A detailed study of the water balance of a lichen-heath tundra underlain by permafrost was begun in September 1976 near Schefferville, Quebec. The study was centred on a 0.9 ha hillside and an adjacent 100 ha catchment. The study revealed that the transfer of latent heat by moisture transport occurs during the development of the active layer as well as during freeze-up. The transfer of sensible and latent heat does not have a major impact on the maximum depth of the active layer on hillslopes, but does strongly control the maximum depth of thaw in the valley bottoms. The study also demonstrated that a simple form of the Priestley-Taylor model yields accurate estimates of evapotranspiration from several types of surfaces. A water budget model based on the Priestley-Taylor model gave an accurate estimate of the seasonal runoff from the experimental catchment. A daily water budget model indicated that a significant proportion (31%) of the net runoff (precipitation minus evapotranspiration) is stored within the still-frozen part of the active layer (primarily in the valley bottoms) early in the thaw season. That stored water is released only when the active layer approaches its maximum depth of thaw.

This thesis is a contribution to the work of the Texas Environmental Observatory (TEO), which provides environmental information from the Greenbelt Corridor (GBC) of the Elm Fork of the Trinity River. The motivation of this research is to analyze the short-term water dynamic of soil in response to the substantial rainfall events that occurred in North Texas in 2007. Data collected during that year by a TEO soil and weather station located at the GBC includes precipitation, and soil moisture levels at various depths. In addition to these field measurements there is soil texture data obtained from lab experiments. By comparing existing water dynamic models, water balance equations were selected for the study as they reflect the water movement of the soil without complicated interrelation between parameters. Estimations of water flow between soil layers, infiltration rate, runoff, evapotranspiration, water potential, hydraulic conductivity, and field capacity are all obtained by direct and indirect methods. The response of the soil at field scale to rainfall event is interpreted in form of flow and change of soil moisture at each layer. Additionally, the analysis demonstrates that the accuracy of soil characteristic measurement is the main factor that effect physical description. Suggestions for model improvement are proposed. With the implementation of similar measurements over a watershed area, this study would help the understanding of basin-scale rainfall-runoff modeling.

No description available.

Issues arising from climate change and long-term natural climate variability have become the focus of much recent research. In this study, we specifically explore the impacts of long-term climate variability and climate changes upon flood frequencies. The analyses of the flood frequencies are carried out in a comparative manner in catchments located in semiarid-temperate and tropical landscapes in Australia, namely Perth, Newcastle and Darwin, using a process-based derived flood frequency approach. The derived flood frequency analyses are carried out using deterministic rainfall-runoff models that capture the intrinsic water balance variability in the study catchments, and driven by temporal rainfall event sequences that are generated by a stochastic rainfall model that incorporates temporal variabilities over a multiplicity of time scales, ranging from within-event, between-event to seasonal, multi-annual and multi-decadal time scales. Six climate scenarios are considered for Newcastle, that combine the ENSO (El Niño Southern Oscillation) and IPO (Inter-decadal Pacific Oscillation) modes of variability, and six different climate scenarios are considered for Perth and Darwin that combine these different ENSO modes and step changes in climate (upwards or downwards) that occurred in 1970 in both regions, which were identified through statistical analysis. The results of the analyses showed that La Niña years cause higher annual maximum floods compared to El Niño and Neutral years in all three catchments. The impact of ENSO on annual maximum floods in the Newcastle catchment is enhanced when the IPO is negative and for Perth, the impact of ENSO weakens in the post-1970 period, while it strengthens in Darwin in the same period. In addition, the results of sensitivity and scenario analyses with the derived flood frequency model explored the change of dominant runoff generation processes contributing to floods in each of the study catchments. These analyses highlighted a switch from subsurface stormflow to saturation excess runoff with a change of return period, which was much more pronounced in Perth and Darwin, and not so in Newcastle. In Perth and Darwin this switch was caused by the interactions between the out-of-phase seasonal variabilities of rainfall and potential evaporation, whereas the seasonality was much weaker in Newcastle. On the other hand, the combination of higher rainfall intensities and shallower soil depths led to saturation excess runoff being the dominant mechanism in Newcastle across the full range of return periods. Consequently, within-storm rainfall intensity patterns were important in Newcastle in all major flood producing events (all return periods), where they were only important in Perth and Darwin for floods of high return periods, which occur during wet months in wet years, when saturation excess runoff was the dominant mechanism. Additionally, due to the possibility of a change of process from subsurface stormflow to saturation excess when conditions suited this switch, the estimates of flood frequency are highly uncertain especially at high return periods (in Darwin and Perth) and much less in Newcastle (when no process change was involved).

In common with other natural systems, aquatic ecosystems provide a wealth of economically valuable services and long-term benefits to society. However, growing human populations, coupled with increased aspirations for improved quality of life, have lead to intense pressure on the world's finite freshwater resources. Frequently, particularly in developing countries, there are both perceived and genuine incompatibilities between ecological and societal needs for freshwater. Environmental Flow Assessment (EFA) is essentially a tool for water resources management and its ultimate goal should be the integration of ecological and societal systems. While other ecological components (i.e. biological and geomorphological) are equally important to EFA, this thesis investigates the role of the hydrological cycle and the hydrological regime in providing the ecosystem goods and services upon which society depends. Ecological and societal systems operate at different temporal, spatial and organisational scales and hydronomic zoning or sub-zoning is proposed as an appropriate water resources management technique for matching these different scales. A major component of this thesis is a review of the South African water resources management framework and, in particular, the role of the Reserve (comprising a basic human right to survival water as well as an ecological right of the aquatic resource to maintain ecological functioning) in facilitating ecologically sustainable water resources management. South African water resources management is in the early stages of water allocation reform and the Department of Water Affairs and Forestry has stated that "the water allocation process must allow for the sustainable use of water resources and must promote the efficient and non-wasteful use of water". Thus, new ways of approaching the compromise between ecological and societal needs for freshwater water are required. This thesis argues that this requires that the focus of freshwater ecosystems be extended beyond the aquatic resource, so that societal activities on the catchment are linked to the protection of instream flows. Streamflow variability plays a major role in structuring the habitat templates that sustain aquatic and riparian ecological functioning and has been associated with increased biodiversity. Biodiversity and societal well-being are interlinked. However, there is a need in EFA for knowledge of the most influential components of the streamflow regime in order that stakeholders may anticipate any change in ecosystem goods and services as a result of their disruption to the hydrological cycle. The identification of high information hydrological indicators for characterising highly variable streamflow regimes is useful to water resources management, particularly where thresholds of streamflow regime characteristics have ecological relevance. Several researchers have revisited the choice of hydrological indices in order to ascertain whether some indices explain more of the hydrological variability in different aspects of streamflow regimes than others. However, most of the research relating to hydrological indices has focused primarily on regions with temperate climates. In this thesis multivariate analysis is applied to a relatively large dataset of readily computed ecologically relevant hydrological indices (including the Indicators of Hydrological Alteration and the South African Desktop Reserve Model indices) extracted from long-term records of daily flows at 83 sites across South Africa. Principal Component Analysis is applied in order to highlight general patterns of intercorrelation, or redundancy, among the indices and to identify a minimum subset of hydrological indices which explain the majority of the variation among the indices of different components of the streamflow regimes found in South Africa. The results indicate the value of including several of the IHA indices in EFAs for South African rivers. Statistical analysis is meaningful only when calculated for a sufficiently long hydrological record, and in this thesis the length of record necessary to obtain consistent hydrological indices, with minimal influence of climatic variation, is investigated. The results provide a guide to the length of record required for analysis of the high information hydrological indices representing the main components of the streamflow regime, for different streamflow types. An ecosystem-based approach which recognises the hydrological connectivity of the catchment landscape in linking aquatic and terrestrial systems is proposed as a framework for ecologically sustainable water resources management. While this framework is intended to be generic, its potential for application in the South African Water Allocation Reform is illustrated with a case study for the Mkomazi Catchment in KwaZulu-Natal. Hydronomic sub-zoning, based on the way in which societal activities disrupt the natural hydrological processes, both off-stream and instream, is applied to assess the incompatibilities between societal and ecological freshwater needs. Reference hydrological, or pre-development, conditions in the Mkomazi Catchment are simulated using the ACRU agrohydrological model. Management targets, based on the statistical analysis of pre-development streamflow regimes, are defined to assess the degree of hydrological alteration in the high information hydrological indices of the Mkomazi Catchment as a result of different societal activities. Hydrological alteration from predevelopment conditions is assessed using the Range of Variability Approach. The results indicate that the proposed framework is useful to the formulation of stakeholder-based catchment management plans. Applying hydrological records (either observed or simulated) as an ecological resource is highly appropriate for assessing the variability that ecosystems need to maintain the biodiversity, ecological functioning and resilience that people and society desire. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

This thesis compares the in situ water balance of common annual production systems (wheat, lupin, subclover and serradella) with a grazed perennial system (lucerne) at a site in the Avon Catchment, Western Australia. Using a physically-based water balance approach the value of a plant based solution in redressing the hydrological imbalance that has become a feature of much of the dryland agricultural region of Western Australia is investigated. The effectiveness of lucerne in providing greater available storage for buffering large rainfall events, as compared to the annual systems, is illustrated. Continued transpiration following out-of-season rainfall events maintains a larger available storage capacity. In contrast, the annual systems that are fallow over summer only withdrew a small fraction of water by soil evaporation between rainfall events. Under annual systems, the profile moisture store was sequentially increased to the extent that additional increments of rainfall could potentially contribute to deep drainage. A particular focus of this study has been to investigate the presence of soil constraints to root growth, and to assess how these constraints affect the water balance. A site survey indicated the soil penetration resistance was sufficient to impose a physical constraint to root growth. Published literature on the site shows soil acidity is also at a level imposing chemical constraints to root growth. A root growth model “Rootmodel”, for predicting root growth with and without soil constraints is examined in detail as a method for providing root growth parameters for inclusion into the numerical water balance model, SWIM based on Richard’s equation. Functions developed from “Rootmodel” adequately describe the effect of profile limitations to root growth, such as soil strength, moisture availability and temperature. Recommendations are made for inclusion of a growth suppressing function in “rootmodel” based on the chemical limitation of low pH. The effects of soil acidity on the root growth of several species is investigated experimentally and the resultant root data provided a reference point by which the simplified prediction of root growth built into SWIM could be adjusted using a linear reduction function. A similar linear reduction function is also employed to impose a physical constraint in the form of high penetration resistance.

In most of the urban cities of developing countries piped water supply is intermittent and they receive water on alternate days for about few hours. The Unaccounted For Water (UFW) in these cities is very high due to aged infrastructure, poor management and operation of the system. In the cities of developing countries, supplied water is not able to meet the demand and there is huge gap between supply and demand of water. To meet the water demand people are depending on other sources of water like groundwater, rain water harvesting, waste water treatment, desalination etc. Huge quantity of groundwater is extracted without any account for the quantity of water used. The main challenge for water authorities is to meet the consumer demands at varying loading conditions. However, the present execution of decisions in the operational management of WDS is through manual control. The manual control of valve throttling and control of pump speed, reduces the efficiency and operation of WDS. In such cases, system modeling coupled with automated control can play a significant role in the appropriate execution and operation of the system. In the past few decades, there has been a major development in the field of modeling and analysing water distribution systems. Most of the people in Indian mega cities are facing water problems as they are not able to receive safe reliable drinking water. In rapidly growing cities, the water resources management has been a major concern for the Government. There is always a need to optimize the available water resources when the rate of demand constantly beats the rate of replenishments. Mathematical modeling of WDS has become an indispensible tool since the ages to model any type of WDS. Development of mathematical models of WDS is necessary to analyse the system behavior for a wide range of operating conditions. Using models, problems can be anticipated in proposed or existing systems, and solutions can be evaluated before time, money, and materials are invested in a real-world project. In the present study, we have developed a model of WDS of a typical city like Bangalore, India and analysed them for several scenarios and operating conditions. Bangalore WDS is modeled using EPANET. Before a network model is used for analysis purpose, it must be ensured that the model is predicting the behavior of the system with reasonable accuracy. The process of matching the parameters of the developed model and the field observed data is known as calibration. All WDS require calibration for effective modeling and simulation of the system. Demand and roughness are the most uncertain parameters and they are adjusted repeatedly to get the required head at nodes and flow in the pipes. The calibration parameters usually include pipe roughness, valve settings, pipe diameter and demand. Pipe roughness, valve settings and pipe diameter are associated with the flow conditions and the demands relate to the boundary conditions. For Bangalore WDS, the values of roughness coefficient and demand are available; and the values of valve settings are not available. Hence, this value is estimated during calibration process. Dynamic Inversion (DI) nonlinear controller with Proportional Integral Derivative (PID) features (DI-PID) is used for calibrating WDS for valve settings on the basis of observed flow and roughness coefficient. From the obtained results it is observed that, controllers are capable of achieving the target flow to all the GLRs with acceptable difference between the flow meter readings and the simulated flow. After calibrating any real WDS to the field observed data, it will be useful for water authorities if the consumer demands are met up to certain extent. This can be achieved by using the concept of equitable distribution of water to different consumers. In the urban cities of developing countries, often large quantities of water are supplied to only a few consumers, leading to inequitable water supply. It is a well known fact that quantity of water supplied from the source is not distributed equitably among the consumers. Aged pipelines pump failures, improper management of water resources are some of the main reasons for it. Equitable water to different consumers can be provided by operating the system in an efficient manner. Most of the urban cities receive water from the source to intermediate reservoirs and from these reservoirs water is supplied to consumers. Therefore, to achieve equitable water supply, these two supply levels have to be controlled using different concepts/ techniques. The water requirement of each of the reservoirs has to be calculated, which may depend on the number of consumers and consumer category. Each reservoir should receive its share of water to satisfy its consumer demand and also there must be provision to accommodate shortages, if any. The calibrated model of Bangalore WDS is used to achieve equitable water supply quantity to different zones of Bangalore city. The city has large undulating terrain among different zones which leads to unequal distribution of water. Dynamic Inversion (DI) nonlinear controller with Proportional Integral Derivative (PID) features (DI-PID) is used for valve throttling to achieve the target flows to different zones/reservoirs of the city at different levels. Equitable water distribution to different reservoirs, when a part of the source fails to supply water is also discussed in this thesis. From the obtained results it is observed that, controllers were responding in all the cases in different levels of targets for such a huge network. When there is change in supply pattern to achieve the equitable supply of water to different zones, the hydraulics of the WDS will change. Therefore, it is necessary to understand whether the system is able to handle these changes. The concept of reliability can be used to analyse the performance of WDS for wide range of operating conditions. Reliability analysis of a WDS for both normal and likely to occur situations will give a better quality of service to its consumers. Calculating both hydraulic and mechanical reliability is important as the chances of occurrence of both the failure scenarios are equal in a WDS. In the present study, a methodology is presented to model the nodal, system and total reliability for water supply networks by considering the hydraulic and mechanical failure scenarios. These two reliability measures together give the total reliability of the system. Analysing a real and complex WDS for the probable chances of occurrence of the failure scenarios; and then to anlyse the total reliability of the system is not reported in the literature and this analysis is carried out in the present study for Bangalore city WDS. The hydraulics of the system for all the operating conditions is analysed using EPANET. Hydraulic reliability is calculated by varying the uncertain independent parameters (demand, roughness and source water) and mechanical reliability is calculated by assuming system component failures. The system is analysed for both the reliability scenarios by considering different chances of failure that may occur in a real WDS; and hence the total reliability is calculated by making different combinations of hydraulic and mechanical failure scenarios. Sensitivity analysis for all the zones is also carried out to understand the behavior of different demand points for large fluctuation in hydraulics of the system. From the study, it is observed that, Hydraulic reliability decreases as the demand variation increases. But, as the roughness variation increases, there is no much change in the nodal or system reliability. Consumer demand or reliability of the WDS can be increased by saving the water lost in the system. This can be achieved by tracking the water parcel from the source till the consumer end, which will give an idea about the performance of different stages and zones in achieving the target flows. Huge quantity of water is lost in WDS and hence it is necessary to account for the water lost at different levels, hence the system can be managed in a better way. In most of the intermittent water supply systems demand is controlled by supply side; there is also a need to understand the demand variation at the consumer end which in turn affects the supply. Matching this varied supply-demand gap at various levels is challenging task. To get a better control of such problem, water balance (WB) equations need to be derived at various levels. When we derive these WB equations it should be emphasized that UFW is one of the major component of this equation. Given this back ground of the complex problem, for a typical city like Bangalore, an attempt is made to derive WB equations at various levels. In the present study, stage-wise and zone-wise WB is analysed for different months based on the flow meter readings. The conceptual model developed is calibrated, validated and also the performance of the model is analysed by giving a chance of error in the flow measurement. Based on all the above observations, stage-wise and zone-wise water supply weights are also calculated. From the study it is found that, there is no much loss of water in all the four stages of supply. Water loss is minimal of about 3 % till water reaches from source to GLRs. Water is transferred between the stages during some days of the month, may be due to shortage of water or due to unexpected demand. Huge quantity of water is lost in the distribution main which is of about 40 to 45% for all the moths which is analysed. This type of model will be extremely useful for water supply managers to manage their resources more efficiently and this study is discussed in detail as a part of this thesis. As mentioned above, huge quantity of groundwater is used in urban cities and the quantity of water extracted is not accounted. In the present study, zone wise and sub zone-wise piped water and ground water used in different parts of the cities is analysed with the help of available data. From the study it is observed that, the quantity of piped water supply and UFW is consistent for the time period analysed and the quantity of water withdrawn from the borewells are varying considerably depending on the yield of the borewlls in different zones. The main components of urban water supply are piped water, ground water, rainfall and runoff generated, UFW, waste water produced and other water quantities which may be minute. In future, to manage the water resources properly, integrated water management is necessary in city scale which will give an idea about the total water produced and the water utilized at the consumer end. Therefore, integrated water management concept is carried out in Hebbal region, (a small part of Bangalore) using the available data. From the analysis we noticed that, domestic water supplied to North sub zones are better when comparing to East sub zones. This type of total water balance can be studied in other parts of Bangalore, to understand the behavior of different water components and to make better decisions. The developed model, analysis and operating conditions of this study can be applied to other similar cities like Bangalore. This type of study may be useful to water authorities for better control of the resources, or in making better decisions and these types of models will act as decision support systems.