Typescript (photocopy). / Digitized by Kansas Correctional Industries

Graduation date: 1992

Recent advances in satellite sensor technology and micrometeorological instrumentation for water flux measurement, coupled with the expansion of automatic weather station networks that provide routine measurements of near-surface climate variables, present new opportunities for combining satellite and ground-based instrumentation to obtain distributed estimates of vegetation water use over wide areas in South Africa. In this study, a novel approach is tested, which uses satellite leaf area index (LAI) data retrieved by the Moderate Resolution Imaging Spectroradiometer (MODIS) to inform the FAO-56 Penman-Monteith equation for calculating reference evaporation (ET₀) of vegetation phenological activity. The model (ETMODIS) was validated at four sites in three different ecosystems across the country, including semi-arid savanna near Skukuza, mixed community grassland at Bellevue, near Pietermaritzburg, and Groenkop, a mixed evergreen indigenous forest near George, to determine potential for application over wider areas of the South African land surface towards meeting water resource management objectives. At Skukuza, evaluated against 170 days of flux data measured at a permanent eddy covariance (EC) flux tower in 2007, the model (ETMODIS) predicted 194.8 mm evapotranspiration relative to 148.9 mm measured fluxes, an overestimate of 31.7 %, (r² = 0.67). At an adjacent site, evaluated against flux data measured on two discrete periods of seven and eight days in February and May of 2005 using a large aperture scintillometer (SLS), ETMODIS predicted 27.4 mm and 6.7 mm evapotranspiration respectively, relative to measured fluxes of 32.5 and 8.2 mm, underestimates of 15.7 % and 18.3 % in each case (r² = 0.67 and 0.34, respectively). At Bellevue, evaluated against 235 days of evapotranspiration data measured using a surface layer scintillometer (SLS) in 2003, ETMODIS predicted 266.9 mm evapotranspiration relative to 460.2 mm measured fluxes, an underestimate of 42 % (r² = 0.67). At Groenkop, evaluated against data measured using a SLS over three discrete periods of four, seven and seven days in February, June and September/October respectively, ETMODIS predicted 9.7 mm, 10.3 mm and 17.0 mm evapotranspiration, relative to measured fluxes of 10.9 mm, 14.6 mm and 23. 9 mm, underestimates of 22.4 %, 11.2 % and 24.1 % in each case (r² = 0.98, 0.43 and 0.80, respectively). Total measured evapotranspiration exceeded total modelled evapotranspiration in all cases, with the exception of the flux tower site at Skukuza, where evapotranspiration was overestimated by ETMODIS by 31.7 % relative to measured (EC) values for the 170 days in 2007 where corresponding modelled and measured data were available. The most significant differences in measured versus predicted data were recorded at the Skukuza flux tower site in 2007 (31.7 % overestimate), and the Bellevue SLS flux site in 2003 (42 % underestimate); coefficients of determination, a measure of the extent to which modelled data are able to explain observed data at validation periods, with just two exceptions, were within a range of 0.67 – 0.98. Several sources of error and uncertainty were identified, relating predominantly to uncertainties in measured flux data used to evaluate ETMODIS, uncertainties in MODIS LAI submitted to ETMODIS, and uncertainties in ETMODIS itself, including model assumptions, and specific uncertainties relating to various inputs; further application of the model is required to test these uncertainties however, and establish confidence limits in performance. Nevertheless, the results of this study suggest that the technique is generally able to produce estimates of vegetation water use to within reasonably close approximations of measurements acquired using micrometeorological instruments, with r² values within the range of other peer-reviewed satellite remote sensing-based approaches.

The change in total evaporation through alteration of vegetative cover is a major influence on catchment hydrology. The transformation of grassland and scrub habitats to commercial tree plantations, as well as the uncontrolled spread of invasive alien plants (lAPs) to ecologically sensitive systems, riparian zones in particular, are a threat to biodiversity and integrity of natural systems. Furthermore, critical low flow periods are of particular concern to water managers and local communities, as well as the associated impacts of potentially compromised water resources for rural livelihoods. The Working for Water (WfW) programme was implemented in 1995 by the Department of Water Affairs and Forestry and its main goals are to remove lAPs in order to improve water supply while at the same time providing employment to marginalised communities. In this study, the hydrological response to lAPs in the Upper Blyde River catchment is assessed. This is done by developing a classification structure for lAPs as a land use using detailed mapping available from WfW for use in a hydrological model, and then configuring and running the ACRU hydrological model for the Upper Blyde River catchment in Mpumalanga. In the classification, lAPs are represented as spatially explicit land use units in the ACRU model according to the type of habitat they invade, viz. riparian or non-riparian; as well as by type of plant, i.e. tree or shrub; and their area and density. The results obtained from simulating catchment hydrological responses using the ACRU model indicate that riparian lAPs have a great er impact on streamflow than do landscape invasions alone, specifically during periods of low flow. An increase in streamflow after removing lAPs from riparian and non-riparian habitats is a consistent outcome at both subcatchment and catchment scales. Using a spatially explicit method in order to model the hydrological response of different types of lAPs for different density classes in both riparian and non-riparian habitats is found to be a useful technique in determining the degree to which lAPs influence catchment streamflow. Recommendations for future research include focussing hydrological assessments of lAPs on critical flow periods and their impacts on water quality; investigation into the water use of invasive and indigenous vegetation for more accurate estimates from modelling exercises; and finally, applying the classification system for lAPs with other land use sensitive hydrological models for validation, and their wider application by incorporating methodologies into guidelines for use by WfW at national and provincial level. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

Soil water deficits greatly affect forage production. To evaluate the effects of soil moisture stress on forage production, a budgeting model was developed. The soil water budgeting model uses the initial soil water content which can be assumed or calculated. Stress was calculated as a difference between potential evapotranspiration and actual evapotranspiration at a level of - 5 bar. A radiation method was used to calculate the potential evapotranspiration and the soil water budgeting model was used to calculate the actual evapotranspiration. The Soil Conservation Service method was applied to calculate runoff and effective rainfall was calculated by subtraction of runoff from original rainfall and used in the model for calculation of actual evapotranspiration. Calculated stress was correlated to the yield and stepwise multiple regression were used to produce prediction equations. Observed soil water data and yield for calibration and validation of the models were obtained from Santa Rita Forest and Range Experimental Range in southeastern Arizona.

The eMpofana riparian rehabilitation project (eMRRP) is a pilot project started by Umgeni Water (UW) to demonstrate how effective the removal of invasive alien vegetation is in improving the water yield of a catchment. The disturbance of the country's vulnerable wetland and riparian zones is a major factor contributing to water· stress. The study area was eMpofana riparian areas of Kwazulu-Natal midlands. The study was conducted to establish perceptions of property owners and project employees on eMpofana riparian rehabilitation project with regard to control of invasive alien vegetation. Apart from· these two categories of stakeholders, others whose perceptions were included in the study are one official each from MONDI, SAPPI, the National Working for Water Programme (WFWP) and Kwazulu Natal Nature Conservation Services. However, property owners and project employees were· the main respondents of study. Although all .stakeholders play a crucial role in the project, property owners were selected because clearing takes place on their properties. Similarly project employees perceptions were vital as they are physically involved in clearing invader species and are direct beneficiaries of the project through job creation; To enable interviewees to give their perceptions on various steps on the project cycle; the following key issues were selected; Awareness, Process, Water, Biodiversity, . Tourism, Capacity building, Support, and Sustainability of control of alien invasive plants. Based on these key issues, a questionnaire was drawn. There were fifty-two respondents: 25 property owners and 27 project employees.. The approach used in the study was survey research, and social science methods were employed. Survey research was chosen for this research because of its capacity to provide appropriate data on perceptions of stakeholders of the eMpofana project. The method is useful in a variety of situations such as providing solution to a problem of public policy, provide required data for managing a business or simply for testing hypotheses developed by scientists in the social world. The questions on awareness of the eMpofana riparian rehabilitation project (eMRRP). and the National Working for Water Programme{WFWP) revealed low awareness levels of the two projects. Almost half (48%) property owners indicated little awareness of the national WFWP and almost the same percentage i.e. 42% had little awareness of the provincial WFWP. Also 96% of eMpofana project employees indicated no awareness of the WFW national level and 70% said they were not aware of the WFW provincial level. Given that WFW is a national programme with over 200 alien plant control progratmhes countrywide, one wonder why awareness was so low among the respondents. As for involvement in the project conceptualisation, none of the respondents interviewed indicated involvement in that project phase. However all the project employees indicated that the project was successful (85% very successful and 15% successful). Fifty six per cent property ~wners indicated very strong 'support mainlybecause ofreestablishment of biodiversity through ridding the riparian areas of iilvader species. Ninety-five per cent of the project workers indicated that UW solely supports the eMpofana project and that that support is mainly financial. As for job creation, 88% project workers were of the view that eMpofana riparian project was very successful in creating jobs. It is worth noting that both property owners and the employees shared the same view on water users and project employees being the main beneficiaries of the project. The impact of clearing invader species oil water by the eMRRP was rated as being very significant. Moreover, 52% employees and 44% property owners felt that the project's main beneficiaries were water users in the cities and property owners themselves. As for linkage with the National WFW programme, the perceptions of property owners and project employees revealed a general preference for eMpofana project to continue running independently. On. succesSes achieved in various project phases, most property owners felt the planning phase of the project was the most successful, even though most of them were not involved in the phase. Thirty per cent of the employees felt execution was successful followed by financing, 30%. As the responses from both property owners and employees show, most respondents (property owners and project employees) were of the view that the project goal of reinstating biological diversity was very important. The property owners were of the view that the re-establishment of the naturalness of the area would contribute favourably towards tourism in the area, which they rated very high. The rating explain why property owners also rated biodiversity conservation and the naturalness of the area equally high. On the other hand, Umgeni Water's top priority is water security and the differing priorities between UWs and eMRRP could be seen as a weakness of the project. However, as a holistic view of biodiversity conservation necessitates protection of water resource in the area, the difference could be synchronised to become a strength ofthe eMRRP (see recommendations). The eMRRP has opportunities on a number of areas such as the opportunity to participate in the national campain on control of invader species by teaming up with WFWP and other stakeholders. Also joinirig this partnership would accord eMRRP stakeholders the pride of contributing to the national campaign on control of invader species. Although there is marked success made by UW in planning, financial support, job creation, gender equity in the eMRRP, there is need to address sustainability of the project. In conclusion, it is clear that the eMRRP started off with most stakeholders having low awareness ofits activities and those ofWFW Programme. However, by clearing invasive alien plants in eMpofana riparian areas, the project has gained support from property owners and its employees. Property owners support the project mainly because of possible re-establishment of naturalness of the area (biological diversity) and the employees give their support mainly because of the employment that they receive. However, the goal of sustainability of the eMRRP is likely to remain elusive as long as priorities are not harmonised: property owners' priority (based on benefits drawn) is biodiversity conservation whereas that of UW is water security. / Thesis (M.Env.Dev.)-University of Natal, Pietermaritzburg, 2000.

Conserving the earth's precious water supply is of increasing importance in light of the growing population and climate dynamics; therefore, this study focuses on identifying those exotic species that are best suited for the changing climate and environment of the Lower Kanawha Valley Region in West Virginia without compromising the water sustainable qualities once exhibited by the indigenous species. This task was accomplished by reviewing, analyzing, and evaluating the plant hydraulics and habitat matching characteristics associated with the identified native and exotic species. These species were limited to those produced or found in the local nurseries and garden centers in the designated region, thereby providing a practical and water sustainable plant list for the local homeowners and design professionals. The final list of species was translated into a master planting design of an arboretum displaying and demonstrating water conservation on the grounds of the Hurricane Valley Park. / Department of Landscape Architecture

[Truncated abstract] Understanding the ecohydrological dynamics of native vegetation can provide a benchmark for future efforts to restore landscape hydrology and allow predictions of potential landscape responses to climate uncertainty and associated changes in vegetation cover. The key drivers of evapotranspiration (Et) involved in maintaining a hydrological balance that minimises deep drainage in semi-arid ecosystems operate at a range of scales, and in this thesis I assessed the water relations of functionally and taxonomically diverse plant communities in south-western Australia from the leaf-level to ecosystem scale. For three key communities; heath shrubland, mallee (small multistemmed eucalypt) -heath, and open eucalypt woodland, populating a typical catenary sequence of soil types along a slope, I addressed the following questions: 1) What are the predominant water use strategies of wheatbelt native plant communities and what underlying trade-offs determine the distribution of plant water use strategies along the topographical gradient? 2) What are the roles of soil water and hydraulic limitation in controlling the spatial and temporal dynamics of transpiration in different functional types? 3) What is the magnitude and partitioning of total Et in the woodland community and what processes determine Et fluxes on a seasonal and annual basis? 4) What are the seasonal differences in Et among contrasting community-types and how do these patterns relate to canopy attributes and transpiration capacity along the topographical gradient? A key philosophical step in working with species-rich communities was to develop the concept of 'hydraulic functional types' (HFTs) to identify groupings of species using associations of physiological and morphological traits that define their hydrological functioning. .... However, as shallow soils dried during spring and summer, Et fluxes were significantly lower at the heath site (0.35 versus 0.66 mm day-1 for the woodland in February), demonstrating that the seasonality of Et fluxes differentiates communityscale contributions to regional water balance. Land-surface exchange of water over native vegetation is by no means uniform, but varies according to the spatial and temporal availability of water along topographical gradients. In general, shallow soils present fewer opportunities for water use partitioning and favour drought hardiness and a transpiration response that tracks recent rainfall patterns, whereas deeper soils promote greater differentiation in water use strategy and support canopies responsive to atmospheric demand. This thesis provides a unique description of ecosystem water balance in a global biodiversity hotspot by viewing complex vegetation mosaics in terms of their relevant hydrological units. This information is fundamental to sustainable agroforestry and revegetation efforts and our ability to gauge possible changes in vegetation structure and function under a changing climate.

South Africa is classified as a semi-arid environment with limited natural water sources. Amenity landscapes provide broad ranging benefits for society. Amenity landscapes account for between 31% - 50% of water supplied for domestic and urban use. To reduce water use and water conservation in amenity landscapes, strategies, regulations and interventions are required. Every landscape is a unique complex system with a large number of variables that differ from each other. The variability can be summarized into management/design, irrigation, climatological, edaphic and plant related aspects. Several amenity landscape water use models have been developed around the world and two in South Africa. This study developed a comprehensive South African hydrozone based plant database and an Amenity Landscape Water Use Model South Africa (ALWUMSA). This will improve hydrozoning of amaneity landscapes and ultimately also improve water conserbvation for these sites. It allows users/owners to determine water use requirements through an extensive data gathering, from aspects such as design, management, microclimate, environmental, edaphic, irrigation and plant related factors. Comparisons of results from ALWUMSA to three test sites, selected existing models and a range of scenarios produced results demonstrating that ALWUMSA consistently projected lower water requirements. The model also allows for site aspects to be changed thus encouraging end users to implement specific water saving intiatives with the amenity landscape to reduce water use. These savings will be translated into both water-use savings as well as financial savings for users of the amenity landscape water use model. / Environmental Sciences / Ph. D. (Environmental Science)

Work presented in this dissertation was performed in the salt-desert environment of the Owens Valley of California. The area experiences low-rainfall, hot summers, but has a high water table, seldom more than 5 meters from the surface. To test differences in plant species wateruse, a steady-state porometer was used for transpiration measurements while a 2-meter point-frame was used to estimate leaf area index on each species studied. The five species studied (Atriplex torreyi, Chrysothamnus nauseosus, Distichlis stricta, Sporobolus airoides, and Sarcobatus vermiculatus) varied with regard to photosynthetic pathways and leaf morphology. Water-use differences among species are hypothesized to be related to the differing physiological and morphological characteristics observed in the different species studied. This work focuses upon methods for integrating porometric transpiration rates and point-frame measured leaf area to estimate daily plant water-use. Daily water-use values are correlated with environmental growth conditions. A computer program was developed for scenario testing so that conclusions could be drawn concerning how given plants respond to different conditions of soil moisture and atmospheric evaporative demand. The computer-aided calculations led to conclusions that low water-use behavior characterizes A. torreyi, and high water-use behavior characterizes C. nauseosus. C4 photosynthesis and low leaf conductance may contribute to the success of A. torreyi on fine-textured soils when water transfer rates to roots are limiting to transpiration. Fine-textured soils may inhibit production in C. nauseosus because the species requires higher rates of transpiration to achieve optimal growth than soil hydraulic conductivity allows. These conclusions have implications for land managers who should recognize that climax plant communities in saltdesert regions are better at conserving water and stabilizing soil than is colonizing vegetation. Management should seek to maintain climax vegetation cover because restoration is difficult once vegetation disturbance occurs.