<p>Rainwater harvesting techniques are ancient practices that have been used for many years by different countries and civilizations. Runoff water harvesting is a promising technique to collect water and store it effectively in surrounding plant or crop areas. With global warming and climate change, water availability and accessibility are becoming even more critical, particularly in arid and semi-arid areas of the world. Annual rainfall is either scarce or insufficient to support farming practices in many areas. Thus, it is necessary to capture, store, and utilize water when it is sufficient for the growing season of different crops. In this sense, it is also important to evaluate differences in watersheds in terms of determining where the water flows (runoff areas) and where it can be collected for in situ use (run on areas). Based on land use, surface types, land cover, and soil group parameters, the amount of water changes within a watershed so it is crucial to determine and combine those factors. The aim of this study is to develop methodologies for determining the runoff harvesting potential of watersheds in arid and semi-arid areas. Specifically, to: 1) Identify potential areas for in-situ runoff harvesting (IRH)within watersheds; and 2) Estimate surface runoff volumes in areas as identified. The pilot study area for this study is Winters Wash Watershed, which is a sub-watershed of Centennial Wash located in Arizona (HUC number: 15070104). This watershed serves as a proxy for arid and semi-arid areas and was selected because it has sufficient data for the planned analysis. Based on the analysis, <a>17,615 ha (25% of the watershed area) were classified as being suitable or highly suitable as runoff sources, while 14,092 ha (20% of the watershed area) were better suited as run on collection areas. Total collectible runoff was determined on an average annual basis.</a> Finally, recommendations on suitable water harvesting techniques were made based on land use, soil, surface structure, and slope in the watershed. The results will provide a methodology for the decision-making process for identifying both run on and runoff areas and examples of real practices that could be used in places that are arid and semi-arid. </p>

No description available.

Natural coastal habitats throughout Chesapeake Bay are increasingly threatened with shoreline modification due to population growth and rising rates of development. The replacement of these natural coastlines with hardened structures such as seawalls (bulkheads) and stone revetments (riprap) not only compromises vegetation at the land-water interface, but also can influence several elements of local aquatic food webs. Effects of these alterations have been well-studied with respect to fish assemblages and intertidal communities, particularly in conjunction with larger-scale watershed development, and recently, interest has shifted toward investigation of the effects of shoreline development on subtidal benthic infaunal communities.This study evaluated the direct, local impacts of bulkhead and riprap compared to natural marsh shorelines, as well as the effects of sediment characteristics, predator abundance, and system-specific physical features on benthic infauna in the Patuxent River, Chesapeake Bay. Forty-five sites were divided among three shoreline types and distributed across three main river zones. At each site, a benthic infaunal suction sample (3-mm mesh), push-core sample (500-μm mesh), sediment samples, water-quality measurements, and trawls for predators were taken. Samples were sorted to determine density, diversity, and biomass of infaunal organisms. Data were assessed using an Information-Theoretic approach (AIC analysis) to determine the most influential variables, of those measured, on the infaunal community for two benthic data sets: 3-mm-suctions and 500-μm-cores. Results from these analyses on 3-mm samples suggested that shoreline type was the best predictor of diversity, while wave energy, sediment chlorophyll concentration, sediment type, and predator abundance best predicted density and biomass. Benthic responses within the 500-μm dataset were not strongly affected by shoreline type. Rather, responses were best predicted by sediment chlorophyll, wave energy, sediment type, predator abundance, and sediment organic carbon (TOC) content.Results indicate that, compared to other Bay tributaries, the Patuxent River is a relatively degraded system. The small range in long-term responses of Patuxent infauna from previous work provides a possible explanation as to why I was unable to see significant differences in infaunal response among shoreline types in the current study (i.e., there was little scope for change by shoreline in the system as a whole). However, I suggest that natural marsh habitats are healthier subsystems of the Patuxent River, due to the greater variety of infaunal feeding guilds and higher infaunal biomass observed at these compared to hardened sites. Higher predator abundance was associated with higher infaunal biomass at natural marsh sites in both size fractions, suggesting the bottom-up control of higher-trophic-level species in this system, as predators seek out suitable prey items. Given these observations, and the fact that influential variables such as wave energy, sediment nutrient and chlorophyll content, predator abundance, and sediment type may vary according to shoreline type, the replacement of natural shoreline with hardened structures will lead to complex changes in subtidal benthic communities in Chesapeake Bay tributaries and should be minimized to maintain qualities of the natural system.

<p>  </p> <p>Irrigation water is crucial for agricultural production and farmers’ livelihoods in many regions of the world. Water scarcity, however, due in part to extended droughts and groundwater depletion, is putting ever-increasing pressure on regulatory agencies to implement water conservation policies, possibly hampering farmers’ livelihoods and food supply. It is therefore imperative to implement policies that allocate scarce water resources in the most efficient way, while allowing water buyers and sellers to benefit from trading. In this dissertation, I study the design of water policies that are in use for agricultural water management in many dry regions: markets, quotas, and water pricing. A key distinction among them is that water markets constitute a decentralized allocation mechanism, while the other policies are centralized. </p> <p>In my first two essays, I compare two prominent market designs, namely once-a-year trading (i.e., non-recursive design) and year-round trading (i.e., recursive design). I examine the effect of these competing market designs on efficiency and distributional outcomes. I do so by accounting for two unique characteristics of irrigation water markets: 1) farmers differ in the marginal valuation of water, and 2) water is thinly traded. In my first essay, I theoretically develop a 3-seller and 3-buyer trading model and show that a recursive design can hinder efficiency when traders differ substantially in their water valuations. This is because sellers greatly increase markups, which strengthens trading frictions. </p> <p>Theoretical predictions from essay 1 rest on rather strong behavioral assumptions – sellers and buyers are able to identify and play a rather complicated subgame perfect Nash equilibrium. But human subjects may deviate from these due to many reasons, including bounded rationality and off-equilibrium beliefs, among others. In my second essay, I conduct a laboratory experiment with human subjects to examine the extent to which they follow theoretical predictions, and the effects of their behavior on the relative performance of competing market designs. Experimental evidence shows that subjects do deviate from predicted equilibrium, particularly when agents are highly heterogeneous. As a result, I find that some of my theoretical predictions are reversed in the laboratory. In particular, the recursive design outperforms the non-recursive design because experimental agents behave much more competitively under the recursive design than predicted by my subgame perfect Nash equilibrium.</p> <p>In my third essay, I empirically compare the performance of quantity and price policies, as well as a hybrid to conserve water, using observational data from Mexican farmers. A fixed cap (the policy chosen by Mexican regulators) effectively limits water consumption, but the rigidity of the cap results in substantial welfare losses due to volatile weather patterns that induce drastic fluctuations in water demand. Consequently, I study two counterfactual policies, a price policy and a hybrid that combines quantity and price policies. I find that the hybrid policy performs very well relative to its pure counterparts because it provides an intermediate level of flexibility in water consumption, preventing large losses under anomalous weather. </p>

No / This paper presents results of the relationship between the degree of saturation and the matric suction head at static equilibrium and during dynamic flow of water using a Buchner funnel and a fully instrumented two-dimensional tank, respectively. The major influences of the dynamic flow on the relationships between the suction head and the degree of saturation are highlighted and discussed. The experimental results show that dynamic flow of water strongly affects the volume of entrapped air. The results also reveal that any scanning curve can be described as two parts, namely, transition and coinciding. The transition curve starts from the recent reversal degree of saturation and continues up to the previous reversal degree of saturation. The shape of the transition curve and the amount of hysteresis are not only a function of the reversal degree of saturation but are also a function of the saturation path history. The experimental results are used to examine the validity of the proposed analytical model by Parker and Lenhard in 1987 for describing the relationships between the degree of saturation and the matric suction head. It was found that Parker and Lenhard¿s model provides a good prediction of the relations provided that care should be taken for the value of the reversal degree of saturation at zero suction head.

The environmental impacts of agricultural non-point source pollution, due in part to the intensification of agriculture to meet the nutritional needs of a growing population, indicate a need for the further implementation of Best Management Practices (BMPs) that can mitigate soil erosion and reduce the export of sediment and nutrients to receiving waters. Water and Sediment Control Basins (WASCoBs) and cover crops are both considered effective in-field BMPs that have been utilized by landowners to reduce soil and nutrient losses from fields. While each of these BMPs has been individually researched for their impacts on soil and water quality, there is little existing research that examines the impact of WASCoBs paired with cover crops on water quality. This study compared four sub-watersheds on the same field near Atterberry, Illinois: 1) a basin drained by a WASCoB, 2) a basin drained by a WASCoB and planted with a cover crop, 3) a basin drained by an ephemeral gully and planted with a cover crop, and 4) a control basin drained by an ephemeral gully. Runoff samples were collected from these watersheds and analyzed for total phosphorus, dissolved reactive phosphorus (DRP), ammonium-nitrogen, nitrate-nitrogen, and total suspended solids (TSS). Nutrient and sediment concentrations were used along with the discharge and duration of runoff events in order to determine event loads for each watershed. The WASCoBs utilized in this study were able to trap 97.3-99.2% of total phosphorus, 84.3-94.4% of DRP, 51.4-78.6% of ammonium-nitrogen, 11.8-56.3% of nitrate-nitrogen, and 98.68-99.21% of TSS. The cover crop treatments in this study did not show a significant impact on water quality, which was likely attributed to poor establishment of the cover crop. These results suggest that early planting is critical for maximizing cover crops establishment and benefit. Reductions in nutrient and sediment loads in this study suggest that WASCoBs have the potential to reduce the discharge of nutrients and sediment to waterways, indicating that their continued implementation may help to accomplish water and soil conservation goals.

No description available.

The mass loadings of pollutants common in surface waters result from the discharges of many different sources. In the last few years it has been noted that nonpoint sources contribute more pollutants than point sources. This is because in many cases the point source discharges have been, by law, reduced drastically. In the State of Florida many water quality parameters were examined to estimate the mass loadings in streams related to, drainage area, average flow, land use, soil type and management practices. A total of sixteen streams were examined. The information was first calculated for mass loadings as a function of stream flow. Next the slopes and intercepts were related to drainage area. Both steps were accomplished using bi-variate regression analysis. The final results show a relationship of Total Organic Carbon, Orthophosphate, Total Phosphate and Nitrate to drainage area and stream flow. However, the final results of this study when related to another study in Florida showed different mass loading rates for TOC and TP. The differences were attributed to background levels of pollutants, local geology, hydrologic variability and management practices.

This research investigates organic polymers, inorganic coagulants and separate unit operations for their effect on the total tri-halogenated (TTHM) residuals in a finished water. The water samples utilized for this project were taken from a highly colored Central Florida potable water supply which is used by municipality which has a TTHM concentration in the finished water in excess of the proposed Federal limit. Results indicate that (1) organic polymers are not a significant source of THM precursors, (2) organic polymers, when used as a settling aid after coagulation in Jar tests, are an effective means of filtration for removing THM precursors, (3) THM residuals produced after coagulation increased directly with chlorination pH, (4) there was no significant difference in the THM precursor removal after coagulation for any coagulant tested and (5) coagulation removed a significant amount of THM precursor from the raw water.

yes / Managing global water resources and providing water services to the world¿s people raises a continuing series of challenges, driven by increasing expectations, and a growing competition for water, which will be exacerbated by climate change. This paper explores how concepts of water governance and sustainability may help us to meet those challenges. Water governance is often equated with the role of government or management in the provision of water services. By contrast, we see governance as the system of actors, resources, mechanisms and processes, which mediate society¿s access to water. A broad conceptual framework is presented for the analysis of water governance, based on linkages between the resources available to society, the mechanisms that shape access to water and the outcomes of those mechanisms, both for people and the ecosystem. These linkages are mediated both by stakeholders and by management processes. It is argued that this conceptual framework offers a robust analytical tool for planning for sustainability as it is able to account for the complexities of water governance (of contexts, stakeholders, arrangements and uses). The paper concludes with observations about the ways in which the framework can be used to understand how different water governance arrangements produce variable outcomes in terms of sustainability.