Technical and Special Reports

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http://hdl.handle.net/1969.1/6064

These technical and special reports contain the results of TWRI-funded research.

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Water Conservation for Restoration of Wildlife Habitats
(Texas Water Resources Institute, 2002) Ueckert, Darrell N.; Petersen, Joseph L.
Healthy rangelands are relatively efficient at conserving rainfall, but they may become dysfunctional in this regard as vegetative cover diminishes and aggregation of the surface soil layer is destroyed by overgrazing, drought, and establishment of excessive densities of low-value or noxious brush and weeds. Special water conservation treatments, such as contour ripping, furrowing, pitting, reseeding, or brush and weed control, may be necessary for restoration of rangelands and wildlife habitats that have deteriorated beyond a critical threshold in the downward desertification spiral. This paper describes these technologies and gives details of their utility for restoration of dysfunctional rangelands in arid and semiarid regions. Contour ripping of a degraded clay loam range site near San Angelo, Texas facilitated penetration of water from convectional thunderstorms to a depth of 48 to 54 in. compared to only 4 to 5 in.on adjacent, untreated rangeland. Over a period of 4 to 5 years, total herbage production on ripped rangeland was 1700 lb/acre compared to only 490 lb/acre on adjacent, untreated rangeland. Ripping increased the carrying capacity of the clay loam range site from 8.2 animal unit years (AUY)/section to 28.7 AUY/section.
Simulating Water Use of Irrigated Corn on the Texas High Plains
(Texas Water Resources Institute, 2002) Gerik, T. J.; Howell, T. A.; Williams, J. R.; Harman, W. L.; Steglich, E. M.
Seepage Losses for the Rio Grande Project (Franklin Canal Case Study)
(Texas Water Resources Institute, 2002) Sheng, Zuping; Wanyan, Yaqi; Aristizabal, Luis S.; Reddy, Kadambari
The El Paso Del Norte Region, composed of the cities of El Paso, Texas; Las Cruces, New Mexico in the United States; and Ciudad Juarez, Chihuahua, in Mexico, is facing a severe drought and, as a result, a significant reduction in surface water allotments is forecasted for the upcoming irrigation season. Water conservation strategies have become even more urgent. Preliminary studies have shown that there was a great potential for improvement of water delivery efficiency (water savings or reduction in water diversions for a given level of surface water diversion) through lining of canals within this region. Through canal lining, water losses in the conveyance system due to seepage losses will be minimized, thereby maximizing delivery for the available diversion amount. Since canal lining is a project that requires a significant investment of money, water losses need to be determined prior to the execution of the project. This paper presents a study of seepage losses in Elephant Butte Irrigation District (EBID) and the El Paso Count Water Improvement District No. 1 (EPCWID). This study was conducted by TA&MU and NMSU scientists and engineers in collaboration with El Paso County Water Improvement District No. 1 in Texas, and with The Elephant Butte Irrigation District, in New Mexico. Authors first selected several canal sections with large seepage losses based on the Districts' operation experience and previous studies. Three ponding tests were conducted in Franklin Canal, El Paso, Texas. The canals were blocked into several sections by earth dams, and water was fed into the blocked sections. Canal banks were allowed to saturate for over 48 hours before the measurement of water level started. The water level was measured with a pre-installed staff gage. Water level measurements were taken for 2 or 3 days. The water levels in the ponding sites dropped at a rate ranging from 0.11 ft/day to 0.35 ft/day, which includes an evaporation rate of 0.006 ft/day on average. Based on geometry of the canal and water level changes, seepage rates were estimated. The results indicated that the seepage rate for the Franklin Canal ranged from 0.85 to 3.03 gal/sq. ft/day (0.11385 to 0.40261 cubic feet per day per square feet of the wetted area). The results also indicated that seepage rates changed from one location to another, and the seepage rate tended to reduce with drop of water levels in the canal. Authors concluded that there would be a great potential for improvement of delivery efficiency by lining canals. Preliminary results from inflow-outflow tests in EBID’s main canals indicate losses of 3 to 7 cfs per mile. Work is continuing to provide replication, greater detail, and to measure additional canals.
Site Specific Management of Row and Vegetable Crops with Center Pivot Irrigation Under Traditional and Conservation Tillage
(Texas Water Resources Institute, 2002) Falkenberg, Nyland; Di Giovanni, George; Laffere, Megan; Masters, Ben; Watkins, H. O.
In March of 2002, Nyland Falkenberg was awarded a $5,000 grant from TWRI to work with researcher Giovanni Piccinni at the Texas A&M Agricultural Research and Extension Center in Uvalde. The focus of this project, which is supported by U.S. Geological Survey funds, is to develop a way to assess all the various stresses that crops go through in their growth cycle, and to implement management strategies that will alleviate the adverse effects of these stressors. This paper was written by a team of Texas Agricultural Experiment researchers, including Piccinni, Falkenberg, and many others, and it presents some of the research Nyland is doing for TWRI in this project.
Shared and unique features of predator-associated morphological divergence in three livebearing fishes
(Texas Water Resources Institute, 2002) Langerhans, R. Brian; Layman, Craig A.; Shokrollahi, A. Mona; DeWitt, Thomas J.
Divergent natural selection (fitness trade-offs) between environments often drives intraspecific diversification. When multiple species face a common environmental gradient their patterns of divergence might exhibit both shared and unique elements. We investigated shared and unique elements of diversification for three species of livebearing fishes (Poeciliidae) across a predator gradient (piscivorous fish vs. no piscivorous fish). All species (Gambuia affinis from the United States, G. hubbsi from the Bahamas and P. reticulata from Trinidad) exhibited a posterior shift in body allocation and more elongate bodies in predator populations. This morphological shift applied not only across species, but across age/gender classes, particular predator species and gross habitat types. Each species also had unique features of divergence, which may reflect peculiarities unique to their natal environments. We hypothesize much of the predator-associated morphology enhances fitness in the presence of predators but decreases fitness in the absence of predators. Preliminary evidence supports this hypothesis. We additionally found gonopodium size divergence in both Gambusia species that was opposite a trend previously found in P. reticulata. Partitioning phenotypic variation for multiple species into shared and unique responses across environmental gradients is a useful tool for elucidating general and localized mechanisms of diversification. Divergent natural selection (DNS) is a powerful mechanism that generates and maintains phenotypic diversity (Rice and Hostert 1993; Orr and Smith 1998; Schluter 2000b). DNS is created by functional trade-offs between alternative environments (Robinson and Wilson 1994; Robinson et al. 1996; Schluter 2000b). Depending on how environments vary (e.g. fine- or coarse-grained variation; sensu Levins 1968), DNS can lead to evolution of either canalized genetic differences between populations or phenotypic plasticity (West-Eberhard 1989; Robinson and Wilson 1994; Orr and Smith 1998; Schluter 2000b). DNS results in population differentiation through either of these mechanisms. That is, populations may differ from each other because of fixed genetic differences or because each is similarly plastic but their current environments differ. Environmental differences that typically produce population divergence include predation, competition, or abiotic stresses (Magurran and May 1999; Schluter 2000b). Consider the case where the sign of selection on focal traits differs across environments. Consider also that several species are evolving adaptive solutions in these environments. Some elements of evolutionary response will be similar across species. For example, species A and B may largely respond in a similar manner. Yet other aspects of response to DNS will be speciesspecific (A responds one way; B responds differently). In theory, after accounting for gross differences between species, the unique and shared elements of response to DNS can be identified. This approach allows one to integrate the study of phenotypic variation across selective environments, populations and species. Empirical studies of diversification in vertebrates has focused on resource competition and niche partitioning (Robinson and Wilson 1994; Van Valkenburgh and Wayne 1994; Smith and Skulason 1996; Schluter 2000a). However, predation is among the most important factors structuring natural populations (Sih et al. 1985; Kerfoot and Sih 1987; Jackson et al. 2001). Predators should not only change the distribution and abundance of species (via lethal and behavioral impacts on prey), but should also produce diversification—changes in the distribution and abundance of phenotypes within species (Endler 1995; DeWitt et al. 2000; Trussell 2000; Van Buskirk and Schmidt 2000). Although predation is often thought responsible for the evolution of inducible defenses among invertebrates (Harvell 1986; Havel 1987; Tollrian and Harvell 1999), studies investigating the importance of predation in vertebrate diversification are less common. Most studies of vertebrate evolutionary responses to predation center on life history changes (e.g. Skelly and Werner 1990; Rodd and Reznick 1997; Belk 1998; Johnson and Belk 2001; Reznick et al. 2001). Investigation of morphological divergence between alternative predator environments in vertebrates is less common (Brönmark and Miner 1992; Van Buskirk et al. 1997; Walker 1997; Lardner 2000; Relyea 2001). In this study, we examined body shape divergence in three species of livebearing fishes across alternative predator regimes. Furthermore we evaluate trends within and between species to identify both unique and shared aspects of diversification among prey species.
Effect of Irrigation Application Devices on Boll Set, Cotton Yield and Fiber Quality
(Texas Water Resources Institute, 2002) Ontai, Stacey L.; Bordovsky, James
Previous research concluded that water sprayed above the canopy on open flowers interrupted pollination causing flower drop and subsequent reduction in boll set and lint yield. The effect of water delivered through three different irrigation applicators (spray above canopy, spray below canopy and LEPA or drag socks) on boll set, lint yield and fiber quality of irrigated cotton was evaluated. Lint yield and the average number of bolls per plant were not affected by the type of applicator used (P<0.05, LSD). However, lint yield was 9.9% less in the spray above canopy applicator treatment than the spray below canopy and LEPA treatments. The type of applicator used did not affect fiber quality.
The Pecos River Ecosystem Project
(Texas Water Resources Institute, 2002) Hart, Charles R.
The banks of the Pecos River in Far West Texas are currently covered with dense stands of Saltcedar (Tamarix spp.), not uncommon to an increasing number of rivers in Texas. Saltcedar is known for its heavy consumption of water by evapotranspiration, and its contribution to salinity of the water and soil that it surrounds. The Pecos River Ecosystem Project is currently underway to attempt to decrease the impacts that Saltcedar has on the river ecosystem. The project is designed to increase water flow and decrease soil and water salinity by decreasing the number of Saltcedar along the banks of the river.
Questions about Groundwater Conservation Districts in Texas
(Texas Water Resources Institute, 2002) Lesikar, Bruce; Kaiser, Ronald; Silvy, Valeen
Groundwater is and will continue to be a major source of water for Texans. However, in many parts of the state, more groundwater is being used that is being replenished through natural means. If this practice continues, Texans water costs will rise, land could subside, water quality could decline and people in the area could run out of water. To address this problem, the Texas Legislature has provided a way for the groundwater resources to be managed and protected locally, through the creation of groundwater conservation districts (GCDs). A GCD is a local unit of government authorized by the Texas Legislature and ratified at the local level to manage and protect groundwater.
Irrigating Cotton with Salty Water and Subsurface Drip Irrigation
(Texas Water Resources Institute, 2002) Enciso, Juan; Multer, Warren; Colaizzi, Paul
An experiment with a Subsurface Drip Irrigation system was planned on a Texas farm with salty water to develop design and management recommendations for SDI systems. The objectives of this study were: 1) Compare 0.20 and 0.30 m depth, and 1.02 and 2.03 m drip spacings when water is salty. 2) Determine if pre-season irrigation can be used to control the soil salinity level on the soil profile when deficit irrigation is practiced on SDI systems. The experiment consisted of a complete randomized experiment with 8 treatments and four replications, with a total of 32 plots. Lint yield, seed yield and total gross return resulted statistically higher for the 1.02-m than the 2.03-m drip spacing indicating higher yields for closer spacing. Lint yield and total gross return resulted statistically higher for the 0.3-m than the 0.2-m drip depth indicating higher yields for deeper drip depth, probably because of the higher soil evaporation of the shallower drip depth. The depth and the spacing of the drip tape did not have an effect on cotton quality as it was indicated for the loan value. There was no effect of the different pre-water treatments on lint yield, seed yield, loan value, and total gross return.
Effect of Row Pattern and Spacing on Water Use Efficiency for Subsurface Drip Irrigated Cotton
(Texas Water Resources Institute, 2002) Enciso-Medina, J.; Unruh, B. L.; Henggeler, J. C.; Multer, W. L.
Cotton production is an important economic base for Far West Texas; however, the region has erratic and limited rainfall and is dependent on limited groundwater supplies. Maximizing water use efficiency (WUE) for cotton lint yield is therefore a strategic goal in conserving limited water resources. In this study different plant row patterns, row spacings and irrigation levels were evaluated to investigate water use efficiency for cotton under subsurface drip irrigation (SDI). An experiment with three row-spacings, two plant row patterns, and four water levels was conducted during three years in Far West Texas. The row spacing treatments were ultranarrow rows (UNR), 0.76 and 1.02-m rows. The row patterns for the 0.76 and 1.02 m row spacings were every row planted, one planted and one skipped, and two rows planted and one skipped. The UNR cotton was solid-planted in 0.25-m rows in 1997 and 0.38-m rows in 1998 and 1999. The drip lines were placed beneath each planted row, except in the case of the UNR rows where the rows were planted over the 0.76-m drip line spacing. The UNR and the 0.76-m row spacing resulted in higher WUE than the 1.02-m row spacing for the highest water level in 1997, and the lowest water level in 1998 for the every row pattern. When the three years of data were combined for analysis, it was observed that for the lowest water treatment (0.6-mm/d inseason irrigation), the UNR spacing produced a higher WUE (0.258 kg/m3) than the 0.76 and 1.02-m row spacings (0.198 kg/m3). The average WUE of the UNR spacing for three years of the experiment was 11.7 and 21.3% higher than the 0.76-m and 1.02-m row spacing respectively. Although, the 0.76-m and 1.02-m row spacing were not significantly different, the WUE of 0.76- m row spacing was 10.5% higher than the 1.02-m row spacing. Therefore, we conclude under our conditions row spacing can have a moderate impact on WUE for SDI systems. The narrower cotton spacing exhibited trends toward higher WUE. When the row planting patterns were analyzed by combining three years of data, it was found that row pattern did not have an influence on WUE for the 0.76-m and 1.02-m row spacings.
Creating Land Cover Input Datasets for the SWAT Model Using Landsat Imagery
(Texas Water Resources Institute, 2002) Peschel, Josh
Josh Peschel is one of the many people TWRI has funded in 2002. Here are some materials he has developed in association with his ongoing research associated with this topic.
Impacts of the Flood Impoundments on Water Balances of Downstream Riparian Corridors
(Texas Water Resources Institute, 2002) Muttiah, Ranjan S.; Duke, Jacquelyn R.; White, Joseph D.; Allen, Peter M.
Over 10,450 flood control damns have been built in 47 states. Many are nearing their design life of 50 years and have significant rehabilitation needs, the cost of which approaches over $540 million. While assessment of the engineering safety is a major consideration, little is known about the effects of these structures on downstream riparian corridors. Detailed monitoring of local water budgets conducted downstream of one structure has verified links between the flow regime of the damn and the riparian vegetation. Stream flow, soil water and transpiration rates were measured in a downstream riparian communityfor a one-year period. This monitoring showed that riparian vegetation is linked directly to both the stream and the groundwater system. The riparian zone is enhanced be low flow release from the upstream structure in which plants utilize available stream water via a groundwater pathway. This positive feedback system has direct benefits for the downstream ecosystem through increased and constant water availability.
Streamflow Characteristics of Individual Watersheds on the Edwards Plateau
(Texas Water Resources Institute, 2002) Mayer, Randy
Randy Mayer is one of the students TWRI funded through the Mills Scholarships in 2002. Here are some materials he has developed in association with his ongoing research associated with this topic.
Management of Produced Water in Oil & Gas Operations: Produced Water Treatment and Re-use in Field Demonstrations of Natural Habitat Restoration
(Texas Water Resources Institute, 2002) Burnett, Dave
An Analysis of the HSPF Model for Predicting In-stream Fecal Coliform Concentrations
(Texas Water Resources Institute, 2002) Paul, Sabu; Matlock, Marty; Haan, Patricia; Mukhtar, Saqib
Saludo Creek in Bexar County, Texas is one of 65 streams listed as impaired water bodies in the Clean Water Act’s 303(d) list for its high concentration of fecal coliform bacteria (TNRCC, 1998). The restoration of water quality of the impaired streams starts with acquiring knowledge about the system, including the amount and sources of pullutant loading and the sources that are to be controlled. Since the HSPF model is suitable for modeling in-stream fecal coliform concentrantion and thus it is widely used for bacterial TMDL studies. Although the usefulness of water quality models as an aid in stream qater quality restoration is unquestionable, in recent years US EPA started emphasizing the importance of incorporating the variability and uncertainty in modeling process (USEPA, 1997).
Desalination of Produced Water Using Reverse Osmosis
(Texas Water Resources Institute, 2002) Morales, Graciela; Barrufet, Maria
Many oil and gas wells, particularly those in mature fields, produce large amounts of brine along with the hydrocarbons. Disposing of the brine can be costly, due to its composition and large volume. For example, in the Permian Basin of West Texas and New Mexico more than 490 million gallons of water per day are produced and reinjected. The prospect of many millions of barrels of produced water from coalbed methane wells planned for the Powder River Basin has complicated development of that resource. Historically, the oil and gas industry has not promoted on-site water desalination. The reinjection or surface discharge alternatives were much less costly and there was little demand for the water. However, growing demand for fresh water in many areas and the development of lower-cost technologies for removing contaminants from water are beginning to provide compelling arguments for produced brine desalination. The Texas Water Resources Institute (TWRI) at Texas A&M University (TAMU) currently is supporting a multidisciplinary program, led by the Department of Petroleum Engineering to develop technologies to treat produced water and make it safe for use in agriculture and wildlife habitat restoration. The aim of the TAMU project is the development of small-scale, modular, transportable units capable of treating relatively small amounts of brine inexpensively. The team will utilize new technology in solids and oil removal and advances in remote process control to create units exhibiting low maintenance and high reliability in the field. These small scale units will utilize nanofiltration (NF) and reverse osmosis (RO) to remove contaminants from oilfield brines. Similar pressure-driven membrane filtration equipment installations are widely used in desalination of brackish and seawater and compete successfully with traditional thermal desalination operations. However, if RO is to assume a more prominent role in produced water treatment, there is a need for sound engineering designs adaptable to modular operations. As one portion of this effort, the TAMU team has developed a static model using parametric curves to allow scale-up of an integrated RO system. They are also developing a dynamic model that will be the basis for a control system and automatic operation. This article provides some basic background on RO systems in general, along with a brief description of the static model.
Soil & Water Assessment Tool (SWAT) Documentation
(Texas Water Resources Institute, 2002) Neitsch, S. L.; Arnold, J. G.; Kiniry, J. R.; Srinivasan, R.; Williams, J. R.
Official SWAT website: https://swat.tamu.edu/
Conditional Reliability Modeling To Support Short Term River Basin Management Decisions
(Texas Water Resources Institute, 2002) Salazar, A. Andres; Wurbs, Ralph A.
The objective of this research was to develop a conditional reliability model that would support short-term river basin management activities in which consideration of current reservoir storage levels is important. The results are the probability of meeting water demands and instream flow requirements given specific storage conditions and water management premises. The model is a part of the Water Rights Analysis Package (WRAP), which is the set of computer programs adopted by the State of Texas through the Texas Natural Resources Conservation Commission (TNRCC) for the development of water availability studies. Two new programs, WRAP-CON and TAB-CON, were developed for incorporation in the WRAP package. The research studied a methodology for the prediction of inflows based on conditional frequency duration curves developed for specific storage intervals. The reservoir storage is considered as a link between past flows and future flows, performing a similar role to the autocorrelation coefficient. Usually, streamflows have some degree of autocorrelation, meaning that the flow tomorrow will depend partially on the flow recorded today. In the proposed model, the reservoir level takes the place of the autocorrelation coefficient and the flow tomorrow depends on reservoir storage today. Since the reservoir preserves some memory of the flows in the past, the storage behavior contains inherently the autocorrelational properties of inflows. This model is designed to override the assumption of all alternative flow sequences being equally likely to occur. Portions of historical inflows are routed in separate simulations, and the exceedence probability of flows is related to the diversion amountor storage achieved in each simulation. This produces the likelihood of meeting water requirements and storage levels. The reliability in the basin is expressed with parameters such as the probability of meeting or exceeding percentages of target diversions, volume and period reliability, distribution of storage in the next months, and other statistical parameters. The model can be applied in the formulation and evaluation of drought contingency plans and operational activities. It was tested in two river basins in Texas: Guadalupe-San Antonio and Nueces. The research included the development of methodologies for the application of the model and investigation of pertinent modeling complexities.
Verification of a Methodology for Targeting Brush Control to Maximize Water Yield Through Hydrologic Modeling
(Texas Water Resources Institute, 2003) Afinowicz, Jason D.; Munster, Clyde L.; Wilcox, Bradford P. Wilcox
Brush control strategies have been implemented for many traditional grasslands that have been impaired by wooded species. However, little information is known concerning what site specific characteristics may be most beneficial for increasing water yields by returning shrub encroached areas to native grasslands. This paper discusses a number of potential targeting criteria for successful brush management and outlines a methodology for testing the role of steep slope, brush density, and shallow soils on successful use of vegetation replacement for increasing water yield.
Field Instruments for Real Time In-Situ Crude Oil Concentration Measurements
(Texas Water Resources Institute, 2003) Fuller, C.B.; Bonner, J. S.; Page, C. A.; Arrambide, G.; Sterling Jr., M. C.; Ojo, T.
The Texas Water Resources Institute awarded a Mill Scholarship to M.C. Sterling, Jr in 2002. This project describes five sensors for rapid monitoring of crude oil concentrations in an aquatic system. These measurements are critical for monitoring plume transport. They are also useful for estimating polycyclic aromatic hydrocarbons (PAH) exposure concentrations as a component of toxicity risk assessments. A submersible multi-angle laser scattering instrument (LISST-100, Sequoia Instruments), an ex-situ single wavelength fluorometer (AU-10 field fluorometer, Turner Designs), an in-situ single wavelength fluorometer (Flashlamp, WET Labs), and two in-situ multiple wavelength fluorometers (ECO-FL3 and SAFire, WET Labs) are evaluated for sensitivity and bias. For each instrument, a brief discussion of its operating principles is presented. Crude oil emulsions of various concentrations were analyzed using the above instruments. The implications of potential interferences and instrument limits are discussed relative to their importance for real time monitoring of crude oil spills.

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