Journal of Irrigation and Drainage Engineering

This paper presents the development and application of a stochastic dynamic programming model with fuzzy state variables for irrigation of multiple crops. A fuzzy stochastic dynamic programming (FSDP) model is developed in which the reservoir storage and soil moisture of the crops are considered as fuzzy numbers, and the reservoir inflow is considered as a stochastic variable. The model is formulated with an objective of minimizing crop yield deficits, resulting in optimal water allocations to the crops by maintaining storage continuity and soil moisture balance. The standard fuzzy arithmetic method is used to solve all arithmetic equations with fuzzy numbers, and the fuzzy ranking method is used to compare two or more fuzzy numbers. The reservoir operation model is integrated with a daily-based water allocation model, which results in daily temporal variations of allocated water, soil moisture, and crop deficits. A case study of an existing Bhadra reservoir in Karnataka, India, is chosen for the model application. The FSDP is a more realistic model because it considers the uncertainty in discretization of state variables. The results obtained using the FSDP model are found to be more acceptable for the case study than those of the classical stochastic dynamic model and the standard operating model, in terms of 10-day releases from the reservoir and evapotranspiration deficit.

This study develops an approach aimed at improving the capability of regional irrigation monitoring and evaluation to identify relevant factors and subareas influencing irrigation performance. Its objective is to contribute to improve the productivity of irrigable areas in a cost-effective manner by overcoming the lack of sufficient updated field data observed in conventional remote sensing studies. To do this, several performance indicators are calculated and analyzed by combining remote sensing with district database programs that irrigation districts use in their administrative and water management tasks. This approach was applied in Riegos del Alto Aragón (Spain), a large (124,596 ha) and heterogeneous project divided into 53 surface and sprinkler irrigation districts. The 2004 and 2005 seasons were analyzed, with the latter showing a severe water shortage. Under no water scarcity, most districts applied higher relative water supplies regardless of irrigation systems and other factors. Cropping patterns were less intensive in surface irrigation districts regardless water availability. Six districts and four main factors were identified as those most important to bridge the economic gaps that this performance implies.

Drainage continues to be a vital and necessary component of agricultural production systems in consolidated paddy fields in northern Iran. Agricultural and environmental sustainability in these fields requires more attention to the water quality impact of drainage water disposal. This study aimed to quantify the influence of different drain spacings and depths on the salinity of drainage water. Data on drainage flows and salinity were collected from 4.5 ha of paddy fields of Sari Agricultural Sciences and Natural Resources University, Iran, during four successive rice-canola-rice-canola growing seasons (July 2011 to May 2013). By increasing drain spacing, the electrical conductivity (EC) and volume of drainage water and total salt load decreased. On the other hand, decrease in drain spacing in relation to increase in drain depth had greater environmental effects from salinity point of view. So, where a new drainage system is to be installed, there is the opportunity to design a drainage system that provides adequate salinity and waterlogging control while minimizing salt loads.

The content of this article provides interesting history, facts, and information about the drainage systems of ancient theaters in mainland Greece and Asia Minor from prehistoric times until the Hellenistic period. This study comprises representative examples of drainage systems in theaters at Knossos, Phaistos, Dionysus in Athens, Arcadian Orchomenos, Ephesus, and Delos. Moreover, the aim is to demonstrate that these drainage systems represent evolutionary techniques and principles that can still be used today to avoid wasting water resources. Moreover, these techniques may prove attractive for the development of sustainable strategies to counter mounting problems, especially those of a socioeconomic nature. In addition, the article presents evidence for the conception that adaptations to individual environmental and hydraulic characteristics of specific locations were considered in relation to drainage systems of ancient theaters. Thus, through a case study of the carrying capacity of drainage channels at Dionysus’s theater in Athens, the sustainable nature of this construction is demonstrated, including its capacity for the management of stormwater.

Surface irrigation is the main irrigation system used in the inter-Andean valleys of Bolivia. However, the region’s steep terrain precludes the use of conventional surface irrigation methods. Zigzag corrugated furrows, the most widely used irrigation method in the region, have proved suitable for the local conditions and are environmentally sound as they substantially reduce soil loss from water erosion. Satisfactory water management, however, appears to be lacking so our paper aims to study water use and suggest improvements. The experimental field work was carried out in Cebollullo, a rural community 2,780 m above sea level located southeast of the city of La Paz. The characteristics of the furrows vary with crop type and soil (class and slope). Lettuce crops grown in an experimental $566\text{-}{\mathrm{m}}^2$ plot with an average slope of 16.46% were studied. The plot was irrigated a total of 21 times at 2–3 days intervals and the effects of 10 of the irrigation events were evaluated taking weekly measurements during each event. Advance curves were constructed from data obtained at 16 measurement points. Advance and recession times, as well as inflow and outflow rates were determined on the basis of measurements made a 5-min intervals. Inflow rates at some measurement points were found to vary widely due to the indiscriminate use of water by farmers upstream of the experimental plot. Advance curves were found to be linear rather than potential or exponential as is usually the case with this type of irrigation system. Also, advance and recession curves were virtually parallel, which indicates uniform infiltrated volumes along the furrows. The average water application efficiency, surface runoff, and deep percolation loss for the 10 irrigation events examined were 17.47, 68.36, and 14.17%, respectively. Based on these results, the zigzag furrow irrigation system in the area investigated in the research reported in this paper would appear to be badly managed and implemented.

This research evaluated the relative evaporative losses and water balance components in two soybean [Glycine max (L.) Merr.] fields under subsurface drip irrigation (SDI) and center pivot irrigation (CPI) systems in south-central Nebraska. Meteorological and surface energy balance components, including actual evapotranspiration (ET), above the crop canopy was measured using Bowen ratio energy balance systems installed at the center of both fields. Crop transpiration ($T$) was estimated based on the variable stomatal resistances using the Penman-Monteith equation in conjunction with fractional green canopy cover. Evaporation ($E$) losses were estimated as the difference between measured ET and estimated $T$. Average soil water content (ASWC) in the crop root zone and effective rainfall were estimated using the water balance method. The relative evapotranspiration (${\mathrm{ET}}_{\text{rel}}$) was 99.8% for the SDI field in both years (2007 and 2008), and it was 103.4% in 2008 and 93.9% in 2010 for the CPI field. The mean ${\mathrm{ET}}_{\text{rel}}$ between sites and across years were not significantly different ($P>0.05$). There were revealing differences in the relative contribution of $T$ and $E$ to total seasonal ET between the SDI and CPI fields. In the SDI field, $T$ and $E$ were 88 and 12% of ET, respectively, in 2007, and in 2008 they were 84 and 16% of ET, respectively. In the CPI field, $T$ and $E$ were 78 and 22% of ET, respectively, in 2008, and in 2010 they were 75 and 25% of ET, respectively. At full canopy cover, $T$ contributed more than 85% of the total ET. Although $E$ is assumed negligible at the full canopy cover stages, the data indicated that $E$ was 6 and 9% of ET in SDI fields during the midseason growth stage at full canopy cover in 2007 and 2008, respectively, and 14 and 21% of ET in CPI fields during the same growth stage in 2008 and 2010, respectively. On a 2-year average, the CPI field had approximately 10% higher $E$ losses as compared with the SDI field under these experimental conditions, which can have a large impact on crop water productivity when crop production under water-limiting conditions is considered. The reduction in $E$ in the SDI field can be expected to be greater in arid and semiarid regions than in subhumid regions.

The curve number (CN) method is widely applied around the world to estimate direct runoff and the corresponding hydrograph of a rainfall event. However, there is no information on its performance in olive orchards on the catchment scale. In this work, the CN method was applied in three small catchments in southern Spain with different soil types, topography, and management. A rainfall-runoff data set of six years was used to test the usefulness of the method and the accuracy of its reference parameterization (CNs) and of the initial abstraction ($I_a$). CN medians in the catchments were between 83 and 87. Classical equations based on the use of the 10th, 50th, and 90th CN percentiles for determining the antecedent moisture content (AMC) provided very good results in two of the catchments. In the third catchment, with the most arid hydrological pattern (annual rainfall $<400\mathrm{mm}$) and the most impervious areas of parental material, very poor performance was achieved. In addition, cumulative precipitation was not a good indicator of AMC. Finally, significant deviations were observed in reference CNs for sandy soils that should be treated with caution for hydrological planning. They illustrate the need for new studies evaluating the hydrological behavior of olive orchard catchments with different environmental features and management practice.

Decision support systems (DSSs) for irrigation system management have many benefits, which include water savings and the development of optimal water delivery schedules, while maintaining farmer productivity. To address water shortage and improve water delivery, DSSs have been developed and utilized throughout the United States and the world and can be used to predict crop depletions using weather data to schedule water delivery on the basis of crop demand. The overall utility of DSSs is that they allow managers to continue water delivery and equitably distribute supplies during a water shortage. For a decision support system to be successfully utilized, the complicated challenge of implementation needs to be addressed. Decision support system implementation is often met with harsh resistance from water users and managers alike, and, in many cases, a scientifically sound model is often rejected because of misinformation and lack of user education. This paper presents the successful implementation of a DSS and scheduled water delivery in the Middle Rio Grande Conservancy District (MRGCD). The implementation of the DSS was accomplished using a multifaceted approach that included gaining political support of the MRGCD Governing Board, training water masters and ditch riders in the use of the DSS, providing on-the-ground support and assistance, refining parameters in the DSS to address complexities, and gaining public acceptance for scheduled water delivery utilizing a DSS. A total of two key components for the implementation of the DSS and scheduled water delivery were linking it to the MRGCD supervisory control and data acquisition system (SCADA) and conducting a large public outreach and education campaign. The overall results of the DSS implementation were successful, and managers were able to deliver water to irrigators in a more efficient manner than traditional practice.