<p> The objective of this research was to investigate the role of land cover changes through time in influencing spatial variability of the surface urban heat island of the metropolitan area of Reno-Sparks, Nevada. Free and widely available thermal data from Landsat 7 ETM+ (Enhanced Thematic Mapper Plus) sensor was gathered for a period between 2004 and 2017 and processed to at-satellite surface temperature. Using parcel data and the National Land Cover Database, the time series of Landsat data was sampled for areas which had undergone development during that time. This sample was cross-validated with ten iterations of equal sample size, with a mean correlation coefficient of 0.623 (standard deviation of 0.008) versus the model&rsquo;s value of 0.624. A set of generalized linear models was conducted on this sample to determine expected temperature change with land cover class. It was found that recently developed regions within Reno-Sparks are 0.6 &deg;C warmer on average than the undeveloped desert grasses and sage. When wetlands/irrigated greenery were converted to impervious surfaces, it resulted in a positive surface temperature change of over 2 &deg;C. Once developed, no significant difference was found in the surface temperature trends. This research, using remote sensing technologies, has shown that the Reno-Sparks surface urban heat island has undergone local, but measurable growth in the last fourteen years.</p><p>

Climate change is projected to increase the intensity and frequency of storm events that would increase flooding hazards. Urbanization associated with land use and land cover change has altered hydrological cycles by increasing stormwater runoff, reducing baseflow and increasing flooding hazards. Combined urbanization and climate change impacts on long-term riparian flooding during future growth are likely to affect more socially vulnerable populations. Growth strategies and green infrastructure are critical planning interventions for minimizing urbanization impacts and mitigating flooding hazards. Within the social-ecological systems planning framework, this empirical research evaluated the effects of planning interventions (infill development and stormwater detention) through a risk assessment in three studies. First, a climate sensitivity study using SWAT modeling was conducted for building a long-term flooding hazard index (HI) and determining climate change impact scenarios. A Social Vulnerability Index (SoVI) was constructed using socio-economic variables and statistical methods. Subsequently, the long-term climate change-induced flooding risk index (RI) was formulated by multiplying HI and SoVI. Second, growth strategies in four future growth scenarios developed through the BMA ULTRA-ex project were evaluated through land use change input in SWAT modeling and under climate change impact scenarios for the effects on the risk indices. Third, detention under climate sensitivity study using SWAT modeling was investigated in relation to long-term flooding hazard indices. The results illustrated that increasing temperature decreases HI while increasing precipitation change and land use change would increase HI. In addition, there is a relationship between climate change and growth scenarios which illustrates a potential threshold when the impacts from land use and land cover change diminished under the High impact climate change scenario. Moreover, spatial analysis revealed no correlation between HI and SoVI in their current conditions. Nevertheless, the Current Trends scenario has planned to allocate more people living in the long-term climate change-induced flooding risk hotspots. Finally, the results of using 3% of the watershed area currently available for detention in the model revealed that a projected range of 0 to 8% watershed area would be required to mitigate climate change-induced flooding hazards to the current climate conditions. This research has demonstrated the value of using empirical study on a local scale in order to understand the place-based and watershed-specific flooding risks under linked social-ecological dynamics. The outcomes of evaluating planning interventions are critical to inform policy-makers and practitioners for setting climate change parameters in seeking innovations in planning policy and practices through a transdisciplinary participatory planning process. Subsequently, communities are able to set priorities for allocating resources in order to enhance people's livelihoods and invest in green infrastructure for building communities toward resilience and sustainability.

The impact of anthropogenic activities on environment, especially the effect of land-use and climate changes was investigated in a series of studies. A comprehensive study of 16 research sites in different parts of Sweden was evaluated by using one dimensional hydrological model (CoupModel) to represent water and heat dynamics in layered soil profile covered with vegetation. Simulations are based on daily values and the results are representatives of variations in daily values and changes over years. The models accuracies controlled by measured run-off and snow depth values. However, there are uncertainties in both input data and simulated parameters. The interaction between run-off and snow depth were obtained when the models constrained by both run-off and snow depth. Parameters values variations and models performances changes in different time domains indicate the changes in land-use and climate over time and the model ability to handle these changes respectively. The strong interaction between meteorological stations density and models performances were indicated by comparing results with interpolation radius used for input data preparation.

Climate change and land use transition are the main drivers of watershed hydrological processes. The main objective of this study was to assess the hydrometeorological responses to climate and land use changes in the Jhelum River Basin (JRB), Pakistan. The development of proper climate information is a challenging task. To date, Global Climate Models (GCMs) are used for climate projections. However, these models have a coarse spatial resolution, which is not suitable for regional/local impact studies such as water resources management in the JRB. Therefore, different downscaling methods and techniques have been developed as means of bridging the gap between the coarse resolution global models projection and the spatial resolution required for hydrological impact studies. Statistical Downscaling Model (SDSM) and Long Ashton Research Station Weather Generator (LARS-WG) are selected in this study for downscaling of temperature and precipitation. Both downscaling approaches consider three climate models and two emission scenarios (i.e., RCP4.5 and RCP8.5) in order to sample the widest range of uncertainties in climate projections. Current land use and land cover (LULC) maps are generated from Landsat imagery to analyze the pattern and dynamic of land use change. Both climate projections and LULC are fed into SWAT (Soil and Water Assessment Tool) hydrological model to investigate the streamflow dynamics. The results indicate good applicability of SDSM and LARS-WG for downscaling of temperature and precipitation in three future periods (2020s, 2050s and 2080s). Both models show an increase mean annual max temperature, min temperature and precipitation as 0.4-4.2°C, 0.3-4.2°C and 4.4-32.2% under both RCPs scenarios. Similarly, results of SWAT model suggest an increase in mean annual discharge about 3.6 to 28.8% under RCP4.5 and RCP8.5. The study also revealed that water yield and evapotranspiration in the eastern part of the basin (sub-basins at high elevation) would be most affected by climate change. The results of LULC change detection show that forest exhibited maximum positive change while agriculture showed maximum negative change during 2001-2018. SWAT model simulations suggested that implementation of afforestation in the watershed would reduce surface runoff and water yield while enhancing the evapotranspiration. It is recommended that authorities should pay attention to both climate change and land use transition for proper water resources management.

Thesis (Ph.D. (Plant Production)) -- University of Limpopo, 2022 / Changes in climate and land-use, collectively called environmental changes, have been a source of concern globally, particularly in dryland grasslands, where people still heavily rely on services from these ecosystems. Extreme climatic conditions have been projected to increase both in intensity and frequency globally. In semi-arid regions, drought is anticipated to occur more frequently and to last longer as a consequence of climate change. Moreover, as human populations continue to grow, there is an increase in demand for natural resources that are already diminishing. Consequently, the combination of these factors has a negative effect on the functions and services of the dryland grassland ecosystems. Therefore, to counteract the degradation of these socioeconomically significant ecosystems, it is vital to understand how these systems respond to the long-term effects of drought and grazing. Limpopo province is largely dominated by drylands; comprising arid, semi-arid and dry sub-humid ecosystems. In Limpopo province, rangelands and agroforestry systems deliver important ecosystem services. Arable lands, rangeland, agroforestry, and orchards are three major land-use types contributing greatly to local livelihoods within Limpopo’s multi-use landscapes. Motivated by the above mentioned factors this study had the following objectives; (i) to review the impact of climate change on dryland grasslands, (ii) to evaluate ecosystem functioning through the assessment of climate related effects on taxonomic diversity and density demography from the grass layer, (iii) to analyse the effects of drought and grazing on the grass layer and to understand the factors affecting tree populations, particularly tree establishment patterns, (iv) to measure ecosystem service provision from the savanna ecosystem and also, to bridge the knowledge gap on the importance of biodiversity in an ecosystem. To achieve the aforementioned objectives, a comprehensive literature analysis was conducted on the effects of climate change on dryland grasslands to assess the magnitude of this impact and the existing understanding of vegetation dynamics in the face of climate change. The study also took advantage of the large-scale field experiment which evaluated, through precipitation manipulation, the impact of drought on grazed and ungrazed vegetation in the dryland grasslands of Limpopo province, South Africa, labeled drought Act experiment. In the Drought Act experiment, passive rain-out shelters and grazing ex-closure fences were set up to simulate a severe drought in combination with differing resting schemes of the rangeland. This was done in order to assess the effect of previous drought events on herbaceous vegetation. Grazing and drought treatments were implemented across four treatment plots per block, via a full factorial design. The study also took advantage of the steep gradient of climatic aridity in Limpopo province and used a space-for-time substitution to evaluate the effects of climate-induced risks and factors impacting the establishment of encroaching woody species under conditions of climate change. Two climate zones and soil types were selected; semi-arid vs. dry sub-humid zone, and Glenrosa soil vs. Hutton soil. Data analysis was executed using the R statistical software package. The examination of literature revealed that African dryland ecosystems are especially vulnerable to the effects of climate change, resulting in biodiversity loss, structural and functional changes to the ecosystem, and a diminished capacity to deliver ecosystem services. Climate change’s most susceptible species and functions have a great potential to be utilized as early warning signs. Furthermore, precipitation manipulation experiments are a great tool for investigating the impact of climate change as they allow for precipitation reduction below the natural range. There is still a general lack of information regarding the effects that extreme climatic conditions have on ecosystems and the mechanisms that determine how ecosystems respond and recover from stress and disturbances. The Drought Act experiment showed that prolonged drought had a substantial and negative impact on the biomass output of the vast majority of taxonomic groups and plant functional types (PFTs). This reduction in biomass production from the grass layer results in limited grazing for livestock, which is a primary ecosystem service provided by dryland grasslands. However, the study revealed that few species and PFTs were resistant to the effects of prolonged drought and grazing. In general, the study showed that long-term drought and grazing winners were primarily forbs and narrow-leaved perennial grasses with low leaf area (LA) and high leaf dry matter content (LDMC). Furthermore, the negative impact of drought on the taxonomic richness and species per unit area and ultimately diversity, worsened as the drought period increased. Additionally, grazing exclusion (resting) was shown to have a negative influence on species richness, abundance, and diversity, especially over long periods of time. Bottom-up mechanisms such as soil type had a greater impact on the establishment, recruitment, and survival of invading woody species than top-down mechanisms such as precipitation. In addition, the significant correlation that was established in the study between the age of trees and the circumferences of their stems, measured at breast height, provided evidence that non-destructive methods of estimating the age of trees are feasible. Further development of non-invasive approaches in the field of dendrochronology is also made possible by these findings. The findings of this thesis indicate, on the whole, that; to gain a better understanding of dryland vegetation dynamics in the face of drought, researchers need to investigate further the impact of climatic extremes on ecosystem functions and services. Moreover, winners and losers of long-term drought can be distinguished by their unique characteristics; hence, taxonomic groups and functional characteristics could be utilized as early markers of veld degradation, which would permit timely management interventions. The negative impact of long-term drought and grazing on the grass layer limits the ecosystem’s capacity to carry livestock and wildlife for extended periods, thus impacting the livelihoods of the people who rely on these ecosystems. In addition, the tendency of higher tree establishment in lower rainfall years suggests that drought could be a driving factor for woody vegetation propagation. The trait-based approach is very instructive when it comes to researching the dynamics of vegetation in dryland grasslands. This is especially true when considering the effects of changing climate and land-use. This study has contributed to a better knowledge of the ecosystem function under changing climate and land-use, which is the basis of enhancing the resilience of different land-use systems and reducing risks to ecosystem functions and services while optimizing production. / NRF, DAAD, UL, SALL net, Universitat Potsdam

Study region Nyangores River watershed, headwater catchment of Mara River basin in Kenya. Study focus Climate variability and human activities are the main drivers of change of watershed hydrology. The contribution of climate variability and land use change to change in streamflow of Nyangores River, was investigated. Mann Kendall and sequential Mann Kendall tests were used to investigate the presence and breakpoint of a trend in discharge data (1965–2007) respectively. The Budyko framework was used to separate the respective contribution of drivers to change in discharge. Future response of the watershed to climate change was predicted using the runoff sensitivity equation developed. New hydrological insights for the region There was a significant increasing trend in the discharge with a breakpoint in 1977. Land use change was found to be the main driver of change in discharge accounting for 97.5% of the change. Climate variability only caused a net increase of the remaining 2.5% of the change; which was caused by counter impacts on discharge of increase in rainfall (increased discharge by 24%) and increase in potential evapotranspiration (decreased discharge by 21.5%). Climate change was predicted to cause a moderate 16% and 15% increase in streamflow in the next 20 and 50 years respectively. Change in discharge was specifically attributed to deforestation at the headwaters of the watershed.

The irrigated agriculture in the Lower Chenab Canal (LCC) of Pakistan is characterized by huge water utilization both from surface and groundwater resources. Need of utilization of water from five rivers in Punjab province along with accelerated population growth has forced the construction of world’s largest irrigation network. Nevertheless, huge irrigation infrastructure, together with inappropriate drainage infrastructure, led to a build-up of shal-low groundwater levels, followed by waterlogging and secondary salinization in the soil profile. Following this era, decreased efficiency of irrigation supply system along with higher food demands had increased burdens on groundwater use, which led to a drop in groundwater levels in major parts of LCC. Previous studies in the study region revealed lacking management and maintenance of irrigation system, inflexible irrigation strategies, poor linkages between field level water supply and demands. No future strategy is present or under consideration to deal with this long time emerged groundwater situation particularly under unchanged irrigation water supply and climate change. Therefore, there is an utmost importance to assess the current profile of water use in the irrigation scheme and to device some workable strategies under future situations of land use and climate change. This study aims to investigate the spatio-temporal status of water utilization and performance of irrigation system using remote sensing data and techniques (SEBAL) in combination with other point data. Different irrigation performance indicators including equity, adequacy and reliability using evaporation fraction as main input parameter are utilized. Current profiles of land use/land cover (LULC) areas are assessed and their change detections are worked out to establish realistic future scenarios. Spatially distributed seasonal net recharge, a very important input parameter for groundwater modeling, is estimated by employing water balance approaches using spatial data from remote sensing and local norms. Such recharge results are also compared with a water table fluctuation approach. Following recharge estimation, a regional 3-D groundwater flow model using FEFLOW was set up. This model was calibrated by different approaches ranging from manual to automated pilot point (PP) approach. Sensitivity analysis was performed to see the model response against different model input parameters and to identify model regions which demand further improvements. Future climate parameters were downscaled to establish scenarios by using statistical downscaling under IPCC future emission scenarios. Modified recharge raster maps were prepared under both LULC and climate change scenarios and were fed to the groundwater model to investigate groundwater dynamics. Seasonal consumptive water use analysis revealed almost double use for kharif as compared to rabi cropping seasons with decrease from upper LCC to lower regions. Intra irrigation subdivision analysis of equity, an important irrigation performance indicator, shows less differences in water consumption in LCC. However, the other indicators (adequacy and reliability) indicate that the irrigation system is neither adequate nor reliable. Adequacy is found more pronounced during kharif as compared to rabi seasons with aver-age evaporation fraction of 0.60 and 0.67, respectively. Similarly, reliability is relatively higher in upper LCC regions as compared to lower regions. LULC classification shows that wheat and rice are major crops with least volatility in cultivation from season to season. The results of change detection show that cotton exhibited maximum positive change while kharif fodder showed maximum negative change during 2005-2012. Transformation of cotton area to rice cultivation is less conspicuous. The water consumption in upper LCC regions with similar crops is relatively higher as compared to lower regions. Groundwater recharge results revealed that, during the kharif cropping seasons, rainfall is the main source of recharge followed by field percolation losses, while for rabi cropping seasons, canal seepage remains the major source. Seasonal net groundwater recharge is mainly positive during all kharif seasons with a gradual increase in groundwater level in major parts of LCC. Model optimization indicates that PP is more flexible and robust as compared to manual and zone based approaches. Different statistical indicators show that this method yields reliable calibration and validation as values of Nash Sutcliffe Efficiency are 0.976 and 0.969, % BIAS are 0.026 and -0.205 and root mean square errors are 1.23 m and 1.31 m, respectively. Results of model output sensitivity suggest that hydraulic conductivity is a more influential parameter in the study area than drain/fillable porosity. Model simulation results under different scenarios show that rice cultivation has the highest impact on groundwater levels in upper LCC regions whereas major negative changes are observed for lower parts under decreased kharif fodder area in place of rice, cotton and sugarcane. Fluctuations in groundwater level among different proposed LULC scenarios are within ±1 m, thus showing a limited potential for groundwater management. For future climate scenarios, a rise in groundwater level is observed for 2011 to 2025 under H3A2 emission regime. Nevertheless, a drop in groundwater level is expected due to increased crop consumptive water use and decreased precipitations under H3A2 scenario for the periods 2026-2035 and 2036-2045. Although no imminent threat of groundwater shortage is anticipated, there is an opportunity for developing groundwater resources in the lower model regions through water re-allocation that would be helpful in dealing water shortages. The groundwater situation under H3B2 emission regime is relatively complex due to very low expectation of rise in groundwater level through precipitation during 2011-2025. Any positive change in groundwater under such scenarios is mainly associated with changes in crop consumptive water uses. Consequently, water management under such situation requires revisiting of current cropping patterns as well as augmenting water supply through additional surface water resources.:ABSTRACT VIII ZUSAMMENFASSUNG X ACRONYMS 1 Chapter 1 3 GENERAL INTRODUCTION 3 1 Groundwater for irrigated agriculture 3 2 Groundwater development in Pakistan 4 3 Study area 6 4 History of groundwater use in the study area 7 5 Research agenda 8 5.1 Problem statement 8 5.2 Objectives and scope of the study 9 Chapter 2 12 OVERVIEW OF PUBLICATIONS 12 Chapter 3 16 GENERAL CONCLUSIONS AND POLICY RECOMMENDATIONS 16 REFERENCES 20 ANNEXES 23 ACKNOWLEDGEMENTS 123