Project Completion Report, OWRT Project No. A-086-ARIZ / Agreement No. 14-34-0001-8003, Project Dates: 10/01/77-9/30/78 / Acknowledgement: The work upon which this report is based was supported by funds provided by the State of Arizona and the United States Department of Interior, Office of Water Research and Technology as authorized under the Water Resources Act of 1964. / From the Introduction: "The research work under this contract has been conducted by graduate student David B. Dunbar and summarized in his M.S. thesis entitled "Analysis of a Parameter Estimation Technique for Linear Hydrologic Systems Using Monte Carlo Simulation" submitted to the Department of Hydrology and Water Resources, University of Arizona, Tucson, in 1981. The present report is a brief summary of Mr. Dunbar's thesis." David Dunbar's thesis is available at: http://arizona.openrepository.com/arizona/handle/10150/191728 / The primary accomplishment of this research has been demonstrating the power of the deconvolution technique developed by Neuman and de Marsily (1976) in dealing with noisy rainfall- runoff records of short duration. Such records are encountered in arid environments where rainfall often occurs in short isolated bursts and the data are measured with a considerable margin of error. Our research work consisted of superimposing known noise on synthetic rainfall- runoff data and examining the ability of the Neuman -de Marsily deconvolution method to estimate the correct impulse response of the system when the data include only a single storm event. Approximately 50 Monte Carlo simulation runs were performed for each of three different noise models considered in our work. The results clearly demonstrated that the deconvolution model leads to reliable estimates and can be used with confidence in the presence of realistic noise levels. In addition to the Monte Carlo simulation tests and their analysis, certain improvements were introduced into the original deconvolution technique. In particular, the original version of the technique required that the hydrologist exercise subjective judgement in choosing the "best" solution for the deconvolution problem from a large number of admissible solutions. Our new method of selecting the "best" result is based on a comparative analysis of residuals and is more reliable than the earlier subjective approach. The improved method has been applied to real as well as synthetic rainfall -runoff data.

Project Completion Report, OWRT Project No. A-051-ARIZ / Agreement No. 14-31-0001-5003 / Project Dates: July 1974 - June 1975 / Acknowledgement: The work upon which this report is based was supported by funds provided by the United States Department of the Interior, Office of Water Research and Technology, as authorized under the Water Resources Research Act of 1978. / Bio-physicochemical measurements were made on treated sewage effluent releases at established locations within the channel of an ephemeral stream, the Santa Cruz River of Southern Arizona. Water samples were taken in chronological sequence as the effluent moved downstream, to trace changes in quality parameters during low and high hydrograph stages. Results indicate that dissolved oxygen (DO) concentrations at low effluent flows were higher than DO concentrations at high effluent flows; while, conversely, biochemical oxygen demand (BOD) concentrations at low effluent flows were generally lower than BOD concentrations at high effluent flows. Biochemical oxygen demand concentrations are affected by waste loadings, flow conditions, phytoplankton growth and nitrification. Mean river deoxygenation rates (k ) in sewage flows after six river miles from the Tucson Sewage Treatment Plant were always negative or increasing, indicative of nitrification, algal growth, and concentration of organic constituents through seepage losses.

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Hydrology is a multi-disciplinary science, and therefore derives data from diverse sources, with the data often of a spatio-temporal nature. A recent trend has been to combine these data with GIS, due to the data’s geographic origin, and inherently requires an abstraction of reality in order to deal with the multitude of data that would otherwise result. Consequently, data models have been developed for this purpose, and these require a generalisation of processes and variables, while offering a simplified structure for their storage. The purpose of this study was to develop a data model for the storage and dissemination of hydrological variables and associated data used in hydrological modelling. Data would be of a spatial and temporal nature, and thus the design of the new data model needed to provide for this. A number of existing geographic data models were therefore reviewed, including the geodatabase model. This data model and the object-relational database model upon which it was built, were ascertained as being the most suitable for the study, and were therefore included in the design of the new data model. The related Arc Hydro data model was subsequently reviewed, since it offered an established means by which to model geographic features associated with surface hydrology. Following this, an investigation into time series storage methods was carried out, as it was important that the new data model be able to store large time series datasets in an efficient manner. Thus a number of methods were identified and evaluated as to their advantages and disadvantages. A new data model was thereby conceived, using the geodatabase as its foundation, and was developed in order to offer efficient storage of hydrological data. The data model developed was subsequently tested by populating it with data from the Quaternary Catchments database which supports the ACRU model. Finally, additional functionality was added to the data model, in the form of export options. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

Water is characterised by both its quantity (availability) and its quality. Salinity, which is one of the major water quality parameters limiting use of a wide range of land and water resources, refers to the total dissolved solutes in water. It is influenced by a combination of several soil-water-salt-plant related processes. In order to develop optimum management schemes for environmental control through relevant hydrological modelling techniques, it is important to identify and understand these processes affecting salinity. Therefore, the various sources and processes controlling salt release and transport from the soil surface through the root zone to groundwater and streams as well as reservoirs are extensively reviewed in this project with subsequent exploration of some hydro salinity modelling approaches. The simulation of large and complex hydrological systems, such as these at a catchment scale, requires a flexible and efficient modelling tool to assist in the assessment of the impact of land and water use alternatives on the salt balance. The currently available catchment models offer varying degrees of suitability with respect to modelling hydrological problems, dependent on the model structure and the type of the approach used. The A CR U agrohydrological modelling system, with its physically-conceptually based characteristics as well as being a multi-purpose model that is able to operate both as a lumped and distributed model, was found to be suitable for hydro salinity modelling at a catchment scale through the incorporation of an appropriate hydro salinity module. The main aim of this project was to develop, validate and verify a hydro salinity module for the ACRU model. This module is developed in the object-oriented version of ACRU, viz. ACRU2000, and it inherits the basic structure and objects of the model. The module involves the interaction of the hydrological processes represented in ACRU and salinity related processes. Hence, it is designated as ACRUSalinity. In general, the module is developed through extensive review of ACRU and hydrosalinity models, followed by conceptualisation and design of objects in the module. It is then written in Java object-oriented programming language. The development of ACRUSalinity is based mainly on the interaction between three objects, viz. Components, Data and Processes. Component objects in ACRU2000 represent the physical features in the hydrological system being modelled. Data objects are mainly used to store data or information. The Process objects describe processes that can take place in a conceptual or real world hydrological system. The Process objects in ACRUSalinity are grouped into six packages that conduct: • the initial salt load determination in subsurface components and a reservoir • determination of wet atmospheric deposition and salt input from irrigation water • subsurface salt balance, salt generation and salt movement • surface flow salt balance and salt movement • reservoir salt budgeting and salt routing and • channel-reach salt balancing and, in the case of distributed hydro salinity modelling, salt transfer between sub-catchments. The second aim of the project was the validation and verification of the module. Code validation was undertaken through mass balance computations while verification of the module was through comparison of simulated streamflow salinity against observed values as recorded at gauging weir UIH005 which drains the Upper Mkomazi Catchment in KwaZuluNatal, South Africa. Results from a graphical and statistical analysis of observed and simulated values have shown that the simulated streamflow salinity values mimic the observed values remarkably well. As part of the module development and validation, sensitivity analysis of the major input parameters of ACRUSalinity was also conducted. This is then followed by a case study that demonstrates some potential applications of the module. In general, results from the module evaluation have indicated that ACRUSalinity can be used to provide a reasonable first order approximation in various hydrosalinity studies. Most of the major sources and controlling factors of salinity are accommodated in the ACRUSalinity module which was developed in this project. However, for a more accurate and a better performance of the module in diversified catchments, further research needs to be conducted to account for the impact of salt loading from certain sources and to derive the value of some input parameters to the new module. The research needs include incorporation in the module of the impact of salt loading from fertilizer applications as well as from urban and industrial effluents. Similarly, further research needs to be undertaken to facilitate the module's conducting salt routing at sub-daily time step and to account for the impact of bypass flows in heavy soils on the surface and subsurface salt balances. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

An unresolved problem in hydrology has been to establish relationships between catchment attributes and the flow characteristics of the stream. Such information is commonly sought to improve streamflow predictions, often in a process of extrapolating research results obtained from relatively few, but intensively studied catchments, to a broader region. This study has attempted to clarify terminology related to streamflow generation processes and mechanisms, and to investigate relevant physiographic and climatic characteristics which critically influence the hydrological responses of catchments. Fourteen catchments were selected for this study. They comprised both operational and research catchments. These catchments were selected to be representative of variations in climate, topography, vegetation and geology occurring throughout the Republic of South Africa (RSA). The selection of catchments was also restricted to areas less than 100 krrr', and to the higher rainfall regions of the country, where runoff is significant and any land use changes may lead to marked changes in evapotranspiration and streamflow. A catchment was also selected from an arid zone in the USA, to capture the flow characteristics that are typical of such areas. A frequently applied simulation model on RSA catchments is the ACRU model. While physical-conceptual in structure it contains some parameters which, while not determining total streamflow magnitudes, governs the time distribution of the streamflows generated. Two such parameters from the ACRU model selected were the coefficient of baseflow response (COFRU) and the quickflow response fraction of the catchment (QFRESPj. These parameters are not explicitly physically based, and therefore improved guidelines of initial parameter values are required. Relationships between catchment characteristics and these two parameters were sought to provide guidelines for effective parameterisation of these parameters in future studies. Trends between QFRESP and COFRU, and catchment physical and climatic attributes such as catchment area, average depth of the soil profile, maximum basin relief, MAP and profile plant available water were identified, and could prove useful to future users of the ACRU model and guide experimentation in estimating initial parameter values. However, only a single significant multiple regression model was obtained for the baseflow release fraction COFRU from a catchment using MAP, catchment area and profile plant available water. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

The Umzimvubu catchment on the eastern coastal escarpment of South Africa is sensitive to anthropogenic influences,with commercial and subsistence agriculture, irrigation, domestic and rural settlements and forestry compete for water use. An adequate supply of water to the region is seen as imperative in the light of the recent establishment of forest cultivation. In order to provide a sound assessment of the impacts of afforestation on the catchment, the subsurface hydrological processes of hillslopes on the Molteno sedimentary formations of the region must be clearly understood. Since the runoff hydrograph is, to a large degree, dependent on the subsurface processes, a number of models that simulate small catchment runoff have been developed. However, recent successful application of tracer techniques to hydrological modelling has shown that the subsurface processes are still not fully understood (Schultz, 1999), and whether or not the subsurface processes are modelled adequately is most often not verified, since there is a lack of relevant data. It is, therefore imperative that the subsurface component of these small catchment runoff models be improved. This can be achieved by first observing detailed subsurface water dynamics and assessing these against the catchment runoff response. In this dissertation, results from a detailed experiment that was initiated in a 1.5 km2 catchment in the northern East Cape Province are shown. Nests of automated tensiometers, groundwater level recorders and weather stations have been placed at critical points around the catchment, and these , together with soil hydraulic and physical characteristics are used to define and identify the dominant hillslope processes. Two crump weirs record runoff from these hillslopes. The results of this subsurface study highlight the dynamics of surface and subsurface water in the hillslope transects. It is evident that the subsurface processes are strongly influenced by the -bedrock topography as well as the soil characteristics, such as macropore flow and deep percolation. Using the monitored data and 2-D vadose zone modelling, the dominant hillslope processes have been defined and are used to aid in the selection of critical parameters to be used in estimating the catchment runoff. Results show that a clear understanding of the subsurface dynamics can lead to a realistic estimation of catchment scale runoff response. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

South African water management areas could find themselves without enough water for its users due to new methods of performing water allocation as stipulated in the National Water Act of 1998. A water accounting system would address the need for accurate metering, monitoring and auditing of South Africa’s water resources to ensure that users are complying with their allocations. Such a system should be able to provide information such as comparisons between the simulated and observed flow of water at a point, comparisons between the amount of water allocated to a user and the actual water used by that user, and the source and destination of water at a point. This document contains a literature review, an explanation of the methods used to develop a prototype water accounting system and a discussion of the results from testing the system. A literature review was undertaken which covered topics in water resources planning, water resources operations, local legislation for water allocation and new technologies which could be applied to aid the management of water resources in South Africa. The results from the literature review indicated real time water accounting systems can give effect to water allocation rules. The water accounting system is comprised of two simulation models and a database. The models used for the study were the ACRU2000 model and the MIKE BASIN model. These models require data as well as a means to automate the transfer of data between the models and thus a database was developed. The database was developed in Microsoft Access and, in addition to the construction of a number of tables required to house the data, a database dashboard was made to control the functions of the database. An assessment of the ACRU2000 and MIKE BASIN models was performed in order to determine if they are suitable for use as water accounting tools. ACRU2000 was used for its process based, daily rainfall-runoff modelling capabilities. Due to the process based modelling capabilities of ACRU2000, forecasts of rainfall can be used as input to the simulations. Hot starting is the storing of internal model state variables at a particular time and the use of these variables in a different simulation to start the model up again. It was expected that, due to long simulation run times for ACRU2000, it would be beneficial to enable ACRU2000 to be hot started and an attempt to hot start ACRU2000 is presented. This would have allowed for significantly decreased simulation run times as the model can be warmed up for two years and thereafter hot started to run only for one day at a time. An assessment of the MIKE BASIN network allocation model to be used as a water accounting system was performed by attempting to meet the project objectives through building a fictional water supply network. The network is composed of a small catchment containing six runoff generating regions, a reservoir and ten water users. Three network allocation scenarios were constructed in order to fully test the rule sets and allocation capabilities currently available in the MIKE BASIN model. The study has shown that the tools and models used are capable of forming a rudimentary water accounting system. This is encouraging as it shows that there is the potential to improve the water resources management in South Africa using tools that already exist. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Anthropogenically-induced climate change has the potential to have serious implications on aquatic ecosystems and may ultimately affect the supply and quality of freshwater lakes and rivers throughout the world. As a class of ecosystems, inland waters are vulnerable to climatic change and other pressures, due to their small size and their position in the landscape. There is therefore a need to assess the impact of projected climatic change on aquatic ecosystems. Owing to this need, ecological indicators have been developed as a method of quantifying, identifying, monitoring and managing the ecological integrity of aquatic environments. The aim of this research was to develop techniques in order to conceptualise the higher order impacts of projected climate change on environmentally related streamflows and water temperature in South Africa, and to simulate these using an appropriate hydrological model. For this dissertation the downscaled daily climate output from the ECHAM5/MPI-OM General Circulation Model (GCM) was used as an input into the daily time step conceptualphysical ACRU Agrohydrological Modelling System in order to simulate the impacts of projected climate change on selected eco-hydrological indicators at the Quinary Catchment spatial scale. In this research these indicators were grouped into two broad categories: 1. Ecological Flow Indicators and 2. Water Temperature Indicators. The results of this research took the form of maps and time series graphs. The ecological flow indicator results investigate the magnitude and duration of flow events and were analysed spatially for the 5 838 hydrologically interlinked and cascading Quinary Catchments constituting the southern Africa study region. The ECHAM5/MPI-OM GCM projects the magnitude and duration of both annual subcatchment runoff and accumulated streamflows to increase in the eastern parts of southern Africa for the intermediate future climate scenario (2046 - 2065), with this trend strengthening in the distant future climate scenario (2081 - 2100). The computationally intensive water temperature indicator results were analysed spatially at the scale of the Thukela Catchment. The Thukela catchment was selected as a case study area because of its diversity - in altitude, rainfall, soils and ecological regions, as well as in its population geography and levels of education and employment. This diversity presents a challenge to studies of impacts of projected climate change, including its potential impacts on water temperatures. The spatial analyses indicate that subcatchment runoff, accumulated streamflows and mixed maximum water temperature are all likely to increase under projected future climate conditions. A temporal investigation, in the form of time series analyses, focused on four water temperature indicators and was performed for 15 selected Quinary Catchments, located within the Thukela Catchment. These temporal analyses indicate that the absolute variability (i.e. standard deviation) of both individual subcatchment runoff and accumulated catchment streamflows, are projected to increase in the future, while the relative variability (i.e. coefficient of variation) is likely to remain much the same or even decrease slightly over time period. These temporal analyses also indicate that there is a noticeable difference in the mixed maximum water temperature within a single Quaternary Catchment due to hydrological flow routing, with an increase in water temperatures as the water cascades downstream from the upper Quinaries to the Quinaries at lower altitudes. The techniques developed and used in this research could aid decision makers involved in ecological and water management planning. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

Advances in hillslope hydrology have been numerous in the past two decades. However many of these advances have been highly site specific in nature, without identifying any means of linking processes across different spatial scales. Meaningful Prediction in Ungauged Basins (PUB) requires the understanding and observation of processes across a range of scales in order to draw out typical hydrological controls. Contempory tracer based methods of quantifying a combination of hillslope processes have identified hillslope geology as the main determinant in different catchment response types. A range of hillslope scale models have been developed in the last 20 years, using different levels of detail to simulate hillslope hydrological responses. Often the data heavy requirements of hillslope scale models make them impractical to apply at larger scales. While catchment scale models lack the ability to represent hillslope scale processes. In order to overcome this, a scale applicable model with the ability to represent hillslope and catchment dynamics is required to accurately quantify hillslope and catchment hydrological processes. This study aims to characterize typical hillslope soil type responses through inferring qualitative hillslope descriptions into a numerical catchment scale model allowing for lateral subsurface routing between adjacent soil horizons. Hydrometric and tracer observation are used to describe and quantify dominant hillslope hydrological processes. Simplifications of hillslope process descriptions are used to calibrate the model to represent the subsurface hillslope connectivity. Results show that hillslope scale hydrological process characteristics can be faithfully simulated with quaternary scale climate, land use and soils data, discriminating only between different hillslope soil types. The simplification of hillslope soils into three distinct groups allows for the further derivation of dimensionless descriptors of hillslope hydrological response using the Advection Dispersion Function. Slopes with shallower stratified soils showed rapid responses to rainfall in the soil water, while those with deeper soils and less horizontal stratification showed appreciably slower responses to rainfall, with older hillslope water dominating soil water for longer periods. This identifies soils as a dominant determinant in hillslope runoff characteristics. This allows for the characterization and ultimately a simplified classification of different hillslope soils and their response types, which is applicable at a range of scales. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.