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We measured the rate of dispersal of saltcedar leaf beetles (Diorhabda carinulata), a defoliating insect released on western rivers to control saltcedar shrubs (Tamarix spp.), on a 63km reach of the Virgin River, U.S. Dispersal was measured by satellite imagery, ground surveys and phenocams. Pixels from the Moderate Resolution Imaging Spectrometer (MODIS) sensors on the Terra satellite showed a sharp drop in NDVI in midsummer followed by recovery, correlated with defoliation events as revealed in networked digital camera images and ground surveys. Ground surveys and MODIS imagery showed that beetle damage progressed downstream at a rate of about 25kmyr-1 in 2010 and 2011, producing a 50% reduction in saltcedar leaf area index and evapotranspiration by 2012, as estimated by algorithms based on MODIS Enhanced Vegetation Index values and local meteorological data for Mesquite, Nevada. This reduction is the equivalent of 10.4% of mean annual river flows on this river reach. Our results confirm other observations that saltcedar beetles are dispersing much faster than originally predicted in pre-release biological assessments, presenting new challenges and opportunities for land, water and wildlife managers on western rivers. Despite relatively coarse resolution (250m) and gridding artifacts, single MODIS pixels can be useful in tracking the effects of defoliating insects in riparian corridors.

I estimated patterns of shorebird abundance and species diversity in the Colorado River Delta and Upper Gulf of California wetlands in order to determine the relative contribution of intertidal wetlands and non-tidal anthropogenic wetlands to support shorebird habitat use. Species richness varied from 15 to 26 species among sites and 29 species were detected across sites. Density during the peak migration month was higher at the anthropogenic wetland Cienega de Santa Clara (mean = 168 ind/ha, 95% C.I. 29-367), and the intertidal Golfo de Santa Clara (mean = 153 ind/ha, 95% C.I. 17-323). Anthropogenic wetlands (playa and lagoons) supported high abundance of shorebirds along with intertidal wetlands in the Colorado River Delta (mudflats). In contrast, intertidal wetlands farther south on the Sonoran Coast presented lower abundance but higher diversity of shorebird, likely as a result of the higher diversity of habitats (rocky shore, sandy beach, estuary). I modeled water management scenarios for the Cienega in order to determine the response of the dominant vegetation (southern cattail, Typha domingensis Pers.) and the area of the outflow pool below the marsh to different scenarios of water management. The model indicates that if the inflow rate is reduced below the current 4-5 m³s⁻¹ the vegetated area of the Cienega that supports habitat for marsh birds would decrease in proportion, as would the area of the outflow pool in the Santa Clara Slough identified previously as shorebird habitat. Increases in salinity will also reduce the vegetated area due to the low salt tolerance of T. domingensis. In winter about 90% of inflow water exits the Cienega into the Santa Clara Slough due to low evapotranspiration contributing to inundate areas that are used by wintering and migrating shorebirds. Lastly, I explored the feasibility of using Vegetation Indices (NDVI and EVI) to model Yuma Clapper Rail detections in the Cienega de Santa Clara as well as the effects of adding other

A series of studies were conducted on an emerging disease in farmed penaeid shrimp. This disease was first named as Early Mortality Syndrome (EMS) or more descriptively as Acute Hepatopancreatic Necrosis Syndrome (AHPNS). As part of the outcome of this research, the etiology of EMS/AHPNS was demonstrated. EMS was first classified as an idiopathic disease because no causative agent had been identified. Preliminary studies conducted in Vietnam in 2012 by the University of Arizona Aquaculture Pathology Laboratory (UAZ-APL) indicated that EMS is infectious (Tran et al., 2013). The agent was identified as a unique strain of Vibrio parahaemolyticus. Hence, EMS has a bacterial etiology confirmed by satisfying Koch's Postulates. Further studies focusing on the bacterial isolate causing EMS revealed that the agent could produce toxin(s), which is responsible for the primary pathology in affected shrimp. Since the causative agent has been identified, we propose a new name for EMS as Acute Hepatopancreatic Necrosis Disease (AHPND). Characterizations of the AHPND-causing Vibrio parahaemolyticus: Biochemical methods and molecular methods were used. Based on these results, various diagnostic methods were developed including polymerase chain reaction (PCR) test and biochemical tests. Other aspects of the AHPND causing V. parahaemolyticus were also run to determine such as antibiogram and the development of resistance mechanism of the bacteria exposed to farm conditions with antibiotic medications, pathogenicity, and infection dose of the bacteria, mode of infection, mechanisms governing the toxin production, and effects of environmental parameters on the invasion of the agent. Some proposed control measures for AHPND: Several antibiotic-free approaches were tested to determine viable control methods for AHPND. The principle proposed control method is to increase biosecurity. With the PCR method that has been developed, potential sources of the pathogen such as post-larvae and broo

The Cienega de Santa Clara is a 5600 ha, anthropogenic wetland in the delta of the Colorado River in Mexico. It is the inadvertent creation of the disposal of brackish agricultural waste water from the U.S. into the intertidal zone of the river delta in Mexico, but has become an internationally important wetland for resident and migratory water birds. The marsh is dominated by Typha domengensis with Phragmites australis as a sub-dominant species in shallower marsh areas. The most important factor controlling vegetation density was fire. The second significant (P<0.01) factor controlling NDVI was flow rate of agricultural drain water from the U.S. into the marsh. Reduced summer flows in 2001 due to canal repairs, and in 2010 during the YDP test run, produced the two lowest NDVI values of the time series from 2000 to 2011 (P<0.05). Salinity is a further determinant of vegetation dynamics as determined by greenhouse experiments, but was nearly constant over the period 2000 to 2011, so it was not a significant variable in regression analyses. Evapotranspiration (ET) and other water balance components were measured in Cienega de Santa Clara; we used a remote sensing algorithm to estimate ET from meteorological data and Enhanced Vegetation Index values from the Moderate Resolution Imaging Spectrometer (MODIS) sensors on the Terra satellite. We used Landsat NDVI imagery from 1978-2011 to determine the area and intensity of vegetation and to estimate evapotranspiration (ET) to construct a water balance. Remote sensing data was supplemented with hydrological data, site surveys and literature citations. The vegetated area increased from 1978 to 1995 and has been constant at about 4200 ha since then. The dominant vegetation type is Typha domingensis (southern cattail), and peak summer NDVI since 1995 has been stable at 0.379 (SD = 0.016), about half of NDVI(max). About 30% of the inflow water is consumed in ET, with the remainder exiting the Cienega as outflow water, mainly du

The acquisition of remote sensing data having an investigated quality level constitutes an important step to advance our understanding of the vegetation response to environmental factors. Spaceborne sensors introduce additional challenges that should be addressed to assure that derived findings are based on real phenomena, and not biased or misguided by instrument features or processing artifacts. As a consequence, updates to incorporate new advances and user requirements are regularly found on most cutting edge systems such as the MODIS system. In this dissertation, the objective was to design, characterize and assess any possible departure from current values, a MODIS VI algorithm for restoring the continuity 16-day 1-km product, based on the new 8-day 500-m MODIS SR product scheduled for MODIS C6. Additionally, the impact of increasing the time resolution from 16 to 8 days for the future basic MODIS C6 VI product was also assessed. The performance of the proposed algorithm was evaluated using high quality reference data and known biophysical relationships at several spatial and temporal scales. Firstly, it was evaluated using data from the ASRVN, FLUXNET-derived ecosystem GPP and an analysis of the seasonality parameters derived from current C5 and proxy C6 VI collections. The performance of the 8-day VI version was evaluated and contrasted with current 16-day using the reported correlation of the EVI with the GPP derived from CO2 flux measurements. Secondly, we performed an analysis at spatial level using entire images (or "tiles") to assess the BRDF effects on the VI product, as these can cause biases on the SR and VIs from scanning radiometers. Lastly, we evaluated the performance of the proposed algorithm for detecting inter-annual VI anomalies from long-term time series, as compared with current MODIS VI C5. For this, we analyzed the EVI anomalies from a densely vegetated evergreen region, for the period July-September (2000-2010). Results showed a high gene

Throughout the arid and semi-arid regions, researchers have been looking at different ways to deal with the salinity problem of the soil and water as well as feed for the livestock. Study 1 focused on a pilot project conducted in an irrigation district in Marana, AZ, USA, looking at using Reverse Osmosis (RO) concentrate on Atriplex lentiformis (quailbush) and then harvesting the plant to be tested for its possible use as a supplement in feed for livestock. Three irrigation treatments were tested based on the potential evapotranspiration rate (ET(o)): (1) plots irrigated at ET(o) adjusted daily via an on-site micrometeorology station; (2) plots irrigated at 1.5 ET(o) adjusted daily; (3) plots irrigated at a constant rate throughout the year based on the mean of annual ET(o). The plants produced 15-24 tons ha⁻¹ year⁻¹ of biomass and could be irrigated at the rate of ET(o), ca. 2 m yr⁻¹ at this location. It was concluded that irrigation of halophyte forage crops provide a viable strategy for extending water supplies and disposing of saline water in arid-zone irrigation districts. Study 2 focused on a field data from Study 1 and two greenhouse experiments. The greenhouse experiments were conducted in 2007 and 2010. The 2010 greenhouse trials, under well-watered conditions, showed that the apparent zero-point-salinity for yield was 47.3 g L⁻¹ TDS. An additional greenhouse experiment was conducted in which plants in sealed pots were grown to the wilting point on a single application of water. The experiment was conducted at different salinities to see if salinity and water stress were additive factors in reducing yield and Water Use Efficiency (WUE). To the contrary, yield and WUE actually increased as a function of salinity, perhaps due to conversion from C3 to C4 photosynthesis over the salinity range (noted in other studies with A. lentiformis). We conclude that xerohalophytes such as A. lentiformis could greatly extend the useful range of salinities under which forag

Improving the efficiency of production, profitability and nutrient utilization are the most important factors for aquaculture companies. Many research efforts have been focused to develop strategies that improve the productive performance of shrimp farms. One recognized strategy is polyculture, which can considerably improve farm production yields by optimizing use of available resources.Tilapia production in shrimp ponds (with and without shrimp) has increased rapidly in many countries including Thailand, the Philippines, Honduras, Mexico, Peru, and the inland desert of Arizona.A current practice in extensive, semi-intensive and intensive culture systems is the integration of tilapia with shrimp to increase total productivity. I tested this hypothesis in the present trials experimentally by co-cultivating tilapia and Pacific white shrimp in closed recirculating systems. The present series of experiments were carried out over a period of three years between 2007 and 2009. All of these studies were developed and conducted at the facilities of the Environmental Research Lab (ERL) of the University of Arizona in Tucson, AZ.A preliminary study included three treatments in low salinity water (5 ppt). White shrimp post larvae were stocked into cylindrical plastic pools and Red tilapias were stocked into aquaria. Equal numbers of shrimp were placed in all the treatments whereas fish (Red tilapia) density was variable. We found good growth and 100 % survival of shrimp and tilapia.The first experiment included five treatments with four replicates each with saline water of 10 ppt. Shrimp and Nile tilapia were weighed and distributed in 20 fiberglass tanks with capacity of 200 liters. There were evaluated finding statistically significant differences in growth of tilapia (P< 0.05) but no significant difference in growth of shrimp at different fish densities (P> 0.05)The second and third experiments included four treatments with four replicates each using the same shrimp densit

In arid lands, wetland loss is the result not only of the scarcity of water itself, but of the management of water to maximize off-stream uses. Declaring a wetland as a protected natural area is not enough when its water supply is not protected as well. In a fully-diverted, over-allocated, drought-prone Colorado River ecosystem, its delta has no instream flows allocated. Water use efficiency (WUE) is touted as the panacea for water shortages and lack of instream flows. I evaluated the relationships between water use in the Mexicali Irrigation District and the water supply for the Colorado River delta wetlands. The survey applied to 521 farmers complemented the GIS analysis to create a spatial distribution of agronomic and socio-economic factors influencing farmers’ options to improve WUE in irrigation. Mexicali farmers apply 10,496 m³/ha/yr; 4% higher than the legal allotment. Still, 28% of the district’s soils are salt-affected (ECe > 8dS/m), 19% are sodic (ESP > 50%), and 39% of the salt load in irrigation water accumulates in the soils. Thus, Mexicali farmers apply more water than plants need in order to maintain the sustainability of their soils. From an agronomic perspective, increasing WUE is feasible in 80% of the valley. However, high costs and lack of technical knowledge limit farmers’ options to either continue using as much water as they do now or rent/sell their water rights to larger farming operations or urban developments. Mexicali’s agriculture provides 87 Mm³ of water to the delta marshes, and seepage from unlined canals and subsurface flows generated by irrigation contribute to sustain riparian areas. Agricultural “inefficiencies” become the main source of water for wetlands when flows are fully diverted. The Irrigation District 014 is an integral part of the delta ecosystem; this is a required change in the agriculture-wetland paradigm. The restoration of arid and over-allocated rivers requires the integration of irrigation practices and WUE with

Yucca (Yucca schidigera) and Soapbark (Quillaja saponaria), both native desert plants, are major commercial sources of saponin extracts. Yucca schidigera is native to the southwestern United States and to the arid Mexican desert, and Quillaja saponaria is found in arid areas of Chile. Saponins have detergent or surfactant properties with both water-soluble and fat-soluble components.The use of natural saponins from yucca and soapbark as an additive in the diet, has improved production in aquatic organisms. The purpose of this study was to evaluate the effect of inclusion of Nutrafito plus (NTF+), which is a mixture of Yucca and Soapbark extracts, on growth, survival, and development of Nile tilapia Oreochromis niloticus and the effect on growth, survival, development, and digestive enzyme activities for juvenile Pacific white shrimp Litopenaeus vannamei.The extracts were included at different levels in the diets of tilapia and shrimp in four experiments. In experiment 1, at the end of 6 weeks there was no significant difference (p > 0.05) between growth rates of tilapia fed 6 different diets, with no mortality nor abnormal behavior in any of the treatments. Water quality parameters were determined weekly and remained within recommended limits for Nile tilapia culture.In the second trial, at the end of 40 days, there was no significant difference (p > 0.05) between growth rates of fish fed 7 different diets with various levels of Nutrafito. There were no mortalities during the experiment.In the third trial, 20 tanks (140 L each) were stocked with 10 shrimp each. Tanks were divided into 5 treatments with 4 replicates each. There was significant difference (p < 0.05) between growth rates of shrimp fed 5 different diets, with higher growth rate at higher levels of inclusion.In the fourth trial, 15 tanks (140 L each) were stocked with 10 shrimp each. Tanks were divided into 5 treatments with 3 replicates each. There was significant difference between growth rates and fee

Revegetation of riparian tree species along the lower Colorado River is currently a major activity for federal and state agencies. Revegetation methods for Fremont cottonwood (Populus fremontii), Goodding's willow (Salix gooddingii), and coyote willow (S. exigua) have historically consisted of cutting collection and vegetative propagation. If direct seeding could be implemented, large cost-savings could be realized while enhancing restoration results due to increased genetic and structural diversity. The following documents laboratory, greenhouse, and field studies conducted to establish seed storage practices, irrigation techniques, and seeding methods and rates which maximize germination and growth rates of these riparian tree species. Experimental seed storage study results indicated that seed viability was maintained for at least a two-year window by freezing, during which seed can be utilized for direct seeding or seedling production. Greenhouse study results include: (1) seed cleaning resulted in higher tree establishment; (2) adverse soil conditions reduced growth rates; (3) organic fertilizer amendment mitigated negative effects of sandy soil for Fremont cottonwood but not for willow; (4) mixed seeding resulted in cottonwood dominance, indicating that reduced rates or separate seeding of this species might be required to improve success of willow species seeding. Small-scale field study results include the following: (1) Fremont cottonwood establishment averaged 7% of pure live seed rates, whereas willow species establishment was less than 1%; (2) sprinkler irrigation did not affect establishment, and decreased tree growth rates; (3) hydroseeding resulted in higher canopy cover, establishment, and above-ground biomass compared to broadcast seeding for all three species; (4) furrow or border irrigation did not affect Fremont cottonwood or coyote willow establishment, but furrow irrigation resulted in higher Goodding's willow establishment. Volunteer species w

In this research, I describe the use of false rings to reconstruct local histories of seasonal drought in riparian ecosystems in semiarid regions. In tree-ring analysis, false rings are boundary-like features often formed as a response to drought within the growing season. Drought can be a common feature in hydrologic regimes of dryland rivers but in recent decades drought has been intensifying due to climate change and increasing water use by cities, agriculture and industry. Identifying when and where water availability has decreased along the river course is critical for understanding, and therefore managing, these generally endangered ecosystems. The higher density of trees compared to instrumental data make them ideal candidates for reconstructing site-specific drought patterns.The first part of this dissertation is an observational study conducted on the San Pedro River in southeastern Arizona during 2002. I used dendrometer data and local hydrological data to show that a period of negligible radial growth in cottonwood during the middle of the growing season coincided with a channel drying event. Tree-ring core samples confirmed that false-rings had formed in each of the instrumented trees. The second part of this dissertation is an experimental study designed to evaluate the effect of different levels of water stress on false-ring formation in cottonwood and willow. I showed that experimental decreases in water availability for periods as short as ten days were enough to induce false-ring formation in willow. Longer periods of reduced water availability were generally required to induce false-ring formation in cottonwood. In the final part of this dissertation, I reconstructed false-ring occurrence in Fremont cottonwoods at three sites along the San Pedro River. I infer from false-ring frequencies that the severity of summer drought has been increasing over the last four to six decades but that the drought severity varies along a hydrological gradient. Overa

Phytostabilization is an emerging technology for the remediation of mine tailings sites. In arid and semiarid environments, mine tailings disposal sites are a major source of environmental pollution as they are subject to eolian dispersion and water erosion. Mine tailings are acidic to neutral, high in metal content, and nutrient poor. Furthermore, these sites remain unvegetated even after decades of no additional mining activity. In arid and semiarid regions, climatic variables such as high winds, salinity, and drought exacerbate the problem. The Klondyke mine tailings site is a model site for studying plant establishment in mine tailings within semiarid regions. It was a lead and zinc ore- processing operation from 1948 to 1958 and is similar in physicochemical characteristics to other acidic pyritic mine tailings.In a greenhouse study, a native drought tolerant halophyte, Atriplex lentiformis (Torr.) S. Wats., was evaluated for its potential as a phytostabilization candidate in compost-amended tailings from the Klondyke site. Germination, plant growth, and metal uptake of A. lentiformis were examined, and the microbial community was monitored by enumeration of autotrophic iron- and sulfur-oxidizing bacteria as well as heterotrophic bacteria. Results demonstrated that with 10 to 15% compost addition, growth of A. lentiformis was not affected and shoot metal concentrations were generally not a concern for foraging animals. Furthermore, the heterotrophic bacterial community is severely stressed but recovers with compost addition and successful plant growth. Therefore, A. lentiformis is a good candidate for phytostabilization of mine tailings with compost amendments.Poor revegetation of mine tailings has been attributed to the microbial community involved in acidifying tailings; however, no thorough microbial studies have been conducted. The second study characterizes the bacterial community of the Klondyke site and compares it to an offsite control sample. Results d

As aquaculture has become a significant provider of the human diet, the interest to have better quality of sea and fresh products has been increasing. However the potential hazards associated with pathogenic agents resulting in losses to the industry are major concerns that provided the motivation for this study.The use of ultraviolet irradiation is an alternative to disinfect water in inlet and outlet water sources. However the ultraviolet disinfection method has some drawbacks including no disinfectant residuals and high cost of lamp fouling and replacement. The ultraviolet system needs to be calibrated according with the life time of the ultraviolet lamps.The MS-2 coliphage in this study is an approach to determine a good indicator for determining if an ultraviolet system can be effective in an aquaculture recirculation system. The susceptibility of this system can provide an indication if WSSV can be inactivated and possible other pathogenic agents.The WSSV experiment was successful in reducing mortality. Further studies have to be completed and analyzed before recommending for control of other pathogens.

This study aimed to address the current status of the United Arab Emirates date palms. The first chapter focused on the development of the date palm sector in the UAE. A huge increase in the date palm number was achieved in the past few decades. In the same time, there are critical issues facing this development, such as water demand, salinity, and Red Palm Weevil. The second chapter is a greenhouse experiment to test the growth of twelve date palm seeds at four NaCl levels, control, 3000, 6000, and 12000 ppm. Optimal growth found at control and 3000 ppm of NaCl. Relative growth rate (RGR), biomass, and NL decreased significantly by increasing salinity; however, no significant differences were observed in the average SGR for any cultivars. Increased NaCl leads to significant decreases in K+, Mg2+, and Ca2+ contents of plants. Na:K ratios were lower in shoots than in roots. Lulu, Fard, Khnaizi, Nabtat Safi, and Razez cultivars showed higher RGR and biomasses whereas Khnaizi, Mesally, and Safri had higher Na:K ratios than other cultivars in the control indicating higher Na+ discriminations from plant parts. The third chapter studied the vegetation change in the eastern region of the UAE. Due to shortage of fresh water resources, the vegetation of the eastern region of the UAE has experienced a series of declines resulting from salinization of groundwater. To assess these changes, field measurements combined with Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) based Soil Adjusted Vegetation Index (SAVI) were analyzed. Images from two dates, 1987 and 2000 were acquired to enable the computation of the greenness anomalies for three sites in the eastern region, Fujairah, Kalba, and Hatta. The results show an overall increase in the agricultural area, associated with a severe decrease in vegetation greenness and health conditions, particularly in the Kalba study area. The SAVI values decreased with increased soil salinity, permitting the identification of sal

The objectives of dissertation were to examine vegetation and water indices from AVIRIS and MODIS data for monitoring semiarid and upland vegetation communities related with moisture condition and their spatial and temporal dependencies in estimating evapotranspiration (ET). The performance of various water indices, including the normalized difference water index (NDWI) and land surface water index (LSWI), with the chlorophyll-based vegetation indices (VIs), the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI) was evaluated in 1) investigating sensitivity of vegetation and land surface moisture condition 2) finding optimal indices in detecting seasonal variations in vegetation water status at the landscape level, and 3) their spatial and temporal scale dependency on estimating ET. The analyses were accomplished through field radiometric measurement, airborne-based and satellite data processing accompanied with water flux data.The results of these studies showed vegetation and landscape moisture condition could be identified in VI - WI scatter-plot. LSWI (2100) showed the biggest sensitivity to variation of vegetation and background soil moisture condition as well. Multi-temporal MODIS data analysis was able to show water use characteristic of riparian vegetation and upland vegetation. Results showed water use characteristics of riparian vegetation are relatively insensitive to summer monsoon pulse, while upland vegetation is highly tied to summer monsoon rain. The relationship between water flux measurement from eddy covariance tower and satellite data has shown that MODIS derived EVI and LSWI (2100) have similar merit to estimate ET rate, but better correlation was observed from the relationship between MODIS EVI and ET.Pixel aggregation results using fine resolution AVIRIS data showed moderate resolution spatial scale 250m or 500m, best predicted ET rates over all study areas. Surface fluxes temporally aggregated to weekly or biwee

The Lower Colorado River Giant Salvinia Task Force has tried a series of physical and chemical activities in an effort to control and eradicate giant salvinia (Salvinia molesta) since 1999. Because these efforts have not produced satisfactory results, biological control using the weevil Cyrtobagous salviniae (Coleoptera: Curculionidae) was applied on the Lower Colorado River by the Animal and Plant Health Inspection Service, United States Department of Agriculture offices in California and Arizona. They released the weevil at four sites in the summer of 2003, four sites in 2004, and eight sites in 2005.We monitored physico-chemical and biological parameters at release and 10 m and 1 km down stream from release sites. Weevils established their colony in the field, but control has not been determined. Integrated pest management (physical, chemical, and biological methods) will be essential for successful management of salvinia in the Lower Colorado River.The low temperature resistance and survival rates of the weevils were tested under three different diurnal temperature regimes (5 to 15 oC , 10 to 20 oC , and 15 to 25 oC ) and two different salvinia densities. At the low temperature range, the survival rate of the weevil was sharply decreased. The relationship between low temperature resistance of weevils and giant salvinia population was tested at the 5 to 15 oC range. The experiment was conducted at three different giant salvinia populations (0, 1, and 3 salvinia per container). The salvinia density had no significant effect on the survival of the weevil.To examine a more efficient method of biological control, we conducted a nitrogen fertilizer experiment on the river. Our goal was to demonstrate that plants fertilized with nitrogen would support a faster growing population of C. salviniae. In the Lower Colorado River, the weevil successfully survived winter and dispersed down the river.

Egypt witnesses an increasing population growth concomitant with limited water and agricultural land resources. The objectives of this study were to utilize remotely sensed data for the inventory of agricultural lands in the Nile Delta, monitoring spatial and temporal variations in agricultural lands and quantifying agricultural land losses due to urbanization. Inventory of agricultural lands was designed using two approaches: thresholding and linear mixture analysis. We utilized 12 images from the Landsat satellite: 4 from Multi-Spectral Scanner (1972), 4 from Thematic Mapper (1984) and 4 from Thematic Mapper (2003) covering the entire Nile Delta. In addition, a set of 480 NDVI images were obtained from the Advanced Very High Resolution Radiometer (AVHRR) sensor that cover the period 1984-2003. Landsat images were subjected to atmospheric, radiometric and geometric corrections as well as image mosaicking. Normalized Difference Vegetation Index (NDVI) was applied and thresholding for agricultural land cover revealed that the areal extent of agricultural lands was 3.68, 4.32 and 4.95 million acres (one acre = 0.96 Egyptian Feddan) in 1972, 1984 and 2003, respectively. Linear mixture analysis of the AVHRR-NDVI with the TM-NDVI images showed that agricultural lands approached 4.11 and 5.24 million acres in 1984 and 2003, respectively. Using multitemporal Principal Component Analysis (PCA) for the TM and AVHRR images proved that reclamation activities were mostly along the western margins of the Nile Delta. Spatio-temporal analysis showed that middle delta has the highest agricultural vigor compared with the margins. Agricultural land loss was estimated in some cities within the delta as well as in Greater Cairo area. We studied the land cover classification and change in Greater Cairo area based on 5 Landsat images acquired in 1972, 1984, 1990, 1998 and 2003. Agricultural lands lost 28.43% (32,236 acres) between 1972 and 2003 with an annual loss of 1040 acres. Agricult

Two aspects of salinity in arid land were investigated as part of the present dissertation: the first was the potential re-use of industrially generated brine for irrigating landscape plants, and the second was the ecological restoration of saline farmland. The following is a summary of the most important points. With water conservation efforts accelerating in arid environments, industrial wastewater is considered a candidate for re-use. We investigated the use of high EC (electrical conductivity) cooling-tower water to irrigate nine common landscape plants in an urban environment. Each plant (replicated in a block design) was irrigated according to water demand determined by the soil moisture deficit, with one of three water treatments: blowdown water (3.65 dS m⁻¹), well water (0.52 dS m⁻¹) and a 1:1 blend (2.09 dS m⁻¹). Results indicate the salinity of the irrigation water did not have a significant effect (P>0.05) on growth or water use but, soil salinities were higher in basins irrigated with blowdown water compared to those irrigated with well water. The overall feasibility of reusing industrial brines to irrigate urban landscapes is discussed in light of the results. Restoring abandoned arid farmland can be challenging because topographic, geomorphic and hydrologic features have been degraded and cannot support a diverse native plant community. Typical amelioration practices depend upon good quality water to restore the soil’s physiochemical properties, however the long-term availability of any water is rare. A mitigation banking project to return 432 hectares of farmland to an open-space designation involved the collaboration of scientists, landscape architects and engineers to achieve five main goals: water management, erosion control, decreasing soil salinity, and increasing species diversity and vegetation cover. Two strategies evolved in the planning process that work in tandem to achieve these goals: a water management system that redirects storm water a