As water resources become restricted for use on amenity turfgrass systems, the inability for consumers to delineate incremental drought stress relating to plant health can result in the misuse of water resources during drought conditions. Seven cultivars of St. Augustinegrass (SA) [Stenotaphrum secundatum (Walt.) Kuntze] and two root zone depths were evaluated for drought response and recovery during consecutive 60‐d drought and 60‐d recovery periods over 2 yr. Using digital image analysis, drought response and recovery were quantified as the number of days to decrease or increase to 50% green ground cover, respectively. Both study years provided unique conditions for investigating drought response as the mean time to reach 50% green ground cover differed by 24 d between the 2 yr of study. Some SA cultivars lost 50% green ground cover in 23 d while other cultivars lasted the entire 60 d drought period without losing 50% green ground cover. Floratam provided the most consistent drought response and recovery compared to other SA cultivars. Once water was no longer limited, cultivars demonstrated up to a 52 d difference in attaining 50% green ground cover. Results could significantly impact home consumer irrigation behaviors and influence consumer expectations of turfgrass following drought conditions.

Traditional field survey methods for detection of water leaks in irrigation canal systems are costly and timeconsuming. In this study, a rapid, cost-effective method was developed for identifying irrigation canal locations likely to have leaks and/or seepage. The method involves the use of a multispectral imager equipped with red, near infrared, and thermal sensors which is mounted on an aircraft and flown at low altitude to collect the images. A three-step process, image acquisition, image processing, and field reconnaissance, was developed for processing the imagery and identification of locations likely to have leaks. The method was evaluated in the Lower Rio Grande Valley of Texas, USA. Images were collected of 24 selected canal segments within 11 irrigation districts in this region. Evaluation of the imagery indicated that 140 sites had possible canal leakage problems (point leak and/or seepage). A field site evaluation form was developed and used to document the type and severity of the leaks at 28 of the sites. Twenty-six sites were confirmed to have leaks, representing a success rate of 93%. The methods used in this study should have widespread application for detecting leaks and seepage in irrigation canals. Les méthodes utilisées dans cette étude devraient avoir une application généralisée de détection des fuites et des infiltrations dans les canaux d'irrigation.

Four different methods of representing drain tubes in finite elements for field drainage problems were studied. A finite-element solution to the Richards equation was used to compare the performance of each method for three conditions: flow to parallel drains from a ponded surface, transient drainage, and flow to and past an interceptor drain. Differences in predictions of hydraulic heads and drain flow rates were found among the four methods. A method using logarithmically varying adjustment factors for hydraulic conductivity and a modified grid system in the vicinity of the drain was found to be relatively easy to implement and to produce accurate estimates of drain flow rates and hydraulic heads for the drainage problems simulated.

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