{\text{max}}$ and $q_{\text{min}}$ to design emitter flow rate $q_d$ , emitter discharge variation $q_{v\left(qd\right)}$ expressed by the difference between $q_{\text{max}}$ and $q_{\text{min}}$ to average emitter flow rate $q_{\left(\text{avg}\right)}$ , emission uniformity $\left({\text{EU}}_{\left(q\text{avg}\right)}\right)$ expressed by $q_{\text{min}}$ to $q_{\text{avg}}$ , and ${\text{EU}}_{\left(qd\right)}$ expressed by $q_{\text{min}}$ to $q_d$ . Furthermore, the relationships of CV versus UCC, CV versus DU, CV versus $q_{v\left(qd\right)}$ , CV versus $q_{v\left(q\text{max}\right)}$ , CV versus $q_{v\left(q\text{avg}\right)}$ , CV versus ${\text{EU}}_{\left(q\text{avg}\right)}$ , and CV versus ${\text{EU}}_{\left(qd\right)}$ were also discussed. The results of the study revealed that the field slope does not obviously affect the relationships of CV versus UCC, CV versus $q_{v\left(q\text{max}\right)}$ , and CV versus $q_{v\left(q\text{avg}\right)}$ for any of the slopes evaluated, which include uphill, zero slope, and downhill. Furthermore, the effect of slope on the relationships of CV versus ${\text{EU}}_{\left(q\text{avg}\right)}$ , CV versus ${\text{EU}}_{\left(qd\right)}$ , and CV versus $q_{v\left(qd\right)}$ was obvious, especially when large downhill slopes with a $\text{CV}>0.05$ were considered. However, the effect of slope on the relationships of CV versus DU was intermediate. Taken together, the results of this study indicated that the UCC, $q_{v\left(q\text{max}\right)}$ , and $q_{v\left(q\text{avg}\right)}$ should be recommend in addition to CV when evaluating the water application uniformity of the microirrigation systems, regardless of slope, and that $q_{v\left(qd\right)}$ and ${\text{EU}}_{\left(qd\right)}$ should be recommend when evaluating systems placed in fields with a slope of zero or an uphill slope.